What are three functional roles of the 7-methlyguanosine cap?
> 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
> How is the process of X-chromosome inactivation similar to genomic imprinting? How is it different?
> 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?
> 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.
> How many times would telomerase have to bind to a different site in the telomere to make a segment of DNA that is 36 nucleotides in length?
> Why do eukaryotes need multiple origins of replication?
> What is a functional consequence of RNA editing?
> What features of the structure of DNA enable it to be replicated?
> What is the function of the nuclear matrix?
> Describe the distinguishing features of the solenoid and zigzag models.
> What is the diameter of a nucleosome?
> What are two reasons for the wide variation in genome sizes among eukaryotic species?
> What are some differences between the types of sequences found in eukaryotic chromosomes versus bacterial chromosomes?
> In your own words, describe the step that requires the use of ATP.
> Why is strand separation beneficial?
> How many nucleoids are in this bacterial cell? 0.3 um
> Would you expect to find active genes in regions of heterochromatin or euchromatin?
> Explain why release factors are called “molecular mimics”.
> What is a chromosome territory?
> What types of sequences constitute most of a bacterial genome?
> What are the base-pairing rules for RNA?
> What types of bonds hold nucleotides together in an RNA strand?
> What are the structural differences between B DNA and Z DNA?
> Describe the major and minor grooves.
> What holds the DNA strands together?
> Which components of nucleotides form the backbone of a DNA strand?
> Which of these components of nucleotides are not found in DNA?
> What was the purpose of adding RNase or protease to a DNA extract?
> What is the role of peptidyl transferase during the elongation stage?
> Explain why a triploid individual is usually infertile.
> What are some common advantages of polyploidy in plants?
> Approximately how many copies of chromosome 2 are found in a polytene chromosome in Drosophila?
> Describe the imbalance in gene products that occurs in an individual with monosomy 2.
> Explain why the mouse in part (d) died.
> What adjectives can be used to describe a fruit fly that has a total of seven chromosomes because it is missing one copy of chromosome 3?
> Explain why these chromosomes form a translocation cross during prophase of meiosis I.
> If these segregation patterns are equally likely, what is the probability that a gamete produced by the individual who carries the translocated chromosome will result in a viable offspring with a normal phenotype?
> Which of these two mechanisms might be promoted by the presence of the same transposable element in many places in a species’ genome?
> Explain why these homologous chromosomes can synapse only if an inversion loop forms.
