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Osmosis Movement of water across a semipermeable membrane down its concentration gradient, from high to low Endosymbiosis A hypothetical evolutionary event in which one cell engulfed a second cell resulting in the second cell becoming an organelle part of the second cell, inherited...

Osmosis Movement of water across a semipermeable membrane down its concentration gradient, from high to low Endosymbiosis A hypothetical evolutionary event in which one cell engulfed a second cell resulting in the second cell becoming an organelle part of the second cell, inherited through the generations Phagocytosis A mechanism where one cell can eat another by internalizing it into an intracellular membrane (sac) and destroying it for purposes of nutrition or immunity Symbiosis Prolonged close living together of 2 organisms often with 1 partner being multicellular and the other being bacterial Imagine a population of bacteria is exposed to penicillin, what will happen to most of the bacteria? They will swell and burst due to a weakened cell wall Antibiotic penicillin interferes with bacterial enzyme transpeptidase and prevent it from crosslinking and strengthening the bacterial wall, without a good cell wall bacteria will not be ale to resist pressure from water entering by osmosis and cells will burst What will happen to the bacterium if it has betalactamase? The bacterium will survive because betalactamase can destroy penicillin Is it possible for the ability to destroy the penicillin to spread from the single cell to other bacteria nearby? Yes, if other nearby cells get some of the DNA encoding the β-lactamase enzyme, they will be able to make their own β-lactamase, and become resistant to penicillin. ATP synthesis in bacteria is generally proportional to: The surface area of the cell (amount of plasma membrane) Researchers recently discovered that some eukaryotic lineages do not contain mitochondria and have anaerobic metabolic pathways. Which statement best explains this phenomenon? Mitochondria were lost in eukaryotic lineages that adapted to environments where other traits were more suitable for survival. Seeing that the ATP synthesis machinery is on the inner blue membrane, which way is it oriented Protons will be pumped into the space between the 2 membranes and ATP will be made in the innermost space (blue). In some mitochondria, special proton channels are inserted across the inner mitochondrial membrane. What effect(s) would such a channel have? -Decreases ATP production -Increase pH of inter-membrane space -Raise the temperature What does it mean for Mendel's pea plants to have been "pure-breeding"? When fertilization happens within the same strain of plants all the offspring look like their parents What does it mean to have a "cross" like this in Mendel's pea plants? To transfer the pollen from one breed of pea plants to fertilize the ovules of the other breed of pea plants When Mendel looked at the F1 offspring of his cross between pure-breeding round-pea-bearing plants and pure-breeding wrinkled-pea-bearing plants, he was intrigued to find that 100% of the peas produced by 100% of the F1 plants were round, What can we infer about this finding? The allele for wrinkled peas is recessive to the allele for round peas What symbols should be used to indicate the gene alleles for the round and wrinkled traits? R for round r for wrinkled If the parents (Fo generation) in this cross are DIPLOID, which terms properly describe(s) the offspring from this cross? Describes all F1 offspring: -Heterozygous for seed shape - DIploid - Hybrid Describes NO F1 offspring: -recessive -Dominant -Homozygous for seed shape gene -Haploid -3:1 ratio -Sterile -Sex-linked What was the significance of the 5474 : 1850 finding shown in Mendel's pea plants? It showed that there were about 3 times as many round pea-producing than wrinkled pea-producing plants, 3:1 ratio Homozygous dominant RR Homozygous recessive rr Heterozygous Rr For the 3 possible genotypes (RR, rr, Rr), in what ratio are they found in the F2 generation? Let's set the frequency of RR to one (1). RR Rr rr 1 : 2. : 1 let's imagine 2 people who are each heterozygous for "personality gene" alleles, but different alleles, adding up to 4 total alleles, Given that each offspring (child) will inherit 2 alleles of this gene, one from each parent, how many different combinations of alleles are possible in the children? 4 different combinations (HW 9 Q14)To practice these principles, consider what would happen if Mendel crossed one of his F0 true-breeding wrinkled-pea plants with one of the F1 hybrids, What would be the ratio of genotypes among the offspring of such a cross? 1:1 ratio, The true-breeding F0 plants are rr (homozygous recessive). The F1 are Rr (heterozygous), there are only 2 kinds of offspring in terms of genetic make-up, see diagram. These 2 kinds are equal in frequency, or 1:1 cont, how about if Mendel crossed one of his F0 true-breeding ROUND-pea plants with one of the F1 hybrids from the screen above. What would be the ratio of TRAITS among the offspring of such a cross? 1, all the same, the true breeding Fo plants are RR and the F1 are Rr, possible offspring genotypes have at least one dominant R allele (whether homozygous RR or heterozygous Rr), therefore, all the offspring will have the dominant round pea trait What are the three main causes of mutations? DNA polymerase error, ionizing radiation such as UV or X-rays, or chemicals Estimates suggest that about 1 in 300 people are carriers of serious mutations in the XPB gene. Approximately how many married couples will BOTH be carriers of serious disease alleles of XPB? 1 in 90,000 1/300 x 1/300 = 1/90,000 If 2 people heterozygous for serious mutations in the XPB gene do marry, what are the changes that their first-born child is homozygous, and afflicted with the serious Xeroderma pigmentosum disease? 25% chance, 1/4 What are some factors that can contribute to a genetic disease being much more common? -Caused by mutations on X-chromosome genes -Number of heterozygous carriers of disease allele is high, due to some sort of advantage -High degree of consanguinity in the populations --> small pops or cousins marrying Imagine a married couple in which the father is a carrier of the Glu ► Val mutation (a carrier is heterozygous), and the mother is homozygous for the healthy hemoglobin allele. 1. If this couple has a single daughter, what is the chance that she will be a carrier of the sickle cell mutation? 2. What is the chance that their daughter will suffer from sickle cell disease? 3. The brother of the father above is also a Glu►Val mutation carrier, and marries a woman who is herself also a Glu►Val carrier. If they have 2 children (a boy and a girl), what is the likelihood that one of them will suffer from sickle cell disease? 4. The 2 brothers also have a sister, and she is NOT a Glu►Val mutation carrier. She marries a man who IS a Glu►Val carrier, and has 4 sons. What is the likelihood that their first-born is a carrier? 1. 50% (The father has 2 different alleles of hemoglobin. Any child he has will inherit ONE of those alleles. There is a 50/50 chance for each of the alleles to be inherited. So there is a 50% chance of any child inheriting the Glu►Val mutation, and be a heterozygous "carrier" of the mutation.) 2. 0% 3. 50% 4. 50% (With 2 parents, one of whom is heterozygous, there is a 50% chance that any particular child will inherit the Glu►Val allele from that parent, and also be a heterozygous carrier. This would be true whether it is the first-born child, the second-born, etc.) Which of Mendel's principles best explains how it is possible for two parents who are nearly identical to each other in appearance to have puppies with such a variety of characteristics? The principle of independent assortment explains how many different combinations of alleles can be formed during meiosis. List the following events times and organisms in the sequence as they appeared, starting with earliest ending with most recent Earliest: -10 BYA - Molten hot earth formed -Earth cooled -Cell like organisms -LUCA -Bacteria -Photosynthesis by cyanobacteria -SIngle-celled eukaryotes -Ethanol fermentation -Photosynthesis by ancestor of plants and algae -Multicellular animals -Humans Latest: Why is the inner membrane of a mitochondria typically wrinkled? It increases space for more electron transport chains DNA can encode proteins T/F? True DNA can bind proteins T/F? True DNA is a physical substance that can undergo chemical reactions T/F? True DNA can be used to infer phylogeny T/F? True DNA has a sugar phosphate backbone that can never be broken T/F? False Can be broken by exposure to UV, chemicals, etc, as well as during meiotic recombination DNA was the genetic molecule of LUCA T/F? True Not all DNA encodes proteins T/F? True DNA can be transferred between cells T/F? True In all 3 species, the hemoglobin protein begins with "M", What is the best explanation for this? All proteins begin with M, since it is encoded by the start codon. When thinking about the hemoglobin from 3 different mammal species, what process created the slight differences in amino acid sequence among the 3 hemoglobin variants? Missense mutations in the DNA that encodes the hemoglobin protein occurred in some ancestors. Describe how the proper reading frame is established The first AUG in an mRNA molecule sets the reading frame for the ribosome, which then proceeds to translate 1 codon at a time, in a 5' ► 3' direction. Considering the image of the central dogma of molecular biology... The arrow connecting DNA and mRNA represents the process by which the DNA in a gene is: Used to make an RNA version of the gene Considering the image of the central dogma of molecular biology... The arrow connecting mRNA to protein represents the process by which the mRNA of a gene is: Used to make a specific protein product Why don't silent mutations affect the amino acid sequence of a protein? Multiple codons can code for the same amino acid T/F? The third base in a given codon is the least important with respect to binding with tRNA True What are some ways in which the universality of the genetic code has been harnessed in beneficial ways? - Design mRNA molecules that encode part of virus, and encase them in a membrane sac to be a vaccine that tricks our bodies into making antibodies that bind the virus. - Engineer bacteria to make proteins for human use, such as insulin. When biologists say that the genetic code is "redundant," what do they mean? Some amino acids are coded for by more than one codon Ex, stop codon, Phenylalanine Which of the following sequence changes are most likely to disrupt the function of the protein product of this gene? ATGGAA...CAGTGA a. ATGTGA...CAGTGA b. ACGGAA...CAGTGA c. ATGGAA...CAATGA d. ATGGAG...CAGTGA a. ATGTGA...CAGTGA b. ACGGAA...CAGTGA A particular blood disorder is the result of a single amino acid deletion in a critical region of the hemoglobin protein. All of the other amino acids of the protein are the same. If you examined the DNA sequence of the gene, what would you most likely find? a three-base deletion in the coding region would eliminate a single amino acid while not changing the reading frame. All of the other amino acids would still be the same, which is consistent with the observations of the amino acid sequence of the protein Which of these mutations in a gene would likely result in no protein product being made at all? Select all that apply. a. a single-base mutation in the stop codon b. a single-base mutation in the gene's promoter that prevents RNA polymerase from binding to the promoter c. a single-base mutation in the start codon d. a single-base mutation in the transcription termination site b. a single-base mutation in the gene's promoter that prevents RNA polymerase from binding to the promoter c. a single-base mutation in the start codon Imagine a protein-coding gene randomly picks up a missense mutation in the DNA that codes for the start codon: How will this mutation likely impact transcription of this gene? The RNA transcript made by RNA polymerase will have a slightly different sequence. Imagine a protein-coding gene randomly picks up a missense mutation in the DNA that codes for the start codon: How will this missense mutation likely impact translation of the mRNA encoded by this gene? The start codon determines the first amino acid in a polypeptide and sets the reading frame. If the start codon is mutated to a different codon, translation will not initiate in the right place. This could lead to no protein product at all, or a very different protein product if the ribosome starts translating at a different AUG codon nearby. Silent mutation Changes the original codon to a different codon, but does not change the amino acid, codon codes for the same type of amino acid Missense mutation A codon that specifies an amino acid is mutated into a codon that specifies a different amino acid Suppose that an error in transcription occurred that changed the mRNA sequence transcribed from a gene. Imagine that now, the mRNA is missing a specific base, All the bases to the right of the red A would then be shifted over one position to the left. Would this change the reading frame? Yes, the reading frame would now be AUG GGC AAC (instead of AAA) CGG (instead of CCG)... Suppose that an error in transcription occurred that changed the mRNA sequence transcribed from a gene. Imagine that now, the mRNA is missing a specific base, Does the polymerase error result in a mutation? No, because mistakes by RNA polymerases do not lead to heritable changes in DNA. What are some processes that are prevented by a cell wall? - Cell bursting - Phagocytosis Using the diagram from codon, following exposure to penicillin. Most of the bacteria are dead, but now we see more of the bacteria that are alive, due to their possession of the β-lactamase gene, and synthesis of the β-lactamase enzyme. What could explain the increased abundance of the bacteria with the β-lactamase? The original two bacteria with β-lactamase divided. Which organisms have the enzyme that can catalyze a Nitrogen fixation reaction? Some species of bacteria Considering a Gibb's Free energy graph, is it entropy or enthalpy considerations that makes the activation energy so high? Enthalpy What aspect of cell function/composition is dependent on a Nitrogen fixation reaction? Macromolecules such as nucleic acids and proteins The last eukaryotic common ancestor has traits which are also found in bacterial and archaeal lineages, connecting them evolutionarily. What traits would you find in the last common ancestor of bacteria, archaea, and eukaryotes? - Cell wall - Ribosomes Sexual recombination cycle orderL 1. Meiosis 2. Gamete (n) 3. Fertilization 4. New individual (2n) Experiment from Chapter 13 of textbook, what overall question was the experiment meant to address? Whether sexual reproduction is beneficial against pathogen infection. What describes the term "maleness"? Making small gametes Who do we inherit our mitochondria from? Mother Who do we inherit our X-Chromosome from? Father Consider a girl who has the exact same X chromosome as her father, what is the best explanation for this? Meiosis in females but not males results in meiotic recombination of the X chromosome. RNA strand transcribed from the following DNA: 5' C G T A C C A T G G C G 3' GCCAUGGUA Central dogma Flow of information within the cell DNA (genes) codes for RNA —> RNA codes for protein —> Protein codes for nothing DNA —> RNA —> Proteins  Transcription mRNA Translation DNA - instructions DNA contains the instructions for every protein in the cell 4 types of DNA monomers A C T G 4 types of RNA monomers A C U G Number of codons that nucleic acids code for amino acids Three - triplet codon Codon Triplet of nucleotides How many types of protein monomers (amino acids) are there? 20 amino acids Degenerate/redundant codonMultiple codons encode the same Amino acid Wobbly codon The third position often does not matter Ribosome Nano-machine that decodes RNA and makes proteins What kind of bonds do ribosomes form? Peptide bonds How does the ribosome move? The ribosome slides along RNA in steps of 3 nucleotides (codons) from a 5' to 3' direction What is the process of ribosome movement called? Translation Replication DNA —> DNA (synthesis, replication) Enzyme: DNA polymerase Analogy: reprinting a cookbook Performed: before cell division occurs Transcription DNA —> RNA (RNA synthesis) Enzyme: RNA polymerase Analogy: photocopying a recipe Performed: when a cell needs to make a protein Translation RNA —> protein (protein synthesis) Enzyme: ribosome Analogy: making the cake Performed: when cell needs to make a protein Enzymes -almost always made of proteins -made by cells -often end in -ase Protease, lactase, Na+/K+ ATPase -never alter overall delta G of reactions -only lower activation energy 2 major functions of enzymes1. Speed up chemical reactions by lowering activation energy 2. Some enzymes couple exergonic and endergonic process which allow unfavourable endergonic processes to happen , such as chemical reactions or pumping across membranes Ribosomes explained - rare molecular machine made of RNA, not protein - starting at 5' slides along mRNA strand 1 codon at a time - reads mRNA triplet code and inserts correct amino acid - start at AUG codon - adds amino acids to growing protein chain until it reaches a stop codon - at stop codon, ribosome lets go, is ready to translate new RNA What is a gene? Stretch of DNA that encodes a protein What does a gene include? Start codon and end codon If the typical protein is 1000 amino acids long, how long would a typical gene be? 3000 base pairs How many reading frames does mRNA have? 3 reading frames, established by the first AUG Cam encode 3 totally difffeeent proteins of different lengths dependent on stop codon DNA —> transcription —> RNA —> translation —> protein in cake analogy Cookbook —> photocopying the recipe —> photocopy of recipe —> chef —> cake In the cake analogy, what would be the best analogy for ribosomes? The cook, makes the cake following RNA instructions Purpose of DNA replication Duplicate DNA to pass on identical copies to daughter cells during cell division Two kinds of information flow? 1. From generation to generation 2. Within a cell, mRNA What statements regarding ribosome function are true of all cells, both prokaryotes and eukaryotes? - starting at 5' slides along mRNA strand 1 codon at a time - reads mRNA triplet code and inserts correct amino acid - start at AUG codon - adds amino acids to growing protein chain until it reaches a stop codon The genetic code -The same in all domains of life -"evolutionarily conserved" -ribosomes from one organism can translate RNA from any other organism Useful applications of the genetic code being the same in all domains of life? 1. Bacteria to manufacture insulin 2. We can put genes encoding fluorescent proteins from marine organisms into other organisms —> genes from one organism can be put into another organism and still work 3. We can trick cells into making virus proteins —> vaccines mRNA for vaccines -has mRNA encoding spike protein -phospholipid binaries carrier particles have no DNA 1. Our ribosomes translate the RNA 2. Temporarily make spike proteins 3. Activates immune white blood cells (B cells) to make antibodies Central dogma information flow DNA —> RNA - information coding Protein —> carbohydrates and lipids - protein enzymes catalyze the formation of lipids and carbohydrates Genes that are on in almost all cells -ATP synthase -Na+/K+ pump -Enzymes of glycolysis Genes on in only certain cellsKeratin (hair cells) Hemoglobin (RBC's) What conditions cause genes to turn on in offspring as a response? - nutrient availability (glucose transporters) - infection (immunity genes) What is a mutation? Permanent changes to an organisms DNA What are the 2 main causes of mutations in DNA? 1. DNA replication error 2. DNA damage, chemicals, ionizing radiation (UV light, X rays) Electromagnetic spectrum Shorter wavelengths have higher energy Energy can break bonds Different kinds of mutations 1. Point mutations 2. Insertions/deletions Point mutations 1 nucleotides changes to another A —> G Silent mutations Changes 1 letter in the codon, but the amino acid remains the same CAA —> CAG Both encode for Q glutamine Misses mutations The amino acid completely changes CAA —> CAC Q (Gln) —> H (His) Nonsense mutations Creates a stop codon CAA —> TAA Q (Gln) —> stop Mutations only exist in..? DNA, but translation is of RNA What kind of point mutations occurs the most frequently? Missense mutations because most random mutations will cause an amino acid change What kind of point mutations is the most harmful? Nonsense mutations because a stop codon will end the protein Insertions/deletion mutations Insertions or deletion of either single or multiple nucleotides in DNA What kind of insertion/deletion is the least harmful? Triple nucleotides insertion Life involves flows and transformations of: Information Matter Energy Which of the following is NOT the way that mutations can happen? a. DNA polymerase copying error b. ribosome translation error c. Chemical damage B. Ribosome translation error cannot cause mutations To determine the seriousness of a point mutation, you should? Translate the coding sequence (DNA or RNA) and see whether it causes an amino acid substitution or stop codon, missense or nonsense What factors are NOT important for assessing whether an insertion/deletion mutation has serious consequences? - wether the. 3rd position nucleotides in a codon is deleted - whether insertion/deletion is near the start vs the end of gene coding sequence Can mutations be inherited? Yes, DNA is the molecule of heredity Are mutations always inherited? Not always -sometimes mutation kills the organism and/or prevents it from reproducing -while all cells have DNA that can be mutated, not all cells contribute to the next generation Ex, mutation in skin cell may cause damage for cancer but will not be passed to next generation Can mutations ever be harmless? Yes - silent mutation have no effect on the organism - not all missense mutations are harmful What could be an example of a silent mutation of CGA (alanine)? GCG, GCC, GCT, all encode for alanine Can missense mutations ever be harmless? Yes, differences between organisms began as mutations that were inherited Can mutations ever be beneficial? Sometimes yes Missense mutations cause amino acid changes, if the AA difference is beneficial and makes the organism better suited for environments or challenges, if beneficial it will more likely be transmitted to the next generation Evolution Change in Characteristics of populations of organisms over time through multiple lifetimes and generations Mutations are raw. Arterial for evolution We can use DNA variations to construct...? Phylogenetic trees Organisms with fewer differences are more closely related Reading phylogenetic trees X axis: represents time Nodes: represent hypothetical common ancestors Ancestors are shared by all the organisms that follow them Which domain of life is the most ancient? Domain bacteria Which domain of life is the youngest? Domain eukarya LUCA Last Universal Common Ancestor Factors common to all life forms on earth today - genome made of DNA - proteins do the most work in the cell - central dogma -ribosomes - lipid bilayer membrane - ATP and ATP synthase - electric transport chain - high K+ low Na+ Ancestors of LUCA Have no descendants today What strain of bacteria killed people during the 1918 flu epidemic? Pneumococcus Alexander Fleming wartime Leader in search for treatments for infected wounds at war front Identification of bacteria from wounds, infections were a new science, tried lots of wound sterilization techniques but most were harmful Alexander Fleming 13 years later (1928) One day noticed his bacterial plates were contaminated - mold, the Penicillium fungus contaminated plate, staphylococcus could not grow near the mold - mold releases "anti bacterial poison" What was the first antibiotic? Penicillin What are antibiotics? Drug/molecule that kills bacteria, but not eukaryotic cells - can treat bacterial infections without harming the host How do antibiotics work? Work by interfering with bacterial wall assembly Bacterial cell walls - strong network of peptidoglycan ( amino acids + carbohydrates ) - function is to protect them from bursting Transpeptidase a bacterial enzyme that cross-links the peptidoglycan chains to form rigid cell walls - catalyzes the peptide links -penicillin binds and inhibits transpeptidase What is transpeptidase important for? Cell wall formation When bacteria divide, they need to make more...? Cell wall Why does mold or fungus make an antibacterial "poison"? Have evolved to kill bacteria How do antibiotics work without harming eukaryotes? Antibiotics interfere with parts of cell function that are only specific to prokaryotes, such as cell wall synthesis, therefore eukaryotes not affected How did most antibiotics form? Began as natural products, by microbes Antibiotics resistance The ability of bacteria to survive antibiotic exposure - bacteria evolve fast and can swap genes that protect from antibiotics What is the genetic material for all cells on earth? DNA What macromolecules have nitrogen? Protein and nucleotides How do we get our nitrogen? From our food, plants and animals we eat How do plants get nitrogen? From the soil, but soil does not have much Bacterial nitrogenase enzyme Main source of bio available nitrogen -lowers activation energy -couples ATP hydrolysis to bond breaking Ammonia -bio available -can be converted by cells into amino acids and nucleotides -in many fertilizers Non animal protein sources Legumes Symbiosis A close relationship between two species that benefits at least one of the species, "living together" Legume plants root symbiosis with nitrogen fixing bacteria Legumes get NH3, bacteria get glucose Nitrogen fixing bacteria root symbiosis important in: Agriculture: A. Crop rotation , cover crops are legumes B. Native Americans, plant beans corn and squash together Natural ecosystems Antibiotic resistance is a phenomenon where: Certain bacterial genes encode proteins that disable or pump out a particular antibiotic, enabling the bacteria with the gene to survive in the presence of this antibiotic Role of the appendix Has a reservoir of symbionts, can protect us from infection from pathogenic bacteria What do the bacteria in our gut do? -protect us from infection -produce chemicals we need such as vitamins and chemicals in our brain of bacterial origin Antibiotic problems 1. Antibiotic resistance 2. Antibiotics can kill our good bacteria History of life on earth4 BYA Earliest prokaryotes Cyanobacteria invent photosynthesis 3 BYA Earliest eukaryotes once enough oxygen in the air 2 BYA Eukaryote differences from prokaryotes 1. Cells got much larger, have complex system of internal organelles 2. Started carrying 2 copies of all genes, diploid -DNA broken into multiple chromosomes, DNA kept within the nucleus, sexual reproduction 3. Got rid of cell walls -plants and fungi later evolved walls again 4. Capable of multicellularity - evolved separately into different lineages Eukaryotes - unicellular and multicellular - has a nucleus - only domain with multicellular forms -cells are large in size -have internal membrane structures, mitochondria, nucleus, mitochondria, ER, golgi, etc Do prokaryotic cells have a nucleus?No Do eukaryotes have a nucleus? Yes, membrane bound nucleus Size difference of proks and euks Proks tiny, euks about 10 times the size Volume of a sphere V=4/3πr³ How much bigger is a eukaryotic cell volume than prokaryotes? 1000x bigger Chromosome large DNA molecule, threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes. DNA chromosomes of proks Small circulars chromosomes in the cytoplasm DNA chromosomes in euks DNA in pieces inside the nucleus -two copies of of most chromosomes Mitochondria and chloroplasts have their own circular chromosomes Lynn Margulis hypothesis Mitochondria and chloroplasts originate from bacteria Do all eukaryotes have mitochondria? Yes Do all eukaryotes have chloroplasts?Only some Lynn Margulis Hypothesis confirmed Sequencing of chloroplasts and mitochondria DNA helped support, chloroplasts similar to Cyanobacteria, mitochondria similar to proteobacteria Where is the electron transport chain in mitochondria? Across the Inner membrane Where are protons pumped in mitochondria? Between the two membranes, intermembrane space Where is ATP made in the mitochondria? In the inner space If a bacteria doubles its diameter, what happens to the surface area of its plasma membrane? SA will increase by 4x If bacteria double its diameter, what happens to its volume? Volume will increase 8x SA increases as a function of? r2 Volume increases as a function of? r3 Problem with bacteria size Big bacteria would t have enough membrane to make enough ATP to keep up with needs of large volume Large cells need to...? Pump more K+ in and Na+ out, and make more macromolecules (ATP) Chloroplasts were a ______ endosymbiosis event in ancestors of plants and algae Secondary ATP channels allow ATP to exit to the cytoplasm where it is needed, sometimes cells insert proton channels across the mitochondrial membrane, why?To produce heat How do mitochondrial protein channels produce heat? -substances flow down the gradient, exergonic process releases heat -if energy released is not harnessed in beneficial biochemical way, it will be released as heat What is the only tissue type in humans that creates mitochondrial protein channels that produce heat? Brown fat Brown fat -has lots of mitochondria with proton channels inserted - help keep us warm - helps with weight loss - brown color comes from mitochondria, Iron in the ETC gives rusty appearance Eukaryotic cells are diploids Have 2 copies of every chromosome, and so every gene Homologous chromosome Same genes but different variations, Different versions of the same structure How many chromosome pairs do humans have? 23 pairs Are human cells haploid or diploid? Diploid How many homologous pairs do humans have? 23 homologous pairs Diploid number present in all cells? 46, 2 of each chromosome Alleles Different versions/variants of a gene Ex, eye color has blue and brown alleles How many alleles of each gene do we have? 2 alleles of each gene, one for, each parent Small ways that alleles differ in sequence from each other Same amino acid encoded, silent Large ways that alleles differ in sequence from each other Key amino acids are different, stop codon Allele differences Caused by mutations Create variation among individuals Examples of alleles that cause noticeable trait differences -hair, skin color -eye color -lactose tolerance -sneeze when looking at sun -color blindness Examples of serious allele differences -sickle cell anemia -cystic fibrosis -predisposition to cancer -genetic diseases Homozygous Both alleles of a gene are the same RR, for Hetrozygous The two alleles of a gene are different Rr Mendel's pea plants Studied inheritance, pea shape and color, flower shape, pod shape Pea reproduction Each flower gives rise to one pod, ovary, with up to 10 peas Peas in a pod can have different fathers due to separate pollination Mendel controlled pollination by bringing stamen, males with pollen from one plant, to female stigmas of other plants Are round peas or wrinkled peas true bred? Both are purebred Is pea shape an inherited trait? Yes What happens when you pollinate a round pea plant with pollen from a wrinkled pea flower? They are all round What happens when you pollinate a wrinkled pea plant with pollen from a round pea flower? All seeds will appear round because the dominant R allele masks the recessive r allele After finding that inheritance does not work by blending, what did Mendel do next? Took the round hybrid pea plants and planted them What did the hybrid pea plants look like? 75% round, 25% wrinkled F0 generation Pure breeding parents meet, one parent produces round seeds one parent produces wrinkled seeds F1 generation Offspring of pure breeding parents are hybrids All have round seeds F2 generation Offspring of the hybrid F1 generation, have a 3:1 ratio, mostly round, some wrinkled Mendels inferences 1. Genes do not blend 2. Individual can have 2 versions of any gene 3. When an individual has 2 different versions of a gene ex in a hybrid, one version will be apparent, dominant allele, and one version will be hidden, recessive allele 4. 2 versions of each gene separate during reproduction and are inherited separately Pure breeding F0 parents are homo or hetero? Homozygous Seeds with Rr genes Heterozygous, look round because R is dominant to r Rr F1 parents Pass along either R or r to F2 offspring F2 offspring inherit Either R or r from father (pollen) Either R or r from mother (ovule) 4 possible genetic combinations Rr Rr RR round rr wrinkled Is lactose tolerance or intolerance dominant? Lactose tolerance is dominant Lactase Enzyme that helps break down (hydrolyses) lactose into 2 monosaccharides (Two individual sugars) What gene encodes lactase? Lactase Lactose intolerance Individuals cannot digest lactose, milk sugar -everyone can digest lactose as a baby as they have the lactase enzyme -some people switch off lactase gene after infancy, causes intolerance Lactose tolerance Maintenance of lactase through adulthood 2 alleles of lactase r switches off after infancy R stays on through life If you inherit one of each lactase allele, will you be able to drink milk? Yes, lactose tolerance is dominant allele Most genetic disease arise from recessive alleles, so the disease is only apparent in the individual...? When the individual is homozygous, Rr How does someone become homozygous for disease causing alleles? By receiving one recessive allele from each parent, both parents are heterozygous Rr How many genes do humans have? 30,000 How many recessive lethal mutations do most people carry? 1-2 What are the chances of marrying someone with hidden disease allele in the same gene as you? Very small chance, with two exceptions 1. You are related 2. Small number of genetic diseases are already common in certain populations Sickle cell disease Missense mutation in hemoglobin, RBC protein that carries oxygen -having one h allele is protective against malaria Why are heterozygotes common? Heterozygous advantage, sometimes Hh survives better than HH Cystic fibrosis heterozygous advantage Protection from diarrhea What does it mean for an allele to be recessive? It is masked if heterozygous female vs male chromosomes Females: XX Males: XY Males get X from mother and Y from father How many genes do X chromosomes have?About 900 How many genes do Y chromosomes have?About 40 X-linked genetic disorders Are much more common in males -girl only affected if both parents are carriers -boy can be affected if just mother is a carrier Gamete types in animals Males make sperm, females make eggs Gamete types of plants Males make Pollen, females make ovules Gamete types of fungi and single celled euks Male and female mating types Haploid one set of chromosomes Diploid 2 sets of chromosomes, one from each parent Sexual reproduction cycle Haploid germ cells/ gametes (n) —> Fertilization —> diploid cell (2n) —> meiosis Meiosis Cell division that produces reproductive cells in sexually reproducing organisms, special kind of nuclear division Meiosis starts with DNA replication, from 2n to 4n Meiosis second step Two rounds of cell division 4n —> 2n 2n —> n Ends with 4 haploid n cells What process would duplicate chromosomes? Replication Meiosis generates...? Gametes that are all unique 2 processes that generate gamete diversity 1. Independent segregation / random segregation 2. DNA crossing over, meiotic recombination Independent segregation/random segregation Maternal and paternal chromosomes are randomly distributed to gametes -eukaryotes have genomes broken into multiple chromosomes which allows randomization during meiosis DNA crossing over Occurs after DNA replication, is the random recombination between paternal and maternal chromosomes 1st meiotic division Homologous pairs of chromosomes align with each other before separating, recombined sister chromatid pairs stay stuck together and yield 2 daughter cells, each 2n After 1st meiotic division two non identical daughter cells, 2n and 2n formed 2nd meiotic division Attached chromosomes line up, detach, then separate After 2nd meiotic division 4 non identical haploid daughter cells (sperm, eggs, pollen, ovule) Diversity in each generation comes from? 1. Uniqueness of gametes made in meiosis, think back to the two mechanisms 2. Random pairing of egg and sperm What is the primary function of ribosomes in cells? To synthesize proteins What is the role of RNA polymerase? Synthesize RNA Degenerate codon multiple codons encode a single amino acid What is the purpose of enzymes in a reaction? Lowers activation energy What is the role of ribosomes in the genetic code? Decode RNA and synthesize proteins What is the significance of the genetic code being the same across all domains of life? It enables gene transfer between different organisms What is the role of a start codon in a gene? Initiate protein synthesis What is the primary function of mRNA in vaccines? To encode spike proteins What kind of mutation creates a stop codon? Nonesense mutation What is not a cause of mutations? Ribosome translation error What kind of mutation involves change in a single nucleotide? Point mutation Example of a gene commonly active in all cells? ATP synthase What can trigger genes to turn on in offspring? Nutrient availability Characteristic of missense mutation Can sometimes be harmless How do plants obtain nitrogen from the soil? Through symbiotic relationships with bacteria What is the purpose of ATP channels in mitochondria? To allow ATP to exit to the cytoplasm What happens to alleles during reproduction according to Mendel's inferences? Alleles are inherited separately from each other What is the term for the offspring of pure breeding parents in Mendels experiments ? F1 generation What is the result of inheriting one of each lactose allele? Lactose tolerance