Question: Assuming that such a fly would be

> In a P1 transduction experiment, the P1 lysate contains phages that carry pieces of the host chromosomal DNA, but the lysate also contains broken pieces of chromosomal DNA (see Figure 7.10). If a P1 lysate is used to transfer chromosomal DNA to another b

> In Chapter 23, the technique of fluorescence in situ hybridization (FISH) is described. This is another method for examining sequence complexity within a genome. In this method, a DNA sequence, such as a particular gene sequence, can be detected within a

> What causes the cleavage furrow in an animal cell to ingress?

> Although 61 codons specify the 20 amino acids, most species display a codon bias. This means that certain codons are used much more frequently than other codons. For example, UUA, UUG, CUU, CUC, CUA, and CUG all specify leucine. In yeast, however, the UU

> The protein known as tyrosinase is needed to make certain types of pigments. Tyrosinase is composed of a single polypeptide with 511 amino acids. The molecular mass of this protein is approximately 61,300 Da, or 61.3 kDa. People who carry two defective c

> The technique of Western blotting is described in Chapter 21 and also in experimental question E5. Let’s suppose a researcher is interested in the effects of mutations on the expression of a proteinencoding gene that encodes a protein we will call protei

> Chapter 21 describes a blotting method known as Western blotting that can be used to detect the production of a polypeptide that is translated from a particular mRNA. In this method, a protein is detected with an antibody that specifically recognizes and

> Describe the structure of a polysome, which is depicted in Figure 13.13a. From Figure 13.13a: Ribosome Polypeptide MRNA 0.1 um H

> Discuss how the elucidation of the structure of the ribosome can help us to understand its function.

> Polypeptides can be translated in vitro. Would a bacterial mRNA be translated in vitro by eukaryotic ribosomes? Would a eukaryotic mRNA be translated in vitro by bacterial ribosomes? Why or why not?

> In the experiment of Figure 13.7, what would be the predicted amounts of amino acids incorporated into polypeptides if the RNA was a random polymer containing 50% C and 50% G? From Figure 13.7: Experimental level Conceptual level 1. Place the cell

> When a chi square analysis is applied to solve a linkage problem, explain why an independent assortment hypothesis is proposed.

> Describe the unique features of ascomycetes that lend themselves to genetic analysis.

> During which phase are sister chromatids separated and sent to opposite poles?

> Researchers have discovered that some regions of chromosomes are much more likely than others to cross over. We might call such a region a “hot spot” for crossing over. Let’s suppose that two genes, gene A and gene B, are 5,000,000 bp apart on the same c

> In most two-factor crosses involving linked genes, we cannot tell if a double crossover between the two genes has occurred because the offspring will inherit the nonrecombinant pattern of alleles. How does the inability to detect double crossovers affect

> If the likelihood of a single crossover in a particular chromosomal region is 10%, what is the theoretical likelihood of a double or triple crossover in that same region? How would positive interference affect these theoretical values?

> Though we often think of genes in terms of the phenotypes they produce (e.g., curly leaves, flaky tail, brown eyes), the molecular function of most genes is to encode proteins. Many cellular proteins function as enzymes. The following table gives the map

> When true-breeding mice with brown fur and short tails (BBtt) were crossed to true-breeding mice with white fur and long tails (bbTT), all of the F1 offspring had brown fur and long tails. The F1 offspring were crossed to mice with white fur and short ta

> In humans, a rare dominant disorder known as nail-patella syndrome causes abnormalities in the fingernails, toenails, and kneecaps. Researchers have examined family pedigrees with regard to this disorder and have also examined the blood types of individu

> What is the difference in meaning between the terms genetic recombination and crossing over?

> As described in Chapter 22, researchers have been able to clone mammals by fusing a cell having a diploid nucleus (i.e., a somatic cell) with an egg that has had its nucleus removed. A. With regard to maternal effect genes, would the phenotype of such a

> Explain why maternal effect genes exert their effects during the early stages of development.

> Suppose that a gene affects the anterior morphology in house flies and is inherited as a maternal effect gene. The gene exists in a functional allele, H, and a recessive nonfunctional allele, h, which causes a small head. A female fly with a normal head

> Where are the two ends of a kinetochore microtubule?

> Suppose a maternal effect gene exists as a functional dominant allele and a nonfunctional recessive allele. A mother who is phenotypically abnormal produces all normal offspring. Explain the genotype of the mother.

> For Mendelian inheritance, the nuclear genotype (i.e., the alleles found on chromosomes in the cell nucleus) directly influences an offspring’s traits. In contrast, for non-Mendelian inheritance patterns, the offspring’s phenotype cannot be reliably pred

> A Drosophila embryo dies during early embryogenesis due to a recessive maternal effect allele called bicoid−. The wild-type allele is designated bicoid+. What are the genotypes and phenotypes of the embryo’s mother and maternal grandparents?

> A maternal effect gene exists in a dominant N (functional) allele and a recessive n (nonfunctional) allele. What would be the ratios of genotypes and phenotypes for the offspring of the following crosses? A. nn female × NN male B. NN female × nn male

> Describe the inheritance pattern of maternal effect genes. Explain how the maternal effect occurs at the cellular level. What are the expected functional roles of the proteins that are encoded by maternal effect genes?

> How many Barr bodies would you expect to find in humans with the following abnormal compositions of sex chromosomes? A. XXY B. XYY C. XXX D. X0 (a person with just a single X chromosome)

> On rare occasions, a human male is born who is somewhat feminized compared with other males. Microscopic examination of the cells of one such individual revealed that he has a single Barr body in each cell. What is the chromosomal composition of this ind

> Describe the molecular process of X-chromosome inactivation. This description should include the three phases of inactivation and the role of the Xic. Explain what happens to the X chromosomes during embryogenesis, in adult somatic cells, and during ooge

> Describe when X-chromosome inactivation occurs and how this leads to phenotypic results at the organism level. In your answer, you should explain why XCI causes results such as variegated coat patterns in mammals. Why do two different calico cats have th

> Among different species, describe three distinct mechanisms for accomplishing dosage compensation.

> What is the difference between homologs and sister chromatids?

> What is a Barr body? How is its structure different from that of other chromosomes in the cell? How does the structure of a Barr body affect the level of X-linked gene expression?

> With regard to the numbers of sex chromosomes, explain why dosage compensation is necessary.

> Define the term epigenetic inheritance, and describe two examples.

> Which blood type phenotypes (A, B, AB, and/or O) provide an unambiguous genotype? Is it possible for a couple to produce a family of children in which all four blood types are represented? If so, what would the genotypes of the parents have to be?

> The blood serum from one individual (let’s call this person individual 1) is known to agglutinate the red blood cells from a second individual (individual 2). List the pairwise combinations of possible genotypes that individuals 1 and 2 could have. If in

> A seed dealer wants to sell four-o’clock seeds that will produce only a single color of flowers (red, white, or pink). Explain how this should be done.

> An allele in Drosophila produces a star-eye trait in the heterozygous individual. However, the star-eye allele is lethal in homozygotes. What would be the ratio of phenotypes of surviving offspring if star-eyed flies were crossed to each other?

> A nectarine is a peach without the fuzz. The difference is controlled by a single gene that is found in two alleles, D and d. At the molecular level, do you think that the nectarine is homozygous for a recessive allele or that the peach is homozygous for

> Let’s suppose a recessive allele encodes a completely defective protein. If the functional allele is dominant, what does that tell you about the amount of the functional protein that is sufficient to cause the phenotype? What if the allele shows incomple

> Huntington disease is a rare dominant trait that causes neurodegeneration later in life. A man in his thirties, who already has three children, discovers that his mother has Huntington disease though his father is unaffected. What are the following proba

> What is the difference between the G0 and G1 phases?

> Wooly hair is a rare dominant trait found in people of Scandinavian descent in which the hair resembles the wool of a sheep. A male with wooly hair, who has a mother with straight hair, moves to an island that is inhabited by people who are not of Scandi

> What would be the sex of a human with each of the following sets of sex chromosomes? A. XXX B. X (also described as X0) C. XYY D. XXY

> What is meant by a gene interaction? How can a gene interaction be explained at the molecular level?

> A woman with an abnormally long chromosome 13 (and a normal homolog of chromosome 13) has children with a man with an abnormally short chromosome 11 (and a normal homolog of chromosome 11). What is the probability of producing an offspring that will have

> Three coat-color patterns that occur in some breeds of horses are termed cremello (beige), chestnut (brown), and palomino (golden with light mane and tail). If two palomino horses are mated, they produce about 1/4 cremello, 1/4 chestnut, and 1/2 palomino

> A sex-influenced trait in humans affects the length of the index finger. A short allele is dominant in males and recessive in females. Heterozygous males have an index finger that is significantly shorter than the ring finger. The gene affecting index fi

> In humans, a very rare dominant allele that causes the little finger to be crooked has a penetrance of 80%. In other words, 80% of heterozygotes carrying the allele will have a crooked little finger. If a homozygous unaffected person has children with a

> Compare phenotypes at the molecular, cellular, and organism levels for individuals who are homozygous for the hemoglobin allele, HbA HbA, and the sickle cell allele, HbS HbS.

> Let’s suppose you have pedigree data from thousands of different families involving a particular genetic disease. How would you decide whether the disease is inherited as a recessive trait as opposed to one that is dominant but shows incomplete penetranc

> What is the function of the FtsZ protein during binary fission?

> What type of bonding is responsible for the formation of the two types of secondary structures?

> The pedigree shown here involves a trait determined by a single gene (affected individuals are shown in black). Which of the following patterns of inheritance are possible for this trait? A. Recessive B. X-linked recessive C. Dominant D. Sex-influenc

> Based on the pedigree shown here for a trait determined by a single gene (affected individuals are shown in black), state whether it would be possible for the trait to be inherited in each of the following ways: A. Recessive B. X-linked recessive C. D

> The trait of feathering in fowls is a sex-limited trait controlled by a single gene. Females always exhibit hen-feathering, as do HH and Hh males. Only hh males show cock-feathering. Starting with two heterozygous birds that are hen-feathered, explain ho

> In cats, a temperature-sensitive allele produces the Siamese phenotype, in which the cooler extremities are dark and the warmer trunk area is lighter. A Siamese cat that spends most of its time outside was accidentally injured in a trap and required seve

> Discuss the differences among sex-influenced, sex-limited, and sex-linked inheritance. Give examples.

> In rabbits, the color of body fat is controlled by a single gene with two alleles, designated Y and y. The outcome of this trait is affected by the diet of the rabbit. When raised on a standard vegetarian diet, the dominant Y allele confers white body fa

> Scurs in cattle is a sex-influenced trait. A cow with no scurs whose mother had scurs had offspring with a bull with scurs whose father had no scurs. What are the probabilities of each of the following combinations of offspring? A. The first offspring wi

> Incontinentia pigmenti, a rare, X-linked dominant disorder in humans, is characterized by swirls of pigment in the skin. If an affected female, who had an unaffected father, has children with an unaffected male, what are the predicted ratios of affected

> Hemophilia is an X-linked recessive trait in humans. If a heterozygous woman has children with an unaffected man, what is the probability of each of the following combinations of children? A. An affected son B. Four unaffected offspring in a row C. An

> A human disease known as vitamin D–resistant rickets is inherited as an X-linked dominant trait. If a male with the disease produces children with a female who does not have the disease, what is the expected ratio of affected and unaffected offspring?

> How are homologs similar to each other and how are they different?

> Propose the most likely mode of inheritance (autosomal dominant, autosomal recessive, or X-linked recessive) for the following pedigrees. Affected individuals are shown with filled (black) symbols. I-1 I-2 Il-1 II-2 II-3 II-4 III-1 III-2 III-3 III-4

> In chickens, the Leghorn variety has white feathers due to an autosomal dominant allele. Silkies have white feathers due to a recessive allele in a second (different) gene. If a true-breeding white Leghorn is crossed to a true-breeding white Silkie, what

> In Shorthorn cattle, coat color is controlled by a single gene that can exist as a red allele (R) or a white allele (r). The heterozygotes (Rr) have a color called roan that looks less red than the RR homozygotes. However, when examined carefully, the ro

> A type A woman is the daughter of a type O father and a type A mother. If she has children with a type AB man, what are the following probabilities? A. A type AB child B. A type O child C. The first three children with type AB D. A family composed of

> A woman with type B blood has a child with type O blood. What are the possible genotypes and blood types of the father?

> Describe the differences among dominance, incomplete dominance, codominance, and overdominance.

> A cell is diploid and contains three chromosomes per set. Draw the arrangement of the chromosomes during metaphase of mitosis and metaphase of meiosis I and II. In your drawing, make one set dark and the other lighter.

> Identify the key events during meiosis that result in a 50% reduction in the amount of genetic material per cell.

> For the following events, specify whether they occur during mitosis, meiosis I, or meiosis II: A. Separation of conjoined chromatids within a pair of sister chromatids B. Pairing of homologous chromosomes C. Alignment of chromatids along the metaphase

> How does the attachment of kinetochore microtubules to the kinetochore differ in metaphase of meiosis I compared to metaphase of mitosis? Discuss what you think would happen if a sister chromatid was not attached to a kinetochore microtubule.

> How do you think the end results would be affected if the cells were not treated with a hypotonic solution?

> A species is diploid and has three chromosomes per set. Make a drawing showing what the chromosomes would look like in the G1 and G2 phases of the cell cycle.

> With regard to sister chromatids, which phase of mitosis is the organization phase, and which is the separation phase?

> What is a sister chromatid? Are sister chromatids genetically similar or identical? Explain.

> Three genes (A, B, and C) are found on three different chromosomes. For the following diploid genotypes, describe all of the possible gamete combinations. A. Aa Bb Cc B. AA Bb CC C. Aa BB Cc D. Aa bb cc

> Describe the timing of meiosis I and II during human oogenesis.

> At puberty, the testes contain a finite number of cells and produce an enormous number of sperm cells during the life span of a male. Explain why testes do not run out of spermatogonial cells.

> Describe the cellular differences between male and female gametes.

> Let’s suppose that a gene affecting pigmentation is found on the X chromosome (in mammals or insects) or the Z chromosome (in birds) but not on the Y or W chromosome. It is found on an autosome in bees. This gene exists in two alleles:&

> The arctic fox has 50 chromosomes (25 per set), and the common red fox has 38 chromosomes (19 per set). These species can interbreed to produce viable but infertile offspring. How many chromosomes would the offspring have? What problems do you think may

> Corn has 10 chromosomes per set, and the sporophyte of the species is diploid. If you performed a karyotype, what is the total number of chromosomes you would expect to see in each of the following types of cells? A. A leaf cell B. The sperm nucleus of

> Where is the information to make a polypeptide stored?

> List several ways in which telophase appears to be the reverse of prophase and prometaphase.

> The period between meiosis I and meiosis II is called interphase II. Does DNA replication take place during interphase II?

> What is a homolog? With regard to genes and alleles, how are homologs similar to and different from each other?

> Explain why the products of meiosis may not be genetically identical, whereas the products of mitosis are.

> A diploid species has four chromosomes per set for a total of eight chromosomes in its somatic cells. Draw such a cell as it would look in late prophase of meiosis II and prophase of mitosis. Discuss how prophase of meiosis II and prophase of mitosis dif

> Nine-banded armadillos almost always give birth to four offspring that are genetically identical quadruplets. Explain how you think this happens.

> Why is it necessary for the chromosomes to condense during mitosis and meiosis? What do you think might happen if the chromosomes were not condensed?

> Eukaryotic cells must sort their chromosomes during mitosis so that each daughter cell receives the correct number of chromosomes. Why don’t bacteria need to sort their chromosomes?

> With regard to question C13, how would the phenomenon of crossing over affect the results? In other words, would the probability of a gamete inheriting only paternal chromosomes be higher or lower? Explain your answer. From C13: A cell has four pairs of