Question: A diploid fruit fly has eight chromosomes.

> What are the building blocks of a nucleotide? With regard to the 5′ and 3′ positions on a sugar molecule, how are nucleotides linked together to form a strand of DNA?

> Look up the meaning of the word transformation in a dictionary and explain whether it is an appropriate word to describe the transfer of genetic material from one organism to another.

> Within a protein, certain amino acids are positively charged (e.g., lysine and arginine), some are negatively charged (e.g., glutamate and aspartate), some are polar but uncharged, and some are nonpolar. If you knew that a DNA-binding protein was recogni

> A DNA-binding protein recognizes the following double-stranded sequence: 5′–GCCCGGGC–3′ 3′–CGGGCCCG–5′ This type of double-stranded structure could also occur within the stem region of an RNA stem-loop. Discuss the structural differences between RNA and

> On further analysis of the DNA described in conceptual question C21, you discover that the triplex DNA in this alien organism is composed of a double helix with a third strand wound within the major groove (just like the DNA in Figure 9.15). How would yo

> Let’s suppose you have recently identified an organism that was scraped from an asteroid that hit the earth. (Fortunately, no one was injured.) When you analyze this organism, you discover that its DNA is a triple helix, composed of six different nucleot

> An organism has a G + C content of 64% in its DNA. What are the percentages of A, T, G, and C?

> After the DNA from type S bacteria is exposed to type R bacteria, list all of the steps that you think must occur for the type R bacteria to start making a capsule.

> Discuss the structural significance of complementarity in DNA and in RNA.

> What ethical issues may be associated with human cloning?

> What structural feature allows DNA to store information?

> Which of the following DNA double helices would be more difficult to separate into single-stranded molecules by treatment with heat, which breaks hydrogen bonds? A. GGCGTACCAGCGCAT CCGCATGGTCGCGTA B. ATACGATTTACGAGA TATGCTAAATGCTCT Explain your choi

> Compare the structural features of a double-stranded RNA structure with those of a DNA double helix.

> Write a sequence of an RNA molecule that could form a stem-loop with 24 nucleotides in the stem and 16 nucleotides in the loop.

> Draw the structure of deoxyribose and number the carbon atoms. Describe the numbering of the carbon atoms in deoxyribose with regard to the directionality of a DNA strand. In a DNA double helix, what does the term antiparallel mean?

> List the structural differences between DNA and RNA.

> What part(s) of a nucleotide (namely, phosphate, sugar, and/or base) is(are) found in the major and minor grooves of doublestranded DNA, and what part(s) is(are) found in the DNA backbone? If a DNA-binding protein does not recognize a specific nucleotide

> Discuss the differences in the structural features of B DNA and Z DNA.

> Make a side-by-side drawing of two DNA helices: one with 10 bp per 360° turn and the other with 15 bp per 360° turn.

> What is the meaning of the term genetic material?

> How might a better understanding of our genes be used in the field of medicine?

> Explain why inversions and reciprocal translocations do not usually cause a phenotypic effect. In a few cases, however, they do. Explain how.

> An inversion heterozygote has the following inverted chromosome: What would be the products if a crossover occurred between genes H and I on the inverted chromosome and a normal chromosome? Centromere A B CD JI HGF E, KL M Inverted region

> An inversion heterozygote has the following inverted chromosome: What would be the products if a crossover occurred between genes H and I on the inverted chromosome and a normal chromosome? Centromere A BJI HGF ED CKLM Inverted region

> Two chromosomes have the following orders for their genes: Normal: A B C centromere D E F G H I Abnormal: A B G F E D centromere C H I Does the abnormal chromosome have a pericentric or a paracentric inversion? Draw a sketch showing how these two chro

> Following a gene duplication, two genes will accumulate different mutations, causing them to have slightly different sequences. In Figure 8.7, which pair of genes would you expect to have more similar sequences, α1 and α2 or &

> What is a gene family? How are gene families produced over time? With regard to gene function, what is the biological significance of a gene family?

> A triploid plant has 18 chromosomes (i.e., 6 chromosomes per set). If we assume a gamete has an equal probability of receiving one or two copies of each of the six types of chromosome, what are the odds of this plant producing a haploid or a diploid game

> The karyotype of a young girl who is affected with familial Down syndrome revealed a total of 46 chromosomes. Her older brother, however, who is phenotypically unaffected, actually had 45 chromosomes. Explain how this could happen. What would you expect

> The kidney bean plant, Phaseolus vulgaris, is a diploid species containing a total of 22 chromosomes in somatic cells. How many possible types of trisomic individuals could be produced in this species?

> Which of the following terms should not be used to describe a human with three copies of chromosome 12? A. Polyploid B. Triploid C. Aneuploid D. Euploid E. 2n + 1 F. Trisomy 12

> Can you think of another example of a model organism?

> A diploid fruit fly has eight chromosomes. Which of the following terms should not be used to describe a fruit fly with four sets of chromosomes? A. Polyploid B. Aneuploid C. Euploid D. Tetraploid E. 4n

> While conducting field studies on a chain of islands, you decide to karyotype two phenotypically identical groups of turtles, which are found on different islands. The turtles on one island have 24 chromosomes, but those on another island have 48 chromos

> How does a chromosomal duplication occur?

> Describe some of the advantages of polyploid plants. What are the consequences of having an odd number of chromosome sets?

> Explain how polytene chromosomes of Drosophila are produced and how they form a six-armed structure.

> What is mosaicism? How is it produced?

> What is endopolyploidy? What is its biological significance?

> 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 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

> 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?