Biology MCAT Complete Study Guide
Biology MCAT Complete Study Guide Biology MCAT
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Date Created: 12/03/14
BIOLOGY Enzyme structure and function e Function of enzymes in catalyzing biological reactions 0 Enzymes are catalysts which are things that increase the rate of a reaction but does not get used up during the reaction 0 Structure determines function A change in structure gt a change in func on 0 Important biological reactions catalyzed by enzymes Metabolism DNA synthesis RNA synthesis Protein synthesis Digestion Reduction of activation energy Free senersgy P Transition sztjate Ea 1 f Heaniztza nits P P atit r Pro IJIEIE ProgrE55 of reactiitirl rcatalrEeoi REateannt5 t39 3939 Prooi Iuizts Free ElFlEllgjl39 Fquotro grE55 of reaaztirt jab Enzymes decrease the activation energy Ea of a reaction by lowering the energy of the transition state Enzymes increase the rate of a reaction by decreasing the activation energy Enzymes will increase the rate constant k for the equation rate kAB Enzymes do NOT change the Keq of a reaction Enzymes do not change Keq because it lowers the activation energy for BOTH forward and reverse reactions Enzymes will make the reverse reaction go faster also Enzymes do not change AG the net change in free energy O O Krebs cycle Electron transport chain Steps of anaerobic metabolism don39t need oxygen 0 O Glycolysis Alcohol or lactic acid fermentation Aerobic metabolism of glucose 0 Complete oxidation of metabolite glucose to carbon dioxide 36 ATP produced per glucose C5H12O5 602 gt 6CO2 6H2O C6H12O5 this is glucose You get it from your diet 602 this is molecular oxygen that you breath in GCO2 this is carbon dioxide produced by the Krebs cycle Both the carbon and oxygen in this CO2 comes from the metabolite glucose 6H2O this is water produced in the electron transport chain The oxygen comes completely from the molecular oxygen that you breath in If we were to follow the carbon in the metabolite glucose it will end up in carbon dioxide If we were to follow the oxygen in the metabolite glucose it will end up in carbon dioxide If we were to follow the oxygen you breath in it will end up in water As for the hydrogens they39ll either be in water exist as protons in solution or be transferred to some other entity As we can see the total reaction involves complete oxidation of the metabolite glucose and complete reduction of molecular oxygen When electrons pass from the metabolite glucose to molecular oxygen energy is released The electron transport chain harnesses this energy Anaerobic metabolism of glucose 0 Partial oxidation of metabolite glucose to pyruvate 2 net ATP produced per glucose Pyruvate is then reduced to either alcohol or lactate Bacteria reduce pyruvate to alcohol in a process called alcohol fermentation Humans reduce pyruvate to lactate in a process called lactic acid fermentation Glycolysis anaerobic and aerobic substrates and products 0 Glycolysis convert glucose 6 carbons to 2 molecules of pyruvate 3 carbons Location cytosol 2 net ATP made for every glucose 2 input ATP 4 output ATP 2 NADH made for every glucose Occurs under both aerobic and anaerobic conditions Glycolysis is inhibited by ATP Aerobic decarboxylation mitochondrial matrix convert pyruvate 3 carbons to an acetyl group 2 carbons 1 NADH made for every pyruvate Only occurs in the presence of oxygen Acetyl group attaches to Coenzyme A to make acetyl CoA Anaerobic fermentation cytosol redox reaction reduce pyruvate oxidize NADH 1 NAD made for every pyruvate Alcohol fermentation pyruvate reduced to ethanol Lactic acid fermentation pyruvate reduced to lactate The purpose of anaerobic fermentation is to regenerate NAD which is needed for glycolysis Krebs cycle substrates and products general features of the pathway 0 O 0 Location matrix of mitochondria Acetyl CoA feeds into the cycle 3 NADH made per acetyl CoA 1 FADH2 made per acetyl CoA 1 ATP GTP made per acetyl CoA Coenzyme A is regenerated during the first step of the cycle Krebs cycle TCA Tricarboxylic acid cycle citric acid cycle all mean the same thing Krebs cycle is Inhibited by ATP and NADH Electron transport chain and oxidative phosphorylation substrates and products general features of the pathway 0 0 Location the cristae inner membrane of mitochondria Input NADH Proton gradient The electron transport chain ETC is essentially a series of redox reactions where NADH gets oxidized to NAD and 02 gets reduced to H20 The series of redox reactions consists of electrons passing from NADH to FMN to Coenzyme Q iron sulfur complexes and cytochromes cytochrome b c and aa3 before finally being used to reduce oxygen NADH is highest in energy while 02 is lowest in energy When electrons are passed from NADH down a series of proteins and finally to 02 energy is released FADH2 is lower in energy than NADH that39s why it releases less energy when it gets oxidized FADH2 skips FMN and passes its electrons to Coenzyme Q On a per gram basis fats give more energy than any other food source 0 Protein metabolism Proteins are broken down into amino acids by peptidases The nitrogen in the amino acid is converted to urea for desert animals birds and reptiles it is uric acid The carbon in the amino acid is converted to pyruvate or acetyl CoA or other metabolical intermediates such as oxaloacetate depending on what amino acid it is The carbon products from amino acid metabolisms can either feed into the Krebs cycle or be the starting material for gluconeogenesis DNA Structure and Function Watson Crick model of DNA double helix 0 The quotdoublequot in the double helix means that DNA is found in a double stranded form 2 single stranded chains of DNA stuck to each other via hydrogen bonding of the base pairs 0 The 2 singe strands are anti parale to each other Going from 539 to 339 of one strand means going from 339 to 539 of the other strand 0 The quothelixquot in the double helix means that the entire thing is wound up in a spiral DNA composition purine and pyrimidine bases sugars phosphate N h dtcnit1c 2 Tf1 jr39f1tiiit39lI E II r4 Et1anit1c z E5 Ejytosinc o A forms 2 hydrogen bonds with T o G forms 3 hydrogen bonds with C 0 GO bonds are stronger DNA with high GC content will be harder to break apart 0 Complementary strands of DNA hydrogen bond with each other 0 539 ATGC 339 will be complementary to 539 GCAT 339 or 339TACG 539 but NOT 539 TACG3 make sure you get the 539s and 339s right o Function in transmission of genetic information 0 Because of the complementary nature of base pairing DNA can transmit genetic information through replication 4 Replication occurs once every cell generation during the S phase Cell division may occur twice in meiosis but replication still occurs once only Semi conservative nature of replication 1 2 Newly synthesized DNA contains one old strand and one new strand Meselson and Stahl proved this by experiment Basically they used heavy 5N DNA as the old pre replication DNA and used light MN nucleotides for the synthesis of new DNA They can tell the difference between heavy and light DNA by centrifugation What they found was that when heavy DNA undergoes one round of replication in light nucleotides the DNA made is of intermediate weight After the second round of replication the DNA is split between intermediate and lightweight If DNA replication were completely conservative only heavy and light DNA would be seen and nothing in between This was not the case If DNA replication were dispersive everything would be of intermediate weight Again this was not the case because after the second round of replication light DNA was seen Repair of DNA Repair during replication 0 DNA polymerase has proof reading activity also called 339 gt 539 exonuclease activity If a wrong nucleotide gets incorporated the polymerase will quotback upquot and replace it with the correct one The special polymerase that replaces the RNA primers with DNA also have 539 gt 339 activity This allows the polymerase to clear away short stretches of incorrect nucleotides RNA or incorrect DNA and replace it with the right ones DNA This process is also called repair Repair of mutations O Mismatch repair enzymes recognize incorrectly paired base pairs and cuts out the stretch of DNA containing the mismatch Then polymerase re adds the correct nucleotides in During mismatch repair the repair enzyme must decide what strand of DNA to cut since DNA contains 2 strands To do this the enzyme cuts the DNA strand that do not have methylations The original old DNA has methylations but the newly synthesized DNA do not have them until 5 ht it T T an 3139l T T A a at 51ZltZljIquotEFlIdE 5quot Z t 3 muntends O 0 Some restriction enzymes cut to make sticky ends which can hybridize 0 Some restriction enzymes cut to make blunt ends which cannot hybridize o Hybridization o Hybridization also called annealing is where DNA strands base pair with each other 0 In Southern blotting DNA probes are used to hybridize onto DNA fragments containing a target sequence 0 In gene cloning hybridization refers to the process where sticky ends from a restriction fragment of a gene base pairs with the same sticky ends on a plasmid See below for a diagram of this Gene cloning o The plasmid must have a restriction site because you need to open it up for the insertion of your gene 0 The plasmid must have an origin of replication because you want to clone your gene which is inside your plasmid o The plasmid must have an antibiotic resistant gene because this lets you kill competing useless bacteria that doesn39t have your plasmid When you add an antibiotic only the bacteria with the antibiotic resistant plasmid will live 0 Plasmids replicate independently of the genomic DNA of the bacteria PCR 1 I239Ena39ttIrH39tian 2 unnaaailing 3 Elongation E A r 5 El quot1 539 339 539 5 3 A F 7quot 1quot ll 3 E9 E3 5 3 5 A at Fiep aa t rl cycles 239 2 mpIi iica39Iioan o Denaturation heat 90 C to separate double stranded DNA template 0 Annealing cool reaction in order for primers to anneal to the now single stranded DNA template Excess amount of primers so they out complete re annealing of the template strands o Elongation use heat stable polymerase to extend the primers 0 Repeat steps 1 to 3 for n cycles The resulting amplification of the original DNA template after n cycles is 2 Genetic code Central Dogma DNA gt RNA gt protein 1 DNA resides in the nucleus It codes information in genes 3 The codon anticodon relationship During translation codons pair with anticodons so that the correct amino acids can be linked to a given codon Missense nonsense codons 1 Missense codon mutated codon that results in a different amino acid 2 Nonsense codon mutated codon that results in something other than an amino acid For example a stop codon Initiation termination codons function codon sequences 1 Initiation codon AUG signals the start of translation Lies just downstream of the Shine Dalgarno sequence Kozak sequence for eukaryotes 2 Termination codon UAGUGAUAA signals the end of translation Unlike other codons tRNA are not involved Instead a protein called quotrelease factorquot comes along and terminates translation Transcription Eukaryotic mRNA 539 cap nucleotides 339 polyA Prokaryotic mRNAs don39t have the 539 cap or polyA tail rRNA composition and structure eg RNA nucleotides Both tRNA transfer RNA and rRNA ribosomal RNA are products of transcription However they do not serve as the template of translation tRNA is responsible for bringing in the correct amino acid during translation rRNA makes up the ribosome which is the enzyme responsible for translation tRNA is made of nucleotides many of which is modified for structural and functional reasons At the 339 end of the tRNA the amino acid is attached to the 339OH via an ester linkage tRNA structure clover leaf structure with anticodon at the tip and the amino acid at the 339 tail rRNA is made of nucleotides many of which is modified for structural and functional reasons rRNA is highly structured because it contains the active site for catalysis The rRNA of the large ribosomal subunit is responsible for catalyzing peptide bond formation and can do this even without ribosomal proteins o Mechanism of transcription RNA polymerase promoters primer not required 0 0 Chain Initiation RNA polymerase binds to the promoter TATA box of the double stranded DNA closed complex The double stranded DNA template opens up open complex Chain elongation nucleoside triphosphates AUGCs adds corresponding to the DNA template No primer is required RNA elongates as the RNA polymerase moves down the DNA template RNA is made from the 539 to 339 direction Chain termination there are 2 ways that transcription can terminate 1 Intrinsic termination specific sequences called a termination site creates a stem loop structure on the RNA that causes the RNA to slip off the template Rho p dependent termination a protein called the p factor travels along the synthesized RNA and bumps off the polymerase Role and structure of ribosomes O O Ribosome is the enzyme that catalyzes protein synthesis Ribosome has 2 subunits the large and the small The large subunit is responsible for the peptidyl transfer reaction The small subunit is responsible for the recognizing mRNA and binds to the Shine Dalgarno sequence on the mRNA Kozak sequence for eukaryotes Both subunits are needed for translation to occur and they come together in a hamburger fashion that sandwitches the mRNA and tRNAs in between o Mechanism of translation 0 Chain Initiation To begin translation you need to form the initiation complex The initiation complex is basically an assembly of everything needed to begin translation This includes mRNA initiator tRNA fmet and the ribosome initiation factors and GTP aids in the formation of the initiation complex The initiation complex forms around the initiation codon AUG which is just down stream of the Shine Dagarno sequence The Shine Dalgarno sequence is the quotpromoterquot equivalent of translation for prokaryotes Kozak sequence for eukaryotes Chain Elongation protein is made from the N terminus to the C terminus mRNA codons are read from the 539 to the 339 end Elongation consists of 1 Binding new tRNA with its amino acid tRNAamino acid is called aminoacyl tRNA enters the A site GTP and elongation factor required 2 Peptidyl transfer attachment of the new amino acid to the existing chain in the P site The mechanism is a little strange what happens is that the already existing chain in the P site migrates and attaches to the aminoacyl tRNA in the A site 3 Translocation the lone tRNA in the P site gets kicked off E site and the tRNA in the A site along with the peptide chain attached to it moves into the P site The mRNA gets dragged along also the codon that was in the A site is now in the P site after translocation The A site is now empty and ready for the binding of a new Trwanslatin Elnguatian Tlf lfl si ih GP Pi g A Eukaryotic chromosome organization Chromosomal proteins 1 Histones responsible for the compact packing and winding of chromosomal DNA DNA winds itself around histone octamers 2 nonhistone chromosomal proteins all the other proteins are lumped together in this group Responsible for various roles such regulatory and enzymatic Telomerescentromeres 1 Telomere the 2 ends of the chromosome 2 Centromere a region on the chromosome can be at the center or close to one of the ends After replication sister chromatids are attached at the centromere During mitosis spindle fibers are attached at the centromere and pulls the sister chromatids apart A common question is what is the difference between chromatin and chromosome The answer is chromatin is the quotstuffquot that chromosomes are made of If the chromosome is a cotton shirt then chromatin is cotton Control of gene expression in eukaryotes Transcription regulation 0 Transcription factors protein bind to enhancers or silencers DNA to affect transcription Enhancers increase transcription when bound while silencers decrease it The main difference in eukaryotes that sets them apart from prokaryotes is that enhancerssilencers can be very far away from the actual promoter and can be upstream or downstream The DNA must loop back on itself so that the transcription factor bound to enhancersilencer can actually make contact with the promoter Intermediate proteins are involved in the process 0 Eukaryotes lack the bacterial transcription regulation mechanisms such as the operon exists but very rare and attenuation DNA binding proteins transcription factors 0 DNA binding proteins bind to DNA 0 transcription factors bind to DNA so they have a DNA binding domain RNA splicing sequences called introns are cut out sequences called exons are kept and and spliced joined together Alternate splicing different ways of cutting up and RNA and rejoining the exons pieces make different final RNA products 539 capping and 339 polyA tail these help to protect the RNA from degradation so they can last longer After the correct modifications RNA is transported out of the nucleus where they can function in translation After some time RNA is degraded The rate and timing of RNA degradation can be controlled by the cell Mendelian concepts Phenotype and genotype 0 Phenotype what is observed For example height color whether the organism exhibits a trait Genotype the genetic make up For example homozygous dominant TT heterozygous Tt homozygous recessive tt Gene a gene is a stretch of DNA that codes for a trait In molecular biology the gene codes for a protein which acts to bring about a trait Locus location of a gene on a chromosome Allele single and multiple 0 An allele is a variant of a gene A gene may have a number of alleles All alleles of the same gene exist at the same locus A cell holds 2 alleles of each gene One allele from mom one allele from dad When a gene has only 2 alleles then that39s the simple case we39re used to seeing For example the trait for height in peas is governed by T and t TT and Tt gives tall plants and tt gives short ones When a gene has more than 2 alleles then that39s called multiple alleles For example blood type is governed 3 alleles IA IB and i Because a cell can only hold 2 of these alleles the different combinations an individual can have are Incomplete dominance leakage penetrance expressivity o Incomplete dominance notype henotype between A and B An example of incomplete dominance is the color of chickens A cross between black chickens and white chickens give rise to bluish grey chickens o leakage gene flow from one species to another 0 Penetrance is the frequency that a genotype will result in the phenotype 100 penetrance means that if you have the genes for being smart then you39ll definitely be smart Less than 100 penetrance means that you may have the genes for being smart but you may not actually be smart o Expressivity is to what degree a penetrant gene is expressed Constant expressivity means that if your genes for being smart manages to penetrate show up as a trait then your IQ is 120 Variable expressivity means that your IQ doesn39t have to be 120 it could be somewhat lower or somewhat higher Gene pool all of the alleles in a population Meiosis and genetic variability Significance of meiosis meiosis introduces genetic variability by genetic recombination Genetic recombination is the product of independent assortment and crossingover which introduces genetic variability o Crossing over occurs during prophase I the actual site of cross over is the chiasma The chiasma is made possible because of pairing of homologous chromosomes called the tetrad which is formed by a process called synapsis 0 single crossovers results in genetic recombination The chromatids involved in this single crossover exchange alleles at a given locus Results in 24 recombinants 0 double crossovers Scenario 1 results in no genetic recombination The chromatids involved in this double crossover exchange alleles at first but then it exchanges them back resulting in no net recombination This is called the 2 strand double crossover Results in 04 recombinants Scenario 2 results in genetic recombination The chromatids exchange alleles during a crossover Then one of the crossover chromatid exchanges with a different chromatid This is called the 3 strand double crossover Results in 24 recombinants Scenario 3 results in genetic recombination The chromatids exchange then 2 totally different chromatids on the same chromosome exchange This is called the 4 strand double crossover Results in 44 recombinants Sex linked characteristics gene for the characteristic is on the X chromosome 0 very few genes on Y chromosome The Y chromosome is very small and carries few genes of importance All the sex linked alleles are carried on the X chromosome 0 sex determination XX female XY male 0 cytoplasmic inheritance Mutation Cytoplasmic inheritance inheritance of things other than genomic DNA All cellular organelles such as mitochondria is inherited from the mother o inborn errors of metabolism genetic diseases resulting in faulty metabolism For example PKU Phenylketonuria is an inborn error of metabolism where people can39t metabolize phenylalanine There39s no cure but the treatment involves avoiding things containing the amino acid phenylalanine 0 relationship of mutagens to carcinogens Mutagen something that causes mutation Carcinogen something that causes a mutation that causes cancer Carcinogens are almost always mutagens Exception some are direct mitogens increase mitosis Not all mutagens are carcinogens Analytic methods o Hardy Weinberg Principle 0 pq1 o pq21gtp22pqq21 0 Five Assumptions of Hardy Weinberg Infinitely large population no genetic drift No mutation No migration Random mating no sexual selection No natural selection Test cross back cross concepts of parental F1 and F2 generations 0 Test cross so you have something with dominant phenotype It could either be Aa or AA To find out you cross it with the homozygous recessive aa If Aa half the offspring will express the recessive phenotype If AA no offspring will express the recessive phenotype Self replicating biological units that must reproduce within specific host cell Viruses can not replicate by themselves They depend on the host39s replication organelles to replicate The host39s ribosomes will make the necessary protein coats and polymerases that replicate the viral genetic material Retroviruses contain their own reverse polymerase to convert RNA to DNA before the host39s polymerases take over Generalized phage and animal virus life cycles 0 attachment to host penetration of cell membrane or cell wall and entry of viral genetic material use of host synthetic mechanism to replicate viral components Host39s ribosomes synthesize the necessary enzymes Host39s ATP provides necessary energy The host also provides the raw materials such as nucleotides and amino acids self assemby and release of new viral particles The coat proteins and viral genetic material will assemble into viral particles all by themselves Retrovirus life cycle integration into host DNA 0 0 First retrovirus enters the host The viral reverse transcriptase then converts the viral RNA genome into double stranded DNA A virally encoded enzyme called integrase adds in the viral DNA into the host39s genome at a random place When the host replicates the viral DNA gets replicated also o Transduction transfer of genetic material by viruses 0 0 Virus infects cell host DNA degraded into fragments viral DNA takes over control Host DNA fragment gets packed into virus progeny by accident Virus progeny infects another cell injects previous host39s DNA fragment Fragment enters cell find its homologous counterpart and crossover Prokaryotic cell structure bacteria Transduction bacteriophages undergoing Iysogenic life cycle incorporate the viral DNA into the bacterial genome Conjugation Bacteria transfer DNA between one another through the sex pilus o Exponential growth Bacterial growth starts off being exponential because of the nature of binary fission Later when food becomes short and it gets crowded growth slows and eventually plateaus Existence of anaerobic and aerobic variants Obligate aerobe must have oxygen for growth Obligate anaerobe dies when oxygen is present Facultative anaerobe doesn39t need oxygen for growth but grows better with oxygen Symbiotic relationships 0 O Parasitic bacteria benefits at the expense of the host Disease causing bacteria are examples of parasitic relationships Mutualistic both bacteria and host benefits For example the E Coli in your gut the natural flora on your skin Commensalistic one benefits while the other has no effect Prokaryotic cell genetics Existence of plasmids extragenomic DNA transfer by conjugation O Plasmids are double stranded DNA A plasmid can exist and replicate independently of the genomic DNA or be integrated into it Plasmids are inherited Plasmids are not essential for growth and reproduction in the wild Conjugation transfers genetic material between bacteria via a pillus A bacteria able to make the pillus F has a plasmid that contains the pillus genes transcribing mRNA causes the Trp mRNA transcription to terminate Because Trp is not needed When cell is starved of Trp translation occurs slower because Trp amino acid is lacking This slower ribosome movement across the transcribing mRNA causes the Trp mRNA to be made to its completion Nucleus o Defining characteristics membrane bound nucleus presence of organelles mitotic division 0 Defining characteristics what sets eukaryotes apart from prokaryotes o Eukaryotes have a true nucleus membrane bound while prokaryotes don39t 0 Eukaryotes have membrane bound organelles ER Golgi lysosomes mitochondria prokaryotes don39t 0 Eukaryotes divide by mitosis all them chromosomes line up and stuff prokaryotes undergo binary fission no chromosomes just a circular ring of DNA no need for complex mitosis o Nucleus compartmentalization storage of genetic information o compartmentalization nuclear membrane nuclear envelope surrounds the nucleus 0 genetic information is stored inside the nucleus as DNA Nucleolus location and function 0 location is a region inside the nucleus 0 function is to transcribe ribosomal RNA rRNA Nuclear envelope nuclear pores 0 nuclear envelope is a double membrane system made of an outer and an inner membrane Also called nuclear membrane 0 nuclear pores are holes in the nuclear envelope where things can pass into and out of the nucleus Transcription occurs in the nucleus and those transcribed RNA need to pass out of the nucleus Things like transcription Endoplasmic reticulum o rough RER and smooth SER rough ER has ribosomes studded over it smooth ERs don39t RER deals with protein synthesis folding modification and export SER deals with biosynthesis of lipids and steroids and metabolism of carbohydrates and drugs In the muscles the SER or SR stores and regulates calcium 0 RER site of ribosomes the ribosomes attach to the outside of rough ER and synthesis protein into the lumen o role in membrane biosynthesis SER lipids RER transmembrane proteins SER makes lipids of the plasma membrane RER makes transmembrane proteins carries them on its membrane RER membrane forms vesicles and bud off fuses with the plasma membrane transmembrane proteins now on the plasma membrane 0 RER role in biosynthesis of transmembrane and secreted proteins that cotranslationally targeted to RER by signal sequence Transmembrane proteins or proteins that are to be secreted need RER vesicle have a signal sequence right at the beginning When ribosome starts making those proteins they make the signal sequence first Signal sequence recruits a signal recognition particle that drags it to the RER ribosome now on the RER continues making the protein but snakes it into the lumen Signal sequence is clipped off 0 All ERs have a double membrane and is connected to the nuclear membrane an old aamc topic no longer tested 0 Cell signaling pathways Contact signaling physical contact triggers a change inside cell Chemical signaling chemical binding to receptor triggers a change inside cell Nerves use neurotransmitters The endocrine system use hormones Electrical signaling change in membrane potential triggers change in cell Action potential along neurons propagates and cause release of neurotransmitters into synapse Action potential along muscle cell membrane causes contraction o Membrane potential the resting potential of the cell membrane is negative because of the sodium potassium pump Exocytosis and endocytosis exo getting stuff out endo taking stuff in Cell cell communication General concepts of cellular adhesion 0 gap junctions connects two cells and allows stuff to flow through between the cells 0 tight junctions stitchesglues two cells together and does not allow stuff to flow through between the cells A series of cells with tight junctions also effectively forms an impermeable barrier o desmosomes connects two cells together by linking their cytoskeleton They are organized for mechanical strength not an impermeable barrier Cytoskeleton General function in cell support and movement o Microfilaments composition role in cleavage and contractility 0 made of actin o responsible for cytokinesis Supports cell shape by bearing tension lnterphase and mitosis prophase metaphase anaphase telophase o lnterphase G1 Growth S Synthesis replicate DNA G2 Growth 0 Prophase Prepare condense chromatin into chromosomes break down nuclear membrane assemble mitotic spindle centriole pairs move toward opposite poles of the cell 0 Metaphase Middle Chromosomes line up in the middle 0 Anaphase Apart Sister chromatids pulled apart to opposite sides of cell 0 Telophase Prophase in reverse de condense chromosomes re form nuclear membrane break down mitotic spindle Mitotic structures and processes 0 centrioles asters spindles responsible for pulling apart the sister chromatids o chromatids centromeres kinetochores sister chromatids are duplicated copies of the chromosome chromatids are joined at the centromere There39s a protein at the centromere called the kinetochore where spindle fibers attach to pull the chromatids apart 0 nuclear membrane breakdown and reorganization for most eukaryotes the nuclear membrane breaks down at the beginning of mitosis and reforms at the end of mitosis around each of the two newly formed nuclei 0 mechanisms of chromosome movement chromatids move apart during anaphase by the spindle fibers Microtubules cause the chromosome movement Phases of cell cycle G0 G1 8 G2 M 0 G0 no more DNA replication or cell division Examples include nerves and muscles 0 G1 growth make organelles increase in cell size O 0 Contains nucleus and organelles just like any other cell Has well developed RER and golgi makes a lot of proteins Axon structure function 0 O O Axon Conducting region of the nerve Axon terminals secretory regions of nerve Other names for axon terminal synaptic knob bouton Dendrites structure function 0 O Receptive region of the nerve gets input The branching helps to increase the surface area for reception Myelin sheath Schwann cells oligodendrocytes insulation of axon O Myelin sheath Covers the axon intermittently with gaps called nodes of Ranvier The purpose of myelin sheath is to speed up conduction by insulating the nerve in intervals This intermittent insulation causes action potential to jump from one node of Ranvier to the next Schwann cells makes myelin sheath in the peripheral nervous system by wrapping around the axon Oligodendrocytes the central nervous system analogue of Schwann cells makes myelin sheath around CNS axons Insulation of axon achieved by the myelin sheath Insulation occurs in intervals which causes action potential to jump from one node of Ranvier to the next Myelin sheath is a good insulator because it is fatty and does not contain any channels Nodes of Ranvier role in propagation of nerve impulse along axon O 0 Action potential jumps from one node of Ranvier to the next This jumping of action potential speeds up conduction in the axon Synapse site of impulse propagation between cells trigger a full fledged all ornothing action potential in the postsynaptic neuron Neurotransmitters are quickly eliminated destroyed by enzymes reuptake by presynaptic terminal or diffuse away so that they don39t persistently stimulate the postsynaptic neuron Neurotransmitter molecules Acetylcholine ACh Norepinephrine NE Dopamine Serotonin Histamine ATP 0 synaptic knobs Synaptic knob is another name for axon terminal Contains vesicles of neurotransmitters waiting to be exocytosed Action potential reaching the synaptic knob causes an influx of calcium which signals the vesicles to fuse with cell membrane exocytosis to release the neurotransmitters into the synaptic cleft o fatigue Continuous synaptic activity gt depletion of neurotransmitters gt fatigue 0 propagation between cells without resistance loss Action potential is all or nothing As long as the neurotransmitters cause the postsynaptic cell to reach a certain threshold potential the action potential induced is just as large as the presynaptic action potential In summary propagation between cells involves no resistance loss because the postsynaptic action potential is just as large as the presynaptic potential all action potentials are all or nothing 0 Stages of an action potential Resting cell at rest sodium potassium pump maintaining resting potential 70 mV Lots of sodium outside lots of potassium inside Ion channels closed so the established ion gradient won39t leak Depolarization sodium channels open positive sodium rushes inside membrane potential shoots up to 30 mV Lots of sodium inside lots of potassium inside Repolarization potassium channels open sodium channels close positive potassium rushes outside membrane potential drops back down Lots of sodium inside lots of potassium outside opposite of the resting state Hyperpolarization potassium channels doesn39t close fast enough so the membrane potential actually drops below the resting potential for a bit Refractory period the sodium potassium pump works to re establish the original resting state more potassium inside sodium outside Until this is done the neuron can39t generate another action potential Absolute refractory period from depolarization to the cell having re established the original resting state Relative refractory period After hyperpolarization till resting state re estabished o thresholdall or none When a stimulus graded potential depolarizes above a threshold value an action potential will occur Action potentials are al or none meaning that if it occurs all action potential have the same magnitude One graded potential just barely makes the threshold value another overshoots it a lot but both will cause the same action potential 0 sodium potassium pump 3 sodium out 2 potassium in net positive out 0 Cross bridge myosin head binds to actin o Sliding filament model Cross bridge forms myosin head bends power stroke causes actin to move slide in the direction of the power stroke toward the M line When all the actin slide toward the M line like this the muscle fiber contracts 0 Something oounter intuitive about the sliding filament model ATP is not directly needed for the powerstroke ATP binding is needed for detachment of myosin head to actin ATP hydrolysis is needed for de powerstroke unbend myosin head 0 Rigor mortis no ATP after a person dies myosin heads can39t detach after power stroke muscle remain in contracted position 0 So what is troponin and tropomyosin there for Ans tropomyosin on actin blocks the myosin head from forming cross bridges However troponin moves tropomyosin out of the way at high Ca2 levels Ca2 binds to troponin and troponin moves tropomyosin Calcium regulation of contraction sarcoplasmic reticulum va2i EartzolEmma I re E 39 quotquot4H H 39I quot VI 3939 b 391 1quot 1 3 39 39 E L 39 E H AP 1 Action Potential GP redetl Poteential quota n l AP down TiLl139UEquotEFi E39E5SErquotiIZ release IIaET D 391 TTubuIe 5H IET5Err139IairIna Eisrtrernael o Sarcoplasmic reticulum SR smooth ER in muscle stores calcium releases them in response to AP 0 The SR is also called terminal cisternae where it meets T tubues at the edges of the sarcomere Collagen the most common fiber type Very strong Present in large amounts in dense connective tissue Elastic fibers can stretch Reticular fibers can branch and form nets Found in loose connective tissue 0 loose vs dense Loose loose fibers lots of fluff ground substance cells anything that you don39t associate with being fibrous fat paddings around organs Dense dense fibers predominantly collagen genuinely fibrous little fluff ground substance cells tendon ligament o Cartilage chondrocytes matrix elastic flexible used as padding in spinal discs ends of bones ear 0 Extracellular matrix secreted by cells ground substance glue and fibers Endocrine system Hormones o Function of endocrine system specific chemical control at cell tissue and organ level 0 Endocrine system make hormones specific control of all target cells of that hormone o Definition of endocrine gland hormone o endo within crine to secrete o endocrine glands secreting hormones into surrounding tissue fluids 0 endocrine vs exocrine autocrine paracrine endocrine hormone no duct acts long distances exocrine non hormone secretions into ducts autocrine local chemicals act short distances on themselves paracrine local chemicals act short distances on other cells o Pituitary makes FLAT PEG stores ADH and oxytocin FSH Follicle Stimulating Hormone Stimulate ovary follicles to mature testis to produce sperm LH Luteinizing Hormone LH surge triggers ovulation stimulates testis to produce testosterone ACTH AdrenoCorticoTropic Hormone Stimulates adrenal cortex to release glucocorticoids and mineralocorticoids TSH Thyroid Stimulation Hormone Stimulate thyroid to release thyroid hormones PRL Prolactin Stimulates breast to produce milk E Endorphins GH Growth Hormone Stimulates growth of muscle bone burns fat 0 Pineal makes melatonin which makes you sleepy at night 0 Thyroid Thyroid hormones increase metabolism requires iodine Calcitonin turns blood Ca2 into bone Lowers blood Ca2 o Parathyroid makes Parathyroid Hormone PTH which increases blood Ca2 by bone resorption dietary calcium absorption and calcium reabsorption in kidneys o Thymus Thymus hormones thymo thymic stimulates T cells to develop 0 Adrenal Epinephrine and norepinephrine fight or flight response Mineralocorticoids aldosterone increase Na and water retention raises blood pressure Glucocorticoids cortisol stress hormone increase blood sugar Androgens testosterone o Acromegaly too much Growth Hormone later on in life disproportioned growth of certain areas of the body the parts that still respond to growth hormone Major types of hormones 0 amino acid based amino acid derivatives most hormones are this type 0 steroids cholesterol derivatives testosterone estrogen adrenocortical hormones Endocrine system Mechanisms of hormone action Cellular mechanisms of hormone action 0 water soluble hormones Can39t cross the plasma membrane Bind to membrane receptors on the outside of cells Secondary messengers then relay the signal inside the cell 0 lipid soluble hormones Able to cross the plasma membrane Directly activate genes 0 cAMP pathway Amino acid hormone binds membrane receptor G protein activated Adenylate cyclase activated cAMP made Protein kinase cascade o Phospholipid pathway Amino acid hormone binds membrane receptor G protein activated 0 visual image processing The lens of the eye just like a convex lens in physics forms a real image on the retina Real images are inverted The brain processes this inverted image to make it seem upright in your mind The brain combines the two images from each eye to make a 3D image from which you can judge distance Another reason for combining the two images from both eyes is that it gets rid of the blind spot in each eye Circulatory System o Functions circulation of oxygen nutrients hormones ions and fluids removal of metabolic waste 0 Oxygen delivery to tissues 1L 2 3 4 diffuses into the blood in alveolar lung capillaries binds to hemoglobin in red blood cells gets transported to tissues used in cellular respiration 0 Carbon dioxide delivered out 1 3 4 cellular respiration makes CO2 carbonic anhydrase converts it to bicarbonate CO2 gets transported by blood dissolved CO2 dissolved bicarbonate ion major bound to hemoglobin and plasma proteins diffuses out of the alveolar capillaries exhaled out o Nutrients 1 nutrients absorbed either by diffusion or active transport into blood stream in the small intestines Four chambered heart structure function Lung5 Pulmona rt F39ulIquotriorn an F3 ti in iaf39iEl3I39 F Higltt atrium Ht Right isantriclie Ln Left atriu irr Li39I39 Left went ricaE n 39fFrIEl High ire55ure 1 P S rteriies 1 Q 0 S Tl39lIELJE Ii2l iraliiE J R lfiiu iiIll 39Ii 39ii39E39 i39I I 39rquot 395 p Q En HE iJ A tE 39 95 L F39ulI1quoticaitarg value 39L 39lElliiE395 P P 393lIZi1l ii iZ valve L t pressure 0 Deoxygenated blood returns to the heart superiorinferior vena cava gt right atrium O Deoxygenated blood gets pumped to the lungs right atrium gt right ventricle gt pulmonary artery gt lungs 0 Blood arrives at the lungs and gets oxygenated O Oxygenated blood returns to the heart lungs gt pulmonary vein gt left atrium O Oxygenated blood gets pumped to the body left atrium gt left ventricle gt ao a Blood going through the heart including the valves 0 Vena cava 0 Right atrium Large pores facilitate lymphocyte travel to tissues Large pores also facilitate blood cell modifications 0 mechanism of heat exchange 1 radiation your body gives off IR signal 2 conduction you touch something cold or take a hot bath 3 evaporative cooling you sweat and it cools you as it evaporates 0 source of peripheral resistance no longer tested 1 Blood viscosity blood cells and plasma proteins give blood a higher resistance to flow compared to water Diseases that increase the amount of blood cells increase resistance 2 Total blood vessel length more blood vessels you have the more resistance to flow Overweight more blood vessels to service the fat cells more resistance 3 Blood vessel diameter vasoconstriction increases resistance vasodilation decreases it Obstruction from plaques inside blood vessels also increases resistance Composition of blood F la5Iquotiquotia Huffy cat 39Ii39lquotEiI 5 platelets Cent rifugiation Elf HEC5 0 plasma chemicals blood cells 1 plasma water and chemicals mostly water plasma proteins electrolytes gases nutrients wastes hormones 2 blood cells red blood cells RBCs or erythrocytes contain hemoglobin transports O2 and CO2 no nucleus which gives it a biconcave disk shape most abundant cell in blood white blood cells WBCs or leukocytes larger than RBCs lobed or irregular shaped nuclei fights off pathogens platelets technically not cells but cell fragments responsible for clotting blood 0 erythrocyte production and destruction spleen bone marrow 1 2 Bone marrow makes RBCs from stem cells Spleen destroys aged and damaged RBCs Other sites for RBC destruction include the liver and bone marrow Components of hemoglobin from destroyed RBC gets recycled iron recycled heme gt bilirubin gt bile gt excreted in feces protein globin broken down to amino acids 0 regulation of plasma volume 1 Blood osmolarity Higher blood osmolarity gt water goes into blood gt higher blood volume Lower blood osmolarity gt water goes into tissues gt lower blood volume 2 ADH vasopressin 1 water reabsorption in kidney 3 Aldosterone 1 salt reabsorption leads to 1 water reabsorption in kidney 3 each RBC has hundreds of millions of hemoglobin molecules 0 oxygen affinity 1 4 hemoglobin has a sigmoidal oxygen binding curve This is because oxygen binding to one subunit quotrelaxesquot the conformation of the other subunits and makes it easier for additional oxygen to bind carbon monoxide binds hemoglobin tighter than oxygen fetal hemoglobin binds oxygen tighter than adult hemoglobin myoglobin binds oxygen tighter than hemoglobin Details of oxygen transport biochemical characteristics of hemoglobin 3 H39Elquotl39I rEgi bin Eaituratirnn nu fr Elli fcaglohin 3tlerr1aigaIziiri rm2 iIIl irt lw quot39 39l39 lg E1 39t ic1i high Ii3g Pg 0 modification of oxygen affinity 1 Higher levels of carbon dioxide gt lower oxygen affinity of hemoglobin Lower pH gt lower oxygen affinity Higher temperature gt lower oxygen affinity Working muscle hot acidic high CO2 needs oxygen So hemoglobin must unload its oxygen and it does this by lowering its oxygen affinity Lymphatic System Major functions 0 equalization of fluid distribution Basic aspects of innate immunity and inflammatory response Innate first line of defense kills anything that doesn39t look right not specific to a particular pathogen antigen 0 Skin natural flora layer of keratin Mucus membranes traps pathogen in mucus and cilia moves it out Phagocytes engulf pathogen Natural killer cells destroy infected cells Antimicrobial proteins tears lyse bacteria interferons interfere with virus replication complement punches holes in cellpathogen membrane Feverinflammation WBCs are more active at higher temperature and inflammation recruits WBCs to site of infection by sending out chemical signals and making capillaries more permeable Adaptive immunity highly specific for a particular pathogen antigen 0 antigen presenting cells present foreign antigen on their surface antigen is recognized by T and B cells cytotoxic T cells kill infected cells helper T cells activate macrophages T and B cells B cells produce antibodies antibodies bind to antigens and bring about neutralization pathogen can39t adhere to host cell opsonization makes it easier for phagocytosis complement activation kills infected cell by punching holes in cell membrane memory cells are made that are much more efficient does not need T cell activation in proliferating and making antibodies in case the same infection strikes in the future 0 memory cells allow the body to mount a greater and more sustained response against the same pathogen during secondary response econdary re5pruse Iquotl39 lquotl39 lU FIFE FEE FEiquotI SE F ir i 39iarfgf restinse W p p time Fi rst enizurrter 5 u hs quanti 1E riu1uritEr with El pathogen with the aaufne patl It21irErI Concept of antigen and antibody 0 Antibody lock Antigen key Each antibody is specific to the binding of an antigen 0 Antibody is like a Y the tips of the fork bind antigen 0 The tips of the fork are called hypervariable regions because they are unique to each antigen specific antibody 0 The antibody consists of 2 light chains and 2 heavy chains linked together by disulfide bonds Structure of antibody molecule Ar ger quotlee i Hf5fIquot F IquotT39IHE39iiE I region intulca Heat gr zltairi Mechanism of stimulation by antigen antigen presentation 0 pathogen enters antigenpresentingcell APC 0 pieces of the pathogen gets displayed at the surface of APCs o T cell receptors recognize the presented antigen and activates various immune responses scenario 1 extracellular pathogen o macrophage engulfs pathogen 0 pieces of the pathogen becomes the antigen and gets presented at the macrophage39s cell surface 0 helper T cells recognize the presented antigen and activates macrophages to destroy pathogen Helper T cells also activate B cells to produce antibodies against the pathogen scenario 2 intracellular pathogen o pathogen invades host cell 0 pieces of the pathogen gets presented on the host cell surface 0 cytotoxic T cells recognize the presented antigen and signals the infected cell to self destruct General structure and function gas exchange thermoregulation o In lungs oxygen diffuses into blood Carbon dioxide diffuses out of blood 0 The mechanism of this gas exchange follows Henry39s law which basically says that there is an equilibrium concentration of oxygen that should be dissolved in blood 0 When blood reaches the lungs it has less than the equilibrium concentration of oxygen because the body used the oxygen up Therefore oxygen diffuses into blood 0 The CO2 in blood that reaches the lungs is higher than the equilibrium concentration because of the body releases them Therefore CO2 diffuses out of blood 0 Thermoregulation breathing causes you to lose heat you breath out warm moist air protection against disease particulate matter o Nostril hair filters out particles 0 Mucus lining of respiratory tract traps pathogens and particles 0 Cilia on mucus lining of respiratory tract sweeps pathogen and particles out where you either spit it out or swallow it into stomach acid 0 Macrophages reside in alveoli Breathing mechanisms heat wall rii Iage lrrtraleural saute lquotE39gtll39 E Pressure Lung reat hi Pig F Elia hragm diaphragm rib cage differential pressure 0 Diaphragm muscle that pulls downward when contracting which increases chest volume decreases pressure and sucks air into lungs 0 Rib cage expands outward during breath intake lntercostal muscles help this expansion At rest the rib cage maintains lung volume prevent lung from collapsing forms a cage around lungs for protection 0 Differential pressure difference between intrapulmonary inside lung pressure and intrapleural outside lung pressure lntrapulmonary pressure atmospheric pressure lung is open to the outside so has same pressure as outside lntrapleural pressure less than atmospheric pressure sucks on the lungs prevent lung from collapsing During breath intake intrapleural pressure decreases even further causing the lung to expand 0 Negative pressure mechanism in breathing is just a fancy term for sucking You breathe in by establishing negative pressure in the lung sucking However when someone gives you mouth to mouth that39s positive pressure resiliency and surface tension effects 0 Lung is elastic it recoils as soon as you relax after breath intake If not for the rib cage the lung would collapse even further Surface tension causes the lung to collapse Surfactants produced in the alveoli decreases surface tension and helps alveoli to stay open Functions in homeostasis and osmoregulation Heat homeostasis Too cold hair stands up goose bumps vasoconstriction decreases blood supply at skin less heat loss Too hot sweat evaporative cooling vasodilation increases blood supply at skin more heat loss Water homeostasis lnsulates body against water loss Osmoregulation sweat excretes salts and nitrogenous wastes urea uric acid ammonia Some other functions of the skin 0 protect against UV radiation by making melanin absorbs UV make vitamin D upon exposure to sunlight Act as blood reservoir Vasoconstriction in skin shunts blood to other organs Sense touch pressure pain heat cold Protection Functions in thermoregulation hair erectile musculature O O hairs help insulate the body by trapping air in them Normally hair lies at an angle to the skin with erectile muscle attaching to it 0 When it39s cold erectile muscles contract and the hair stands up This erect position helps hair to trap more air providing better insulation fat layer for insulation fat in hypodermis act as insulation sweat glands location in dermis produce sweat cools the body by evaporative coo ng vasoconstriction and vasodilation in surface capillaries 0 When it39s cold vasoconstriction of arterioles reduce blood supply to skin capillaries Leads to less heat loss at skin surface 0 When it39s hot vasodilation of arterioles increase blood supply to the skin capillaries Leads to more heat loss at skin surface Physical protection nails calluses hair 0 nail hard keratin tougher than the soft keratin on skin 0 calluses extra thick layer of dead keratin packed cells on the surface of skin 0 hair hard keratin protection against abrasion disease organisms o Keratin protect skin against abrasion o The tight seal made from keratin packed cells and glycolipids form a barrier against pathogens Chemical protection Sweat is acidic contains antibodies and antimicrobial agents Sebum skin oil kills bacteria Natural flora good bacteria on the surface of skin don39t cause harm to you and they fight off bad bacteria that can harm you Structure Fer small intestine o Keratin is water insoluble and layers of dead keratinpacked cells reside on the skin surface 0 Glycolipids seal the space between the dead keratinpacked cells 0 Sebum skin oil contribute some But oil glands are not present everywhere absent in palms and soles L V 7j V l ilt31tIlIlli Dilge we Eygtem chewing arrrgrlaee Pl1arrnt erielettls tileclt wintlplpe reute tea nasal ca1ri15r clcse Eeciph agii5 peristaleis aqueeaee fectacl clciwri V Eitcl rnacl39ilquotia5 feldegl ll lI E39 quot illli hill churning pretease ipepSin Gall bladder i Srnall lnteetinee l39ia5 ftlcle villi sterec cencentratee IiIe cl enumjeju numiIeum ll arnjylaase re tea5e Iiia5e nuclease Pa ncreasz iutr39ieit and water alieeretlen ma lcee ena5rme5 V I V I Large lriteetlnee incl felcle new villi asate r Ell39EECl39lEI39l39l3I39l Ftectiu rn eta ree feces Table of digestive tract Organ Digestive Activities Mouth echanical digestion chewing hemical digestion saliva contains amylase and lipase echanical digestion churning Stomach tlhemical digestion protease pepsin Small hemical digestion amylase protease lipase assisted by bile from liver gall intestine ladder nuclease all enzymes predominantly from the pancreas utrient and water absorption Large lwater absorption intestine Table of enzymes Enzyme Where found Amylase Mouth and small intestine Protease Stomach and small intestine Lipase Mouth and small intestine Nuclease Small intestine Ingestion 0 saliva as lubrication and source of enzymes 0 saliva dissolves food 0 saliva contains mucin a protein that lubricates the bolus chewed up food ball 0 saliva contains amylase which breaks down polysaccharides starch and glycogen o saliva also contains antibodies and lysozyme that kill pathogens 0 epiglottal action 0 epiglottis ap of cartilage that closes off airway when you39re swallowing pharynx function in swallowing o pharynx throat between mouth and esophagus 0 muscular tube that squeezes and routes food to the esophagus when swallowing closes off pathways to nasal cavity and airway 0 esophagus transport function 0 muscular tube that propels bolus food to the stomach by peristalsis 0 peristalsis squeezing stuff through a tube esophagusgut by smooth muscle Stomach 0 storage and churning of food 0 storage the stomach is a muscular bag that is elastic and can stretch to store food 0 Stores vitamins A D and B12 and iron 0 Detox metabolize alcohol remove ammonia in blood 0 role in blood glucose regulation detoxification 0 Blood glucose regulation by liver Blood sugar too low glucogenesis Blood sugar too high glycogeneis o Detoxification metabolize alcohol alcohol dehydrogenase remove blood ammonia inactivate various other drugstoxins 0 structure gross largest gland in body spans both sides of the abdomen though right side much larger Ducts draining to duodenum and gall bladder Bile 0 storage in gall bladder o Gall bladder stores excess unused bile and concentrates it Secrets it when needed 0 function bile is an emulsifying agent not an enzyme Bile breaks down large fat droplets into smaller microscopic droplets by forming micelles This increases the total surface area of the fat for lipase action Pancreas 0 production of enzymes bicarbonate o Pancreas is the major source for all the digestive enzymes Amylase digests starch Various proteases Lipase digests fat Ribonuclease digests nucleic acids 0 Pancreas makes HCO3 to neutralize the HCl from the stomach synapse gt receptors on motor end plate sarcolemma picks this signal gt graded potential created gt if reaches threshold then action potential created gt action potential travels down the sarcolemma and cause muscle to contract 0 voluntary and involuntary muscles voluntary you can control skeletal muscles eg Biceps involuntary you can39t control smooth eg gut and cardiac heart muscles 0 sympathetic and parasympathetic innervation sympathetic fight or flight heart beat faster pupil dilation raise blood pressure blood to muscles less blood to digestive system parasympathetic rest and digest opposite of sympathetic heart slower pupil constriction lower blood pressure blood to digestive system Both sympathetic and parasympathetic are motor neurons that innervate involuntary muscles Skeletal System Func ons o structural rigidity and support bone forms the body39s framework 0 calcium storage bone stores calcium When blood calcium is low parathyroid hormones signal bone tissue to break down and release calcium 0 physical protection rib cage protects internal organs Skull protects brain Spine protects spinal cord Many large bones also shelter bone marrow that contains stem cells that make blood Skeletal structure 0 specialization of bone types structures Long bones shaped like a rod eg arm leg finger bones Short bones shaped like a cube eg wrist ankle bones Osteoclasts39 role in diameter growth of bones is to remove some bone tissue from the inside of the bone bones are hollow Without osteoclasts diameter growth will result in bones that are too thick and too heavy Even with osteoclasts bones still grow thicker just not unwieldly thick 0 Osteoblasts vs osteoclasts vs osteocytes Osteoblasts stem cells that give rise to osteocytes builds bone Osteocytes mature bones cells reside in bone for housekeeping Osteoclasts large cells that break down bone Reproductive System Male and female reproductive structures and their functions 0 gonads male testes makes sperm in the seminiferous tubules makes testosterone external female ovaries houses immature egg which matures monthly after puberty makes estrogen internal 0 genitalia male testes penis and various ducts and glands sperm made in the seminiferous tubules stored in the epididymis male mostly exte rtrlal Shared passage with urinary tract p i Sapern1at eaene5i5 5 IEFquot39Et39i1I39 s 7 I 1 5 tax t Eu3rn39i passage N V M V1 7 39 1 5 Stuirtinitttt tu5 1IiJL 1tnE5 h hr 1s q 5 Emquot 39 Em 5 3939 39quotquot v q lEpit39ind 39I1i5 m Elias deferens 4 Ejaculattir r Id Us llrE tttra EEPEIiis female mostly internal Separate passage from urinary tract EpquotItE39 k nijI2 FaiirriatttiiquottHa mma A t E I142 rnetrtiu IT 3939 A I39I39t EaFt Fivziirits 3b39 5 55 1 Fri mart JtZJtTfgFE at Pm pltase I T quot 2 SeeGunar a39 IIIiEiIf iquotE at Ftitetap I13 543 II Ergt g genesis befqjie 39irt h 3quot ampgsmnium IlI39iFT39lE Ef asas rIE 0 Secondary spermatocyte n gt meiosos II gt spermatid n Spermatid n gt mature gt sperm n The fancy name for sperm is spermatozoa Female oogenesis occurs in the ovaries then fallopian tubes Oogonium 2n stem cell Oogonium 2n gt mitosis gt primary oocyte Primary oocyte 2n arrests at prophase I occurs before birth One comes out of arrest every month between puberty and menopause Primary oocyte 2n gt meiosis I gt secondary oocyte n Ruptures from ovary follicle into the fallopian tube Secondary oocyte n arrests at metaphase ll Comes out of arrest if fertilization occurs Secondary oocyte n gt meiosis II gt ovum n Ovum and sperm 0 differences in formation quotMale and female gametogenesis side by side quotMale Female Difference Spermatogonium renews its population by permatogomum Oogomum mitosis throughout life Oogonium stops 2 2 39 H H renew1ng 1ts population SOIIICUIIIC before b1rth 39 P 39 Hmary Hmary Pr1mary oocye arrests at prophase I permatocyte oocyte d S d econ My econ My Secondary oocyte arrests at metaphase II permatocyte oocyte erm Ovum Between the secondary spermatocyte and the p sperm there39s the Spermatid o differences in morphology Sperm motile flagella Egg nonmotile round o fertilization 1 Sperm meets egg 2 Acrosomal reaction causes sperm to penetrate egg 3 Cortical reaction causes egg to prevent additional sperm from penetrating 4 Egg completes meiosis ll 5 Sperm and egg nuclei fuse o cleavage 1 Normal mitotic cell divisions cell grows then divides grows again then divides 2 Cleavage mitotic divisions without cell growth 0 blastula formation 1 fertilization produces zygote 2 cleavage produces a solid ball called the morula 3 morula hollows out into the blastula or blastocyst blastula occurs in non mammals blastocyst occurs in mammals 4 blastocyst implants o gastrulation 1 first cell movements Cells from the surface migrate inwards gastrulation occurs slightly different for different animals Some by invagination some by migration some by splitting In mammals the cells start migrating inward at the primitive streak 2 formation of primary germlayers endoderm mesoderm ectoderm Connective blood bone tendons ligaments cartilage Nervous brain spinal cord nerves Muscle skeletal smooth and cardiac muscle Cell communication in development 0 Induction one group of cells changing the behavior of an adjacent group of cells inducer the one that sends the signal for the other to change responder the one that gets the signal and changes For example the optic vesicle is able to induce the ectoderm to develope into lens Another example is the induction of wing feathers in the chick by the dermal mesenchyme Induction mechanisms physical touching of cells juxtracine or by releasing chemicals paracrine Gene regulation in development 0 O 0 Differential gene transcription modification of DNA methylations can shut off or turn on genes modification on histones methylations acetylations that wrap the DNA can shut off or turn on genes to make or not to make transcription factors can regulate what genes get transcribed Differential RNA processing selecting what RNA make it outside the nucleus to be translated alternative splicing of RNA Translation regulation some mRNA are made to last longer than others more proteins translated off of it and some are made to be rapidly degraded less proteins translated off of it Di rectior nal Selaction Frrequen 13 Tra it Directional selection selects for a trait on one extreme For example selection for height of canopy trees in a rainforest trees compete for sunlight so selection favors trees to become higher and higher Etailiiing Eelectin Frrequen 13 Trait Stabilizing selection selects for a trait that is moderate and selects against the extremes For example birthweight too low birthweight means that the baby is premature too high birthweight means that the mom will have a hard time delivering so there39s a quotjust rightquot birthweight that is selected for D i sr3u ENE EElECil i quotI I Freq uan n3r Trait Disruptive selection selects for the extremes For example Speciation is the formation of a new species This can occur due to barriers to successful interbreeding within an initial species 0 polymorphism Polymorphism is just a fancy word for different forms of allelestraits o adaptation and specialization Adaptation is the genetic change in a population caused by natural selection Adaptation is caused by Darwin39s natural selection not by Lamarck39s ideas A giraffe39s neck is long because long necks increase the survival rate so more long necked giraffes survive to reproduce and over many generations the population evolved long necks The wrong idea by Lamarck is that the giraffe had to reach for higher leaves on trees so it stretched itself a longer neck Specialization adaptation of traits to better fill a niche 0 concepts of ecological niche competition A species ecological niche is what resources the species uses to survive in its environment Two species can avoid competition and better use the environment39s resources by occupying different niches As long as two species occupy different niches there39s no competition because they use different resources When niches overlap there39s competition Specialization occurs to better occupy a particular niche o concept of population growth through competition Population growth is checked by competition When resources get scarce competition increases which slows down population growth Competition within a species can force members within the species to occupy different niches which drives speciation Di vergent Emllifi1n 3939irr391e Li neage rquoti39rai1lquotH lE Divergent evolution Same lineage evolving apart to be more different For example bats and horses Both share the same lineage as mammals but the limb of the bat became wings while the horse developed hooves Divergent evolution produces homologous structures bat39s wing and horse39s hoof Parallel E39IlLllilli39IiquotI T ima Lll39iE ge I 3939rait 39laquotElIU E Parallel evolution Same lineage evolving closer together to be similar using similar mechanisms For example the feeding structure in different species of crustaceans The feeding structure came from mutation of pair of legs turning them into mouth parts This is a prime example of parallel evolution same lineage similar traits evolved from similar mechanismsmutations 0 You can compare genome differences between two species to find out how long ago they diverged 0 Another name for this concept is the Molecular Clock fquoti391tIE t Lar Clotzllt e rmrnis diHEl ElquotiCE Divergence Time Origin of life 0 Organic molecules created by atmospheric gases zapped by lightning which falls into the ocean to make primordial soup Oparin and Haldane Urey Miller39s experiment proved this in a lab 0 RNA World hypothesis the simple organic molecules formed RNA polymers that can self replicate Having enzymatic activity as well as serving as template 0 Protocells aggregates of RNA proteins inside lipid envelopes o Prokaryotes first anaerobic heterotrophs because early atmosphere blocks the light required for photosynthesis then anaerobic autotrophs that undergoes photosynthesis and makes oxygen then aerobics that utilize oxygen 0 Eukaryotes evolved by endosymbiosis where a big cell engulfed a smaller cell and then developed a mutualistic relationship Heterotrophs engulfed mitochondria Autotrophs engulfed chloroplasts Comparative anatomy Chordate one of the phylums in the kingdom Animalia Chordate features 0 notochord the quotbackbonequot of the embryo except that it39s not made of bone In vertebrates bones will replace the notochord to form the vertebrae
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