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Describe Mendel's conclusions about how traits are passed from generation to generation - correct answer- - Mendel hypothesized that traits in peas are controlled by specific unit factors. He suggested that unit factors occur in pairs and that unit factors separate from each other during gamete formation.

2. How is the chromosome theory of inheritance related to Mendel's findings - correct answer- - The chromosome theory of inheritance is based on the parallels between Mendel's model of heredity and the behavior of chromosomes during meiosis.
3. In meiosis, there are two sequential divisions of the parent cell, producing four daughter cells. In terms of the behavior of the chromosomes, how does meiosis I compare to meiosis II? - correct answer- - A. Homologous chromosomes separate in meiosis I; sister chromatids separate in meiosis II. One character in peas that Mendel studied was yellow versus green seeds. A cross between a homozygous yellow line (GG) and a homozygous green line (gg) will result in F plants that are heterozygous (Gg) for this trait and produce yellow seeds. Gg x Gg produces F2 seeds. Conditional probabilities apply when the pool of possible outcomes is reduced in some way by additional criteria. Use your knowledge of conditional probabilities and the Punnett square to answer this question.
4. What is the probability that an F2 seed chosen at random from among only the yellow seeds will have a genotype of Gg? - correct answer- - 2/
5. You would like to know whether the progeny of a pair of mated fruit flies in a test cross are distributed among the resulting four phenotypic classes in a 1:1:1:1 ratio. You perform a chi-square test and obtain a p value of 0.04. Assuming you have done the test correctly,

select the best interpretation of this result. - correct answer- - B. The differences between the observed and expected counts are too large to be attributed to chance.

6. In mice, agouti fur is a dominant trait resulting in individual hairs having a light band of pigment on an otherwise dark hair shaft. A mouse with agouti fur is shown here, along with a mouse with solid color fur, which is the recessive phenotype (A = agouti; a = solid color). A separate gene, which is not linked to the agouti gene, can result in either a dominant black pigment or a recessive brown pigment (B = black; b = brown). A litter of mice from the mating of two agouti black parents includes offspring with the following fur colors:

• solid color, black
• solid color, brown (sometimes called chocolate)
• agouti black
• agouti brown (sometimes called cinnamon) What would be the expected frequency of agouti brown offspring in the litter? - correct answer- - 3/

7. In the same mouse species as question 9, a third unlinked gene (gene C/c) also has an epistatic effect on fur color. The presence of the dominant allele C (for color), allows the A/a and B/b genes to be expressed normally. The presence of two recessive alleles (cc), on the other hand, prevents any pigment from being formed, resulting in an albino (white) mouse. The fourth unlinked gene (gene P/p) also affects fur color.

• For mice that are either homozygous dominant (PP) or heterozygous (Pp), the organism's fur color is dictated by the other three genes (A/a, B/b, and C/c).
• For mice that are homozygous recessive (pp), large patches of the organism's fur are white. This condition is called piebaldism. In a cross between two mice that are heterozygous for agouti, black, color, and piebaldism, what is the probability that offspring will have solid black fur along with large patches of white fur? - correct answer- - 9/

8. Which of the following is the most likely example of codominance? - correct answer- - A pure-breeding plant with red flowers is crossed to a pure-breeding plant with white flowers. All their progeny have flowers with some red patches and some white patches.
9. Cationic trypsinogen is an enzyme made in the pancreas that helps to digest food. It is encoded for by the PRSS1 gene. Individuals with a disorder called hereditary pancreatitis have mutations in the PRSS1 gene, which result in inflammation of the pancreas, possibly leading to permanent tissue damage. The disorder is inherited in an autosomal dominant fashion. Studies of large human populations have determined that the penetrance of a particular PRSS1 mutation, Arg122His, is 86%. - correct answer- - C. They have an 86% chance of showing the associated phenotype.
10. Consider the following family history: Bob has a genetic condition that affects his skin. Bob's wife, Eleanor, has normal skin. No one in Eleanor's family has ever had the skin condition. Bob and Eleanor have a large family. Of their eleven children, all six of their sons have normal skin, but all five of their daughters have the same skin condition as Bob. Based on Bob and Eleanor's family history, what inheritance pattern does the skin condition most likely follow? - correct answer- - D. X-linked dominant
11. Which of the following correctly indicates the linkage in the trihybrid parent (MmDdPp - correct answer- - A. MDP/mdp What can you conclude from the actual data about the location of the three genes in relation to one another - correct answer- - The B and C loci are linked and locus A assorts independently from both B and C loci. How far apart are the linked genes? - correct answer- - 20 map units Which of the following statements about the T4 lytic life cycle is false? - correct answer- -. The phage DNA is injected into the host and integrates into the bacterial chromosome

In your research on amino acid biosynthesis in E. coli, you have identified three new auxotrophic mutants in a mutagenesis screen. Each mutant can grow on minimal medium only if it is supplemented with a specific amino acid, as follows: lys2 mutants require lysine, gly3 mutants require glycine, and phe1 mutants require phenylalanine. To determine exconjugant genotypes based on medium composition, which one of the following statement is not correct? - correct answer- - lys2- bacteria will grow on minimal medium. How do mammals, including humans, solve the "dosage problem" caused by the presence of an X and Y chromosome in one sex and two X chromosomes in the other sex? - correct answer- - In females, one of the X chromosomes is condensed and largely inactive so that each sex has one active X chromosome When the cloned cat Carbon Copy (CC) was born, she had black patches and white patches, but completely lacked any orange patches. The knowledgeable students of genetics were not surprised at this outcome. - correct answer- - The donor nucleus had an orange allele that was inactivated and remained inactivated in CC. The remaining black allele was the only one that could be expressed Which of the following syndromes is not paired with its causative chromosomal aberration?

• correct answer- -. Fragile X syndrome - deletion The incidence of Down syndrome, also known as trisomy 21, increases with increasing maternal age. Which of the following errors most likely produces this condition? - correct answer- - Nondisjunction during either meiosis I or II in the female gamete When a variegated female four o'clock plant is crossed with any male plant, progeny plants can have either green, white, or variegated leaves. Which of the following statements incorrectly explain this result? - correct answer- - The female plant is homozygous in some cells and heterozygous in other cells.

. In the pedigree below, individual I-1 has Leber hereditary optic neuropathy (LHON), an inherited form of vision loss caused by a mutation in mitochondrial DNA. Which members of her family will not inherit LHON? - correct answer- - E. III- 2 Sometimes, a mother who is affected with a mitochondrial disease will have an unaffected child. Which of one of the following incorrectly explains this observation? - correct answer-

• One or more of the children could inherit the majority of their mitochondria from an unaffected father What key observations in crosses between dextrally and sinistrally coiled land snails support the explanation that this phenotype is the result of maternal-effect inheritance? - correct answer- - When eggs from a Dd (but sinistral because of its parent) snail are self- fertilized, all the offspring, even those that are dd, coil dextrally. The following pedigree shows the inheritance of a mild, but very rare condition in Siberian Husky dogs. If individuals 1 and 2 are crossed, what is the probability that they will produce an affected pup? - correct answer- - 4/ In a certain breed of dog, the alleles B and b determine black and brown coats, respectively. However, the allele Q of an unlinked gene is epistatic to the B and b color alleles, resulting in a gray coat (q has no effect on color). If animals of genotype B/b; Q/q are intercrossed, what phenotypic ratio is expected in the progeny? - correct answer- - 3 black, 12, gray, 1 brown The following pedigree depicts the inheritance of a rare hereditary disease affecting muscles: - correct answer- - X-linked recessive . If genes assort independently, a testcrossed dihybrid characteristically produces progeny phenotypes in the ratio: - correct answer- - 1:1:1:

. A male mouse of genotype A/a. B/b is testcrossed multiple times. Overall, these testcrosses produce 11 mice of phenotype A B, 81 mice of A b, 77 mice of a B, and 14 mice of a b. Based on these data, the genotypes of the male mouse's parents are most likely - correct answer- - Ab/Ab and aB/aB. True-breeding tall plants with white flowers are crossed to true-breeding dwarf plants with purple flowers. The F1 plants were tall with purple flowers. The genes that affect these traits independently assort. If the F1 plants were allowed to self-fertilize, the expected ratio of the F2 generation would be - correct answer- - 9 tall/purple flowers: 3 tall/white flowers : 3 dwarf/purple flowers : 1 dwarf /white flowers Mendel's law of segregation can be explained by - correct answer- - the separation of homologs during anaphase I of meiosis. A trait exhibits incomplete dominance. If one of the two alleles is a loss-of-function allele, a reasonable molecular explanation would be - correct answer- - 50% of the functional protein is not enough to give the same phenotype as 100 In mice, brown color (B) is dominant over white (b), long tail (L) is dominant over short tail (l), and straight fur (S) is dominant over curly fur (s). If two mice that are heterozygous for all three genes are crossed to each other, what is the probability that an offspring will be BBLlss? - correct answer- - 1/ An aaBB individual is crossed to an AAbb individual to produce AaBb offspring. The AaBb offspring are then crossed to aabb individuals to produce an F2 generation. What are the genotypes of the F2 recombinant offspring? - correct answer- - AaBb and aabb Two genes are 14 map units apart. A CCDD individual was crossed to a ccdd individual to produce CcDd individuals. The CcDd individuals were then crossed to ccdd individuals to produce an F2 generation. If there are 400 members of the F2 generation, how many would you expect to be ccdd? - correct answer- - 172

. In pea plants, tall (T) is dominant to dwarf (t). Recently, you have discovered a new gene in peas that exists in two alleles, L causes large leaves and l causes small leaves. You begin with two true-breeding strains, tall with small leaves and the other dwarf with large leaves. All of the F1 offspring are tall with large leaves. You then cross the F1 offspring to dwarf plants with small leaves and obtain the following results: 394 Tall, small leaves 110 Tall, large leaves 385 Dwarf, large leaves 111 Dwarf, small leaves

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1000 Total F2 offspring What can you conclude about the relationship between the plant height gene T and the plant leaf size gene L - correct answer- - They are most likely located on the same chromosome. . A biochemical pathway making flower pigments shows the following sequential color conversions (each arrow represents an enzyme catalyzed step). White → yellow → blue → red A B C A plant is homozygous for mutations in enzyme "B," inactivating the active site for this enzyme. The resulting flowers will be - correct answer- - yellow . In the following cell lines, which one contains F factor in the plasmid form carrying a segment of chromosomal DNA? - correct answer- - F' The recessive alleles k (kidney-shaped eyes instead of wild-type round), c (cardinal-colored eyes instead of wild-type red), and e (ebony body instead of wild-type gray) identify three

genes on chromosome 3 of Drosophila. Females with kidney-shaped, cardinal-colored eyes were mated with ebony males. The F1 was wild type in all three traits. When F females were testcrossed with kk cc ee males, the following progeny phenotypes were obtained: Determine the order of the genes on chromosome 3. - correct answer- - k - e - c Which of the following statements best represents variable expressivity and incomplete penetrance? - correct answer- - Polydactyly, a dominant trait in humans does not develop to the same degree in different heterozygous individuals and provides an example of variable expressivity; the extreme case, where a heterozygote does not develop polydactyly is an example of incomplete penetrance. Mutations in mitochondrial DNA appear to be responsible for a number of neurological disorders, including myoclonic epilepsy and ragged-red fiber disease, Leber's hereditary optic neuropathy, and Kearns-Sayre syndrome. In each case, the disease phenotype is expressed when the ratio of mutant to wild-type mitochondria exceeds a threshold peculiar to each disease, but usually in the 60 to 95 percent range. Can you suggest a general approach that might be used to treat, or perhaps even cure, these disorders? For example, Compared with the vast number of mitochondria in an embryo, the number of mitochondria in an ovum is relatively small. Might such an ooplasmic mitochondrial bottleneck present an opportunity for therapy or cure? - correct answer- - It may be possible to alter the heteroplasmic ratio by microinjection of mitochondria.

. The genes encoding the red- and green-color-detecting proteins of the human eye are located next to one another on the X chromosome and probably evolved from a common ancestral pigment gene. The two proteins demonstrate 76 percent homology in their amino acid sequences. A normal-visioned woman (with both genes present on each of her two X chromosomes) has a red-color-blind son who was shown to have one copy of the green- detecting gene and no copies of the red-detecting gene. Which of the following is the most plausible explanation for these observations? - correct answer- - An X chromosome lacking the red-detecting gene was produced by a crossover event between the red-detecting allele and the green-detecting genes of the mother's X chromosomes.

In this following pedigree, in order for individual III-1 to be affected with the condition, which four of these requirements must be met? 1). II-2 must be a carrier. 2). II-2 must pass a dominant allele to III-1. 3). II-2 must pass a recessive allele to III-1. 4). II-3 must be a carrier. 5). II-3 must pass a dominant allele to III-1. 6). II-3 must pass a recessive allele to III-1. - correct answer- - C. 1), 3), 4), and 6)

44. A mutation that causes a yellowing of leaves in snapdragon plants was discovered in the early 1900s. Plants with this condition, termed aurea, have less chlorophyll than green plants. Crosses between various combinations of green and aurea plants yielded the following results. green x green = all green aurea x aurea = 2/3 aurea, 1/3 green green x aurea = 1/2 green, 1/2 aurea How can the unusual results from the crosses be explained? - correct answer- - The aurea allele behaves as a recessive lethal allele. In 1928, Frederick Griffith established that heat-killed bacteria harbor the constituent(s) necessary to convey genetic properties to living bacteria. To be certain that the extract prepared from virulent cells still contained the transforming principle that was present prior to lysis, Avery et al. incubated nonvirulent cells with the complete extract in their experiment. If they had observed transformation using only the extracts containing degraded DNA, degraded RNA, and degraded protein, but NOT the extract containing

degraded polysaccharides, they would have concluded that - correct answer- - d. polysaccharides are the genetic material What is the structural difference between ATP and dATP - correct answer- - d. ATP has a 2' OH and 3' OH dATP has a 2' H and 3' OH In bacteria, DNA polymerase III is the enzyme that adds new nucleotides to a primer or growing strand of DNA. Which of the following statements correctly describes the formation of the bond between a new nucleotide and the primer? - correct answer- - a. The newly added nucleotide forms a bond with the hydroxyl (-OH) group on the 3' end of the primer. At a replication fork, the two parental DNA strands separate, and each strand is copied by a DNA polymerase III, synthesizing a new, complementary strand. The diagram below shows a replication fork with the two parental DNA strands labeled at their 3' and 5' ends. The newly synthesized DNA strands are not shown, but the polymerase on each parental strand is shown (labeled 1 and 2). - correct answer- - c. Polymerase 1 elongates its strand toward the replication fork, but polymerase 2 elongates its strand away from the replication fork. DNA Recombination occurs during meiosis between two DNA molecules that have substantial sequence homology, which structures can be involved in recombination - correct answer- - b. Chromatids of homologous chromosomes Clearly, there is a relationship between Tm and %GC for these samples. What might be the molecular basis of this relationship? - correct answer- - c. Higher number of hydrogen bonds in CG pairs than in AT pairs. Histone acetyltransferases (HATs) are capable of remodeling chromatin by adding acetyl groups to various lysine residues in histones that comprise the nucleosome. Following this modification, the lysine residue no longer has a positive charge. Which statement is true? - correct answer- - Histones in general have a net positive charge that allow them to bind to

DNA. Acetylation of histones, decreases their positive charge and weakens the histone- DNA interaction. Chromatin exists in different states of compaction and relaxation that regulate access to DNA by regulatory proteins. Heterochromatic regions of chromosomes are relatively inaccessible to transcriptional proteins either transiently (in the case of facultative heterochromatin) or nearly always (in the case of constitutive heterochromatin). Which of the following region of chromosomes is not example of heterochromatin? - correct answer- - Examples of histone modifications are acetylation (by histone acetyltransferase, or HAT), which is often linked to gene activation, and deacetylation (by histone deacetylases, or HDACs), which often leads to gene silencing typical of heterochromatin. Such heterochromatinization is initiated from a nucleation site and spreads bidirectionally until encountering boundaries that delimit the silenced areas. Position effect was discovered in Drosophila, where repositioning of the w + allele in Drosophila by translocation or inversion near heterochromatin produces intermittent w + activity. In the heterozygous state (w +/w), a variegated eye is produced, with white and red patches. How might one explain position- effect variegation in terms of histone acetylation and/or deacetylation? - correct answer- - b. The white patches are caused by the deacetylation of the histones associated with the DNA of the w + allele RNA splicing is necessary to produce a mature mRNA from the pre-mRNA. Which of the following is a characteristic of RNA splicing in Eukaryotes? - correct answer- - c. Exon/intron boundaries are typically characterized by a 5' GU splice junction and a 3' AG splice junction. Does RNA polymerase move in a set direction along a strand of DNA during transcription - correct answer- - c. Yes, the RNA polymerase moves in a direction that reads the bases of the DNA sequence from the 3' end toward the 5' end of the template strand. Translation is directly dependent on all of the following associations except - correct answer- - c. complementary base pairing between mRNA and DNA

Frameshift mutations alter the reading frame of the genetic message encoded in the mRNA and typically have disastrous effects on the resulting protein. Which of the following mutations would result in a frameshift mutation? - correct answer- - b. deletion of two sequential nucleotides in the coding region of the Proteins may either be translated on free ribosomes or on ribosomes bound to the ER. What is the cellular destination of the majority of proteins that are translated on free ribosomes? - correct answer- - cytoplasm Below is a partial mRNA sequence. Use it to answer the following questions. 5' - GCCGAUCGAACU - 3' Encoded within the partial mRNA sequence is a region of the protein with the amino acid sequence (N-term...Proline-Isoleucine-Glutamic acid...C-term). What is the correct reading frame for this mRNA? - correct answer- - d. 5' - G | CCG | AUC | GAA | CU - 3 ' If a single base-pair deletion occurred in the part of the gene that corresponds to the mRNA above and the resulting partial amino acid sequence was (N-term-...Proline-Methionine- Asparagine...-C-term), which new partial mRNA sequence would be consistent with this change? Bases surrounding the deletion are underlined. - correct answer- - b. 5' - G | CCG | AUG | AAC | U - To carry out its role, each transfer RNA requires at least four specific recognition sites that must be inherent in its tertiary structure. Which of the following is not one of the four specific recognition sites of tRNA? - correct answer- - c. attachment of the specific DNA bases How is the trp operon regulated? Select the only statement that does not apply. a. When tryptophan is present, it binds to the regulatory protein, activating it.

b. When glucose is present, it binds to catabolite activator protein (CAP), which stimulates transcription of the operon. c. When tryptophan is absent, the regulatory protein is inactive. d. The trp operon undergoes negative control. - correct answer- - b. When glucose is present, it binds to catabolite activator protein (CAP), which stimulates transcription of the operon How is the lac operon regulated? Select the only statement that does not apply. a. The lac operon undergoes positive control. b. When lactose (and, therefore, allolactose) is absent, the regulatory protein is inactive. c. The lac operon undergoes negative control. d. When glucose is absent, cAMP binds to catabolite activator protein (CAP), activating CAP to increase transcription of the operon. - correct answer- - b. When lactose (and, therefore, allolactose) is absent, the regulatory protein is inactive. Bacteria respond to changing environmental conditions by using regulatory proteins to turn groups of genes on and off in response to environmental signals. Which of the following best describes the biological role of the lac operon? - correct answer- - It ensures that a cell dedicates resources to the production of enzymes involved in lactose metabolism only when lactose is available in the environment. The leader sequence is located between the promoter/operator region and the structural genes of the trp operon. Which of the following features of the trp operon is likely least essential to the process of attenuation? - correct answer- - d. The order of the structural genes, E, D, C, B, A Attenuator systems such as the one described for regulation of tryptophan synthesis would be just as likely to occur in eukaryotes as in prokaryotes - correct answer- - false

Bacterial strains that are "partially diploid" have two copies of the lac operon because they aquired a plasmid carrying just the lac operon region. One copy of the lac operon region is on the recipient's bacterial chromosome, and the other copy is on the F' plasmid that was introduced into the cell by conjugation. Partial diploid genotypes are written with the F' segment first and the recipient chromosome next. You create a lac operon partial diploid with this genotype: F' I+ P+ Oc Z− Y+ / I− P+ O+ Z+ Y− To determine which genes are transcribed and under what conditions, you need to first consider each genotype separately, and then together. Which of the following summarizes expression of the lac genes in this partial diploid: F' I+ P+ Oc Z− Y+ / I− P+ O+ Z+ Y−? - correct answer- - d. Permease is made both in the presence of and in the absence of lactose; beta-galactosidase is only made when lactose is present. Which statement about the modification of chromatin structure in eukaryotes is not true? - correct answer- - Deacetylation of histone tails in chromatin loosens the association between nucleosomes and DNA. Which of the following statements regarding dispersed promoters is true? - correct answer- - b. Dispersed promoters are found in genes that are transcribed constitutively. Within a DNA sequence, __________ are crucial for determining whether or not transcription can occur, whereas __________ determine that maximal transcription of the gene occurs - correct answer- - c. core-promoter elements; enhancers Which of the following statements regarding the GAL system in yeast is true? a. Transcription of the structural genes occurs when Gal4p is not bound to UAS. b. Gal80p is the inducer. c. Activation of transcription occurs when galactose interacts with Gal3p. d. GAL10 produces a regulatory protein. - correct answer- - Activation of transcription occurs when galactose interacts with Gal3p.

Wild-type organisms exhibit the phenotype (physical appearance) most often seen in the natural population. Mutant organisms carry mutations, which in some cases alter the phenotype of the organism. A grouping of eight homeotic genes on the same chromosome of a fruit fly became known as the homeotic complex, or Hox genes. Identify which of the following statement is not true Hox genes and pattern formation? a. A homeotic mutant fruit fly develops structures on the wrong body segment. b. Mutations in the Hox genes of a fruit fly usually result in abnormal pattern formation. c. Hox genes code for transcription factors that control the formation of specific structures on particular body segments. d. Wild-type fruit flies possess abnormal Hox genes. e. Wild-type fruit flies exhibit typical pattern formation - correct answer- - Wild-type fruit flies possess abnormal Hox genes The diagram depicts the genetic pathway showing the ced-9 gene acts as a "binary switch" controlling cell death in the nematode C. elegans. Analysis of the nematode gene ced-9 and the human gene bcl-2 has revealed extensive DNA sequence similarity, as well as functional similarity. They both control programmed cell death. Which statement is incorrect describing about ced-9, bcl-2, and apoptosis in the context of evolution? - correct answer- - a. C. elegans (nematodes) and humans (mammals) have evolved distinct pathways for apoptosis, although both pathways have the same effect on the cell. A mutation prevents the lac repressor from recognizing allolactose. In the absence of allolactose, the mutant repressor has the same affinity for the lac operator sites as a normal repressor. How would you expect this mutant repressor to affect the regulation of the lac operon? - correct answer- - The operon would be turned off in the presence or absence of lactose in the environment

The following list describes events that are required for transcription of a eukaryotic gene. Put them in the correct order.

1. Chromatin remodeling and histone modification
2. Formation of the pre-transcription initiation complex
3. Elongation
4. Binding of activators - correct answer- - 4,1,2, Which of the following statements about DNA replication in humans is true? a. Both DNA strands are replicated. b. Multiple sites of replication will be found on each replicating chromosome. c. Replication proceeds bi-directionally. d. All of the above e. None of the above - correct answer- - all o the above The B-galactosidase gene and permease gene will never be transcribed in the environment with or without lactose in which one of the following genotypes? I. I+P+O+Z+Y+/I+P+O+Z+Y+ II. I−P+OCZ+Y−/I−P+O+Z−Y+ III. IsP+O+Z+Y-/I+P+O+Z-Y+ IV. I−P+OCZ+Y−/I+P+O+Z−Y+ V. I+P−OCZ−Y+/I−P+OCZ+Y− - correct answer- - 3 What is meant by the term epigenetic inheritance? a. Epigenetic inheritance is the inheritance of chromatin states from one cell generation to the next. b. Genomic imprinting, X-chromosome inactivation, and position effect variegation are examples of epigenetic inheritance.

c. Heritable alterations in which the DNA sequence itself is not changed. d. Only answers A and B are correct. e. Answers A, B, and C are correct. - correct answer- - a b and c A gene encodes a pre-mRNA with 5 exons and 4 introns. A mutation eliminates the 3' splice site from intron 3. What exons would be found in the mRNA after splicing was completed? - correct answer- - Exon 1, 2, 3, 5 The apterous gene in Drosophila encodes a protein required for wing patterning and growth. It is also known to function in nerve development, fertility, and viability. When human and mouse genes whose protein products closely resemble apterous were used to generate transgenic Drosophila (Rincon-Limas et al., 1999. Proc. Nat. Acad. Sci. [USA] 96: 2165 - 2170), the apterous mutant phenotype was rescued. In addition, the whole-body expression patterns in the transgenic Drosophila were similar to normal apterous. - correct answer- - b. It's when the introduction of a gene from an outside source restores the wild- type phenotype of the organism Which statement is wrong interpreting these results about the molecular nature of development? - correct answer- - They indicate that it is likely that all developmentally- regulated mutant genes in Drosophila could be rescued by human or mouse homologs.

1. Generally speaking, which of the following mutations would most severely affect the protein coded for by a gene? - correct answer- - c. a frameshift deletion at the beginning of the gene
2. Which of the following events could result in a frameshift mutation? - correct answer- - base deletion
3. In terms of its involvement in mutagenesis, 5BU is best described as - correct answer- - b. a base analog that can cause either A-T > G-C or G-C > A-T transitions

4. For 5BU to cause a transition mutation, which of the following must occur? - correct answer- - DNA with incorporated 5BU must replicate.
5. How do bacteria "mark" DNA after replication? - correct answer- - b. Methylation occurs shortly after replication, the original template strand is methylated and the newly replicated DNA strand is not.
6. The purpose of the Ames Test is to - correct answer- - c. test the mutagenic effects of chemicals
7. Suppose that a transient tautomeric shift occurred in the guanine base to produce a rare tautomer in the partial DNA sequence just prior to a round of DNA replication. Which base would be added opposite this rare tautomer during DNA replication? - correct answer- - T
8. Suppose that the transient rare guanine tautomer shifted back to the common guanine tautomer prior to a second round of replication. Which DNA sequences (I, II, III, IV, and V) would be present in the sister chromatids after this second round of replication? - correct answer- - II. 5' - T A A - 3' 3' - A T T - 5' V. 5' - C A A - 3' 3' - G T T - 5'
9. Suppose that the top strand is the coding (nontemplate) strand and the three bases shown represent a single in frame codon in a gene. What will be the effect of the tautomeric shift-induced mutation on the amino acid sequence? - correct answer- - c. nonsense mutation
10. Which repair process in E. coli uses visible light to repair thymine dimers? - correct answer- - c. photoreactivation repair

11. Epigenetic effects including DNA methylation and histone modifications contribute to the genetic alterations leading to cancer. How do epigenetic changes in cancer cells contribute to the development of cancers? Select the only one statement below that is NOT correct to answer this question. - correct answer- - d. Epigenetic modifications in cancer cells are irreversible
12. What is the difference between saying that cancer is inherited and saying that the predisposition to cancer is inherited? - correct answer- - a. Inheritance conveys the assumption that when a particular genetic circumstance is present, a particular trait will be revealed in the phenotype. An inherited predisposition usually refers to situations in which a particular phenotype is expressed in families in some consistent pattern and may manifest itself in different ways.
13. Part of the Ras protein is associated with the plasma membrane, and part extends into the cytoplasm. What happens in cases where the ras gene is mutated? - correct answer- - b. It continually signals cell division
14. Radiotherapy (treatment with ionizing radiation) is one of the most effective current cancer treatments. It works by damaging DNA and other cellular components. Why is radiotherapy effective in treating cancer cells - correct answer- - c. Cancer cells divide all the time
15. What is the significance of this table in the context of examining a family or population for BRCA1 mutations that predispose an individual to cancer? - correct answer- - b. Such neutral polymorphisms make screening difficult in that one cannot always be certain that a mutation will cause problems for the patient.
16. Is the PM2 polymorphism likely to result in a neutral missense mutation or a silent mutation? - correct answer- - b. silent mutation

17. Is the PM3 polymorphism likely to result in a neutral missense mutation or a silent mutation? - correct answer- - a. neutral missense mutation A hypothetical population of 200 cats has two alleles, TL and TS, for a locus that codes for tail length. The table below describes the phenotypes of cats with each possible genotype, as well as the number of individuals in the population with each genotype. Which statement about the population is not true? - correct answer- - Assuming random mating, each gamete has a 50% chance of having a TL allele and a 50% chance of having a TS allele. The Human Genome Project has demonstrated that in humans of all races and nationalities approximately 99.9 percent of the sequence is the same, yet different individuals can be identified by DNA fingerprinting techniques. Which one of the following statements best explains this apparent contradiction? - correct answer- - A few repetitive regions of the genome tend to have highly variable repeat lengths that are used in DNA fingerprinting. The majority of the genome has no sequence changes or only single- nucleotide polymorphisms. . How can DNA microarray analysis be used to identify specific genes that are being expressed in a specific tissue? - correct answer- - Microarrays can be used as platforms on which to hybridize DNA or RNA from various tissues. How are GWAS carried out, and what information do they provide - correct answer- - Genome-wide association studies involve scanning the genomes of thousands of unrelated individuals with a particular disease and comparing them with the genomes of individuals who do not have the disease. GWAS attempt to identify genes that influence disease risk Which one of the following is not the technical reason to explain why gene therapy is difficult to carry out effectively? - correct answer- - The vectors available for use in gene therapy are unable to hold even the smallest of human genes

Dominant mutations can be categorized according to whether they increase or decrease the overall activity of a gene or gene product. Although a loss-of-function mutation (a mutation that inactivates the gene product) is usually recessive, for some genes, one dose of the normal gene product, encoded by the normal allele, is not sufficient to produce a normal phenotype. In this case, a loss-of-function mutation in the gene will be dominant, and the gene is said to be haploinsufficient. A second category of dominant mutation is the gain-of-function mutation, which results in a new activity or an increased activity or expression of a gene or gene product. The gene therapy technique currently used in clinical trials involves the "addition" to somatic cells of a normal copy of a gene. In other words, a normal copy of the gene is inserted into the genome of the mutant somatic cell, but the mutated copy of the gene is not re - correct answer- - yes, but only for loss-of-function mutations

. What would be positive consequences of sequencing your genome? - correct answer- - You can be informed about possible genetic diseases In March, 2010 Judge R. Sweet ruled to invalidate Myriad Genetics' patents on the BRCA1 and BRCA2 genes. Myriad Genetics also holds patents on the development of a direct-to- consumer test for the BRCA1 and BRCA2 genes. How would you explain Judge Sweet's ruling to invalidate the patenting of the BRCA1 and BRCA2 genes? - correct answer- - Since a gene is a product of the natural world, it does not conform to section 101 of U.S. patent laws, which govern patentable matter. Which of the following correctly describes a transformed bacterium? - correct answer- - a bacterium that has taken up external DNA, such as a plasmid A 1.5-kb fragment of DNA is cloned into a plasmid vector that is 5.5 kb long at the EcoRI site, and the plasmid vector is then used to transform bacteria. If the plasmid DNA is then extracted from a single bacterial colony and digested with EcoRI, what digestion products will be produced if the plasmid contains the fragment? - correct answer- - One 1.5-kb fragment and one 5.5-kb fragment

. Which of the following statements about ddNTPs is true? - correct answer- - They have a hydrogen at the 3' carbon of the sugar. A study was reported in which DNA samples were extracted from freshly plucked chimpanzee hair roots and used as templates for PCR. The primers used in these studies flank highly polymorphic sites in human DNA that result from variable numbers of tandem nucleotide repeats. Several offspring and their putative parents were tested to determine whether the offspring were "legitimate" or the product of illegal trading. The data are shown. - correct answer- -. Offspring B and C are not the products of these parents and were probably purchased on the illegal market. The data are consistent with offspring A being legitimate. . What is special about the DNA polymerizing enzymes typically used in PCR? - correct answer- - These polymerases were isolated from bacteria growing in hot springs and on thermal vents, lending to their ability to function at extreme temperatures. . In the following figure, cDNA sequences are aligned with genomic sequence. Are cDNAs more important for bacterial or for eukaryotic genome annotations? - correct answer- -. cDNAs are more important for eukaryotic genome annotations because they correspond to the exons in order after the introns have been spliced out. The term "contig" is derived from "contiguous." Which of the following definitions best defines contig? - correct answer- - A set of adjacent DNA sequences assembled using overlapping sequences or restriction fragments A sequenced fragment of DNA in Drosophila was used in a BLAST search. The best (closest) match was to a kinase gene from Neurospora. What conclusions can be made based on this match? - correct answer- -. The two polypeptides likely have some aspects of their function in common. c. The two polypeptides likely share a common three-dimensional structure

When a transposable element is inserted in a pigmentation gene (as per the maize example in the text), what is the expected outcome? - correct answer- - The pigmentation gene will be no longer be expressed.

. Once a transposon has inserted in the pigmentation gene of maize: - correct answer- - it may spontaneously excise if a transposase is present. What is a defining characteristic of an autonomous element? - correct answer- -. An autonomous element can mobilize by itself Why are transposable elements inserted into introns not problematic for the host? a. Introns are not transcribed - correct answer- - Introns are spliced out of the pre-mRNA Why can organisms survive so well with their large accumulations of transposable elements? a. The vast majority of elements can no longer move. b. Many elements have accumulated inactivating mutations over time. c. Many are inactivated by host regulatory mechanisms. d. There are many safe havens for transposable elements. e. All of the above are correct statements. - correct answer- - All of the above are correct statements What is the C - value paradox? - correct answer- - that genome size does not always correlate with biological complexity Translocations can increase the effect of proto-oncogenes by - correct answer- - relocating them next to a new regulatory element

Assume genotypes in a particular classroom are known to be at Hardy-Weinberg for a SNP in the ABCC11 gene that determines human earwax type. The AA genotype at this SNP produces dry earwax, whereas GA and GG produce wet earwax (I have genotype GG, in case you wanted to know). Let's assume that, in that classroom (400 attending-- it's a good day), 16 individuals have dry earwax. Approximately how many people in the class SHOULD be heterozygous? - correct answer- - 128 You're studying a population of an endangered wildcat in India. This population has been hunted aggressively, but there was also a rumor that the remaining ones are heavily inbred. You sample all 500 remaining cats to look for evidence of inbreeding and get the following genotypes: AA: 31, Aa: 188, aa: 281. What do you conclude? - correct answer- - The cats are not detectably inbred You are studying a population and observe the following genotype counts for a gene of interest: BB: 405, Bb: 90, bb: 5 Is this population at Hardy-Weinberg equilibrium for this gene? - correct answer- - yes You're studying the genetics of sand fleas on 3 nearby small islands of the Seychelles chain, named Poivre, Florentin, and South Island. Assume that fleas occasionally drift on floating debris among these three islands (and in roughly similar numbers to/ from each island) but that sand fleas from other islands outside the Seychelles chain never make it to these islands. Right now, the frequency of the "A" allele at a particular gene (not experiencing any selection) in these fleas is 0.2 in Poivre, 0.45 in Florentin, and 0.5 in South Island. What do you expect to happen to the frequency of "A" on Florentin in the next few generations? - correct answer- - goes down Which of the following is not a good use of molecular markers? a. map the position of an unknown gene of interest b. produce highly accurate map of fine resolution c. evaluate the extent of linkage disequilibrium d. study gene expression during development

e. all of the above can apply - correct answer- - E The "distance" between two linked gene pairs can be expressed as a percentage. Name the unit based on percent recombination that was created in honor of the scientists who pioneered the use of fruit flies for genetic research - correct answer- - centi Morgans This is the ratio of the observed number of double recombinants as compared to the expected number. - correct answer- - coeficient of confidence This term indicates the specific place on a chromosome where a gene is located - correct answer- - gene locus

. This describes the "distance" between linked gene pairs and is expressed as a percentage

• correct answer- - gene map unit These are alleles used as experimental probes to keep track of a gene. - correct answer- - genetic marker This is an abstract map that describes chromosomal loci based on recombination frequencies - correct answer- - linkage map This term describes two genes on the same chromosome - correct answer- - linked This is a measure of the independence of crossovers from each other and is calculated by subtracting the coefficient of coincidence from 1. - correct answer- - interference . You are conducting a cross using Drosophila melanogaster, results of your cross indicate that the recombination frequency is very high. How do you feel about the accuracy of your