Solution manual and Testbank for Concepts of Genetics 4th Edition By_merged

Solution Manual for Concepts of Genetics 4th Edition By RobertBrooker Page | 2 Copyright 2022 © McGraw Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. CONCEPTS OF GENETICS, 4/e ANSWERS TO PROBLEM SETS Chapters 1-24 CHAPTER 1 Note: the answers to the Comprehension Questions are at the end of the chapter. Concept Check Questions (in figure legends) FIGURE 1. 1 Understanding our genes may help with diagnoses of inherited diseases. It may also lead to the development of drugs to combat diseases. Other answers are possible. FIGURE 1. 2 Many ethical issues are associated with human cloning. Is it the wrong thing to do? Does it conflict an individual’s religious views? And so on. FIGURE 1. 3 Because females mate only once, sorting out the male mosquitoes and releasing sterile males into the environment can limit mosquito reproduction. FIGURE 1. 4 DNA is a macromolecule. FIGURE 1. 5 DNA and proteins are found in chromosomes. A small amount of RNA may also be associated with chromosomes when transcription is occurring, and as discussed in Chapter 18, some non-coding RNAs may bind to chromosomes. FIGURE 1.6 The information to make a polypeptide is stored in DNA. FIGURE 1. 7 The dark-colored butterfly has a more active pigment-producing enzyme. FIGURE 1. 8 Genetic variation is the reason the frogs look different. FIGURE 1. 9 These are examples of variation in chromosome number. FIGURE 1. 10 If this girl had been given a standard diet, she would have developed the harmful symptoms of PKU, which include mental impairment and foul-smelling urine. FIGURE 1. 11 Page | 3 Copyright 2022 © McGraw Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. A corn gamete contains 10 chromosomes. (The leaf cells are diploid.) FIGURE 1. 12 The horse populations have become adapted to their environment, which has changed over the course of many years. FIGURE 1.13 There are several possible examples of other model organisms, including rats and frogs. End-of-chapter Questions: Conceptual Questions C1. A chromosome is a very long polymer of DNA. A gene is a specific sequence of DNA within that polymer; the sequence of bases creates a gene and distinguishes it from other genes. Genes are located in chromosomes, which are found within living cells. C2. At the molecular level, a gene (a sequence of DNA) is first transcribed into RNA. The genetic code within the RNA is used to synthesize a protein with a particular amino acid sequence. This second process is called translation. C3. A. Molecular level. This is a description of a how an allele affects protein function. B. Cellular level. This is a description of how protein function affects cell structure. C. Population level. This is a description of how the two alleles affect members of a population. D. Organism level. This is a description of how the alleles affect the traits of an individual. C4. Genetic variation is the occurrence of genetic differences within members of the same species or different species. Within any population, variation may occur in the genetic material. Variation may occur in particular genes, so some individuals carry one allele and other individuals carry a different allele. Examples include differences in coat color among mammals or flower color in plants. At the molecular level, this type of genetic variation is caused by changes in the DNA sequences of genes. There may also be variation in chromosome structure and number. C5. An extra chromosome (specifically an extra copy of chromosome 21) causes Down syndrome. C6. You can pick almost any trait. For example, flower color in petunias would be an interesting choice. Some petunias are red and others are purple. There must be different alleles in a flower color gene that affect this trait in petunias. In addition, the amount of sunlight, fertilizer, and water also affects the intensity of flower color. C7. The term diploid means that a cell has two copies of each type of chromosome. In humans, nearly all of the cells are diploid except for gametes (i.e., sperm and egg cells). Gametes usually have only one set of chromosomes. C8. A DNA sequence is a sequence of nucleotides. Each nucleotide may have one of four different bases (i.e., A, T, G, or C). When speaking of a DNA sequence, the focus is on the sequence of those bases. C9. The genetic code is the way in which the sequence of bases in RNA is read to produce a sequence of amino acids within a protein. C10. A. A gene is a segment of DNA. For most genes, the expression of the gene results in the production of a polypeptide, which is a unit of a protein. The functioning of proteins within living cells largely determines the traits of an organism. Page | 4 Copyright 2022 © McGraw Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. B. A gene is a segment of DNA that usually encodes the information for the production of a specific polypeptide. Genes are found within chromosomes. Many genes are found within a single chromosome. C. An allele is an alternative version of a particular gene. For example, suppose a plant has a flower color gene. One allele could produce a white flower, while a different allele could produce an orange flower. The white allele and orange allele are alleles of the flower color gene. D. A DNA sequence is a sequence of bases, which are found within nucleotides. The information within a DNA sequence (which is transcribed into an RNA sequence) specifies the amino acid sequence within a polypeptide. C11. The statement in part A is not correct. Individuals do not evolve. Populations evolve because certain individuals are more likely to survive and reproduce and pass their genes to succeeding generations. C12. A. How genes and traits are transmitted from parents to offspring. B. How the genetic material functions at the molecular and cellular levels. C. Why genetic variation exists in populations, and how it changes over the course of many generations. Application and Experimental Questions E1. There are many possible answers. Some common areas to discuss might involve the impact of genetics in the production of new medicines, the diagnosis of diseases, the production of new kinds of food, and the use of DNA fingerprinting to solve crimes. E2. A genetic cross involves breeding two different individuals. E3. This would be used to a great extent by molecular geneticists. The sequence of DNA is a molecular characteristic of DNA. In addition, the sequence of DNA is interesting to transmission and population geneticists as well. E4. You would see 47 chromosomes instead of 46. There would be three copies of chromosome 21 instead of two copies. E5. A. Transmission geneticists. Dog breeders are interested in how genetic crosses affect the traits of dogs. B. Molecular geneticists. This is a good model organism to study genetics at the molecular level. C. Both transmission geneticists and molecular geneticists. Fruit flies are easy to cross and study the transmission of genes and traits from parents to offspring. Molecular geneticists have also studied many genes in fruit flies to see how they function at the molecular level. D. Population geneticists. Most wild animals and plants would be the subject of population geneticists. In the wild, you cannot make controlled crosses. But you can study genetic variation within populations and try to understand its relationship to the environment. E. Transmission geneticists. Agricultural breeders are interested in how genetic crosses affect the outcome of traits. E6. You need to follow the scientific method. You can take a look at an experiment in another chapter to see how the scientific method is followed. Page | 5 Copyright 2022 © McGraw Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. CHAPTER 2 Note: the answers to Comprehension Questions are at the end of the chapter. Concept Check Questions (in figure legends) FIGURE 2. 1 Compartmentalization means that cells have membrane-bound compartments. FIGURE 2. 2 The chromosomes would not be spread out very well, and would probably be overlapping. It would be difficult to see individual chromosomes. FIGURE 2. 3 Homologs are similar in size, banding pattern, and carry the same types of genes. However, the alleles of a given gene may be different. FIGURE 2. 4 FtsZ assembles into a ring at the future site of the septum and recruits to that site other proteins that produce a cell wall between the two daughter cells. FIGURE 2. 5 In the G1 phase of the cell cycle, a cell may be preparing to divide. By comparison, the G0 phase is a phase in which a cell is either not advancing through the cell cycle or has committed to never divide again. FIGURE 2. 6 Homologs are genetically similar; one is inherited from the mother and the other from the father. By comparison, chromatids are the product of DNA replication. The chromatids within a pair of sister chromatids are genetically identical. FIGURE 2.7 One end of a kinetochore microtubule is attached to a kinetochore on a chromosome. The other end is within the centrosome. FIGURE 2. 8 Anaphase FIGURE 2. 9 Ingression occurs because myosin motor proteins shorten the contractile ring, which is formed from actin proteins. FIGURE 2. 10 The end result of crossing over is that homologous chromosomes have exchanged pieces. FIGURE 2. 11 The cells at the end of meiosis are haploid, whereas the mother cell is diploid. FIGURE 2. 12 In metaphase of mitosis, each pair of sister chromatids is attached to both poles, whereas in metaphase of meiosis I, each pair of sister chromatids is attached to just one pole. FIGURE 2. 13 Polar bodies are small cells that are produced during oogenesis and then degenerate. FIGURE 2. 14 All of the nuclei in the embryo sac are haploid. The central cell has two haploid nuclei, and all of the other cells, including the egg, have just one. Page | 6 Copyright 2022 © McGraw Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. End-of-chapter Questions: Conceptual Questions C1. They are genetically identical, barring rare mutations, because they receive identical copies of the genetic material from the mother cell. C2. A homolog is one of the members of a chromosome pair. Homologs are usually the same size and carry the same types and order of genes. They may differ in that the genes they carry may be different alleles. C3. Sister chromatids are identical copies derived from the replication of a chromosome. They remain attached to each other at the centromere. They are genetically identical, barring rare mutations and crossing over with homologous chromosomes. C4. Metaphase is the organization phase, and anaphase is the separation phase. C5. G1, there should be six linear chromosomes. In G2, there should be 12 chromatids that are attached to each other in pairs of sister chromatids. C6. In metaphase of meiosis I, each pair of chromatids is attached to only one pole via the kinetochore microtubules. In metaphase of mitosis, there are two attachments (i.e., to both poles). If the attachment is lost, a chromosome will not migrate to a pole and may not become enclosed in a nuclear membrane after telophase. If left out in the cytosol, it would eventually be degraded. C7. A. During mitosis and meiosis II B. During meiosis I C. During mitosis, meiosis I, and meiosis II D. During mitosis and meiosis II C8. The reduction occurs because there is a single DNA replication event