MCAT ExamKrackers Biology Notes
MCAT ExamKrackers Biology Notes
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Date Created: 01/30/14
BIOLOGY Most abundant chemical in any living cell water Cytosol is in aqueous water solution All major macromolecules are broken down via hydrolysis Molecules of a liquid are held in liquid via bonds to other molecules Water has many intermolecular bonds hydrogen bonds which are the strongest type of such bonds Water is a polar molecule so it dissolves other polar molecules but not other nonpolar molecules Amphipathic molecule has polar and nonpolar regions Lipids all lipids are not fat 0 Have low solubility in water 0 Six major groups I Fatty acids I Amphipathic The longer the carbon chain the less water soluble the fatty acid I Short chains are slightly water soluble o Unsaturated have lower melting point 0 Saturated all single bonds connect the carbons int eh carbon chain I Triglycerides I 3 carbon chains dangling from a 3 carbon backbone Each carbon chain is attached by an ester group Adding water to ester breaks it into alcohol and carboxylic acid I Phospholipids I 3carbon backbone I Amphipathic I Cell membranes are made of this I Polar regions face aqueous solution inside and outside the cell I Glycolipids I Like phospholipids but with carbohydrate replacing phosphate I Steroids I Usually carried by lipoproteins LDL and HDL ie I Lipoprotein surrounds lipids by phospholipid and protein shell which does dissolve in the blood I Slightly amphipathic I Terpenes I Form of hydrocarbon including vitamin A Proteins made up of long chains of amino acids HAL basic amino acids histidine arginine lysine Nonpolar amino acids hydrophobic 20 essential amino acids those which body cannot produce on its own Primary sequence includes location of disfulfide bonds between cysteines Held together by covalent bonds Secondary structure is held together by hydrogen bonds between amine and carboxy Amino acid is called a residue when it s incorporated into a polypeptide chain Tertiary structure bending of secondary structure into bended shape or glob Many structural proteins do not have tertiary and quaternary structure DISFULFIDE BOND CREATES TERTIARY STRUCTURE AS DO HYDROGEN BONDS ELECTROSTATIC FORCES BETWEEN IONIC PORTIONS OF THE RESIDUE Van der waals forces also Also hydrophobichydrophilic effects cause tertiary structure Quaternary structure consists of 2 or more polypeptides held together by same ve forces which hold together tertiary structure 0 Each polypeptide here is referred to as a subunit Denaturation disrupts the 5 forces which exist in tertiary and quaternary as well as secondary structure Primary structure being held by covalent bonds are not destroyed Carbohydrates CxH20y Glucose is an aldehydes with 4 chiral carbons o In fischer projections the hydroxyl grups are to right left right right Anomeric carbon is the one that is to the right going clockwise after oxygen in the ring Beta anomer when OH on anomeric carbon points up Alpha anomer when OH on anomeric carbon points down Glucose is stored in long carbohydrate chains glycogen I Each glucose molecule attaches to the next via alpha linkage 0 Plant cell walls are made of cellulose beta linkages 0 Animals can break alpha but not beta linkages Water as always breaks nucleic acids in nucleotides Other important nucleic acids 0 Cyclic AMP O O O O o NADH o FAD 0 ATP Minerals inorganic elements which exist as ions inside and outside cell 0 Establish electrochemical gradients 0 Act as cofactors to enable protein function 0 Form matrix compounds in bone and elsewhere Enzymes increase reaction rate by trillions of times and there is an enzynme for nearly every reaction 0 Lowers activation energy 0 Usually a protein 0 Enzyme is usually larger than substrate I Substrate molecule the enzyme works on 0 There is lock and key theory or induced fit theory Enzyme specificity enzyme must be tailormade for a reaction 0 Saturation kinetics since a single enzyme molecule works on one set of substrates at at ime the reaction rate increases only as long as there are unoccupied enzyme molecules There is a Tmax for the number of enzymes Pepsin has optimal pH between 12 Salivary amylase has optimal pH between 67 Feedback inhibition in enzymes occurs when product of reaction near end of chain of reactions inhibits a reaction early in the chain saving the energy which would otherwise be wasted 0 Competitive inhibition I Will bind to active site I Substrates attach to and release from the active site very rapidly many times per second I Competitive inhibitor can be overcome by increasing substrate concentration 0 Noncompetitive inhibition I Bind to an allosteric site I Does not attach to the active site I Changes shape of enzyme by binding to allosteric site substrate does not fit as well I INCREASNIG SUBSTRATE CONCENTRATION DOES NOT HELP 0 Irreversible inhibition 0 I Covalently bond to the substrate Zymogen or proenzyme inactive form of enzyme Enzyme may be activated or deactivated by phosphorylation or dephosphorylation or by control proteins Enzymes are named with ase in the end Cellular respiration 0 Energy acquiring stages of metabolism which begins by breaking down macromolecules into basic nutrients This step requires energy 0 First step glycolysis Some organisms use other reactions that are similar I TAKES PLACE IN CYTOSOL AND NO OXYGEN REQUIRED I Begins with glucose and produce 2ATP 2NADH and 2 3carbon pyruvates I Fermentation ethanol is formed in yeast rather than lactic acid In aerobic respiration products of respiration are transferred to mitochondrion o In mitochondrial matrix each NADH produces 3 ATP via electron transport chain 0 Inside matrix each pyruvate is converted to acetyl coA which transfers two carbons to oxaloacetate to make citrate to begin CAC CAC 0 Makes 1 ATP 3 NADH and 1 FADH 0 Each NADH is converted to 3 ATP via ETC 0 Each FADH is converted to 2 ATP via ETC 0 One pyruvate one turn of krebs cycle 0 One glucose 36 ATP s for two runs of CAC ETC 0 Series of proteins called cytochromes embedded in inner membrane of mitochondrion 0 Use energy of electrons to pump protons into intermembrane space leaving the space with a low pH 0 ATP syntahse is an integral protein of this membrane that allows protons to ow back into the matrix I Uses energy of electrochemical gradient between intermembrane space and matrix to produce ATP Aerobic respiration o Oxidation or combustion of glucose 0 Glucose oxygen goes to carbon dioxide and water 0 Oxygen is final acceptor in ETC Triglycerides 0 Broken into glycerol and fatty acids 0 Glycerol enters glycolysis in middle 0 Fatty acids transported into matrix in mitochondrion and are converted to acetyl coA where 2 NADH are made for every 2 carbons of fatty acid 0 Amino acids enter at various portions of process depending upon AA Protein may be made of one or several polypeptides One gene one polypeptide For most proteins eukaryotes have just one copy but for genes encoding for tRna rRNA and heterochromatin cell contains multiple copies For most proteins one significant mutation causes cell to completely lose that protein Phosphate group in DNA is attached to 5th group on each pentose DNA replication is bidirectional 0 Process begins at middle of double stranded DNA and replication proceeds along both directions 0 DNA helicase unzips the helix 0 Replisome holds helicase and DNA polymerases moving in a single unit along the DNA 0 Moves from 35 direction but operates in the 53 direction 0 DNA ligase ties together okazaki fragments in lagging strand rRNA is synthesized in nucleolus half life of RNA is typically only 30 minutes much shorter than half life of DNA transcription must take place only in nucleus and in mitochondrial matrix 0 begins when initiation factors find a promoter on the DNA promoters in a given species are all similar most common promoter a consensus sequence in prokaryotes promoters may be followed by several genes called an operon in eukaryotes promoters are usually followedby only one gene RNA polymerase synthesizes from 53 Transcription is much slower than replication and has less fidelity I No proofreading and repair system 0 Primary RNA typically contains Introns Post transcriptional processing 0 May consist of nucleotide addition or modification of bases 0 Usually only occurs to rRNA and tRNA in prokaryotes Vector a virus PCR polymerase enzyme is used from Archaea and piece of desired DNA is mixed with many copies of primers 0 Mixture is heated to denature the DNA 0 When cooled primers attach to the SS DNA 0 Mixture is heated again 0 Polymerase replicates the strands 0 Each run doubles the DNA mRNA moves into cytoplasm via nuclear pores and into the ribosome ribosome is made of Large and Small subunits 0 large subunit has E P A sites A site is AA site P is polypeptide site mRNA lines up on large subunit tRNA containing anticodon sits in P site while second tRNA lines up behind it with its amino acid in A site takes place in cytosol or on rough endoplasmic reticulum o if translation occurs in cytosol protein usually works in the cytosol If occurs in RER polypeptide is thrust through RER and into lumen inside space or cavity Down Syndrome is a chromosomal aberration Silent mutation alters codon but not the amino acid Change in amino acid sequence missense mutation Nonsense mutation stop codon in middle of chain Deletions and insertions alter the codon reading frame frameshift mutation 0 Unless they occur in multiples of three Transposition a small ring of DNA is removed from chromosome and transposed to another section Forward mutation for instance if a bacterium lacks the ability to make histidine a forward mutation would be the loss of the ability to make another amino acid OOOOOO O OOOO Most DS DNA is wrapped tightly around histone proteins Humans have 46 chromosomes Cells with homologous pairs of chromosomes diploid cells Chromosome pair 23 designates gender in humans I Cell life cycle processes 0 Interphase I G1 first growth phase Cell is split and energy is devoted to growth in size I S phase where energy is devoted to replication I G2 cell prepares to divide Appropriate cellular organelles double in number 0 Mitosis I Mitosis 0 Nuclear division 0 Prophase chromosomes condense Nuclear membrane disintegrates Centrioles move to opposite cell poles Spindle apparatus is formed by microtubules o Metaphase chromosomes line up along equator of spindle forming metaphase plate 0 Anaphase sister chromatides split and move to either pole Split is called disjunction Cytokineses may begin as early as this and is accomplished through microfilaments o Telephase nuclear membrane reforms and chromosomes recondense 0 Net result two genetically identically daughter cells I Meiosis o 2 divisions and only germ cells undergo meiosis o Spermatogenesis I Meiosis of spermatogonium gonna be a sperm I Diploid cell I After S phase spermatogonium becomes a primary spermatocyte still diploid I Undergoes meiosis I In prophase I each chromosome synapses with homologue Just lining up I Resulting group is called tetrad I Crossing over occurs here I 1 form of genetic recombination I Longest stage of meiosis I Metaphase I tetrads line up at spindle equator I Chiasmata points where crossing over occurs I Anaphse I I Chiasmata are torn apart I Centromeres remain intact I Homologgues are separated I Telephase I I Does not always occur I Nuclear membrane reforms I Net result of Meiosis 1 reduction division Reduces ploidy number Creates 2 haploid cells secondary spermatocytes No homologous pairs I Meiosis 2 is just like mitosis o Oogenesis I Male spermatogenes producse 4 gametes through meisosis I Oogenesis producse only 1 gamete I At time of birth all eggs are arrested at primary oocytes stage I At puberty menarche occurs where upon one primary oocytes undergoes meiosis I At each nuclear division a small nuclear body rather than an entire cell is released I Polar body formed during reductiondivision may or may not occur meiosis 2 I Oocytes produces polar bodies in order to conserve cytoplasm Oogonium produces only 1 gamete I MCAT is mainly concerned with humans I Viruses are comparable in size to large proteins Protein coat on virus capsid Inside are nucleic acids and sometimes proteins Most animal plant and bacteriophaagse have lipid rich envelope borrowed from lipid membrane of host cell gained via reverse endocytotic process Bacteriophagse have icosahedral capside 20sided 0 Have a tail and tail fibers 0 Tail fibers attach on protein receptor on the host cell Living organisms possess both DNA and RNA and are capable of reproduction without enzymes form another cell Viruses are species specific Once viral material is inside cell a lysosome attaches to the phagosome Viral capsid never has to transport across membrane because it is released into cc cytosol Lytic cycle and lysogenic cycle 0 Lytic is immediate o Lysogenic is latent Viral nucleic acids become incorporated in host cell genome Often inactivated by stress to become lytic I Provirus or prophage Virion inactive form of a virus Metabolically inactive but ready to infect a new host cell Virus may possess single or double stranded DNA or RNA in or strand RNA Reverse transcriptase reverse transcribes RNA to DNA HIV Viroids infectious pieces of naked RNA Only infect plants Prions single protein molecule capable of reproducing without using DNARNA mad cow disease All bacteria are prokaryotes with no membranebound nucleus No complex membranebound organelles 70S ribosomes30S50S Eukaryotes are 80S ribosomes40S60S Bacteria have Double stranded DNA Membrane establishes concentration gradients between inside and outside of cell 0 Semipermeable to almost everythingpermeable to a degree Also selectively permeable Size and charge determine how easy it is for a molecule to passively diffuse across a membrane without the use of a carrierprotein channel without using energy Facilitated diffusion is passive transport and must be in direction of electrochemical gradient as opposed to active transport such as sodium potassium pump Secondary active transport electrochem gradient of one molecule is used to pump another molecule across membrane at times against its gradient Does not use ATP directly but rather indirectly Bacteria can be gram positive gram negative depending how they stain Gram positive purple Gram negative pink Gram negative can contain fimbriae or pili Bacterial agella is very different from human agella Made from protein agellin Polymerized to make a long slender helix and rotate powered by a proton pump Move via run and tumble Bacteria move by chemotaxis Bacteria reproduce by binary fission no genetic recombination in this method Bacteria can recombine genes via conjugation transduction and transformation Conjugation bacterium with F plasmid transfers its genetic material to its F partner F is needed for sex pilus Transformation bacteria pick up naked DNA from its environment Transduction transfer of genetic information through a vector such as a virus Endospore high resistance to heat and lethal agents Botulism caused by endospores In order to grow all organisms require carbon energy and electrons Carbon source may be organic or inorganic Organisms that can use CO2 as carbon source autotrophs Heterotrophs rely on organic matter for carbon Energy comes from sun or chemical reactions Gain e from inorganic matter lithotrophs Gain e from organic organotrophs Fungi divides into divisions not phyla All fungi are exodigesters spit on food lie in it and absorb its nutrients Many are considered saprophytic eat dead matter Possess septa cell walls made of chitin Hyphae tangled mass of thread like structure Entire tangled mass mycelium Most life is haploid and capable of asexual reproduction More likely to reproduce asexually in GOOD conditions More likely to reproduce sexually in BAD conditions since its offspring may have genetic variation so it is better able to survive conditions may not be bad for an offspring which is different from either parentIMPORTANT Spores haploid Yeast single celled fungi that evolved from multicell ancestors Produce asexually via fissionbudding Facultative anaerobes that produce ethanol Protists eukaryotes All eukaryotes have a nucleus that contains cell s genetic material chromosomes Surrounded by nuclear envelope double phospholipid bilayer TWO bilayers with a narrow lumen in between RNA leaves nucleus via nuclear pores Nucleolus makes subunits of ribosomes Endocytosis 3 types phatocytosis large material pinocytosis small material and receptor mediated endocytosis All mediated by membranebound proteins In vertebrates only certain white blood cells are capable of phagocytosis Many cells are capable of pinocytosis nonselective method RME specific uptake of macromolecules hormones nutrients Cholesterol is taken up by RME Endosomes represent lumen side of the cell ER separates lumen side from cytosol side of the cell Rough ER appears like at sacs with little black dots dots ribosomes Translates proteins Once in ER lumen proteins go to Golgi apparatus Lysosomes are vesicles that are full of hydrolytic enzymes and bud off of Golgi Work best in acid 0 Break down macromolecules into nutrients and waste products Peroxisomes catalyzes condensation reactions opposite of lysosomes Detox alcohol oxidize hydrogen peroxide DO NOT bud off from golgi Multiply by fission Smooth ER tubular sacs Acts in lipid synthesis especially phospholipid synthesis Detoxifies poisons in liver cells Controls calcium concentration in cytosol Cytoskeleton aids in movement of cellular materials and movement of cell itself Made of microfilaments and microtubules Microfilaments made of polymerization of actinProvide structure for cell and scaffold for movement Microtubules are made of tubulin Major MTOCcentrosome Flagella and cilia are made of microtubules Flagella wiggles to move uid directly away to propel cell as in sperm Cilia acts in whiplike fashion to move uid rapidly Both made in 92 arrangement Mitochondria two membranes Inner has many folds called cristae Space between inner and outer intermembrane space Have own circular DNA Believed to have evolved via endosymbiosis Glycocalyx on exterior surface of cell Important for recognition of other animal cells Allows microbes to recognize host cells and infect them Cancer cells have abnormal glycocalyx Gap junctions little tunnels between contiguous cells to allow passage of ionsnutrients In cardiac and smooth muscle tissue to allow action potential to spread Tight junctions create water tight barrier Serve as barrier to lateral movement of membrane proteins Desmosomes occur usually with tight junctions Matrix made from collagen or plastin to hold cell in place Tissue with extensive matrix connective Single celled organism can have sustained life on its own Multi celled organisms cannot live on their own Tissue epithelial connective muscle and nervous these 4 types in vertebrates 3 systems for communication nervous paracrine and endocrine Neurotransmitters travel short distances Paracrine hormones such as prostaglandins travel millimeters and endocrine hormones travel all over the body Nervous system fast and direct Opposite of endocrine system Neuron cannot divide as it is so specialized Depends on glucose only for energy Transfers signal from dendrites to soma to axon terminals Action potential begins in axon hillock Neuron is positive on outside and negative on inside Resting potential is negative relatively Sodiumpotassium slowly leak across cell membrane Resting is an equilibrium between pumping and leaking rates When sodium rush into cell potential goes up depolarization Minimum change of potential threshold potential Sodium channels are inactivated immediately after opening From repolarization to Hyperpolarization absolute refractory period cannot create another action potential During Hyperpolarization relative refractory period difficult to create another action potential Synapse is where neuron transfers signal to next cell Space between cells synaptic cleft Impulse causes calcium voltage gated ion channels to open Neurotransmitters are spilled into synaptic cleft via exocytosis Unidirectional process Neuroglia support cells Schwann cells and oligodendrocytes contain myelin which wrap around axon and insulate it Allow for salutatory conduction which is much faster than normal transfer of action potential Myelinated axons white matter SAME DAVE sensory is afferent motor is effort Dorsal is afferent ventral is efferent Central nervous system brain and spinal cord and contains interneurons CNS job is integration Peripheral everything else somatic and autonomic parts Somatic is voluntary and innervate skeletal muscle Autonomic are involuntary and innervate smooth cardiac muscle glands and visceral organs Both these parts are divided into sensory and motor neurons Autonomic nervous is divided into sympathetic and parasympathetic areas Sympathetic fight or ight and parasympathetic is rest and digest Muscle gland or organ is usually innervated by both Intestines are Inactivated by sympathetic and are ACTIVATED by parasympathetic unusual Ganglion group of cell bodies in peripheral nervous system Effectors target tissue glands or organs All neurons in PNS use acetylcholine as neurotransmitter except post ganglionic sympathetic neurons which use epinephrine Brain medulla oblongata controls breathing heart rate Cerebellum controls balance equilibrium and muscle coordination Prefrontal cerebral cortex elaboration of thought Hypothalamus hunger thirst sex pleasure pain blood pressure and water balance Eye lens focuses images on the retina Retina is at back of eye and made of rods and cones Rods light and dark Cones colors Iris is group of smooth muscles making opening of eye Ear outer ear contains ear ap or pinna and auditory canal Auditory malleus incus and stapes that transfer sound energy from ear drum to inner ear at oval window Cochlea in inner ear transduces sound to electrical signal Semicircular canals in inner ear monitor position orientation and acceleration of head why cats always land on their feet Exocrine glands release enzymes to external environment via ducts sweat glands ie Endocrine glands release general hormones directly into blood without ducts Each endocrine hormone requires a protein receptor Metabolic activities growth and reproduction Classes of hormones peptides tyrosine derivatives and steroids Peptide hormones may be big or small and often include carbohydrate portions Made at rough ER usually Modified twice before it becomes an active hormone Water soluble and dissolve in blood and can t pass lipid bilayer Once peptide hormone attaches to receptor a second messenger system is activated such as a G protein which may either stim or inhibit another protein called adenylate cyclase which increases cAMP which activates protein kinase which phosphorylates or dephosphorylates an enzyme Second messenger system magnifies effect exponentially Each step involves more and more molecules Steroids similar and usually derived from cholesterol Lipid soluble rings Made at smooth ER and in mitochondria Usually have protein carrier to take through blood and diffuse through lipid bilayer Act at level of transcription in nucleus Adrenal cortex gonads and placenta produce steroids Tyrosine derivatives thyroid hormones and catecholamines epinephrine and Norepinephrine Catecholamines behave like peptides and thyroids behave like steroids Know negative feedback Hypothalamus controls secretions of pituitary glands Posterior pituitary does not produce hormones but hypothalamus produces them PP only releases Pituitary only makes peptide hormones Anterior pituitary releases FSH LH ACTH TSH prolactin and GH ACTH stimulates adrenal cortex to release glucocorticoids Prolactin promotes mammary gland development and milk production GH stimulates growth by increasing transcriptionlation GH somatotropin Posterior pituitary releases vasopressin ADH and oxytocin Oxytocin causes milk letdown and uterine contraction Thyroid is just below larynx Makes Calcitonin T4 and T3 T4 and T3 are lipid soluble and their effect is to increase gene transcription T3 and T4 increase basal metabolic rate and act on nearly all cells Calcitonin lowers plasma calcium concentration and increase calcium in bone Decreases osteoclast activity Parathyroid set of 4 tiny glands attached to thyroid which secrete PTH which increase production of osteolasts and increase absorption of calcium in kidneys and intestines Also affects phosphate secretionabsorption depending on organ Pancreas behind and below stomach Endocrine and exocrine gland Endocrine islets of Langerhans Alpha cells secrete glucagon Beta secrete insulin Glucagon stimulates glycogenolysis and gluconeogenesis in liver Both make glucose Insulin small protein and causes 80 of body to become more permeable to glucose by new formation of protein channels Does not affect neurons When cells become mor permeable to glucose blood glucose goes down Glucagon raises blood glucose Adrenal cortex sit atop kidneys two glands per kidney cortex and medulla Cortex is outside medulla is middle of it Cortex makes only steroids Medulla makes Norepinephrine and epinephrine Aldosterone made in cortex and is mineralocorticoid Increases blood pressure Reabsorbs sodium and pulls in water along with sodium Does not increase concentration of sodium that much since water follows and dilutes it Cortisol glucocorticoid Stress hormone and stimulated by stress conditions Increases blood glucose by mobilizing fat and proteins to make glucose Increases glucocneugenesis and suppresses immune system currently unclear Adrenal medulla is made of chromaf n cells Spermatogenesis is in seminiferous tubules Testosterone hardens epiphyseal plates of long bones Sertoli cells nurture sperm Immature sperm matures in epididymus Prostate bulbourethral and seminiferous add uid to ejaculate uid Oogonia in ovary become primary oocytes in fetal stage Arrested at birth At puberty FSH stimulates zona pellucida to form from granulosa cells Theca cells develop around oocytes and relase androgens Follicle is this complex which bulges from ovary via positive feedback resulting from luteal surge rapid increase in Lh concentration o cause ovulation Follicle bursts upon ovulation Fimbriae sweep oocytes into fallopian tubes and cilia sweep it to uterus Fertilization usually occurs in fallopian tube Placenta secretes estrogen hCG and progesterone Egg undergoes meiosis I and II after penetration by sperm Zygote then undergoes cleavage and becomes morula which is dense body Undergoes blastulation to become blastocyst which is uid filled Invaginates to form gastrula Blastopore becomes mouthanus Deuterosomes make new hole for mouth Formation of three cell layer occurs in gastrulation Ectoderm mesoderm and endoderm Any molecule that can be broken down into nutrients undergoes hydrolysis Food goes mouth esophagus stomach SI LI anus Pancreas liver and gall bladder dispel chemicals into duodenum in SI Digestion begins in mouth via salivary amylase which digests carbohydrates chemically Chewing is physical digestion Tongue assists in making and swallowing the bolus which is partially voluntary and involuntary Epiglottis covers opening of wind pipe to allow swallowing to esophagus Most important job of stomach is store food and releaes little bits of food at a time into intestine Physically digests food by churning Low pH to denature proteins Four cell types mucus parietal G and chief cells Mucus cells protect from acid Parietal release HCl into lumen G cells release gastrin into capillaries around stomach Chief cells secrete pepsinogen inactive pepsin that is activated by HCl Optimal pH of pepsin 2 Stomach makes food into chyme which is released into small intestine bits at a time Surface of each villus is composed of many enterocytes Villi function to increase surface area of SI Microvilli appear fuzzy under microscope and this is brush border with many digestive enzymes Pancreas secretes bicarbonate ion to buffer solution in SI Trypsin amylase lipase and nucleases are also secreted by pancreas Releases at least one molecule for each type of macromolecucle in living cells Trypsinogen is activated to enterokinase and trypsin activates the other enzymes Lipase works to break down lipids especially triglycerides Fat coagulates in SI and it is emulsified by bile which is a physical process of secretion Bile is secreted by liver and gall bladder Duodenum digests J ejunum and ileum do absorption Maj or role of large intestine is to absorb water E coli has mutualistic relationship with humans in L1 by providing vitamins K B12 thiamine and ribo avin Food can only be absorbed if broken down into most basic nutrients Sucrose and lactose disaccharides Chitin is in insect exoskeletons and also in fungi mushrooms ie Animals can t digest cellulose or chitin Lactose glucose and galactose Glucose and galactose are absorbed via secondary active transport mechanism in SI Fructose is absorbed via facilitated diffusion Digestion of protein begins in stomach where HCl denatures it and pepsin attacks middle of polypeptide chains Trypsin and chymotrypsin break down polypeptides into di and tripeptides Most dietary fat triglycerides Micelles are amphipathic molecules FIGURE OUT HOW FATS TRANSPORT Maj or role of liver regulate glucose concentration in blood Has sinosoids to facilitate gas and nutrient exchange Can expand to store blood Also destroys irregular red blood cells Makes most of body s lipoproteins Filters blood Metabolizes fats carbs and proteins Detoxification also Cardiovascular system delivery of nutrients oxygen removal of wastes redistribution of heat transport of hormones Trace a drop of blood right atrium is on left side of the page Left ventricle is strongest part of heart as it must pump blood through entire systemic portion Pulmonary carries blood to lungs to be oxygenated Left ventricle blood goes into aorta Arteries take blood away from the heart Arteries carry oxygenated blood in systemic system opposite of pulmonary system Arteries are elastic and stretch as they fill From aorta goes to arteries arterioles capillaries venules veins and into vena cava Capillaries are one cell thick approx equal to diameter of red blood cell Gas and nutrient exchange occurs across capillary walls Hydrostatic pressure decreases from aorta to vena cavae Osmotic pressure remains constant along capillaries Net pressure force due to hydrostatic and osmotic pressure pushes uid out of capillaries At venule end net pressure pushes uid back into capillaries 10 net loss of uid to interstitial space as blood is passed from one end of capillary to the other Total cross sectional area is greatest at capillaries and velocity is lowest here to allow more time for gasnutrient exchange Vena cavae empty into right atrium which lls right ventricle which feeds pulmonary arteries Pressure decreases as blood moves from pulmonary arteries to pulmonary veins Heart contracts starting at atria and then to ventricles Contraction is created by action potential electrical stimulus which starts at SA node in right atrium SA node is made of myocytes that spontaneously contract at a rate faster than normal heart beat SA node is innervated by vagus nerve parasympathetic which slows heart rate Action potential then spreads via gap junctions in intercalated discs and hesitates at AV node then enters ventricles carried down bundle of His and out across Purkinje fibers Contraction of ventricles systole Signal for breathing begins in medulla oblongata of brain and runs to diaphragm When diaphragm contracts it expands volume of chest Air is pushed into lungs When diaphragm relaxes volume decreases and raises pressure Recoil of lungs drives the air out Nasal cavity lters moistens and warms hair Wind pipe lies in front of esophagus and larynx is at top of it and contains vocal cords Trachea wind pipe Trachea is ciliated to move trapped particles up towards pharynx and branches to become right and left primary bronchi which branch to form bronchioles which end in alveolar sacs Air we breathe is 21 oxygen and 79 nitrogen Nitrogen doesn t react with anything in the body since N2 is so stable CO2 mixes with water in presence of carbonic anhydrase to make carbonic acid As lungs remove Co2 concentration of carbonic acid decrease and pH of blood rises Hemoglobin is inside red blood cells and has four polypeptide chains as subunits Each polypeptide has heme group to hold one iron atom One iron binds to one oxygen atom When first hemoglobin binds affinity of other hemoglobins to bind oxygen increase cooperative binding and this is affected by many conditions such as 23BPG Also affected by partial pressure of Co2 temperature pH and H ions H Co2 BPG and increase in temperature increase hemoglobin affinity of oxygen Heat is produced by breakdown of glucose Products of respiration stimulate hemoglobin to drop off oxygen at tissues Myoglobin has only 1 subunit and does not have cooperativity Not affected by H CO2 or BPG Oxygen dissociation curve compares percent oxygen saturation of hemoglobin and Oxygen partial pressure Oxygen dissociation curve for hemoglobin is sigmoidal caused by presence of BPG Curve shifts to right in presence of H Co2 and heat Myoglobin curve is not sigmoidal but rather to the left of hemoglobins and has parabolic shape Fetal hemoglobin has curve to the left of maternal hemoglobin Chloride shift as blood enters lungs it drops off CO2 Chloride is released from cell as bicarbonate enters As a result arterial red blood cells contain fewer ions than venous red blood cells Lypmph system recycles interstitial uid Drains this and empties into blood and empties at right lympathic duct and at thoracic duct Does NOT drain CNS Thoracic duct services left arm and rest of the body It is an open system as opposed to circulatory system Uses skeletal muscle contraction body movement and arterial pulse to move uid through lymph system Also monitors blood for infection Blood plasma buffy coat and hemotocrit volume occupied by red blood cells 55 in men and 45 in women The higher hematocrit the more viscous the blood Buffy coat is volume of white blood cells Plasma is aqueous with proteins such as albumin and immunoglobulins antibodies and fibrinogen Serum is plasma without clotting factors Erythrocytes red blood cells have no organelles and live for about 120 days All leukocytes function as part of immune system 0 Granulocytes stay in blood for hours only then live in tissue for 45 days 0 Neutrophils phagocytotic cells that indiscriminately attack foreign invaders Release antibiotic proteins against bacteria fungi and viruses 60 of leukocytes in cells Basophils and mast cells release histamines Monocytes are immature and become macrophages in tissue Megakaryocytes remain in bone marrow and form platelets which are little pieces of cells B and T lymphocytes which are involved in acquired immunity Innate immunity non speci c and offers protection against substances indiscriminately Includes all white blood cells other than lymphocytes Also skin stomach acid In ammation is immune response caused by histamines prostaglandins and lymphokines Some of tehse activate macrophages Blood vessels dilate in in ammation to increase blood ow to in amed area Granulocytes and monocytes migrate to in amed area and swells to impede progress of foreign agent to other areas of body Two types of acquired immunity humoral and cell mediated and both are initiated by antigens Antigen illicit an immune response Humoral immunity involves creation fo antibodies by B lymphocytes Antibodies are formed in lymph tissue and attack matching antigens B cells develop in liver and mature in bone marrow When macrophages phagocytize a foreign invader the metabolize it and display its antigens at its surface If B cell with matching antibody protein nds this macrophage and helper T cells are present the B cell is activated T cell releases lymphokine that superaftivates B cell Upon activation B cell is differentiated into plasma cells and memory cells Plasma cells grow large and multiply and secrete antibodies Memory cells look jus tlike original B lymphocyte in case antigen comes back in the future This is all called the primary response requires 20 days to reach full effect once body acquires memory cells secondary response requires 5 days for full potential and usually makes body immune to particular disease Antibodies can activate a protein complement cascade which attracts macrophages and Neutrophils and activates them Can also rupture cell membrane of invader or cause them to agglutinate Activates basal cells and mast cells Antibodies can also cover toxic site of a toxin Cell mediated immunity T Cell immunity mature in Thymus Single T lymphocyte carries thousands of antibodylike proteins Proliferate into memory T cells and killer T cells when differentiated Memory cells are for the future Killer T cells bind to antigen carrying cell and secretes perforins to perforate cell membrane and cause lysis They kill many cells without dying themselves as they do not phagocytize but rather just puncture other cells Suppressor T cell prevents T cells from destroying healthy cells 4 major blood types A B AB 0 named for type of antigen the blood cell carries on its surface 0 blood has neither A nor B antigens A blood does not make A antibodies and so on for the rest 0 is universal donor AB is universal receptor as it does not make any antibodies A and B are codominant and expressed without blending or blood is Rh factor Rh positive can receive or blood as it doesn t make antibodies Rh does not have antigen on blood Important in pregnancy If pregnant woman is rh and fetus is Rh blood may mix in delivery causing blood to make antibodies Only a problem for future pregnancies and may cause anemia in it as antibodies can move through placental barrier Muscle functions body movement stabilization fo position moving substances through body generating heat to maintain body temperature Muscle cells can only pull Skeletal muscle cardiac and smooth are the 3 types Skeletal muscle voluntary Connect via tendons to bone Ligaments connect bone to bone Muscles function in agonistantagonist pairs Sarcomere is made of actin and myosin and is striated Actin thin filament and myosin thick lament Laid side by side to form sarcomere Many sarcomeres are stacked to form myo bril which is wrapped in sarcoplasmic reticulum which is double phospholipid bilayer Several wrapped are wrapped again by sarcolemma which is muscle cell membrane Muscle cell muscle fiber Skeletal muscle cell is multinucleated and cannot divide Sarcolemma has T tubules as tunnel like structures Action potential spreads into T tubules to rapidly deliver action potential to sarcoplasmic reticulum Parts of sarcomere that get smaller in contraction H zone and I band Tropomyosin blocks myosin heads from attaching Sarcoplasmic reticulum releases calcium when action potential comes and calcium enters cytosol and bind to troponin which is attached to tropomyosin to pull it back and reveal attachment site for myosin head Myosin head binds to actin and pulls hard ATP is needed to attach to myosin head to cause it to release the action ATP is hydrolyzed and bends back to original position In rigor mortis myosin head must stick to actin Body controls amount of muscular force using motor units Large motor units one neuron innervates many muscle fibers Motor units are red sequentially from small to large until desired force is reached Fingers have small motor units Back has large motor units Slow twitch type I slower to contract and slower to fatigue Less powerful Calf muscles have mnay of these fibers Biceps have many type II fibers Muscles grow by hypertrophy Cardiac muscle striated Uninucleated Not attached to a bone Connected via intercalated disks at their ends with gap junctions Involuntary innervated by autonomic nervous system just like smooth muscle Smooth muscle is not striated Two types of smooth multi unit and single unit Multi unit smooth muscle each fiber is capable of independent contraction Iris and piloerector muscles Usually innervated by one neuron Single unit smooth muscle hundreds of fiber contract as a single unit Syncytial arrangement just like cardiac muscle Sometimes also called visceral smooth muscle Bone is living tissue has many functions support of soft tissue protection of internal organs assistance in movement mineral storage blood cell production energy storage as adipose cells Body can resorb bone Fat is stored in bone marrow Long bones are curved for strength Short bones are Cuboidal ankle wrist Flat bones have large areas for muscle attachment sternum skulletc Compact bone surrounds all types of bones and made of osteons Forms when osteoclasts burrow through compact bone to form a tunnel Osteoblasts follow along sides of Osteon reforming bone as they go Spongy bone has red bone marrow which also contains adipose cells and macrophages Yellow bone marrow adipose tissue Blood lymph vessels and nerves are found in osteons Remodeling process of bone is continuous Cartilage is exible resilient connective tissue Made from collagen and chondroitin sulfate for elasticity to return to original shape Cells are called chondrocytes with no blood vessels or nerve except for parachondrion Joints are in any place two or more bones meet Fibrous cartilaginous and synovial are 3 types of joints Fibrous has little movement Cartilaginous has limited movement Synovial have much movement such as knees and elbows If both alleles are same for a characteristic homozygous If alleles are different heterozygous Expression of a trait phenotype Each gamete receives only 1 allele by a random process Law of segregation implies complete dominance Two traits are separate and do not blend to form the phenotype Alleles for a given characteristic are found at same locus on chromosomes and gamete receives only one of these Punnett squares are needed for MCAT Law of independent assortment alleles for different characteristic have equal likelihood of going to same or different gametes Only good for characteristics whose alleles are found on separate chromosomes Phenotype of dihybrid cross 933l Incomplete dominance blended expression Codominance both traits are exhibited AB blood type ie Complementarity two genes are mutually dependent upon each other to exhibit wild type Epistasis one gene in chain depends upon another but reverse is not true Collaboration two genes together produces a completely different phenotype Penetrance percentage of those individuals carrying a gene who also express its phenotype Expressivity how the phenotype is expressed Recessive mutations are abundant in populations Heterozygote advantage ie sickle cell anemia and malaria dynamic Inbreeding increases percent of homozygosity resulting in more homozygotic recessive diseases Males lack diploid protection for diseases at the sex chromosome Whatever a male receives from mom whether dominant or recessive he expresses that phenotype ie hemophilia or colorblindness In somatic cells in females one sex chromosome condenses into a Barr body in a random process ie calico cats If half cells express dominant allele dominant phenotype results Holandric traits found on y but not x chromosome Most common is the hairy pinna Evolution change in gene pool Not necessarily the change in phenotype King Philip Came Over from Germany Kingdom phylum class order family genus species Genus is capitalized and species is not Both written in italics Humans phylum chordate Class mammalia order primata Vertebrata is a subphylum of chordata Chordate o Bilateral symmetry Deuterostomes Coelom Notochord Pharyngeal slits Dorsal hollow nerve cord 0 Tail Niche is the way species exploits its environment No two species can occupy a niche indefinitely 0 One will always utilize the niche more effectively Species organisms which can reproduce fertile offspring in the wild Isolations prevent breeding and lead to development of new species Types of isolation geographic seasonal behavioral mechanical gametic incompatibility developmental isolation hybrid isolation Founder effect initial members that were isolated are different from remaining members Allopatric geographically isolated Sympatric share a habitat Fit surviving reproducing and ensuring that offspring reproduce K strategists o Ensures survival of offspring Few offspring Elephant Do well in stable habitats with higher competition for limited resources Better in density dependent factors 0 Growth curve is sigmoidal until carrying capacity R strategists 0 Many offspring Growth curve is sigmoidal until carrying capacity Better in density independent factors Frog For shortlived unpredictable habitats with plentiful resources Mate early Grow rapidly o Shorter life spans Divergent evolution as groups of same population develiop away from eachc other becoming more different Convergent evolution similar structures form on different species as they adapt to similar environmental issues Wings on bats and birds Structures are called homoplasties Mutualism both species benefit as in E coli and humans Commensalism one benefits and one is unaffected as in birds nesting in trees Parasitism one species benefits and the other is harmed OOOOO O O O O OOOOOO Hardy Weinberg gene pool is likely to remain constant under following conditions 0 OOOOO Mutation equilibrium Large population Immigration doesn t alter gene pool Random mate selection Reproductive success is random PA2 2pq qquot2 l Pql Q is recessive alleles and p is dominant alleles Pq is heterozygotes Universe came into being 1215 billion years ago Hot matter was thrown outwards in all directions outwards Solar system arose 10 billion years ago Earth formed 45 billion years ago Life arose 36 billion years ago in heterotrophic prokaryote Chemosynthesis then photosynthesis followed 5 million years ago ancestral line separated from chimpanzees 10k years ago first city was founded
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