BIL 250 Final Dr. Wang Mastering Genetics Chap 1-25

What is the chromosome theory of inheritance? It states that inherited traits are controlled by chromosomes residing on genes that are transmitted to offspring by gametes. It states that inherited traits are controlled by genes residing on chromosomes that are transmitted by gametes. "It states that inherited traits are controlled by genes residing on chromosomes that are transmitted to offspring by somatic cells.

How is it related to Mendel's findings? The chromosome theory of inheritance is based on the parallels between Mendel's model of heredity and the behavior of chromosomes during meiosis. The chromosome theory of inheritance is based on the parallels between Mendel's model of heredity and the mutations of chromosomes. The chromosome theory of inheritance is based on the parallels between Mendel's model of heredity and the behavior of chromosomes during mitosis.

Given the state of knowledge at the time of the Avery, MacLeod, and McCarty experiment, why was it difficult for some scientists to accept that DNA is the carrier of genetic information? Both proteins and DNA were the major chemical components of chromosomes. Since proteins are constructed during translation and also can cut double-stranded DNA at particular base sequences, it looked like proteins are the genetic material. The carrier of genetic information should take part in gene expression. Since tRNAs recognize the information encoded in the mRNA codons and carry the proper amino acids for construction of the protein during translation, they were thought to be the genetic material. Genes possess a variety of functions. Since proteins can contain up to 20 different amino acids, while DNA is made up of only four different nucleotides, proteins should have more functional variations. It seemed likely that proteins should be the genetic material.

Contrast chromosomes and genes. Genes take part in the production of proteins through the processes of transcription and translation. They are the functional units of heredity. Chromosomes carry genes and take part in cell division during mitosis and meiosis. Genes are composed of chromosomes complexed with DNA. They take part in cell division during mitosis and meiosis. Chromosomes are proteins, they take part in gene expression and are the functional units of heredity. Genes are composed of DNA. They carry genetic information and transcribe it into mRNA and tRNA. Chromosomes are composed of proteins and do not carry genetic information. Chromosomes take part in cell division during mitosis and meiosis.

How is genetic information encoded in a DNA molecule? Genetic information is encoded in DNA by the sequence of amino acids. Genetic information is encoded in DNA by the amounts of different bases. Genetic information is encoded in DNA by the sequence of bases and amino acids. Genetic information is encoded in DNA by the amounts of different amino acids. Genetic information is encoded in DNA by the sequence of bases.

Identify the central dogma of molecular genetics. RNA ? protein? DNA DNA ? RNA ? protein RNA ? DNA? protein

How does the central dogma of molecular genetics serve as the basis of modern genetics? Because DNA and RNA are discrete chemical entities, they can be isolated, studied, and manipulated in a variety of experiments that define modern genetics. Because amino acids could be cut during transcription from DNA to RNA and are particular base sequences, they can be isolated on this stage, studied, and manipulated in a variety of experiments that define modern genetics. Because proteins are discrete chemical entities, they can be isolated, studied, and manipulated in a variety of experiments that define modern genetics.

How many different proteins, each with a unique amino acid sequence, can be constructed with a length of 4 amino acids?

What are the arguments for and against human gene patenting by companies and individuals? Patents on genes and genetic tools can be potentially lucrative for consumers but not for patent-holders. Preventing the holding of patents for genes or genetic tools could reduce the incentive for pursuing the research that produces genes and genetics tools. Mechanisms need to be in place to protect consumers to ensure that relatively free and fair access to genetic tools is available. Patents can protect the investments of individuals and institutions that develop needed and useful products.

How has the use of model organisms advanced our knowledge of the genes that control human diseases? What is learned in one organism can usually be applied to all organisms. Most model organisms are more susceptible to disease (easier to understand causes). What is learned in model organisms can always be applied to humans. Most model organisms have peculiarities (ease of growth, genetic understanding, abundant offspring). What is learned in one organism can always be applied to all organisms. Most model organisms do not have mutated genes (no side effects).

If you were in a position to control the introduction of a GM primary food product (rice, for example), what criteria would you establish before allowing such introduction? likelihood of cross-pollination external consistency cost of production environmental impact ability to supply large quantities

The BIO (Biotechnology Industry Organization) meeting held in Philadelphia in June 2005 brought together worldwide leaders from the biotechnology and pharmaceutical industries. Concurrently, BioDemocracy 2005, a group composed of people seeking to highlight hazards from widespread applications of biotechnology, also met in Philadelphia. The benefits of biotechnology are outlined in your text. Predict some of the risks that were no doubt discussed at the BioDemocracy meeting. Check all that apply. Low economical effect. Biotechnical applications to weapons development. Ecological harmony. Safety of genetically modified organisms to human health.

A fundamental property of DNA's nitrogenous bases that is necessary for the double-stranded nature of its structure is ________.

Which list of steps in the eukaryotic cell cycle is given in the correct order? (step order listed left to right) G1 - S - G2 - M - G1 . . . . . . G1 - G2 - S - M - G1 . . . G1 - S - G2 - M1 - M2 - G1 . . . . . . G1 - M - G2 - S - G1 . . .

Haploid cells do not undergo mitosis.

Each of the following events occurs during mitosis except _______. chromosomes condense nuclear membrane breaks down polar microtubules contract, pulling attached chromosomes toward the poles microtubules assemble between centrioles

Which statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II? (Note: Ignore any effects of crossing over.) DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II. DNA content is halved only in meiosis I. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II. DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid only in meiosis II. DNA content is halved only in meiosis I. Ploidy level changes from diploid to haploid only in meiosis II. DNA content is halved only in meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II.

During which stage of prophase I does crossing over take place? Diplonema Pachynema Leptonema Diakinesis

A tetrad is composed of one pair of homologous chromosomes at synapsis of prophase I. True False

When do sister chromatids separate during meiosis? Metaphase II Anaphase I Metaphase I Anaphase II

During oogenesis in an animal species with a haploid number of 6, one dyad undergoes nondisjunction during meiosis II. Following the second meiotic division, this dyad ends up intact in the ovum. How many chromosomes are present in the mature ovum?

How many chromosomes are present in the second polar body?

Following fertilization by a normal sperm, what chromosome condition is created? monosomy disomy trisomy polyploidy

You are given a metaphase chromosome preparation (a slide) from an unknown organism that contains 12 chromosomes. Two that are clearly smaller than the rest appear identical in length and centromere placement. They have similar banding patterns. They would replicate synchronously during the S phase of the cell cycle. They contain identical genetic information. They are homologous chromosomes.

If one follows 60 primary oocytes in an animal through their various stages of oogenesis, how many secondary oocytes would be formed?

How many first polar bodies would be formed?

How many ootids would be formed?

If one follows 60 primary spermatocytes in an animal through their various stages of spermatogenesis, how many secondary spermatocytes would be formed?

How many spermatids would be formed?

Consider a diploid cell that contains three pairs of chromosomes designated AA, BB, and CC. Each pair includes a maternal and a paternal member (e.g., Am and Ap.) Am, Bm, Cm Ap, Bp, Cp Ap, Bm, Cm Am, Bp, Cm Ap, Bm, Cp Am, Bm, Cp Am, Bp, Cp Ap, Bp, Cm

You would like to know whether the progeny of a pair of mated fruit flies 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. The traits being studied are on separate chromosomes. The differences between the observed and expected counts are too large to be attributed to chance. Approximately 4% of the offspring lie outside the range of values expected for a 1:1:1:1 ratio. The phenotypic ratio is actually 9:3:3:1

The larger the number of total individual counts in a chi-square test, the higher the degrees of freedom (df).

The expected ratio of phenotypes among the progeny of a test cross is 1:1:1:1. Out of 200 total resulting progeny, 48 occur in one of the four phenotypic classes. Given this information, which of the following must also be true? At least one additional cell must also contain a count of 48. Since 48 is so close to the expected value, there is no need to calculate chi square before drawing a conclusion about the ratio. The value of observed - expected for this cell = -2. The progeny of this cross do not conform to a 1:1:1:1ratio.

Independent assortment explains _______. why a collection of meiotic products that includes gametes of genotype Ab will also include gametes of genotype AB in roughly the same proportion why meiosis in a cell of genotype AaBb cannot yield Ab gametes why meiosis in a cell of genotype Aa yields A gametes and a gametes, but no Aa gametes why meiosis in a cell of genotype Aa yields A gametes and a gametes in roughly equal numbers

Independent assortment occurs only in cells that are heterozygous for two genes (AaBb) and not in cells that are completely homozygous (AABB or aabb).

Which of the following genotypes represents a gamete produced by a failure to segregate during meiosis in a cell of genotype AaBbCC? aBC ABC abC AaBC

Mendel's monohybrid results served as the basis for all but one of his postulates. Which postulate was not based on these results? When two unlike unit factors responsible for a single character are present in a single individual, one unit factor is dominant to the other, which is said to be recessive. During the formation of gametes, the paired unit factors separate, or segregate, randomly so that each gamete receives one or the other with equal likelihood. When two independent events occur simultaneously, the probability of the two outcomes occurring in combination is equal to the product of their individual probabilities of occurrence. Genetic characters are controlled by unit factors existing in pairs in individual organisms.

In a family of 10 children, where both parents are heterozygous for albinism, what mathematical equation predicts the probability that 6 are normal and 4 are albino? [10! (3/4) 4 (1/4) 6 ] / 6! 4! [10! (3/4) 6 (1/4) 4 ] / 6! 4! [4! (3/4) 6 (1/4) 4 ] / 6! 10! [4! (3/4) 4 (1/4) 6 ] / 6! 10! [6! (3/4) 6 (1/4) 4 ] / 10! 4!

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? 1/8 1/2 1/4 3/16 9/16 not enough information given

In addition to A and a, the "agouti" gene has a third allele, AY . Here is some information about the inheritance of the AY allele. The AY allele is dominant to both A and a. The homozygous genotype (AYAY ) results in lethality before birth. The heterozygous genotypes (AYA or AYa) result in yellow fur color, regardless of which alleles are present for the B/b gene. (This effect exhibited by the AY allele is known as epistasis--when the expression of one gene masks the expression of a second gene.) In a mating of mice with the genotypes AYaBb x AYaBb , what is the probability that a live-born offspring will have yellow fur? Express your answer as a fraction using the slash symbol and no spaces (for example, 1/16).

In the same mouse species, a 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? Express your answer as a fraction using the slash symbol and no spaces (for example, 3/16).

How many different phenotypes are possible in a one gene/three allele system that displays codominance to each other? two three eight six

Which of the following is the most likely example of codominance? 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. A pure-breeding tall plant is crossed to a pure-breeding short plant. All their progeny are of medium height. A pure-breeding plant with red flowers is crossed to a pure-breeding plant with white flowers. All their progeny have pink flowers. A plant with red flowers is crossed to a plant with white flowers. Half their progeny have red flowers, the other half have white flowers.

The color dilution gene in horses is an example of incomplete dominance.

White eye color is an X-linked trait in one line of fruit flies. White eyes is recessive to red eyes. If a red-eyed female and a white-eyed male are crossed, _______. some of their male progeny may have white eyes none of their male progeny could have white eyes all of their progeny will have white eyes all of their female progeny will have white eyes

For X-linked traits in Drosophila, the male phenotype is determined by the maternally inherited allele.

Eye color in Drosophila is an X-linked trait. White eyes is recessive to red eyes. If a Drosophila male has white eyes, which of the following must also be true? His mother had at least one white allele. Some of his female siblings from the same mating must also have white eyes. His father must also have had white eyes. All his male siblings from the same parents must also have white eyes.

Red-green color blindness is due to an X-linked recessive allele in humans. A widow's peak (a hairline that comes to a peak in the middle of the forehead) is due to an autosomal dominant allele. Consider the following family history: A man with a widow's peak and normal color vision marries a color-blind woman with a straight hairline. The man's father had a straight hairline, as did both of the woman's parents. Use the family history to make predictions about the couple's children. If the couple has a child, what is the chance that it will be a son with a widow's peak?

What is the chance that any son the couple has will be color blind with a straight hairline?

Suppose the couple had a daughter with normal color vision and a widow's peak. What is the chance that she is heterozygous for both genes?

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%. What does this means for individuals with the predisposing genotype? They have an 86% chance of showing the associated phenotype. They have a 14% chance of showing the associated phenotype. They will express 86% of the associated phenotypes. They will express 14% of the associated phenotypes.

magine that you are part of a research team interested in determining the penetrance of a different PRSS1 mutation, Ala16Val. Your team has identified 120 individuals with the PRSS1 Ala16Val allele and found that 48 of the individuals did not display any evidence of pancreatitis. From your data, what is the penetrance of the PRSS1 Ala16Val mutation?

a man who is heterozygous for a PRSS1 Ala16Val mutation mates with a woman who is homozygous for normal cationic trypsinogen, what is the probability that their offspring will have hereditary pancreatitis, given the penetrance value obtained in Part B?

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 area How can the unusual results from the crosses be explained? The green allele behaves as a recessive lethal allele. The aurea allele behaves as a recessive lethal allele. The green allele behaves as a dominant lethal allele. The aurea allele behaves as a dominant lethal allele.

With respect to snapdragon color, what can be said of the G and GA alleles? The GA and G alleles exhibit codominance. The GA allele is recessive to the G allele. The GA is dominant to the G allele. The GA and G alleles exhibit incomplete dominance.

In a disputed parentage case, the child is blood type O, while the mother is blood type A. What are the possible blood type(s) for the father? A O AB B

If the child is blood type A, while the mother is blood type B.What blood type would exclude a male from being the father? B AB O A

To construct a mapping cross of linked genes, it is important that the genotypes of some of the gametes produced by the heterozygote can be deduced by examining the phenotypes of the progeny.

In a three?point mapping experiment for the genes y?w?ec, the following percentages of events are observed: NCO events: 65%; SCO events between y and w: 15%; SCO events between y and ec: 17%; DCO events: 3% What is the map distance between y and ec? 15 map units 20 map units 17 map units 18 map units

For linked genes A, B, and C, the map distance A-B is 5 map units and the map distance B-C is 25 map units. If there are 10 double crossover events out of 1000 offspring, what is the interference? 0.2 0.01 0.8 0.0125

The discernible difference in length between the two X chromosomes of the female fruit fly was important in Stern's experiments because _______. it allowed him to predict the phenotypic ratios among offspring it allowed cytological detection of physical exchange between the chromosomes only the longer of the two X chromosomes could be passed on to offspring the carnation eye color phenotype was difficult to detect

Stern observed all of the following results EXCEPT _______ in his experiment. offspring with red, round eyes resulted from fertilization of eggs containing recombinant X chromosomes the number of males was roughly equal to the number of females one of the recombinant phenotypes was associated with an X chromosome of normal length the number of car, B+ male offspring was roughly equal to the number of car+, B male offspring

The results of the Stern experiment supported the general idea that _______. alleles of different genes assort independently only females exhibit incomplete dominance crossing over does not occur in males genetic recombination is a result of physical exchange between homologous chromosomes

What essential criteria must be met in order to execute a successful mapping cross? Recombination must occur in the sex that displays genetic heterogeneity. One parent should be homozygous dominant and the other homozygous recessive for all the genes being mapped. One parent should be heterozygous and the other homozygous recessive for all the genes being mapped. The genotypes of the offspring must be readily determined from their phenotypes.

Colored aleurone in the kernels of corn is due to the dominant allele R. The recessive allele r, when homozygous, produces colorless aleurone. The plant color (not the kernel color) is controlled by another gene with two alleles, Y and y. The dominant Y allele results in green color, whereas the homozygous presence of the recessive y allele causes the plant to appear yellow. In a testcross between a plant of unknown genotype and phenotype and a plant that is homozygous recessive for both traits, the following progeny were obtained: Colored, green 11 Colored, yellow 94 Colorless, green 86 Colorless, yellow 9 Based on the data, what can you say about the genotype of the unknown plant? It was homozygous for both genes. It was heterozygous for one gene, and homozygous for the other. It was heterozygous for both genes.

What is the phenotype of the unknown plant?

Bacteriophage T4 can adsorb to its host because of binding sites in its tail fibers that recognize areas of the E. coli cell wall.

Which of the following statements about the T4 lytic life cycle is false? The phage DNA is injected into the host and integrates into the bacterial chromosome. The phage produces lysozyme, which ruptures the host cell wall and releases newly formed viral particles. The bacterial DNA is degraded. The phage takes over the protein synthesis machinery of the bacteria.

What results would be expected from a plaque assay if the dilution factor of the phage?infected culture were too low? None of these choices The entire lawn of bacteria would be lysed. The plate would have a few plaques. The plate would have no plaques.

If a single bacteriophage infects one E. coli cell present on a lawn of bacteria and, upon lysis, yields 255 viable viruses, how many phages will exist in a single plaque if 5 more lytic cycles occur?

A plaque assay is performed beginning with 1 mL of a solution containing bacteriophages. This solution is serially diluted 2 times by combining 0.1 mL of each sequential dilution with 9.9 mL of liquid medium. Then 0.1 mL of the final dilution is plated in the plaque assay and yields 17 plaques. What is the initial density of bacteriophages in the original 1 mL? Recall that initial phage density = (plaque number/mL) × (dilution factor). Enter your answer to two significant digits (for example: 1.1 * 102).

In Drosophila, the ratio of X chromosomes to autosomes directly influences _______. SXL late protein production repression of sex-specific genes RNA splicing patterns the ratio of sisterless protein subunits to deadpan protein subunits

Which of the following correctly describes a difference between expression of Sxl from the PE promotor and expression of Sxl from the PL promotor? Sxl transcription from promotor PE is constitutive, whereas Sxl transcription from promotor PL is activated by sisterless protein homodimers. Transcription from the PE promotor is activated at a later stage in development than transcription from the PL promotor. Transcription of Sxl is initiated at promotor PE in females, but not in males. The product of expression from Sxl promotor PE is a transcription activator and the product of expression from Sxl promotor PL regulates mRNA splicing.

Which set of events describing sex determination in Drosophila females is most accurate and listed in the order in which the events occur? 1) Activation of Sxl transcription at the PE promotor, 2) Default splicing of mRNA transcribed from the PL promotor 3) Repression of male-specific genes by DSX-F 1) Activation of Sxl transcription at the PE promotor 2) Formation of sisterless protein homodimers 3) Repression of male-specific genes by DSX-F 1) Production of functional TRA protein 2) Splicing of dsx mRNA 3) Repression of male-specific genes by DSX-F 1) Production of functional TRA protein 2) Splicing of dsx mRNA 3) Repression of male-specific genes by DSX-M

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? The son received a dominant red-detecting gene on the Y chromosome. The ovum that was fertilized to produce the son contained one of the mother's green-detecting genes, while the other green-detecting gene and the two copies of the red-detecting genes ended up in the polar bodies. The son received an X chromosome lacking the red-detecting gene from his father. The ovum that was fertilized to produce the son contained the mother's two green-detecting genes, while the red-detecting genes ended up in the polar bodies. 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.

What is the role of the enzyme aromatase in sexual differentiation? It converts estrogens to androgens. It destroys excess estrogens in males. It regulates transcription of estrogen genes. It regulates translation of androgen genes. It converts androgens to estrogens.

In the wasp Bracon hebetor, a form of parthenogenesis (the development of unfertilized eggs into progeny) resulting in haploid organisms is not uncommon. All haploids are males. When offspring arise from fertilization, females almost invariably result. P. W. Whiting has shown that an X-linked gene with nine multiple alleles (Xa , Xb , etc.) controls sex determination. Any homozygous or hemizygous condition results in males, and any heterozygous condition results in females. If an Xa /Xb female mates with an Xa male and lays 50 percent fertilized and 50 percent unfertilized eggs, what proportion of male and female offspring will result? Overall, 100% of the offspring would be male, while 0% would be female. Overall, 50% of the offspring would be male, while 50% would be female. Overall, 25% of the offspring would be male, while 75% would be female. Overall, 75% of the offspring would be male, while 25% would be female.

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. Starting with the somatic ovarian cell used as the source of the nucleus in the cloning process, explain how this outcome occurred. 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. The coat color alleles are carried on mitochondrial chromosomes and were not transferred with the donor nucleus. CC displays only colors from the mitochondria from the egg cell into which the nucleus was injected. The Lyon hypothesis states that only one allele of X-linked loci will be expressed. Therefore it is impossible that a zygote with one black allele and one orange allele could express both as an adult mammal. Ovarian cells do not possess the locus for colors other than black and white. The colors black and white are encoded on a separate locus.

A ________ is the loss of part of a chromosomal segment.

A _______ is the repetition of a segment. The repeated segment may be located next to the original or at a different location, and its orientation may be the same as the original or the reverse.

An _______ is the removal of a segment followed by its reinsertion into the same chromosome in the reverse orientation.

A _______is the transfer of a segment to a nonhomologous chromosome. Translocations may be reciprocal (two nonhomologous chromosomes exchange segments) or nonreciprocal (one chromosome transfers a segment without receiving one).

A cross between a tetraploid and a diploid member of the same species will produce offspring that can undergo sexual reproduction.

Which of the following statements about allopolyploid individuals is true? They can be formed when two sperm simultaneously fertilize an ovum within the same species. They are generated from exposure to colchicine. They result from a mating between individuals of the same species. They may be sterile and unable to produce offspring.

An organism of the genotype AaBbCc was testcrossed to a triply recessive organism (aabbcc). The genotypes of the progeny are presented in the following table. 20 AaBbCc 20 AaBbcc 20 aabbCc 20 aabbcc 5 AabbCc 5 Aabbcc 5 aaBbCc 5 aaBbcc If these three genes were all assorting independently, how many genotypic and phenotypic classes would result in the offspring, and in what proportion, assuming simple dominance and recessiveness in each gene pair? 6, 1:1:1:1:1:1 2, 1:1 4, 1:1:1:1 8, 1:1:1:1:1:1:1:1