Genetics
What is post-zygotic mechanisms?
- Hybrid inviability - Hybrid sterility - Hybrid Breakdown
Stabilizing selection
- has to do body weight, # of offspring, there is less genetic diversity bc it gets rid of alleles with greater variation phenotypes [quantitative traits like numbers] Favor heterozygotes
Define Disruptive Selection
- has to do with two or more alleles, heterozygotes are unfavored, so the homozygous are favored. - This favors polymorphisms which is like variation
Balancing Selections
- has to do with two or more alleles, keeps genetic variation in a populations or species, it maintains two or more forms in a population. Favor heterozygotes
C5. Would each of the following examples of reproductive isolation be considered a result of a prezygotic or postzygotic mechanism? A. Horses and donkeys can interbreed to produce mules, but the mules are infertile. Postzygotic - hybrid sterility B. Three species of orchid genus Dendrobium produce flowers 8 days, 9 days, and 11 days after a rainstorm. The flowers remain open for 1 day. Prezygotic - temporal isolation C. Two species of fish release sperm and eggs into seawater at the same time, but the sperm of one species do not fertilize the eggs of the other species. Prezygotic - gametic isolation D. Two three frogs, Hyla chrysoscelis (diploid) and Hyla versicolor (tetraploid), can produce viable offspring, but the offspring are sterile. Postzygotic - hybrid sterility
A. Post zygotics B. Pre-Zygotic C. pre zygotic D. post zygotic
C27. Antibiotics are commonly used to combat bacterial and fungal infections. During the past several decades, however, antibiotic-resistant strains of microorganisms have become alarmingly prevalent. This resistance has undermined the effectiveness of antibiotics in treating many types of infectious disease. Discuss how the following processes that alter allele frequencies may have contributed to the emergency of antibiotic-resistant strains:
A. Random Mutation - can help them with degrading compounds so they can degrade antibiotics B. Genetic Drift - can get a random mutation that conifers antibiotic resistance so it gets fixed in a population c. Natural Selection - favor in selection to antibiotic resistance if they face antibiotics.
C13. Suppose that weight in a species of mammal is a polygenic trait and each gene exists as a heavy and light allele. If the allele frequencies in the population are equal for both types of alleles (i.e., 50% heavy alleles and 50% light alleles), what percentage of individuals will be homozygous for the light alleles in all of the genes affecting this trait, if the trait was determined by the following number of genes?
A. Two The probability of inheriting two light alleles from a parent would be 0.5 x 0.5 = 0.25. The probability of inheriting two light alleles from both parents would be 0.25 x 0.25 = 0.0625, or 6.25%. B. Three The probability of inheriting three light alleles from a parent would be 0.5 x 0.5 x 0.5 = 0.125. The probability of inheriting three light alleles from both parents would be 0.125 x 0.125 = 0.0156, or 1.56%. C. Four The probability of inherited four light alleles from a parent would be 0.5 x 0.5 x 0.5 x 0.5 = 0.0625. The probability of inheriting four light alleles from both parents would be 0.0625 x 0.0625 = 0.0039, or 0.39%
Which are purines?
Adenine and Guanine (both have two rings)
C9. Alloploids are produced by crosses involving two different species. Explain why alloploids may be reproductively isolated from the two original species from which they were derived. Explain why alloploids are usually sterile, whereas allotetraploids (containing a diploid set from each species) are commonly fertile.
Allotetraploids are usually reproductively isolated from the two original species due to hybrid sterility. The hybrid may survive, but it will not have an even number of sets of chromosomes. When it undergoes meiosis, each chromosome will not have a homolog to pair with. Therefore, the cells that are produced will be highly aneuploid and lead to inviable gametes and/or offspring. Allotetraploids tend to be fertile because they have an even number of chromosomes that can pair during meiosis and do not form aneuploid cells.
C8. In a population, the frequencies of two alleles are B=0.67 and b=0.33. The genotype frequencies are BB=0.50, Bb=0.37, and bb=0.13. Do these numbers suggest inbreeding? Explain why or why not?
Applying the Hardy-Weinberg equation gives these genotype frequencies: BB = (0.67)2 = 0.45, or 45% Bb = 2(0.67)(0.33) = 0.44, or 44% bb = (0.33)2 = 0.11, or 11% Those above are the expected values. The actual data show a higher percentage of homozygotes (compare 45% with 50% and 11% with 13%) and a lower percentage of heterozygotes (compare 44% with 37%) than expected. Therefore, these data are consistent with inbreeding, which increases the percentage of homozygotes and decreases the percentage of heterozygotes. If homozygous dominant increases [that what u expected] and heterozygous dominant decreases [lower than what you expected]then yes there is inbreeding. .
C21. When artificial selection is practiced over many generations, eventually a plateau is reached in which further selection has little effect on the outcome of the trait. This phenomenon is illustrated in Figure 28.11. Explain why it occurs.
In some cases, the alleles that are being selected will become monomorphic in the population, and further selection will have no effect. Alternatively, a second possible reason for a selection limit is natural selection. Some genes that respond to artificial selection have a negative impact on the overall fitness of a population. A selection limit is reached in which the desired effects of artificial selection are balanced by the negative effects on fitness.
base modifiers and give example
Nitrous Acid -> causes adenine to Uracil and Hypoxanthine with cytosine
Let's suppose a researcher was interested in the effects of mutations on the expression of a protein-encoding gene for a protein that is 472 amino acids in length. This protein is expressed in leaf cells of Arabidopsis thaliana. Because the average molecular mass of an amino acid is 120 Da, this protein has a molecular mass of approximately 56,640 Da: Make a drawing that shows the expected results of a Western blot using proteins isolated from the leaf cells that were obtained from the following individuals: Lane 1. A plant homozygous for a nonmutant gene Lane 2. A plant homozygous for a deletion that removes the promoter for this gene Lane 3 heterozygous plant in which one gene is nonmutant and the other gene has a mutation that introduces an early stop codon at codon [112] Lane 4 A plant homozygous for a mutation that introduces an early stop codon at codon 112 Lane 5. A plant homozygous for a mutation that changes codon [08 from a phenylalanine codon into a leucine codon
So 56,640 is the biggest so its at the top, then the 13,000 is in the bottom. L1 - shows at the top since it has everything L2 - shows NOTHING bc the promoter doesnt work so it cant get started L3 - since heterozygous it shows both since it has 1/2 genes of 2 L4 - it would be at the bottom sinse its shorter L5 - the same as L1 bc it would still be the same molecular weight
C33. What are the two main mechanisms by which cells repair double-strand breaks? Briefly describe each one.
The two main mechanisms by which cells can repair Double stranded breaks are are homologous recombination (HR) and nonhomologous end joining (NHEJ). In homologous recombination a segment of an undamaged sister chromatid is used as a template to repair a DSB in the damaged sister chromatid. [Here you need another chromosome] During nonhomologous end joining, the two broken ends of DNA are simply pieced back together (see Figure 19.22).This can lead to more mutations as it it chewd up and then just stuck together.
What do intercalating agents do? and give example
There go in between the DNA -> distortion in the DNA helical structure. frame shift mutations Proflavin and acridine dyes
Alkylating agents
This adds methyl/Ethel groups to the base pairs. nitrogen mustard and ethyl methanesulfonate
In the Western blot shown here, proteins were isolated from red blood cells and muscle cells from two different individuals. One individual was unaffected, and the other suffered from a disease known as thalassemia, which involves a defect in hemoglobin. The blot was exposed to an antibody that recognizes β globin, which is one of the polypeptides that constitute hemoglobin. Equal amounts of total cellular proteins were added to each lane. see figureExplain these results.
This happened bc B globin can only be seen by red blood cells so thats why only lane 1 and 2 show those lanes. Then in 3 and 4 muscle cells do not have the b globulin. Now to talk about why one is smaller it is possible that the 2nd lane is less because they do have that that mutation down promoting the transcription gene.
What type of mutation do you expect from this mutagen? 5 - Bromouracil
Transition Mutation Causes G's to become A's
What type of mutation do you expect from this mutagen? Nitrous Acid
Transition Mutation Causes G's to become A's and C's to become T's.
Non - Sense Mutation
a stop codon is added instead of amino acid
Types of Speciation
allopatric, parapatric, sympatric
Frameshift Mutation
and insertion or deletion changes the code sequence of amino acids and ends in some thing new being translated - mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide
Which are pyrimidines?
cytosine, thymine, uracil
Explain allopatric speciation
there is a population that is seperated by a barrier so they are two DIFFERENT species
Define Directional Selection
- trait or phenotype has a increased survival so it is favored over generations - can get it from a mutations or the environment
. Two populations of snakes are separated by a river. The snakes cross the river only on rare occasions. The snakes in the two populations look very similar to each other, except that the members of the populations on the eastern bank of the river have yellow spot on the top of their head, whereas the members of the western population have an orange spot on the top of their head. Discuss two experimental methods that you might use to determine whether the two populations are members of the same species or members of different ones.
1. karyotyping 2. Do they mate 3. biological species concept
To produce transgenic plants, plant tissue is exposed to A. tumefa- ciens and then grown in media containing kanamycin, carbenicil- lin, and plant growth hormones. explain the purpose of using each of these three agents. What would happen if you left out the kanamycin?
A kanamycin-resistance gene is contained within the T DNA. Exposure to kanamycin selects for the growth of plant cells that have incorporated the T DNA into their genome. The carbenicillin kills the A. tumefaciens. The plant growth hormones promote the regeneration of an entire plant from somatic cells. If kanamycin was left out, it would not be possible to select for the growth of cells that had taken up the T DNA.
What is a addition mutation?
A nucleic acid is added to the gene. Ends in a longer sequence
C27. Antibiotics are commonly used to combat bacterial and fungal infections. During the past several decades, however, antibiotic-resistant strains of microorganisms have become alarmingly prevalent. This resistance has undermined the effectiveness of antibiotics in treating many types of infectious disease. Discuss how the following processes that alter allele frequencies may have contributed to the emergency of antibiotic-resistant strains: A. Random mutation B. Genetic drift C. Natural selection
A. Random mutation B. Genetic drift C. Natural selection
DNA Sequencing can help researchers indentify mutation within genes. Here is data from normal genes and mutant genes: LOCATE AND DESCRIBE THE MUTATION
At the end there is a change from A to G which is a transitional mutation.
A person with a rare genetic disease has a sample of her chromosomes subjected to fluorescence in situ hybridization using a probe that is known to recognize band p11 on chromosome 7. Even though her chromosomes look cytologically normal, the probe does not bind to this person's chromosomes. How would you explain these results? How would you use this information to positionally clone the gene that is related to this disease?
C1. You would conclude that she has a deletion of the gene that the probe recognizes. To clone this gene, you could begin with a marker that is known to be near band p11 and walk in either direction. This walking experiment would be done on the DNA from an unaffected person and compared to the DNA from the person described in the problem. At some point, the walk would yield a clone that contained a deletion in the person with the disease, but the DNA would be present in an unaffected person. This DNA fragment in the unaffected person should also hybridize to the probe.
A conjugation-deficient strain of A. radiobacter is used to combat crown gall disease. Explain how this bacterium prevents the disease, and describe the advantage of using a conjugation-deficient strain.
C2. A. radiobacter synthesizes an antibiotic that kills A. tumefaciens. The genes that are necessary for antibiotic biosynthesis and resistance are plasmid-encoded and can be transferred during interspecies conjugation. If A. tumefaciens received this plasmid during conjugation, it would be resistant to killing. Therefore, use of a conjugation-deficient strain of A. radiobacter prevents the occurrence of A. tumefaciens-resistant strains.
Explain sympatric speciation
Differentiation which occurs within a population
E5. F1 hybrids between two species of cotton, Gossypium barbadense and Gossypium hirsutum, are vigorous plants. However, F1 crosses produce many seeds that do not germinate and a high percentage of very weak F2 offspring. Suggest two reasons for these observations.
For example, the two species may have different numbers and types of chromosomes. the chromosomes of closely related species may differ with regard to inversions and translocations. so they have unbalanced gametes
Explain parapatric speciation
Occurs when populations are separated not by a geographical barrier, such as a body of water, but by an extreme change in habitat. While populations in these areas may interbreed, they often develop distinct characteristics and lifestyles. Extremely rare.
What does Pure As Gold Stand For?
Remembering Adenine and Guanine are purines
Contigs are often made using BAC or cosmid vectors. What are the advantages and disadvantages of these two types of vectors? Which type of contig would you make first, a BAC or cosmid con- tig? Explain.
A BAC vector can contain extremely large pieces of DNA, so it is used as a first step to align the segments of DNA in a physical mapping study. However, it is difficult to work with them in subcloning and DNA sequencing experiments. Cosmids, by comparison, contain smaller segments of the genome. The locations of cosmids can be determined by hybridizing them to BACs. The cosmids can then be used for subcloning and DNA sequencing.
C15. Which would you expect to exhibit a faster rate of evolutionary change, the nucleotide sequence of a gene or the amino acid sequence of the encoded polypeptide of the same gene? Explain your answer.
A gene sequence can evolve more rapidly. The purpose of protein-encoding genes is to encode a polypeptide with a defined amino acid sequence
In the study of plants and animals, it is relatively common for re- searchers to identify a gene using molecular techniques without knowing the function of the gene. In the case of mice, the function of the gene can be investigated by creating a gene knockout. A knockout that causes a phenotypic change in the mouse may provide an important clue regarding the function of a gene. for example, a gene knockout that produced an albino mouse would indicate that the knocked-out gene probably plays a role in pig- ment formation. The experimental strategy of first identifying a gene based on its molecular properties and then investigating its function by making a knockout is called reverse genetics. explain how this approach is opposite to (or the reverse of) the conven- tional way that geneticists study the function of genes.
A person with a rare genetic disease has a sample of her chromosomes subjected to fluorescence in situ hybridization using a probe that is known to recognize band p11 on chromosome 7. Even though her chromosomes look cytologically normal, the probe does not bind to this person's chromosomes. How would you explain these results? How would you use this information to positionally clone the gene that is related to this disease?
C9. The ability to roll your tongue is inherited as a recessive trait. The frequency of the rolling allele is approximately 0.6, and that of the dominant (nonrolling) allele is 0.4. What is the frequency of individuals who can roll their tongues?
Because this is a recessive trait, only the homozygotes for the rolling allele will be able to roll their tongues. If the frequency of the rolling allele is 0.6 and nonrolling allele is 0.4, the frequency of individuals who can roll their tongues is (0.6)2 = 0.36 or 36%. Hardy Weinburg Eq = p^2 + 2pq + q^2 Q is the recessive homozygous P is the dominant homozygous 2pq is the heterozygous PLUG AND CHUG q^2 is 0.6 so to solve its (0.6)^2 you get 0.36 which is 36%
What part of the A. tumefaciens DNA gets transferred to the genome of a plant cell during infection?
C8. The T DNA gets transferred to the plant cell; it is then incorporated into the plant cell's genome.
How would you change a leucine to and arginene?
CCC, CCG, ACA, TCA, TTA 5' GCC,CCC,GAT,CTA,CAT,CAT,TAC,GGC,GAT 3' We want to go from leucine CTA to arginine which is AGA or AGG.
C15. Is each of the following examples due to directional, disruptive, balancing, or stabilizing selection? A. Polymorphisms in color and banding pattern of the shells of land snails, as shown in the Figure 27.12 B. Thick fur among mammals living in cold climates C. Birth weight in humans D. Sturdy stems and leaves among plants exposed to windy climates
Directional - trait or phenotype has a increased survival so it is favored over generations - can get it from a mutations or the environment Disruptive - has to do with two or more alleles, heterozygotes are unfavored, so the homozygous are favored. - This favors polymorphisms which is like variation Stabilizing selection - has to do body weight, # of offspring, there is less genetic diversity bc it gets rid of alleles with greater variation phenotypes [quantitative traits like numbers] Favor heterozygotes Balancing - has to do with two or more alleles, keeps genetic variation in a populations or species, it maintains two or more forms in a population. Favor heterozygotes A. Disruptive B. Directional C. Stabilizing D. Directional
In the procedure in figure 21.1, why was it necessary to link the coding sequence for the A or B chain to the sequence for β-galactosidase? How were the A or B chains separated from β-galactosidase after the fusion protein was synthesized in E. coli?
E3. This was necessary because the A or B chain, by itself, is rapidly degraded in E. coli, whereas the fusion protein is not. The A or B chains were separated from β-galactosidase via cyanogen bromide.
A researcher is interested in a gene found on human chromosome 21. Describe the expected results of a FISH experiment using a probe that is complementary to this gene. How many spots would you see if the probe was used on a sample from an individual with 46 chromosomes or if it was used on a sample from an individual with Down syndrome?
E7. If the sample was from an unaffected individual, two spots (one on each copy of chromosome 21) would be observed. Three spots would be observed if the sample was from a person with Down syndrome, because the person has three copies of chromosome 21.
In the study of plants and animals, it is relatively common for re- searchers to identify a gene using molecular techniques without knowing the function of the gene. In the case of mice, the function of the gene can be investigated by creating a gene knockout. A knockout that causes a phenotypic change in the mouse may provide an important clue regarding the function of a gene. for example, a gene knockout that produced an albino mouse would indicate that the knocked-out gene probably plays a role in pig- ment formation. The experimental strategy of first identifying a gene based on its molecular properties and then investigating its function by making a knockout is called reverse genetics. explain how this approach is opposite to (or the reverse of) the conven- tional way that geneticists study the function of genes.
E7. In Mendel's work, and the work of many classical geneticists, an altered (mutant) phenotype is the initial way to identify a gene. For example, Mendel recognized a gene that affects plant height by the identification of tall and dwarf plants. The transmission of this gene could be followed in genetic crosses, and eventually, the gene could be cloned using molecular techniques. Reverse genetics uses the opposite sequence of steps. The gene is cloned first, and a phenotype for the gene is discovered later, by making an organism with a gene knockout.
C19. The heritability for egg weight in a group of chickens on a farm in Maine is 0.95. Are the following statements regarding this heritability true or false? If a statement is false, explain why. A. The environment in Maine has very little effect on the outcome of this trait. B. Nearly all of the phenotypic variance for this trait in this group of chickens is due to genetic variance. C. The trait is polygenic and likely to involve a large number of genes. D. Based on the observation of the heritability in the Maine chickens, it is reasonable to conclude that the heritability for egg weight in a group of chickens on a farm in Montana is also very high.
False. The environment has very little impact on the amount of variation in the trait. However, environment always contributes greatly to the outcome of every trait. You could not have a living organism without an environment. B. True. C. Probably true, but you cannot say for sure. Quantitative traits are usually polygenic. D. False. You cannot say anything about the heritability of egg weight in Montana chickens. It depends on the amount of genetic variation in the population and on the type of environment in which they are raised.
E13. A homologous DNA region, which was 20,000 bp in length, was sequenced from four different species. The following numbers of nucleotide differences were obtained: Construct a phylogenetic tree. that describes the evolutionary relationships among these four species using the UPGMA method. Your tree should include values that show the percentages of nucleotide substitutions.
For this question you: Look at the smallest # of base pair differences in this case it is betwen species B and D [ those are in the same clade] , you get 423 and divide by 2 to get the average amount of differences so it is 211.5 Then divide by the total abount of bp which is 20,000 so you get 1.06 {THIS IS THE EVOLUTIONARY DISTANCE] Then you look at the 2nd smallest which is species A to b/D which is 443 and 465, add them and divide by 2 to get 227 then divide by total number of bp 20,000 to get 1.14 Then species C is left over which is 719 + 744+723 divided by 3 to get 364.5 and divide by 20,000 to get 1.82
C7. For a gene existing in two alleles, what are the allele frequencies when the heterozygote frequency is at its maximum value, assuming Hardy-Weinberg equilibrium? What if there are three alleles?
For two alleles, the heterozygote is at a maximum when they are 0.5 each. For three alleles, the two heterozygotes are at a maximum when each allele is 0.33. For 4 alleles it would be .25 They need to be whatever number of alleles divided by 100. This because in order for the heterozygous to be at maximum value for the Hardy-Weinberg equation. So they are euqal to 1.
What type of mutation do you expect from this mutagen? Proflavin
Frameshift Mutations because it causes small deletions or additions
What does inbreedign cause in alleles?
Increases the percentage of homozygotes [BB or bb] and decreases the percentage of heterozygotes.[Bb]
What is deamination?
Now there is A with U and C with H [hypoxanthine] causing mutations
Let's suppose an X-linked gene in mice exists as two alleles, which we will call B and b. X inactivation, a process in which one X chromosome is turned off, occurs in the somatic cells of female mammals (see Chapter 5). Allele B encodes an mRNA that is 900 nucleotides long, whereas allele b contains a small deletion that shortens the mRNA to a length of 825 nucleotides. Draw the expected results of a Northern blot using mRNA isolated from somatic tissue of the following mice: Lane 1. --- mRNA from an Xb Y male mouse Lane 2. --- mRNA from an Xb Xb female mouse Lane 3.---- mRNA from an XBXb female mouse.
So we know B is 900 nucleotides and b is 825 nucleotides Male is XbY so they have 825 nucleotides Female XbXb has 825 bc they are little b Female XBXb they woudl have 1/2 of the 900 and 1/2 of the 825. IN a northern blot the stuff at the bottom would have least and closer to the top would be heaver. So at the bottom put the smallest number and at the top bigger, the one with bigger would mark BOTH #'s.
C7. Two different varieties of potato plants produce potatoes with the same mean weight of 1.5 pounds. One variety has a very low variance for potato weight, and the other has a much higher variance. A. Discuss the possible reasons for the differences in variance. B. If you were a potato farmer, would you rather raise a variety with a low or a high variance? Explain your answer from a practical point of view. C. If you were a potato breeder and you wanted to develop plants that produced heavier potatoes, would you choose the variety with a low or high variance? Explain your answer.
The differences in variance could be explained by variation in the way the potatoes are affected by environmental variation, or they could be explained by genetic differences. The strain with a higher variance may have more genetic variation. On the one hand, the strain with a higher variance may be better because the farmer may want to select for individuals that produce larger potatoes. On the other hand, if the farmer wants the size of his/her potatoes to be uniform, the population with a smaller variance would be better. You would use the strain with a higher variance, hoping that a significant proportion of the variance was due to genetic variation.
E3. In a large herd of 5468 sheep, 76 animals have yellow fat, and the rest of the members of the herd have white fat. Yellow fat is inherited as a recessive trait. This herd is assumed to be in Hardy-Weinberg equilibrium. A. What are the frequencies of the white and yellow fat alleles in this population? B. Approximately how many sheep with fat are heterozygous carriers of the yellow allele?
To do this you need to divide 76 yellow sheep by total # of sheep 76/5468 = 0.014 this is our q^2 to got q you square root so you get 0.12 q=0.12 to get P you use P= 1-q So P = 1 - 0.12 P = 0.88 ---------------------- q2 = 0.014 q = 0.12, which is the allele frequency of w p = 1 - q p = 0.88, which is the allele frequency of W ------------------------------------------------------- To solve you need to use 2pq so 2(0.88)(0.12) = 0.21 then you multiply 0.21 by the total # of animals 0.21 * 5468 = 1,148 --------------------------- The heterozygous carriers are represented by 2pq. If you use the values of p and q, which were calculated in part A: 2pq = 2(0.88)(012) = 0.21 Approximately 21% of the animals would be heterozygotes with white fat. If you multiply 0.21 times the total number of animals in the herd: 0.21 x 5,468 = 1,148 animals
E11. A team of researchers has obtained a dinosaur bone (Tyrannosaurus rex) and has attempted to extract ancient DNA from it. Using primers for the 12S rRNA mitochondrial gene, they carried out PCR and obtained a DNA segment that had a sequence homologous to a sequence in crocodile DNA. Other scientists are skeptical that his sequence is really from the dinosaur. Instead, they believe that it may have come from contamination by more recent DNA, such as the remains of reptile that lived much more recently. What criteria might you use to establish the credibility of the dinosaur sequence?
Tyrannosaurus rex DNA from samples that have been obtained from different locations. Samples from different locations would be less likely to be contaminated with the same kind of DNA.
C29. An individual carries a somatic mutation that changes a lysine codon to a glutamic acid codon. Prior to acquiring this mutation, the individual had been exposed to UV light, proflavin, and 5-bromouracil. Which of these three agents would be the most likely to have caused this somatic mutation? Explain your answer.
We know - UV light causes thymin dimers - where T get double binded to T. which causes distortion of DNA. - proflaivn - is framshift mutation so there would be a different amino acid sequence. On the Table the coding for lysine is AAA and AAG, and for glutimic acid its GAA and GAG which are A to G changes. This means we need something with a transitional mutation which we know is the 5 Bromouracil
What is a deletion mutation?
When one or more nucleotides are lost (i.e., deleted) Ends in a shorter sequence
A cloned gene fragment contains a response element that is recognized by a regulatory transcription factor. Previous experiments have shown that the presence of a hormone results in transcriptional activation by this transcription factor. The gel shows a electrophoretic mobility shift assay using the hormone, transcription factor and gene fragment. Explain the action of the hormone.
When there is hormone the transcription factor binds to the rugulatory elemnt and promotes transcription.
C17. Plant seeds contain storage proteins that are encoded by the plant's gene. When a seed germinates, these proteins are rapidly hydrolyzed (i.e., the covalent bonds between amino acids within the polypeptides are broken), which releases amino acids for the developing seedling. Would you expect the genes that encode plant storage proteins to evolve more slowly or more rapidly than genes that encode enzymes? Explain your answer.
You would expect the sequences of plant storage proteins to evolve rapidly. The polypeptide sequence is not particularly important for the structure or function of the protein. The purpose of the protein is to provide nutrients to the developing embryo. Changing the sequence would likely be tolerated. However, major changes in the amino acid composition (not the sequence) may be selected against.
What do Base Analogs mutation do? and give example
gives you 5BU which promotes AT base pairing to become GC base pairing 5 - bromouracil
Silent Mutation
mutation but it still codes the same amino acid sequence EX: GAC -> serine GAA -> serine
Missense Mutation
mutation that ends up with a different amino acid EX: GAC-> serine GAT-> histamine
C7. Describe three or more genetic mechanisms that may lead to the rapid evolution of a new species. Which of these genetic mechanisms are influenced by natural selection, and which are not?
mutations though natural selection Flounder Effect - yes natural selection - subset population moves to a new area Allotetraploidy - not on natural selection -
A mutation changes a codon that specifies tyrosine into a stop codon. This type of mutation is a : a. missense mutation b. nonsense mutation c. framshift mutation d. neutral mutation
nonsense
What is the Hardy-Weinberg equation?
p^2 + 2pq + q^2 = 1 q is the ressesive allele P is the dominante Allele also
What is pre-zygotic mechanisms?
prevents individuals of different species from mating - habitat isolation - temporal differences - Sexual Isolation - mechanical isolation - gametic isolation
What is a transversion mutation?
when you change from purine to pyrimidine
What is a transition mutation?
when you stay in the same category, EX: purine to purine pyrimidine to pyrimidine
