Entire_Biology_Review_Kapoor.pdf BISC 1111
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General Biology Review Guide Created by Elina Kapoor DO NOT COPY ONLY USED FOR STUDY PURPOSES Biochemistry Water has high speci c heat has a high heat of vaporization is the universal solvent exhibits strong cohesion tension and ice oats because it is less dense than water Bicarbonate ion is the most famous buffer substance that resists changes in pH Structural isomers differ in the arrangement of their atoms cistrans isomers differ only in spatial arrangement around double bonds enantiomers are molecules that are mirror images of each other Structural polysaccharides cellulose makes up plant cell walls plants chitin makes up exoskeletons of arthropods animal Storage polysaccharides starch amylose and amylopectin plants glycogen stored in liver and skeletal muscles of humans A fatty acid is a hydrocarbon chain w a CARBOXYL group at one end saturated unsaturated Lipid functions energy storage major components of cell membranes endocrinehormone Phospholipids hydrophilic headfatty acid tails Proteins growth and repair signaling from one cell to another hormones such as insulin lower blood sugar catalyze reactions allow for movement Amino acids carboxyl group and amine group and R groups Primary structure unique linear sequence of amino acids slight change big consequence secondary structure results from hydrogen bonding within the polypeptide molecule alpha heliXbeta pleated sheet tertiary structure intricate threedimensional shape of the protein determines the speci city of a protein includes hydrogen bonding ionic bonding hydrophobic interactions van der Waals disulfide bonds quaternary structure proteins that consist of more than one polypeptide chain pH salt concentration and temperature affect the folding of a protein denaturation Nucleotide consists of pentose sugar nitrogen base ACGTU and phosphate First law of thermodynamics energy cannot be created or destroyed only transformed from one form to another second law during energy conversions the universe is more disordered Exergonic reactions power endergonic ones coupling anabolism building up molecules catabolism breaking down molecules Induced t model NOT lock and key as the substrate enters the active site it induces the enzyme to alter its shape so it ts better Enzymes often require the assistance from cofactors inorganic or coenzymes vitamins Competitive inhibition compounds resemble molecules and reduce the chance of substrate binding to enzyme CAN be overcome by increasing substrate Noncompetitive bind to a different site and change the shape of active site CANNOT overcome The cell Theory of endosymbiosis eukaryotic cells emerged when mitochondria and chloroplasts once free living prokaryotic cells took up permanent residence in larger cells All cells contain plasma membrane cytosol ribosomes and DNA prokaryotes no nuclei or internal membranes have nucleoid nonmembrane bound no ER nuclear membrane mitochondria vacuoles or other organelles naked DNA ribosomes are small metabolism is anaerobic or aerobic no cytoskeleton unicellular eukaryotes contain organelles DNA wrapped around histone proteins into chromosomes ribosomes are larger metabolism is aerobic cytoskeleton is present mainly multicellular with differentiation of cell types ribosomes protein factories free ribosomes are associated w protein production for cell s own use attached ribosomes are for export out of the cell peroxisomes contain catalase which converts hydrogen peroxide into water and oxygen also detoxif1es alcohol nucleus contains chromatin network nuclear envelope and pores ER rough ER is studded w ribosomes and produces proteins smooth ER assists in the synthesis of hormones stores calcium ions in muscle cells detoxif1es drugspoisons Golgi process package secrete proteins Lysosomes hydrolytic enzymes that are the principal site of intracellular digestion autophagy and apoptosis Mitochondria contain cristae their own DNA and are the site of cellular respiration double membrane Vacuoles membranebound structures used for storage derived from ERGA Chloroplast contain chlorophyll that absorbs light and synthesizes sugar inner membrane system called thylakoids own DNA double membrane Cytoskeleton maintains cell shape controls positions of organelles by anchoring cytoplasmic streaming anchors the cell in place Microtubules hollow tubes made up of tubulin that make up cilia agella spindle fibers that help separate chromosomes during mitosis and meiosis Microfilaments from actin filaments allow animal cells to form cleavage furrow during cell division streaming contracting of muscles Plasma membrane selectively permeable uid mosaic phospholipid bilayer amphipathic contain integral proteins nonpolar regions that span the hydrophobic interior of the membrane Peripheral proteins loosely bound to surface of membrane Cholesterol molecules stabilize the membrane imbedded in the layer Functions of proteins in the plasma membrane transport enzymatic activity signal transduction celltocell recognition attachment to cytoskeletonmatrix Passive transport diffusion simple doesn t involve protein channels nephronscountercurrent exchange facilitated requires hydrophilic protein channel and osmosis Solvent substance that does the dissolving solute substance that dissolves hypotonic having lesser concentration of solute than another solution hypertonic having greater concentration of solute than other solutions Osmotic potential the tendency of water to move across a permeable membrane into a solution Water potential pure water zero the addition of solute lowers water potential to a value less than zero water moves across a membrane from the solution w higher water potential to solution w lower water potential Active transport sodium potassium pump pumps 2 K ions for every 3 Na ions electron transport chain contractile vacuole Receptor mediated endocytosis allows a cell to take up large quantities of specific substances ligands attach to receptors and become coated cells Tight junctions belts around epithelial cells that serve as a barrier to prevent leakage into or out of the organs urinary bladder Desmosomes rivet cells together light spot welds gap junctions permit the passage of materials from the cytoplasm of one cell to the cytoplasm of another cell heart like plasmodesmata Autocrine signals diffuse from one part of a cell to another part of the same cell synaptic signaling neurotransmitter is the signaling molecule endocrine signals travel anywhere in the blood to reach target cells Cascade effect amplifies the signal and provides multiple opportunities for coordination and regulation STP evolved hundreds and millions of years ago in a common ancestor Cellular respiration Two types of cellular respiration anaerobic and aerobic Oxygen is not present anaerobic respiration then glycolysis is followed by either alcoholic fermentation or lactic acid fermentation If oxygen is present glycolysis is followed by the Krebs cycle ETC and oxidative phosphorylation Glycolysis breaks down one molecule of glucose into 2 threecarbon molecules of pyruvate and releases four molecules of ATP net gain of 2 wout oxygen ATP is produced by substrate level phosphorylation direct transfer of a phosphate to ADP Facultative anaerobes can tolerate the presence of oxygen but don t use it obligate anaerobes cannot live in an environment containing oxygen Fermentation can generate ATP AS LONG AS there is an adequate supply of NAD to accept electrons during glycolysis NOTE fermentation consists of glycolysis AND the reactions that regenerate NAD Alcohol fermentation cells convert pyruvate from glycolysis into ethyl alcohol and carbon dioxide in the absence of oxygen and also oxidize NADH to NAD Lactic acid fermentation pyruvate from glycolysis into lactate and also oxidize NADH to NAD Citric acid cycle 1 acetyl coA combines with oxaloacetic acid to produce citric acid 2 each molecule of glucose is broken down to 2 molecules of pyruvate during glycolysis so each molecule of glucose results in 2 turns 3 pyruvate must combine w coenzyme A to form acetyl coA which enters the Krebs cycle produces 2 NADH 4 each turn of the Krebs cycle releases 3 NADH 1 ATP 1 FADH and CO2 5 during the Krebs cycle ATP is produced by substratelevel phosphorylation Krebs cycle takes place in the matrix ETC takes place in the cristae membrane NAD is the oxidized form NADH is the reduced form ETC 1 a collection of molecules embedded in the cristae membrane of the mitochondria 2 thousands of copies due to the extensive folding ETC carries electrons deliver by NAD and FAD from glycolysisKrebs cycle to oxygen the final electron acceptor through a series of redox reactions Reduction one atom gains electrons or protons oxidation one atom loses electrons 3 highly EN oxygen pulls oxygen through the ETC 4 NADH delivers electrons to higher energy level in the chain than FADH2 Oxidative phosphorylation 1 it is powered by the redox reactions of the ETC 2 proteins are pumped from the matrix to the outer compartment by the ETC 3 a proton gradient is created bt the outer compartment and the inner matrix 4 protons cannot diffuse across the cristae can only go through ATP synthase chemiosmosis as protons ow through these channels they generate energy to phosphorylate ADP to ATP Oxygen is the final hydrogen acceptor forming water SEQUENCE glucose 9 NAD and FAD 9 ETC 9chemiosmosis 9ATP Cell Division Functions in growth repair and reproduction Mitosis produces two genetically identical daughter cells and is diploid meiosis results in cells that are haploid A replicated chromosome consists of two sister chromatids copies of each other centromere is the region that holds the two chromatids together kinetochore is the disc shaped protein that attaches the chromatid to the spindle Two factors limit cell size and promote cell division the ratio of the volume of a cell to the SA and the capacity of the nucleus to control the entire cell Cell cycle phases G1 intense growth S replication of DNA G2 cell continues to grow an prepares for cell division interphase mitosis cytokinesis Mitosis Prophase nuclear membrane disintegrates strands of chromosomes condense nucleolus disappears mitotic spindle begins to form Metaphase chromosomes line up along the equator centrosomes are positioned at the opposite poles of the cells spindle bers run from centrosomes to kinetochores in the centromeres Anaphase centromeres of each chromosome separate as spindle bers pull apart sister chromosomes Telophase chromosomes cluster at opposite ends of the cell and nuclear membrane forms Cytokinesis cleavage furrow w actin and myosin for animal cells cell plate w sticky middle lamella for plant cells Density dependent inhibition cells grow and divide until they become too crowded anchorage dependence to divide a cell must be attached to a surface cancer cells show neither Meiosis I reduction division process by which homologous chromosomes separate meiosis II sister chromatids separate into different cells Meiosis I Prophase I synapsis the pairing of homologues crossing over the exchange of homologous bits of chromosomes chiasmata visible manifestations of crossing over Metaphase I homologs pairs of chromosomes are lined up DOUBLE file along the metaphase plate spindle fibers are attached to centromeres Anaphase 1 separation of homologues chromosomes as they are pulled by spindle fibers Telophase I homologous pairs continue to separate until they reach the poles of the cell Cytokinesis I same time as telophase I Meiosis II same steps as mitosis The types of genetic variation result from meiosis and fertilization independent assortment of chromosomes crossing over and random fertilization Cell cycle control system checkpoints at Gl restriction point if it receives the go ahead the cell will complete cell division otherwise it enters G zero phase G2 M Protein kinases signal transduction catalyze the phosphorylation of target proteins that regulate the cell cycle CDKs are activated by binding to cyclic which activates the molecule The activity of a CDK rises and falls with the concentration of its cyclin partner Peaks in MPF activity correspond to rises in cyclin Cyclin rises during S and G2 and falls during the M phase MPF triggers cell s passage from G2 into M Purpose of apoptosis no longer needed cells too much genetic damage and may lead to cancer defense against infection for plant cells excessive protein misfolding conserved evolutionary mechanism Heredity Multiplication rule to nd the probability to two independent events happening addition rule when more than one arrangement of events producing the speci ed outcome is possible Law of dominance when two organisms homozygous for two opposing traits are crossed the offspring that are hybrid exhibit only the dominant trait and the hidden trait is recessive Law of segregation during the formation of gametes the two traits carried by each parent separate Tt T and t Law of independent assortment a cross a carried out bt two individuals hybrid for two or more traits that are not on the same chromosome during gamete formation the allele of a gene for one trait such as height Tt segregates independently from the alleles for another trait seed color Yy Incomplete dominance blending codominance blood types both traits show Multiple alleles when there are more than two allelic forms of a gene Pleiotropy the ability of one single gene to affect an organism in several or many ways Epistasis two separate genes control one trait but one gene masks the expression of the other gene 9324 Polygenic blending of several genes that vary along a continuum height skin color etc Penentrance the proportion of individuals in a group with a given genotype actually show the expected phenotype Linked genes genes on the same chromosomes that are inherited together and don t assort independently Of 46 human chromosomes 44 are autosomes and 2 are sex chromosomes Traits on the X chromosome are sex linked If a sex linked trait is due to a recessive mutation a female will express the phenotype only if she carries two mutated genes if she carries only one mutated X linked gene she will be a carrier If a sex linked trait is due to a dominant mutation a female will express the phenotype with only one mutated gene If a male inherits a mutated X linked gene he will express the gene Recessive sexlinked traits include color blindness hemophilia muscular dystrophy All daughters of affected fathers are carriers Sons cannot inherit a sex linked trait from the father because the son inherits the Y chromosome from the father A son has a 50 chance of inherited a sex linked trait from a carrier mother There is no carrier state for males it is uncommon for a female to have a recessive sex linked condition One map unit on a chromosome is the distance within which recombination occurs 1 percent of the time Determining recombination frequencies number of recombinants total offspring x 100 Autosomal recessive PKU cystic fibrosis Taysachs sickecell Autosomal dominant Huntington s Sexlinked recessive hemophilia color blindness muscular dystrophy Down syndrome 47 chromosomes due to trisomy 21 tumer s syndrome XO Klinefelter s syndrome XXY Deletion fragment is lost during cell division inversion reattaches in reverse orientation translocation chromosome fragment becomes attached to a non homologous chromosome Genomic imprinting variation in phenotype depending on whether a trait is inherited from mom or dad Molecular Basis of Inheritance Griffith discovered that bacteria have the ability to transform harmless cells into virulent ones by transferring some genetic factor from one bacteria cell to another bacterial transformation Avery provided direct experimental evidence that DNA not protein was the genetic material Hershey and Chance proved that DNA from the viral nucleus not protein from the viral coat was infecting bacteria Watson and Crick proposed the double helix structure of DNA Meselson and Stahl proved that DNA replicates in a semiconservative fashion DNA replication steps l Helicase unwinds our double helix into two strands 2 Polymerase adds nucleotides to an existing strand 3 Ligase brings together the Okazaki fragments 5 Topoisomerase cuts and rejoins the helix 6 RNA primase catalyzes the synthesis of RNA primers DNA AAA TAA CCG GAC mRNA UUU AUU GGC CUG tRNA AAA UAA CCG GAC STEPS of transcription NO Helicase NO RNA primaseRNA primers Three stages of transcription are initiation elongation and termination NUCLEUS Initiation Transcription factors attach to the promoter Then RNA polymerase II binds to the promoter TATA box and pries the two strands of DNA apart Note the whole complex of RNA polymerase II and transcription factors bound to the promoter transcription initiation complex Elongation RNA polymerase II moves down links together RNA nucleotides complementary to a DNA template strand in a 593 direction DNA retwists into double helix Termination The RNA transcript premRNA not nished yet is released when it nears the polyadenylation signal AAUAAA RNA polymerase II detaches from the DNA RNA processing INCLUDES RNA splicing The 5 end of the premRNA receives a 5 cap a modi ed guanine basically guanine with three phosphates The 3 end receives 50 250 adenine nucleotides polyA tail The premRNA contains BOTH introns intervening sequences and exons expressed sequences snRNPs small nuclear ribonucleoproteins catalyze splicing and recognize splice sites join with other proteins to form a spliceosome SPLICES the intron and LINKS the exons the intron degrades premRNA becomes mRNA which only contains exons STEPS of translation Translation has three stages initiation elongation both of which require GTP termination Initiation a small ribosomal subunit binds to a molecule of mRNA in a bacteria the mRNA binding site on this subunit recognizes a speci c nucleotide sequence on the mRNA The initiator tRNA anticodon UAC basepairs with the start codon AUG thus tRNA carries the amino acid methionine The arrival of the large ribosomal subunit completes the initiation complex Proteins called initiation factors are required to bring all translation components together Hydrolysis of GTP provides the energy for the assembly The initiator tRNA is in the P site the A site is available to the tRNA bearing the next amino acid Elongation Codon recognition the anticodon of an incoming aminoacyl tRNA basepairs w the complementary mRNA codon in the A site hydrolysis of GTP increases efficiency many different aminoacyl tRNAs are present but only the one w the proper anticodon will bindallow the process to continue Peptide bond formation an rRNA molecule of the large ribosomal subunit catalyzes the formation of peptide bond bt amino group of new amino acid A site and carboxyl end of growing polypeptide P site Polypeptide removed from tRNA P site and attaches it to amino acid on the tRNA in the A site Translocation the ribosome translocates the tRNA in the A site to the P site At the same time the empty tRNA in the P site is moved to the E site where it is released the mRNA moves along w its tRNAs bringing the next codon Termination when a ribosome reaches a stop codon on mRNA UAG UAA or UGA the A site of the ribosome accepts a release factor a protein shaped like a tRNA instead of an aminoacyl tRNA The release factor promotes hydrolysis of the bond bt tRNA in the P site and last amino acid of the polypeptide thus freeing the polypeptide from the ribosome The two ribosomal subunits and the other components dissociate Bacteriophage Lytic cycle a type of phage replicative cycle resulting in the release of new phages by lysis and death of the host cell Lysogenic cycle a type of phage replicative cycle in which viral genome becomes incorporated into the bacterial host chromosome as a prophage is replicated along with the chromosome and does not kill the host Retroviruses viruses that contain RNA instead of DNA and replicate in an unusual way reverse the usual ow of information from DNA to RNA Although bacteria can reproduce through a primitive method called conjugation the main mode of reproduction is binary f1ssion F plasmid contain genes for the production of pili that lead to conjugation R plasmid leads to resistance of speci c antibiotics Operon a set of genes and switches that controls the expression of those genes inducible lac operon and repressible tryptophan operon Tryptophan Operon consists of promoter and 5 adjacent structural genes that code for separate enzymes that are necessary to synthesis tryptophan Without RNA polymerase attached to DNA at the promoter transcription ceases tryptophan operon is known as a repressible operon meaning it is always on unless the repressor is activated Three enzymes must be synthesized to break down lactose into glucose and galactose coded for by the lac operon so that Ecoli can use lactose as an energy source To transcribe these genes a repressor must be prevented from binding to the operator and RNA polymerase must bind to the promoter Allolactose is the inducer that facilitates this process by binding to the active repressor and inactivating it REMEMBER tryptophan absent repressor inactive operon on tryptophan produced Tryptophan present repressor active operon off Lactose present repressor inactive operon on Lactose absent repressor active operon off VOCAB RNA polymerase enzyme that transcribes new RNA chain Operator sequence of nucleotides near the start of an operon to which the active repressor can attach which prevents RNA polymerase from attaching to the promoter and transcribing the operon s genes Promoter nucleotide sequence of DNA that is the binding site of RNA polymerase Repressor protein that inhibits gene transcription binds to the operator Regulator gene gene that codes for a repressor located some distance from operon and has its own promoter Prions misfolded versions of protein normally found in the brain PCR a automated technique by which DNA can be rapidly copied or ampli ed cDNA Dna produced by retroviruses CHARRRRRRRRRRRRT Domain Bacteria prokaryotes decomposers pathogens diseasecausers carry out conjugation have cell walls with peptidoglycan some carry out photosynthesis no introns viruses are placed here Domain archea unicellular prokaryotic include extremophiles methanogens obtain energy in a unique way by producing methane from hydrogen halophiles thrive in environments w high salt concentration thermophiles introns in some genes no peptidoglycan Domain Eukarya includes Protista fungi plants animals contain organelles and nucleus no pep Complex animals are triploblastic contain ectoderm outermost layer skin nervous system endoderm innermost layer guts mesoderm middle layer bloodbones In bilateral symmetry the body is organized along a longitudinal axis Sensory apparatus and a brain are clustered at the anterior while digestive and excretory are located in the posterior the coelom is a uidfilled body cavity that arises from within the mesoderm no coelom acoelomates pseudo coelomates have a uidfilled tube between the endoderm and the mesoderm sponges have no symmetry do not move consists of ectoderm and endoderm connected by mesoglea have no true tissues or organs reproduce asexually by fragmentation as well as sexually hermaphrodites hydra and jelly sh invertebrate radial symmetry upside down bowlshaped contains exoderm and endoderm have a gastrovascular cavity where extracellular digestion occurs Also carry out intracellular digestion inside body cells tapeworms invertebrates simplest animals with bilateral symmetry an anterior end three distinct cell layers and cephalization have true tissues and organs acoelomate the body is very at and the digestive cavity is branched roundworms invertebrate bilateral symmetry little sensory apparatuspseudocoleom parasitic Earthworms invertebrates protostome coelomates digestive tract is a tube within a tube closed circulatory system hermaphroditic hemoglobin in blood Clams snail squid invertebrate soft body bilateral symmetry with three distinct body zones headfoot sensors visceral mass digestion excretion reproduction mantle surrounds everything open circulatory system have gills PC crab invertebrate PC segmented into head thorax abdomen has more sensory apparatus exoskeleton open circulatory system trachea lung Starfish invertebrate DC slow moving endoskeleton water vascular system reproduces by fragmentation and regeneration fish mammals either endoderm or ectoderm DC vertebrate dorsal hollow nerve cord notochord a rod that extends the length of the body mammals mothers nourish their babies with milk have hair or fur placental marsupial monotremes egglaying Evolution fossil record uses radiometric dating and half life to accurately measure the age of fossils homologous structures have a common origin and re ect a common ancestry analogous structures have the same function but do not descend from a common ancestor vestigial structures are structures that are no longer used comparative embryology and comparative biochemistry molecular biology and biogeography are evidence of evolution in binomial nomenclature every organism has a name consisting of a genus and a species Cuvier studied fossils and believed that a series of catastrophes were responsible for the changes on earth James Hutton published the theory of gradualism which stated that the Earth has been molded by sudden violent events Lyle stated that geological change resulted from slow continuous actions Lamarck proposed the inheritance of acquired characteristics and use and disuse Wallace published an essay discussing natural selection like Darwin TENETS OF NATURAL SELECTION 1 populations tend to grow exponentially overpopulate and exceed their resources 2 overpopulation it results in competition and a struggle for existence 3 in any population there is variation and an unequal ability of individuals to survive and reproduce 4 only the best fit individuals survive and get to pass traits on to their offspring 5 evolution occurs as advantageous traits accumulate in a population balanced polymorphism is the presence of two or more phenotypically distinct form of a trait out breeding is the mating of organisms within one species that are not closely related heterozygote advantage preserve multiple alleles in a population it is a phenomenon in which the hybrid individual is selected for because it has a greater reproductive success frequencydependent selection is also known as the minority advantage because it decreases the frequency of more common phenotypes genetic drift is change in the gene pool due to chance it limits diversity the bottleneck effect is when natural disasters such as res or earthquakes reduce the size of a population unselectively the founder effect is when a small population breaks away from a larger one to colonize a new area characteristics of the hardyWeinberg principle the population must be very large the population must be isolated from other populations there must be no mutations random mating no natural selection allopatric speciation is caused by geographic isolation sympatric speciation include polyploidy habitat isolation behavioral isolation temporal isolation and reproductive isolation divergent evolution occurs when a population becomes isolated from the rest of the species becomes exposed to new selective pressures and evolves into a new species convergent evolution is when unrelated species occupy the same environment are subjected to the similar selective pressures and show similar adaptations parallel evolution is when two related species that have made similar evolutionary adaptation after their divergence from a common ancestor coevolution is the same as predator prey relationship and monarch butter y and milkweed plants adaptive radiation is the emergence of numerous species from a common ancestor introduce into an environment gradualism is the theory that organisms descended from a common ancestor gradually punctuated equilibrium is a theory that proposes that new species appear suddenly after long periods of stasis the endosymbiosis theory says the chloroplast and mitochondria have their own DNA DNA is more like prokaryotic DNA than eukaryotic DNA organelles have double membrane Plants Classi cation 1 Bryophytes non vascular plants including mosses homworts liverworts 2 Tracheophytes vascular plants seedless plants ferns that reproduce via spores seed plants gymnosperms cone bearing angiosperms owering plants monocotyledon dicotyledon characteristics xylem and phloem for transport ligni ed transport vessels to support the plant roots to absorb water and anchor the plant leaves that increase photosynthetic surface life cycle w dominant sporophyte generation primary growth elongation of plant down into the soil and up into the air apical meristem secondary growth increases girth Plant tissue dermal tissue vascular tissue ground tissue dermal tissue protects the plant vascular tissue consists of the xylem the water and mineral conducting tissue and phloem carries sugars from the photosynthetic lease to the rest of the plant by active transport Ground tissue functions mainly in support storage and photosynthesis parenchymal cells have primary cell walls that are thin and exible but lack secondary cell walls collenchymal cells have unevenly thickened primary cell wall but lacks secondary cell walls sclerenchymal cells have very thick primary and secondary cell walls forti ed with lignin The three functions of roots r to absorb nutrients from the soil anchor the plant and store food taproot single root that gives rise to branch roots brous root systems hold plants rmly in place adventitious roots are aboveground stems contain vascular bundles each bundle contains a xylem on the inside and a phloem on the outside and meristem tissue in the middle monocots scattered dicots ring 0 LEAF The epidermis is covered by a waxy cuticle made of cutin to minimize water loss guard cells are modi ed epidermal cells that contain chloroplasts and controls the opening of the stomates palisade and spongy mesophyll function in photosynthesis Vascular bundles carry water and nutrients from the soil to the leaves and also carries sugar from the leaves to the rest of the plant Xylem uid Rises through transpirational pull the evaporation of water off plant leaves High humidity slows down transpiration wind reduces humidity and increases transpiration increased light intensity increases the rate closed stomates stop it The sexual life cycle of plant is characterized by the alternation of generations in which a haploid and diploid generation alternates with each other The gametophyte n produces gametes through mitosis these gamete fuse during fertilization 2 yield diploid zygotes each they go to develop into a diploid sporophyte which produces haploid spores by meiosis each spore forms a new gametophyte completing the life cycle CHAPTER 12 Digestion in Different Animals Hydra digestion occurs in the gastrovascular cavity where cells of the gastrodermis lining of the gastrovascular cavity secrete digestive enzymes into the cavity for extracellular digestion Earthworm long straight digestive tract food moves to the esophagus crop where food is stored gizzard w muscular walls that grind up food intestines where chemical digestionabsorption occur enhanced by the typhlosole which increases surface area Grasshopper crop and gizzard specialized mouth parts for tasting biting crushing food that has plates of chitin tract also removes uric acid Digestion in Humans Digestion breaking down large molecules and absorption diffusion of smaller molecules in body s cells Fats broken into glycerolfatty acids starch monosaccharides nucleic acids nucleotides proteins amino acids Vitaminsminerals don t need to be digested Digestive tract smooth muscle pushes food through peristalsis Mouth Humans and omnivores have three types of teeth incisors cutting canines tearing molars grinding Salivary amylase released by salivary glands begins chemical breakdown of starch Esophagus Food is directed into the esophagus NOT THE WINDPIPE by the epiglottis cartilage back of pharynx NO DIGESTION occurs Stomach Churns food mechanically secretes gastric juice digests proteins lining of stomach contains gastric pits that have three types of cells Chief cells secrete pepsinogen the inactive form of pepsin that becomes activated by acid Parietal cells secrete HCL that keeps pH of gastric juices at 23 and activates pepsinogen HCL kills injected microorganisms and breaks down protein Renin aids in the digestion of the protein in milk for mammals Lower esophageal sphincter keeps food in the stomach from backing up into the esophagus and burning it Pyloric sphincter bottom of stomach keeps food in the stomach long enough to be digested Excessive acid causes M but Hpylori now does Small intestine Digestion is completed by the duodenum Bile produced in the liver and stored in the gallbladder is released into the small intestine as needed and acts as an emulsifier to break down fats Peptidases trypsin and chymotrypsin break down proteins Nucleases hydrolyze nucleic acids lipases break down fats Lower part of the small intestine absorption aided by villi that absorb nutrients and capillaries that absorb amino acids vitamins and monosaccharides and lacteal a small vessel of the lymphatic system which absorbs fatty acids and glycerol Large intestine Three main functions egestion the removal of undigested waste vitamin production from bacterial symbioses living in the colon removal of excess water If too much water is reabsorbed constipation results if too little water is removed diarrhea results Rectum stores feces until their release Hormones that Regulate the Digestive System Gastrin produced in stomach wall stimulates secretion of gastric juice Secretin duodenum wall stimulates pancreas to release bicarbonate to neutralize acid in duodenum Cholecystokinin duodenum wall stimulates pancreas to release pancreatic enzymes and gall bladder to release bile into small intestine Gas exchange in different animals Spongeshydra gas exchange occurs over the entire surface Earthworms atworms external respiratory surface oxygen is carried by hemoglobin dissolved in blood Grasshopperarthropodscrustaceans internal respiratory surface air enters body through spiracles travels through tracheal tubes oxygen is carried by hemocyanin Fish gills and countercurrent exchange Gas exchange in humans Air enters the nasal cavity is moistened warmed and flltered passes to larynx down to trachea bronchi and bronchioles alveoli Humans have internal respiratory surface Rib cage expands diaphragm contracts and lowers chest cavity expands internal pressure lower than atmospheric pressure air is drawn in via negative pressure Medulla breathing control center monitors C02 levels in the blood by sensing changes in its pH C02 is the byproduct of CR and dissolves forming carbonic acid Higher the C02 concentration the lower the pH Blood lower than 74 causes medulla to increase breathing rate to rid body of more C02 If 02 levels drop drastically chemoreceptors in heart become activated and send nerve impulses to the medulla Hemoglobin Oxygen is carried by hemoglobin which can combine with four oxygen molecules forming oxyhemoglobin The more tightly hemoglobin binds to oxygen in the lungs the more difficult it is to unload the cells Hemoglobin is an allosteric molecule that exhibits cooperativity A drop in pH lowers affinity of hemoglobin for oxygen because C02 dissolves in water to form carbonic acid Transport of C02 C02 is carried by plasma as a part of carbonic acid bicarbonate ion system C02 combines w water to form carbonic acid catalyzed by carbonic acid anhydrase from RBC9carbonic acid dissociates into bicarbonate ion and a proton protons are given up into the plasma lowering the blood pH or taken up by bicarbonate ion raises blood pH Circulation in different animals Spongehydra no system earthworm closed circulatory system grasshopper open circulatory system Human circulation Plasma liquid portion of blood contains clotting factors hormones antibodies nutrients wastes maintains osmotic potential of blood RBC Erythrocytes carry hemoglobin02 doesn t have a nucleus and lives 120 days formed in bone marrow recycled in liver WBC Leukocytes ght infection formed in bone marrow die ghting in infection and are components of pus B limp Produces antibodies Platelets thrombocytes clotting Pathway of clot formation damaged tissueplatelets9thromboplastin and Ca29prothrombin inactive9throbin active9f1brinogen inactive9f1brin clot active Structure and function of blood vessels Arteryarteriole carry blood away from heart under enormous pressure thick elastic smooth muscle Veinvenule carry blood back to heart under little pressure thin walls prevent back ow veins are located in skeletal muscle which propels blood up and back as body moves Capillary allows for diffusion of nutrientswastes bt cells and blood onecell thick The Heart Heart beats about 70 beats per minute Atria receive blood from body cells ventricles pump blood out of heart Systolic number 120 measurement of pressure when ventricles contract diastolic number 80 measure of pressure when heart relaxes Pathway of Blood Vena cava right atrium tricuspid valve right ventricle pulmonary semilunar valve pulmonary artery lungs pulmonary vein left atrium bicuspid valve left ventricle aortic semilunar valve aorta all cells in the body Hormones Produced in ductless glands and moves towards a specific target cell tissue or organ Can produce short lived responses adrenaline speeds up heart rate and increases blood sugar Dramatically alter development of organism ecdysone controls metamorphosis in insects Tropic hormones far reaching effects bc stimulate other glands to release hormones How Hormones Trigger a Response in Target Cells 1 Lipid Steroid Hormones diffuse directly through plasma membrane and bind to a receptor inside the nucleus that triggers the cell s response 2 Protein hormones bind to receptor on surface of the cell flrst messenger binds to receptor on surface of cell secondary messenger inside the cell is triggered converts extracellular chemical signal to a speci c response Testosterone Only cells with testosterone receptors can response to testosterone Androgen insensitivity syndrome AIS XY genotype buck lack testosterone receptors in all cells testosterone is produced in normal amounts but these individuals don t have male reproductive ducts genitals or male secondary sex characteristics Epinephrine Tells the liver to release glucose Acts as the rst messenger when in activates G protein membrane receptors on the surface of liver cells activates adenylyl cyclase to produce cAMP produces a kinase cascade activates glycogen phosphorylase to convert glycogen to glycose inhibits conversion of glucose to glycogen Cascade amplifies the signal Temperature Regulation Behavioral changes that alter temperature Snake warms itself in the sun animals prevent heat loss by huddling together bees swarming in a hive raise its temperature dogs pant and sweat to cool off elephants don t have sweat glands thus cool off by watering themselves and apping ears Ectotherms animals that gain most of their body heat from the environment fish amphibian reptile Endotherms animals that use metabolic processes to produce body heat mammals Poikilotherm having a body temperature that varies with the environment Homeotherm having a constant body temperature despite uctuations in environmental temperature During torpor estivation summer torpor hibernations mammals save energy by drastically decreasing their metabolic ratebody temperature North south cline anatomical differences in mammals that varies across a geographic range Countercurrent heat exchange mechanism in organisms that utilizes parallel pipes of owing uid in opposite directions in order to save energy Osmoregulation management of the body s water solute concentration Marine vertebrates ocean is a strongly dehydrating environment bc it s hypertonic to organisms living in it sh produce very little urine amp drink seawater where salt is actively transported out through the gills Freshwater organisms environment is hypotonic to the organisms constantly gaining waterlosing salt excrete copious amounts of dilute urine Terrestrial organisms get rid of wastes while retaining as much water as possible Excretion Protista contractile vacuole planaria ame cells earthworm nephridia insects malpihigan tubes humans nephrons Excretion removal of metabolic wastes C02 water nitrogenous wastes organs skin lungs kidney liver Nitrogenous wastes ammonia urea uric acid Nitrogenous wastes Ammonia very soluble highly toxic excreted by organisms that live in water Urea not as toxic as ammonia excreted by earthwormshumans formed in the liver from ammonia Uric acid paste like substance not soluble in water not toxic excreted by insects reptiles birds etc The human kidney Functions as an osmoregulation regulates blood volume an concentration and an organ of excretion Blood is supplied form renal artery and renal vein If uid intake is high and salt intake is low kidney will produce large volumes of dilute hyposmotic urine If salt intake is high and water intake is low kidney will produce concentrated hyperosmotic urine The Nephron Capillaries glomerulus Bowman s capsule renal tubule Four steps ltration secretion reabsorption excretion Filtration blood pressure forces uid from blood in the glomerulus into Bowman s capsule From the BC the ltrate travels into the proximal tubule Secretion occurs in the proximal and distal tubules proximal tubule also secretes ammonia to neutralize the acidic ltrate Reabsorption water and solutes glucose amino acids vitamins that enter the tubule during ltration are transported into per tubular capillaries and into the body Loop of henle move salts from the ltrate accumulate them in the medulla surrounding the loop of Henle LOH acts as a countercurrent exchange mechanism establishes a salt gradient to ensure water molecules will continue to ow out of the collecting tubule of the nephron The longer the LOH the greater the reabsorb Of water Excretion removal of metabolic wastes urine passes through the ureter to urinary bladder where it is temporarily stored until it passes out of the body via urethra Remember ltration is passivenonselective secretion is active selective reabsorption is passive active and selective Renin a hormone released from the kidneys which converts an inactive protein into active angiotensin which stimulates the adrenal cortex to release aldosterone which is released in response to decrease in blood pressure ADH opens renal aquaporins in response to dehydration Nervous system Central nervous system brain spinal chord peripheral nervous system everything but CNS The Neuron Consists of a cell body nucleus and cytoplasmic extensionsdendrites receive incoming messages from other cells and relay the signal to the body axon transmits impulse from cell body to another cell myelin sheath wraps axon formed by Schwann cells THREE types of neurons gt Sensory receive an initial stimulus from sense organ eyes ears another neuron gt Motor stimulates effectors muscles glands gt lntemeuron spinal cordbrain receives sensory stimuli transfers information to motor neuron The Re ex Arc lnbom automatic protective Resting potential ALL cells have a membrane potential difference in electrical charge bt cytoplasm and extracellular uid A neuron in its unstipulated or polarized state resting potential has a potential of 70mV Sodiumpotassium pump maintains polarization by actively pumping ions that leak across membrane The larger the resting potential the stronger the stimulus must be to cause the nerve to re Gated channels Gated ion channels openclose in response to a stimulus If a stimulus triggers a sodium ion gated channel to open sodium ows into the cytoplasm membrane becomes depolarized If a stimulus triggers potassium ion gated channel the membrane potential increases and the membrane becomes hyperpolarized making it harder for neuron to re Action potential An impulse action potential can ONLY be generated in the axon Axon overcomes threshold permeability changes impulse passes Sodium channels open and sodium ions ow into the cell potassium channels open and potassium ions ow out of the cell wave of depolarization Reverses the polarity of the membrane action potential localizedshortlasting Sodiumpotassium pump restores membrane to its original polarized condition period of repolarization refractory period During this time neuron CANNOT respond to another stimulus The impulse moves along the axon propagating itself Wout losing any strength 40 Membrane potential mV I Uh U I 90 If axon is large impulse moves faster 1 myelin reduces ion leakage 2 because voltagegated channels are located on nodes impulse jumps from node to node All or none either the impulse is strong enough to cause an action potential or it isn t A strong stimulus establishes MORE action potential than weak ones Peak Overshoot Time msec The Synapse An impulse travels across a synapse chemically Cytoplasm of terminal branch of presynaptic neuron has vesicles that contain thousands of neurotransmitters Depolarization9Ca ions rush to terminal branch through calciumgated channels9vesicles released through exocytosis into synaptic cleft Neurotrans binds W receptors on postsynaptic side9 cell is either inhibited or excited always excited in vertebrates Neurotransmitters are then destroyed by esterase NTs at neuromuscular junctions are acetylcholine others are serotonin epinep noreph dopamine Acetylcholine stimulates cells to release NO Which stimulate other cells Organization of the Human Brain Cerebrum learning emotion memory perception left side receive info and controls right sidevise versa Cerebellum balance motor skills receives sensory information about position of jointsmuscles Brain stem medulla breathing swallowing digestion automatic transfers bt PNS and other brain parts EYE Vocabulary Cones color rods black and white Cornea toughclear covering that protects the eyelets light pass through Humor eye uid Iris colored part controls amount of light entering eye Lens focuses light on retina Retina converts light to nerve impulses carried to brain Muscle Every muscle cell contains muscle fibers that are muscle cells largemultinucleate Sarcoplasmic reticulum SR modi ed ER that contains sacs of Ca for muscle contraction T system tubules that connect SR to extracellular uid Sarcomere functional unit of muscle cell forming boundaries at Z lines Sliding Filament Theory Myo brils consist of thick myosin and thin actin laments Contraction of sarcomere depends on troponin and tropomyosin as well as calcium ions to breakform cross bridges Neuromuscular Junction Neurotransmitter acetylcholine binds to receptors on the sarcolemma depolarizes the muscle cell and establishes an action potential Impulse moves along sarcolemma into T system stimulates SR to release Ca which alters troponintropomyosin interaction and muscle contracts HUMAN IMMUNE SYSTEM Nonspecific Innate Defense Mechanisms First Line of Defense Barrier that prevents pathogens from entering the body skin mucous membranes contain lysosomes cilia stomach acid Second Line of Defense In ammatory response gt histamine triggers vasodilation which increases blood ow to the area and brings phagocytes secreted by basophils and mast cells gt prostaglandins promote blood ow to an area gt pyrogens increase body temperature Phagocytes ingest microbes gt Neutrophils and macrophages migrate to response via chemotaxis gt Neutrophils engulf microbesdie within a few days gt Macrophages extend pseudopods and engulf microbes over long pd Of time Complement a group of proteins that leads to bursting of invading cells Interferons block against celltocell viral infections Natural Killer cells destroy virusinfected body cells cancer cells attack cell membrane and cause lysis ADAPTIVE IMMUNITY Third Line of Defense 1 2 3 T cells Adaptive immunity relies on B and T cells which arise from stem cells and recognize different antigens Recognition antigen receptors on BT cells recognize antigens substances that elicit immune response in BT cells an antigenpresenting cell must present an antigen to BT cell Activation Phase binding of antigen receptor activates BT cells leading to rapid cell division cells form populations of effector cellsmemory cells Effector Phase after being activated B cells produce humoral response antibodies T cells produce cellmediated response Formed in bone marrow and mature in thymus gland T cell antigen receptors bind to antigens displayed on surface of APCs by a MHC APCs macrophages dendritic cells B cells Once activated T cells proliferate and forms T clones Some clones become effector cells other memory cells immunological memory rapidly respond if exposed to same antigen Two types of T cells helper T cells activated by interaction w APC cytotoxic T cells activated by helper T cell Helper announce to immune system that foreign antigens have entered body triggering humoral and cellmediated response activate cytoxoic cells and B cells Helper T cells CD4 cells activated other cells by releasing cytokines interleukin 1 and interleukin 2 Cytotoxic T cells CD8 cells attack and kill body cell infected w pathogen cancer cells by releasing perforin a protein that forms pores in target cell membrane and granzymes enzymes that break down proteins CTC proliferate and differentiate into effector cells and memory cells B Lymphocytes Mature in bone marrow has 100000 antigen receptors on its surface to recognize pathogens Antigen receptor y shaped molecule w 4 polypeptide chains 2 identical heavy and 2 identical light B cell activation APC presents antigenepitope on its surface using a class II MHC a helper T cell that recognizes epitopeMHC molecule complex is activated via cytokines secreted from APC B cell divides producing clones that become effector cellsplasma cells secrete antibodies and memory cells Regulator T cells and SelfTolerance Selftolerance immune does not attack body cells otherwise autoimmune disease B and T cells that are selfreactive are destroyed by apoptosis Regulatory T cells inhibit activation of immune system in response to selfantigens MHCs MHC molecules HLA Human Leukocyte Antigens Cell surface markers that identify cells as self only identical twins have same markers Class I MHC found on surfaces of every nucleated body cell Class II MHC found on specialized cells macrophages B cells activated T cells APCs have MHCI and MHCII on cell surface Clonal Selection Means by which one particular lymphocyte that matches a specific antigen determinant is identified and activated Antibodies The variety of antibodies is unlimited and there is no viral disease where humans cannot produce antibodies Seconda response to A Concentration of circulating antibodies Primary response toA Primary response to B 1U 20 30 40 U 10 20 30 40 Days Days lst injection 2nd injection of A ofantigen A Istinjection ofB Types of Immunity Passive temporary antibodies are transferred to an individual from someone else maternal antibodies that pass through placenta Active permanent the individual makes hisher own antibodies after being ill vaccinations Blood Groups and Transfusion A certain danger in transfusion arises is recipient has antibodies to donor s antigens Group A Group B Group AB Group 0 Red blood cell type l C I N g Antibodies wolf39f ll 3 gtquot in Plasma l 3 b I C AntiB AntiA None AntiA and AntiE Antigens i 1 Red Blood YT Cell A antigen B antigen A and B None anUgens AIDS The virus that causes AIDS HIV attacks cells that bear CD4 molecules on surface helper T cells Retrovirus uses reverse transcriptase and remains as a provirus directing production of other HIV cells Positive Feedback in Immune System Interleukin 1 enhances activity of already activated helper T cells Other topics in immunity Antibiotics medicine that kill bacteriafungi administered after a person is sick Autoimmune diseases MS lupus arthritis juvenile diabetes cannot distinguish bt self and oneself Monoclonal antibodies antibodies produced by single B cell that are selected because produce one speci c antibody Overview speci city diversity memory capacity to distinguish bt self and nonself ANIMAL REPRODUCTION AND DEVELOPMENT Asexual Reproduction Budding splitting off of new individuals from existing ones Fragmentation and regeneration single parent breaks into parts that regenerate into new individuals Parthenogenesis development of egg wout fertilization haploid adult Male 1 tube in the testes where sperm gain motility r e bulb are clusters of cells located between semil39llfet mls tubules that Pmduee 39r k 7 no 39 is the large gland that secretes semen directly into the urethra i 16 the sac outside the abdominal cavity that holds the testes The e001 L i39 7 there enables sperm to survive 39 l l quot secrete mucus fructose sugar WhiCh WOWes 311918 for the sperm K f V z gt n one prostaglnndin which stimulates uterine contractions during sexual are the site of sperm formation in the testes l provide nutrients for developing sperm 39 Singular are the male gonads where sperm are produced g fhembethatcarriessemenandurine g v 39 quot39 quot duct that carries sperm during ejaculation from the L i 39 i Positive and Negative Feedback of Menstrual Cycle During follicular phase estrogen released from follicle stimulates the release of LH from anterior pituitary stimulating the follicle to release even more estrogen During luteal phase LH stimulates corpus leutum to secrete estrogen and progesterone high enough trigger hypothalamus and pituitary to shut off inhibiting LH secretion Spermatogenesis In seminiferous tubules each spermatogonium cell 2n divides by mitosis to produce two primary spermatocytes 2n each undergo meiosis Ito produce two secondary spermatocytes 11 each secondary spermatocyte undergoes meiosis II producing 4 spermatids n Spermatids differentiate and move to epididymis Where they become motile Oogenesis An gonium cell 2n undergoes mitosis to produce primary oocytes 2n FSH periodically stimulates follicles to complete meiosis I producing secondary oocytes n Meiosis 11 doesn t begin until fertilization when sperm penetrates secondary oocyte Differs from sperm formation startstop processes cytokinesis divides cytoplasm unequally polar bodies one primary oogonium cell produces only ONE active egg cell Fertilization Acrosome head of sperm release hydrolytic enzymes that penetrate jelly coat of egg Speci c sperm molecules bind W receptor molecules on Vitelline membrane b4 sperm comes in contact w ovum plasma membrane Once sperm binds to receptors on egg egg is depolarized and no other sperm can penetrate egg membrane fast block to polyspermy9impenetrable fertilization envelope Unfertilized eggs can be activated artificially by electrical stimulation parthenogenesis Embryonic Development Cleavage gastrulation organogenesis Cleavage rapid mitotic cell division of zygote that occurs immediately after fertilization Produces uid filled balls called blastula embryo is called blastocyst pluripotent Inner cell mass inside the blastocyst will become embryo The cells that surround the inner cell mass are trophoblastic Gastrulation process that involves rearrangement of blastula and begins forming blastopore opening into blastula Deutersomes becomes anus protostomes becomes mouth Some cells become archenteron primitive gut Gastrulation forms three layered embryo gastrula with embryonic germ layers ectoderm endoderm mesoderm Ectoderm becomes skin and nervous system Endoderm becomes viscera lungs liver digestive organs Mesoderm becomes muscle blood bones or mesoglea Organogensis process by which cells continue to differentiate producing organs from three embryonic germ layers Frog Embryo Frog egg contains yolk vegetal pole with animal pole and pigmented cap Gray crescent opposite the point of entry of sperm marker of future dorsal side Cleavage and gastrulation cleavage is uneven blastopore forms at the border of grey crescent and vegetal pole Organogenesis rst organs are notochord and neural tube CNS which forms from the dorsal ectoderm Bird Embryo Cleavage and gastrulation so much yolk that embryo begins as a blast disc at disc on top of yolk Primitive streak instead of crescent Extra embryonic membranes yolk sac amnion chorionic allantois support the growing embryo Amnion encloses embryo in protective amniotic uid Chorion lies under the shell and allows for diffusion of gasses Allantois placenta repository for uric acid Factors that in uence embryonic development Cytoplasmic determinants grey crescent Embryonic Induction Ability of one group of embryonic cells to in uence the development of another group of cells The dorsal lip induced the abdomen tissue to become neural tissue named primary embryonic organizer Homeotic Home box or HOX Genes Master regulatory genes that control the expression of genes that regulate the placement of speci c anatomical structures Homeotic gene give instructions place legs here during development ECOLOGY Population group of individuals of the same species that live in the same area Community biological community assemblage of different populations that live together in a de ned area Ecosystem collection of all the organisms that live in a particular place together with their nonliving environment Properties of populations Several assumptions must be met for markrecapture to be accurate 1 Sampling must be random Every individual must have an equal probability of capture 2 The marked animals must distribute themselves randomly within the population so that the second sample will accurately re ect the population 3 This density estimate is based on the ratio of marked to unmarked animals This ratio must not change Formula N Number marked in rst catch X total number in second catch number of recaptures in second catch Dispersion pattern of spacing individuals within the area the population inhabits clumped safety in numbers uniform competition for limited resources random lack of attractions or repulsions There are three generalized types of survivorship curves Type I survivorship curves are characterized by high survival in early and middle life followed by a rapid decline in survivorship in later life They are typical of species that produce few offspring but care for them well including humans and many other large mammals Type II curves are an intermediate between Types 1 and 111 where roughly constant mortality rate is eXperienced regardless of age Some birds and some lizards follow this pattern In Type III curves the greatest mortality is eXperienced early in life with relatively low rates of death for those surviving this bottleneck This type of curve is characteristic of species that produce a large number of offspring see rK selection theory This includes most marine invertebrates For example oysters produce millions of eggs but most larvae die from predation or other causes those that survive long enough to produce a hard shell live relatively long Age structure diagram shows relative number of individuals at each age Limiting Factors Density dependent factors factors that increase directly as population density increases competition for food buildup of wastes predation and disease Density independent factors earthquakes storms res oods Rstrategists many young littleno parenting rapid maturation small young reproduce once ex insect Kstrategists few young intensive parenting slow maturation large young lot of reproduction ex mammals density dependent Polemic coloration bright coloration of poisonous animals as a warning that possible predators should avoid them Batesian mimicry copycat coloration where one harmless animal mimics the coloration of a harmful one Mullerian mimicry two poisonous organisms resemble each other and gain advantage form combined numbers Producers autotrophs green plants greatest biomass Primary consumers heterotrophs herbivores eat producers Secondary consumers heterotrophs carnivores eat primary Tertiary heterotrophs carnivores eat secondary top of chain least biomass Dominant species species that have the highest biomass Keystone species exert major control over other species If the rebuilding begins in a lifeless area where even soil has been removed the process is called primary ecological succession Secondary succession occurs when an existing community has been cleared by some disturbance Tropical forests are found close to the equator O O O O 0 Tropical rain forests receive constant high amounts of rainfall 200 to 400 cm annually In tropical dry forests precipitation is highly seasonal In both air temperatures range between 25 C and 29 C year round Tropical forests are strati ed and competition for light is intense Animal diversity is higher in tropical forests than in any other terrestrial biome Deserts occur in a band near 30 north and south latitudes and in the interior of continents O O O O O Deserts have low and highly variable rainfall generally less than 30 cm per year Temperature varies greatly seasonally and daily Desert vegetation is usually sparse and includes succulents such as cacti and deeply rooted shrubs Many desert animals are nocturnal so they can avoid the heat Desert organisms display adaptations to allow them to resist or survive desiccation Savanna is found in equatorial and subequatorial regions 0 O O O O Rainfall is seasonal averaging 30 50 cm per year The savanna is warm yearround averaging 24 290C with some seasonal variation Savanna vegetation is grassland with scattered trees Large herbivorous mammals are common inhabitants I The dominant herbivores are insects especially termites Fire is important in maintaining savanna biomes Chaparrals have highly seasonal precipitation with mild wet winters and dry hot summers O 0 Annual precipitation ranges from 30 to 50 cm Shrubs and small trees dominate Chaparral with a high diversity of grasses and herbs 0 Plant and animal diversity is high Adaptations to re and drought are common 0 Temperate grasslands exhibit seasonal drought occasional res and seasonal variation in temperature Large grazers and burrowing mammals are native to temperate grasslands Deep fertile soils make temperate grasslands ideal for agriculture especially for growing grain Most grassland in North America and Eurasia has been converted to farmland O 0 Coniferous forest or taiga is the largest terrestrial biome on Earth Coniferous forests have long cold winters and short wet summers The conifers that inhabit these forests are adapted for snow and periodic drought Coniferous forests are home to many birds and mammals These forests are being logged at a very high rate and oldgrowth stands of conifers may soon disappear O O 0 Temperate broadleaf forests have very cold winters hot summers and considerable precipitation A mature temperate broadleaf forest has distinct vertical layers including a closed canopy one or two strata of understory trees a shrub layer and an herbaceous layer The dominant deciduous trees in Northern Hemisphere broadleaf forests drop their leaves and become dormant in winter In the Northern Hemisphere many mammals in this biome hibernate in the winter while many bird species migrate to warmer climates Humans have logged many temperate broadleaf forests around the world 0 Tundra covers large areas of the Arctic up to 20 of the Earth s land surface Alpine tundra is found on high mountaintops at all latitudes including the tropics I The plant communities in alpine and Arctic tundra are very similar The Artic tundra winter is long and cold while the summer is short and mild The growing season is very short Tundra vegetation is mostly herbaceous consisting of a mixture of lichens mosses grasses forbs and dwarf shrubs and trees A permanently frozen layer of permafrost prevents water infiltration and restricts root growth Large grazing musk oxen are resident in Arctic tundra while caribou and reindeer are migratory Migratory birds use Arctic tundra extensively during the summer as nesting grounds Arctic tundra is sparsely settled by humans but has recently become the focus of significant mineral and oil extraction Water Cycle the continuous process by which water moves from bodies of water land and living things on earth39s surface to the atmosphere and back to Earth39s surface Evaporation process by which the surface of a liquid absorbs enough energy to change into a gas Transpiration process by which water is evaporated through a plant39s leaves Condensation process by which a gas changes to a liquid Precipitation different forms of water that falls back to the Earth39s surface Can be rain sleet hail or snow depending on temperature Carbon cycle Photosynthesis and respiration Cell respiration by animals and bacterial decomposers adds C02 into air removes 02 Burning of fossil fuels adds C02 into air Photosynthesis removes C02 and adds 02 Nitrogen 0ur atmosphere contains 78 free nitrogen N 2 All animals including aquatic animals need nitrogen to produce proteins necessary for life Even though most of our atmosphere is nitrogen animals cannot use the nitrogen in this free form They must consume nitrogen by eating nitrogen compounds Four processes are involved in the Nitrogen Cycle Nitrogen Fixation Digestion Decomposition and Waste production elimination Nitrogen Fixation o The nitrogen cycle shows how the free nitrogen in the air is turned into nitrogen compounds and put into the soil by nitrogen fixing bacteria This process is known as Nitrogen Fixation Plants that soak up the nitrogen compounds in the soil are called legumes 0ats Peas Beans Corn starchy vegetables Digestion 0 Animals eat the legumes to get the nitrogen compounds they need to produce protein Digestion Decomposition 0 When animals die bacteria called decomposers break down the organic matter plants animals chemically into all the simple elements that they are made of and these elements return back to the environment 0 For example When an animal dies all the carbon oxygen nitrogen water calcium etc return to the soil and air during decomposition Waste Production elimination 0 When an animal makes a bowel movement the waste is loaded with nitrogen This nitrogen returns to the soil Nitrogen is a great fertilizer Helps plants to grow ANIMAL BEHAVIOR Proximate causes immediate genetic physiological neurological and developmental mechanisms that determine how an individual behaves Ultimate causes result from evolutionary pressures that have fashioned an animal s behavior Fixed action pattern innate highly stereotypic behavior that once begun is continued to completion no matter how useless Migration occurs in response to environmental stimuli like changes in day length precipitation and temperature Learning sophisticated process in which the responses of an organism are modi ed as a result of experience Habituation simplest form of learning use to something Classical conditioning a learning process that occurs through associations between an environmental stimulus and a naturally occurring stimulus Operant conditioning trial and error punishment and reward Imprinting learning that occurs during sensitive period that is irreversible Agonistic behavior aggressive behavior Photosynthesis Two main process of photosynthesis CO2 H20 9 C6Hl206 02 light dependent and light independent reactions Photosynthetic pigments absorb light energy and use it to provide energy to carry out photosynthesis Chlorophyll a and chlorophyll b are green and absorb all wavelengths of light in red blue violet range Carotenoids are yellow orange and red and absorb light in the blue green violet range Chlorophyll a is the pigment that participates directly in the light reactions of photosynthesis contains a magnesium atom in the head surrounded by alternating double single bonds Chloroplast contains photosynthetic pigments grana lightdependent reactions stroma light independent grana contain thylakoids the sites of photosystems I and II Photosystems light harvesting complexes in the thylakoid membranes of chloroplasts contains a reaction center that have chlor a and antenna pigment molecules PS 11 operates rst called P680 and PS I operates next P 700 Two possible routes for electron ow noncyclic ow and cyclic photophosphorylation Noncyclic photophosphorylation electrons enter two ETCs and ATP and NADPH are formed 1 Photosystem II energy is absorbed and electrons from chlorophyll a become energized and move to a higher energy level they are captured in the primary electron acceptor 2 Photolysis water gets split providing electrons to replace those lost from chlorophyll a in P680 as well as two protons and one oxygen two oxygen combine to form 02 waste product 3 ETC electrons from P680 pass along the ETC and ultimately end up in P700 exergonic and provides energy to produce ATP via chemiosmosis resulting in photophosphorylation 4 Chemiosmosis protons from water are pumped by the thylakoid membrane from the stromal into the thylakoid space ATP is produced power for Calvin cycle 5 NADP becomes reduced when it picks up the two protons released from water in P6809NADPH carries hydrogen to Calvin cycle 6 Photosystem I similar to P680 except electrons that escape from chlorophyll a are replaced with electrons from PSII instead of from water OVERVIEW light9P680 oxygen released9ATP produced9P7009NADPH produced which carries H to Calvin Cyclic photophosphorylation sole purpose is to produce ATP No NADPH is produced and no 02 is released Calvin cycle produces the 3 carbon sugar PGAL l The process that occurs during the Calvin cycle is carbon xation 2 It is a reduction reaction since carbon is gaining hydrogen 3 C02 enters the Calvin cycle and becomes attached to a 5carbon sugar RuBP forming a 6carbon molecule that breaks down into 3PGA 3 carbon the enzyme that catalyzes this is rubrics The Calvin cycle doesn t directly depend on light it uses the products of light reactions ATPNADPH The Calvin cycle occurs ONLY in the light even though it is named lightindependent Photorespiration unlike normal respiration no ATP is produced unlike normal photosynthesis no sugar is formed Crustacean acid metabolism plants keep their stomata s closed during the day and open at night
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