Chapter 12 Study Guide – OpenStax Biology 2e

Chapter 12 Study Guide – OpenStax Biology 2e

Reading Assignment: Read Chapter 12: • Section 12/1: you do NOT need to read “probability basics”. • Read all of section 12.2. Take your time! You will need to do genetics problems. Make use of the PowerPoint and in additional study resources there are links to videos of how to complete these problems. • In section 12.3 you should read only about the law of segregation, law of independent assortment and dihybrid crosses. You don’t need the section on the forked-line method or the probability method. We also will not discuss gene linkage in this class. • You should read about epistasis. Terms to know and understand: Allele Autosomes Codominance Dihybrid Dominant Dominant lethal Epistasis F1 F2 Genotype Heterozygous Homozygous Hybridizations Incomplete dominance Law of independent assortment Law of segregation P0 Phenotype Punnett square Recessive Recessive lethal Sex-linked Test Cross Trait X-linked Chapter Review Questions: 1. Who was Gregor Mendel? Describe the plant that he performed his research with and explain at least two reasons why this plant proved to be an ideal model species for early genetic research. 2. Outline the basic hybridization research done by Mendel when crossing a true breading violet flowered plant with a true breeding white flowered plant? In your answer you should indicate the parental generation, the F1, and the F2 results. 1 3. In the results that Mendel obtained above, would the resulting color of the flower be called a phenotype or a genotype? 4. In the results that Mendel obtained, the violet colored flower was dominant to the white flower (which was recessive). What do these terms (dominant and recessive) mean? 5. Define the term allele (try to put it in your own words if you can!). This would be a good time to review the term homologous chromosome as well and to think about how/why these two terms related to each other. 6. Imagine a pea plant has two copies of the recessive allele for flower color. a. Is this plant homozygous or heterozygous for the flower color gene? b. What will be this plant’s phenotype? c. What is this plant’s genotype? 7. Imagine a pea plant one recessive allele for flower color and one dominant allele for flower color. a. Is this plant homozygous or heterozygous for the flower color gene? b. What will be this plant’s phenotype? c. What is this plant’s genotype? 2 8. It is important to learn how to draw and use Punnett squares for this chapter. Lets start with a basic example. a. In pea plants, Tall plants (T) are dominant over dwarf pea plants (t). I am going to cross a heterozygous tall pea plant with a dwarf pea plant. Show a Punnett square of this cross and then explain what is the expected genotype and phenotype ratios for the offspring of my cross? 9. If you have a pea plant with a dominant phenotype (like purple flowers) why might you NOT know its genotype? 10. Explain how you could use a test cross to help you determine the genotype of the purple flower with an unknown genotype mentioned in the previous question. 11. What is a pedigree and why is it useful to a geneticist? 12. Look at the art connection in chapter 12 that shows the pedigree analysis for Alkaptonuria. Can you figure out the genotype for persons 1, 2, and 3 in this pedigree? (Note that you don’t need to use Punnett squares here). 3 13. Not all traits are controlled by dominant and recessive alleles. What does incomplete dominance mean? Give an example. 14. Try this problem using incomplete dominance of flower color. In the snapdragon, Antirrhinum majus (Figure), a cross between a homozygous parent with white flowers (CWCW) and a homozygous parent with red flowers (CRCR) will produce offspring with pink flowers (CRCW). a. Why are none of these alleles written as a lowercase letter? b. Imagine you cross two pink flowers. Write a Punnett square for this cross and determine the flower colors that would result from this cross. 15. What does co-dominance mean? Explain how co-dominance is different from incomplete dominance. 16. One important example of multiple alleles is the human ABO blood type. Explain what “multiple alleles” means. 17. The book does not go into much detail on the ABO blood type but you should learn it – go watch this video now or look through the PowerPoint. https://www.youtube.com/watch?v=KXTF7WehgM8 a. How many alleles can one person have for ABO blood type? 4 b. Blood type is ALSO an example of co-dominance. Which two alleles within the ABO blood type are co-dominant? c. Which one allele is recessive? d. Complete the following blood type Punnett square. If a parent who has type B blood and is heterozygous has children with someone who has type A blood (and is also heterozygous) then what are all the possible blood types of their offspring? 18. If a gene is X-linked, explain why the recessive phenotype would be more often seen in males then in females. Also explain what the term “carrier” means related to these traits. 19. Explain the laws of segregation and independent assortment and why are important when doing something like a dihybrid cross. 20. Define and give an example of epistasis. 5 Chapter 13 Study Guide – OpenStax Biology 2e Reading Assignment: Read section 13.2 in chapter 13. • For this chapter you do not need to read section 13.1! Just read section 13.2 and focus on the different types of chromosomal disorders that can occur. You should know the examples listed below. Terms to know and understand: Autosome Chromosome Inversion Karyotype Monosomy Nondisjunction Polyploid Translocation Trisomy X Inactivation You should know what type of chromosomal disorder each of the following examples are: o Down Syndrome o Klinefelter syndrome o Cri-do-chat syndrome Chapter Review Questions: 1. What is a nondisjunction and why does it lead to chromosomal abnormalities? 2. Examine figure on in section 13.2. a. What does a karyotype show? b. Why would a karyotype be useful to a geneticist? c. Find a pair of sister chromatids in the karyotype in figure 13.1 and a pair of homologous chromosomes. d. Count and notice that there are 46 individual chromosomes in the human karyotype and they are arranged in 23 homologous pairs. 1 3. Explain autosomes and the sex chromosomes. 4. What is X inactivation? 5. Give some details about each of the following chromosomal disorders. o Down Syndrome o Klinefelter syndrome o Cri-do-chat syndrome 6. Sometimes, our scientific understanding of something changes as research is done and scientific knowledge grows. After watching the following video, describe at least two ways in which our understanding of biological sex has changed as compared to the historical understanding that we still often learn about today. o https://www.youtube.com/watch?v=kT0HJkr1jj4 SciShow – “There are more than two human sexes” 2 Chapter 14 Study Guide – OpenStax Biology 2e Reading Assignment: For this chapter you should read sections 14.1, 14.2 (you can skip section on DNA sequencing techniques), 14.3, 14.4 (replication in prokaryotes is ALSO the same basic process as in eukaryotes but eukaryotes have a few extra parts to replication), 14.5, and 14.6. • Sections 14.2 and 14.4 are the key parts of this chapter and are where you will want to put more time and focus. Terms to know and understand: Base pairing Double Helix Helicase Induced Mutation Lagging strand Leading strand ligase mutation nucleotides Okazaki fragments point mutation replication fork sugar-phosphate backbone telomerase telomere Chapter Review Questions: 1. Describe the three parts of every nucleotide and draw one nucleotide of DNA. What are the four possible bases that DNA nucleotides could have? 2. Draw or describe how nucleotides are arranged to form a molecule of DNA in the double helix form. 3. If the nucleotide on one side of the DNA is cytosine, what base will be on the complementary nucleotide on the other side? 4. If the nucleotide on one side of the DNA is adenine, what base will be on the complementary nucleotide on the other side? 5. What type of chemical bond holds together the base pairs in the DNA double helix? 1 6. The sugar and phosphate groups of the DNA molecule make the _____________ of the structure. 7. If one side of a DNA strand has the sequence of bases given below, what will be the complementary sequence on the other strand? ATCGCAATAGAC 8. DNA basic structure: Below, I have drawn a representation of a single strand of DNA. Draw a representation of the complementary strand of DNA with the phosphate-sugar backbone. Be sure to indicate the hydrogen bonds between base pairs, and be sure that you correctly indicate the directionality (5’ and 3’ ends) of the complementary strand. 5’ P D-T | P D-A | P D-C | P D-T | P D-C 3’ 9. Describe the basic process of DNA replication (as described in the section on prokaryotic DNA replications in the book – these steps also occur in eukaryotic cells!). Your answer should include the following terms. DNA polymerase, Helicase, and Primase. 2 10. Why is one side of DNA able to be replicated in one continuous sequence (the leading strand) and the other side of the DNA molecule (the lagging strand) is replicated in small fragments (Okazaki fragments)? 11. Describe at least two facts about the function of telomerase that you learned from this chapter. 12. Why is it important that DNA polymerase conducts proofreading during replication? 13. What has occurred if there is a point mutation on a DNA strand? 14. If a gene mutation occurs, there are several possible outcomes (silent, missense, nonsense, frameshift). Describe these types of outcomes. 15. Think back to the chapter about mitosis and the cell cycle. During which part of interphase would DNA replication be occurring in a cell? 3

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