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Problem set 2, Spring 2017 8 points total student name: 1. Diagram anaphase of mitosis for a diploid organism that contains 2 pairs chromosomes – 1 long and 1 short. 2. Diagram metaphase of mitosis for a haploid organism that contains 2 chromosomes. Note that haploid cells can undergo mitosis just fine. 3. Mitosis resembles the second meiotic division. How are they similar? How do they differ? Similar: -same basic steps -overall process similar -spindle attaches to both sides of centromere Differ: -ploidy of starting cell reduced in meiosis II -2nd meiotic division produces 4 cells -mitosis gives genetically identical daughters -meiosis produces gametes 1 Problem set 2, Spring 2017 8 points total student name: 4. In studying a eukaryotic organism D. webbae, recently discovered on an asteroid floating in space, you find that it has a rather unusual meiosis. In D. webbae, cells destined to undergo meiosis skip S-phase, and then undergo only the first meiotic division. Draw out prophase, metaphase, and anaphase of meiosis, and the daughter cells produced by meiosis, in D. webbae showing the chromosomes. Assume D. webbae is diploid with three pairs of homologous chromosomes. What are the consequences of this unusual type of meiosis? prophase I metaphase I anaphase I telophase I Only two cells will result rather than the usual four. In addition, the lack of sister chromatids may cause problems for crossing over. 2 Problem set 2, Spring 2017 8 points total student name: 5. A B C c B B A A a B A. This diploid cell goes through a normal mitotic cell cycle. Show metaphase of mitosis and the daughters produced, including genes and chromosomes. Note: Daughters are identical to starting cell. Just draw two of them. C C a a c c B B B. Show chromosomes and spindle of this cell in anaphase II of meiosis. (You don’t need to include the genes.) 3 Problem set 2, Spring 2017 8 points total student name: 6. A. schlenzae is a newly discovered red-spotted poison dart frog from Costa Rica. Chromosome analysis of A. schlenzae indicates that the species is diploid with two pairs of chromosomes, one long and one short. Simple genetic analysis indicates that the gene (R) that specifies the red spots is located on the long chromosome, and a gene (L) that specifies body length resides on the short chromosome. A. Show the products at the beginning of G1 phase of a single mitosis of a A. schlenzae cell. Assume the parent cell is heterozygous (i.e. R on one homolog and r on the second, L on one homolog and l on the second) for both genes. How many chromosomes are present in each cell? How many chromatids are present in each cell? R l R l L r r L 4 chromosomes, 4 chromatids B. Diagram the appearance of the chromosomes at metaphase of meiosis I. Draw a circle around the homologous chromosomes and a box around the sister chromatids. Assume the parent cell is heterozygous for both genes. R r L l 4 Problem set 2, Spring 2017 8 points total student name: 7. Do the following occur in meiosis I, meiosis II or mitosis? (Each blank may contain more than one answer. meiosis I a. At least one crossover per homologous pair can occur b. chromosomes line up singly along the metaphase plate mitosis,meiosis II meiosis I c. ploidy level is decreased by half d. DNA synthesis takes place prior to division mitosis,meiosis I e. Produces somatic cells mitosis f. Homologous chromosomes separate from each other meiosis I 8. The cells shown in A through D all came from the same individual. In the spaces below each cell, identify the type of division (mitosis or meiosis) taking place and the stage of that division represented in the cell (anaphase, prophase I, etc.). a. b. Division: meiosis I Stage: anaphase I Division: mitosis Stage: anaphase c. d. 5 Problem set 2, Spring 2017 8 points total student name: Division: meiosis I metaphase I Stage: Division:meiosis II Stage: anaphase II The following questions refer to the figures shown above in a – d. How many chromosomes in cell in d? 6 In which cell(s) are homologues separating? How many chromatids? a In which cell(s) are sister chromatids separating from each other? 6 b, c 12