Question: How is the process of X-chromosome

> A zookeeper has collected a male and a female lizard that look like they belong to the same species. They mate with each other and produce phenotypically normal offspring. However, the offspring are sterile. Suggest one or more explanations for their ste

> Why do you think that humans with trisomy chromosome 13, 18, or 21 can survive but other trisomies are lethal? Even though X chromosomes are large, aneuploidy of this chromosome is also tolerated. Explain why.

> A cytogeneticist has collected tissue samples from members of a certain butterfly species. Some of the butterflies were located in Canada, and others were found in Mexico. Through karyotyping, the cytogeneticist discovered that chromosome 5 of the Canadi

> According to the theory of evolution, why have these changes occurred in horse populations over the course of many generations? From Figure 1.11: Equus Hippidium and other genera Nannippus Stylahipparion 5- Plohippus Hipparion Neohipparion 10- Sinoh

> Female fruit flies homozygous for the X-linked white-eye allele are crossed to males with red eyes. On very rare occasions, an offspring of such a cross is a male with red eyes. Assuming these rare offspring are not due to a new mutation in one of the mo

> Explain how aneuploidy, deletions, and duplications cause genetic imbalances. Why do you think that deletions and monosomies are more detrimental than duplications and trisomies?

> Aneuploidy is typically detrimental, whereas polyploidy is sometimes beneficial, particularly in plants. Discuss why you think this is the case.

> Explain why small deletions and duplications are less likely to have a detrimental effect on an individual’s phenotype than large ones. If a small deletion within a single chromosome happens to have a phenotypic effect, what would you conclude about the

> Two phenotypically unaffected parents produce two children with familial Down syndrome. With regard to chromosomes 14 and 21, what are the chromosomal compositions of the parents?

> A person is born with one X chromosome, zero Y chromosomes, trisomy 21, and two copies of the other chromosomes. How many chromosomes does this person have altogether? Explain whether this person is euploid or aneuploid.

> A diploid fruit fly has eight chromosomes. How many total chromosomes would be found in the following flies? A. Tetraploid B. Trisomy 2 C. Monosomy 3 D. 3n E. 4n + 1

> A phenotypically abnormal individual has a phenotypically normal father with an inversion on one copy of chromosome 7 and a phenotypically normal mother without any changes in chromosome structure. The orders of genes along the two copies of chromosome 7

> Explain why a translocation cross occurs during metaphase of meiosis I when a cell contains a reciprocal translocation.

> Which of the following types of chromosomal changes would you expect to have phenotypic consequences? Explain your choices. A. Pericentric inversion B. Reciprocal translocation C. Deletion D. Unbalanced translocation

> The leaf cells of a corn plant contain 20 chromosomes each. How many chromosomes are found in a gamete made by a corn plant?

> With regard to the segregation of centromeres, why is adjacent-2 segregation less frequent than alternate or adjacent-1 segregation?

> Two phenotypically normal parents produce a phenotypically abnormal child in which chromosome 5 is missing part of its long arm but has a piece of chromosome 7 attached to it. The child also has one normal copy of chromosome 5 and two normal copies of ch

> A phenotypically normal individual has the following combinations of normal and abnormal chromosomes: The normal chromosomes are shown on the left in each pair. Suggest a series of events (breaks, translocations, crossovers, etc.) that may have produced

> An individual has the following reciprocal translocation: What would be the outcome of alternate segregation and of adjacent-1 segregation? A E

> Which changes in chromosome structure cause a change in the total amount of genetic material, and which do not?

> Briefly describe the lytic and lysogenic cycles of bacteriophages. In your answer, explain what a prophage is.

> Each species of bacteria has its own distinctive cell surface. The characteristics of the cell surface play an important role in processes such as conjugation and transduction. For example, certain strains of E. coli have pili on their cell surface. Thes

> Think about the structure and transmission of F factors and discuss how you think F factors may have originated.

> What is the role of sex pili during conjugation?

> What is the role of the origin of transfer during F+- and Hfr mediated conjugation? What is the significance of the direction of transfer in Hfr-mediated conjugation?

> Prior to fertilization, where is the male gamete located?

> Most genes encode proteins. Explain how the structure and function of proteins produce an organism’s traits.

> At the molecular level, what is a gene? Where are genes located?

> What are the primary interests of researchers working in the following fields of genetics? A. Transmission genetics B. Molecular genetics C. Population genetics

> What is the difference between an F+ and an Hfr strain? Which type of strain do you expect to transfer many bacterial genes to recipient cells?

> With regard to biological evolution, which of the following statements is incorrect? Explain why. A. During its lifetime, an animal evolves to become better adapted to its environment. B. The process of biological evolution has produced species that ar

> Explain the relationship between each of the following pairs of genetic terms: A. Gene and trait B. Gene and chromosome C. Allele and gene D. DNA sequence and amino acid sequence

> What is the genetic code?

> What is a DNA sequence?

> Pick any example of a genetic technology and describe how it has directly affected your life.

> A woman with achondroplasia (a dominant form of dwarfism) and a phenotypically unaffected man have seven children, all of whom have achondroplasia. What is the probability of producing such a family if this woman is a heterozygote? What is the probabilit

> Why do these two frogs look so different? From Figure 1.8:

> What enzymatic function is missing in the strain 2 mutants?

> Describe how a biparental pattern of extranuclear inheritance would resemble a Mendelian pattern of inheritance for a particular gene. How would they differ?

> Acute murine leukemia virus (AMLV) causes leukemia in mice. This virus is easily passed from mother to offspring through the mother’s milk. (Note: Even though newborn offspring acquire the virus, they may not develop leukemia until much later in life. Te

> Which of the following traits or diseases is(are) determined by nuclear genes? A. Snail coiling pattern B. Prader-Willi syndrome C. Leber hereditary optic neuropathy

> Explain the likely evolutionary origin of mitochondrial and chloroplast genomes. How have the sizes of the mitochondrial and chloroplast genomes changed since their origin? How has this occurred?

> If you mix together an equal number of F+ and F− cells, how would you expect the proportions to change over time? In other words, do you expect an increase in the relative proportion of F+ or of F− cells? Explain your answer.

> Discuss the structure and organization of the mitochondrial and chloroplast genomes. How large are they, how many genes do they contain, and how many copies of the genome are found in each organelle?

> Extranuclear inheritance often correlates with maternal inheritance. Even so, paternal leakage may occur. What is paternal leakage? If a cross produced 200 offspring and the rate of mitochondrial paternal leakage was 3%, how many offspring would be expec

> Among different species, does extranuclear inheritance always follow a maternal inheritance pattern? Why or why not?

> What is a reciprocal cross? Suppose that a gene is found as a wildtype (functional) allele and a recessive mutant (nonfunctional) allele. What would be the expected outcomes of reciprocal crosses if a true-breeding normal individual was crossed to a true

> What is extranuclear inheritance? Describe three examples.

> Which butterfly has a more active pigment-producing enzyme, the dark- or light-colored one? From Figure 1.7c: Dark butterfly Light butterfly

> Genes that cause Prader-Willi syndrome and Angelman syndrome are closely linked along chromosome 15. Although people with these syndromes do not usually reproduce, let’s suppose that a couple produces two children with Angelman syndrome. The oldest child

> On rare occasions, people are born with a condition known as uniparental disomy. It happens when an individual inherits both copies of a chromosome from one parent and no copies from the other parent. This occurs when two abnormal gametes happen to compl

> In what types of cells would you expect de novo methylation to occur? In what cell types would it not occur?

> When does the erasure and reestablishment phase of genomic imprinting occur? Explain why it is necessary to erase an imprint and then reestablish it in order to always maintain imprinting from the same sex of parent.

> Conjugation is sometimes called bacterial mating. Is it a form of sexual reproduction? Explain.

> What is the spreading phase of X-chromosome inactivation? Why do you think it is called a spreading phase? 

> A black female cat (XB XB ) and an orange male cat (X0 Y) were mated to each other and produced a male cat that was calico. Which sex chromosomes did this male offspring inherit from its mother and father? Remember that the presence of the Y chromosome d

> Certain forms of human color blindness are inherited as X-linked recessive traits. Hemizygous males are color-blind, but heterozygous females are not. However, heterozygous females sometimes have partial color blindness. A. Discuss why heterozygous fema

> Antibiotics such as tetracycline, streptomycin, and bacitracin are small organic molecules that are synthesized by particular species of bacteria. Microbiologists have hypothesized that the reason why certain bacteria make antibiotics is to kill other sp

> At the molecular level (with regard to loss-of-function alleles), explain why the ttvv homozygote has an ovate seed capsule.

> Researchers who study the molecular mechanism of transformation have identified many proteins in bacteria that function in the uptake of DNA from the environment and its recombination into the host cell’s chromosome. This means that bacteria have evolved

> Which bacterial genetic transfer process does not require recombination with the bacterial chromosome?

> Describe the steps that occur during bacterial transformation. What is a competent cell? What factors may determine whether a cell will be competent?

> As described in Figure 7.10, host DNA is hydrolyzed into small pieces, which are occasionally assembled with phage proteins, creating a phage with bacterial chromosomal DNA. If the breakage of the chromosomal DNA is not random (i.e., it is more likely to

> When bacteriophage P1 causes E. coli to lyse, the resulting material is called a P1 lysate. What type of genetic material would be found in most of the P1 phages in the lysate? What kind of genetic material is occasionally found within a P1 phage?

> What is cotransduction? What determines the likelihood that two genes will be cotransduced?

> The terms conjugation, transduction, and transformation are used to describe three different natural forms of genetic transfer between bacterial cells. Briefly discuss the similarities and differences among these processes.

> By conducting testcrosses, researchers have found that the sweet pea has seven linkage groups. How many chromosomes would you expect to find in leaf cells of the plants?

> If you try to throw a basketball into a basket, the likelihood of succeeding depends on the size of the basket. It is more likely that you will get the ball into the basket if the basket is bigger. In your own words, explain how this analogy applies to t

> A diploid organism has a total of 14 chromosomes and about 20,000 genes per haploid genome. Approximately how many genes are in each linkage group?

> Explain why a single gene knockout does not always have an effect on the phenotype.

> A crossover has occurred in the bivalent shown here What is the outcome of this single crossover event? If a second crossover occurs somewhere between A and C, explain which two chromatids it would involve and where it would occur (i.e., between which t

> A crossover has occurred in the bivalent shown here. If a second crossover occurs in the same region between these two genes, which two chromatids would be involved to produce the following outcomes? A. 100% recombinants B. 0% recombinants C. 50% rec

> Mitotic recombination can occasionally produce a twin spot. Let’s suppose an animal species is heterozygous for two genes that govern fur color and length: one gene affects pigmentation, with dark pigmentation (A) dominant to albino (a); the other gene a

> What is mitotic recombination? A heterozygous individual (Bb) with brown eyes has one eye with a small patch of blue. Provide two or more explanations for how the blue patch may have occurred.

> What is the difference between an endonuclease and an exonuclease?

> Why is carboxyl terminal domain (CTD) phosphorylation functionally important?

> What is the functional role of the TATA box?

> Why is NusA important for this termination process?

> What would be the consequences if a mutation removed the rut site from this RNA molecule?

> What feature of the –10 sequence makes it easy to unwind?

> What do the terms epistasis and complementation mean?

> Why is it necessary for portions of σ-factor protein to fit into the major groove?

> What does the term consensus sequence mean?

> What are three functional roles of the 7-methlyguanosine cap?

> A pre-mRNA with 7 exons and 6 introns is recognized by just one splicing repressor that binds to the 3´ end of the third intron. The third intron is located between exon 3 and exon 4. After splicing is complete, would you expect the mRNA to contain exon

> Describe the roles of snRNPs in the splicing process.

> Which of these three mechanisms is very common in eukaryotes?

> If a mutation changed the start codon into a stop codon, would this mutation affect the length of the RNA? Explain.

> Does the oxygen in the newly made ester bond come from the phosphate or from the sugar?

> Is DNA strand breakage necessary for catenane separation?

> What is the advantage of having the replication machinery in a complex?

> What is the key difference between autopolyploidy and allopolyploidy?

> Describe the differences in the synthesis of the leading and lagging strands

> Is the template strand read in the 5′ to 3′ or the 3′ to 5′ direction?

> Look ahead to Figure 11.9. Why is primase needed for DNA replication? From Figure 11.9: 5 3' Cannot link nucleotides - 3 5' in this direction 5 3 Can link nucleotides w/ 3 5 ' in this direction in

> How many replication forks are formed at the origin?

> What are the functions of the AT-rich region and DnaA boxes?

> Explain what the word nondisjunction means.

> Describe what happens to cohesin from the beginning of prophase through anaphase.

> Describe what structural changes convert a chromosomal region that is 300 nm in diameter to one that is 700 nm in diameter.