Download Biology 122, Spring 2014 Activities for the week of March 10

Biology 122, Spring 2014
Activities for the week of March 10-14
Directions. In lieu of class on 3/10, 3/12, and 3/14, you should work on the
following activities. You should devote the amount of time you spend in class in
Biology 122 to these activities, i.e. 150 minutes for the week. You are welcome to
work with others on these activities, and in fact it might be good to assemble in
Nygreen 2 at 2:15-3:05 on 3/10, 3/12, and 3/14 as a way to collaborate with your
peers on these assignments.
You will bring your assignments to class on March 24th and we will discuss them
on that day.
You should be caught up on previous cinelectures and study the cinelectures for
the week of 3/10-3/14 before doing these assignments.
Assignment 1. Write a brief essay describing the cell cycle, and the ways that
cyclins and their dependent kinases control the cell cycle, concentrating on the
G1>S checkpoint and the role of the retinoblastoma protein.
Assignment 2. Write an essay describing the differences between oncogenes
and tumor suppressor genes. Include in your essay explanations for why
mutations in proto-oncogenes lead to tumor formation and why this can also be
true for tumor suppressor genes. Also include an explanation as to why mutant
oncogenes are dominant (only one copy of the mutant gene is capable of tumor
promotion), whereas tumor suppressor gene mutations are recessive (a cell
needs two mutant copies for tumor promotion).
Assignment 3. Assume an organism has 2 pairs of chromosomes in its diploid
genome. Imagine a cell of this organism going through the cell cycle to produce 2
daughter cells. Briefly describe the process of the cell cycle from the
chromosomes’ points of view. Draw out the behavior of these chromosomes in
the Mitotic phase of the cell cycle, i.e. how do the chromosomes, which have
replicated in the S phase, segregate to daughter cells after cytokinesis?
Assignment 4. As for Assignment 3, describe the process of the 2 cell cycles of
MEIOSIS from the chromosomes’ points of view. When does chromosome (DNA)
replication take place? Draw out the behavior of these chromosomes in
MEIOSIS, i.e. how are the chromosomes, which have replicated in the S phase
of Meiosis I, segregated into haploid reproductive cells at the end of Meiosis II?
Assignment 5. Describe in detail, using drawings, the behavior of chromosomes
during meiosis, this time assuming the following genotypes for Mendelian alleles
carried on the chromosomes:
Case (a) A/A homozygote
Case (b) A/a heterozygote
Case (c) T/t ; S/s double heterozygote, i.e. 2 genes, each on a different
chromosome and, in this genotype, represented by 2 alleles.
Assignment 6. Do as many of the Sample Transmission Genetics problems
found at the bottom of the online course syllabus as you have time for.