Reference no: EM132597978
1. a) Describe the two main phases of the cell cycle.
b) What must happen before mitosis can begin?
c) What is produced by mitosis?
d) What are the four steps of mitosis, in order?
2. a) How does meiosis introduce genetic variation into offspring?
b) How do the products of meiosis compare to the original cell?
c) Why are there two sets of phases during meiosis, but only one during mitosis?
3. A plant can have either tall (T) stems or short (t) stems. Two plants are crossed. One has the genotype Tt and the other has the genotype Tt.
a) Fill in the Punnett square below for this cross.
b) What is the genotype ratio for this cross?
c) What is the phenotype ratio for this cross?
d) Two different plants are crossed. One has the genotype tt and the other has the genotype Tt. Fill in the Punnett square below for this cross.
e) What is the genotype ratio for this cross?
f) What is the phenotype ratio for this cross?
4. A plant can have yellow (Y) or green (y) leaves. It can also have smooth (S) or rough (s) seeds. Answer the following questions about this plant.
a) A plant has YySs. What is the phenotype?
b) What possible gametes can the plant produce?
c) One plant with genotype YySs is crossed with another plant with the same genotype. Use the Punnett square below to find all the possible outcomes of this cross.
d) Out of the 16 possible outcomes, how many have yellow leaves?
e) Out of the 16 possible outcomes, how many have green leaves?
f) Out of the 16 possible outcomes, how many have green leaves and rough seeds?
5. The family tree below shows the trait of having attached earlobes. Having attached earlobes is recessive, and having detached earlobes is dominant. People with attached earlobes are shaded in.
a) Describe the sex and characteristics of the person labeled A.
b) Describe the genotype of the person labeled B.
c) Describe the genotype of the person labeled C.
d) Could the person labeled D have a recessive allele? Explain.
6. Each person's DNA contains certain genes that code for specific traits. List at least 15 traits that make up your body's appearance.
7. If someone had the list of traits you provided in question 6, do you think he or she would be able to find you in a group of 1000 people? Why or why not? If not, what other information encoded in your genes might distinguish you from the others in the group?
Instructions: Read the passage below and answer questions 8 - 11.
Tumor cells are different from normal cells in that they grow and divide in an unregulated fashion. The cell cycle is no longer regulated correctly. In many cases, there are mutations in the DNA of the cell that cause this loss of regulation. There are many reasons for a cell to develop these mutations, such as smoking, absorption of ultraviolet radiation, or exposure to certain chemicals.
8. A normal cell can go through mitosis about 50 times before dying. Many tumor cells do not have this limit. How does this affect the growth of tumors?
9. Why is it unlikely for a cell that spends a large amount of time in G0 phase to be a tumor cell?
10. Different proteins control different parts of the cell cycle. Proteins can cause or prevent the cell from entering the next step in the cycle. For example, there is a protein - the p53 protein - that prevents the cell cycle from continuing if the DNA in the cell is damaged.
a) How could a malfunction in the p53 protein lead to a cell becoming cancerous?
b) Another protein, p27, has the function of preventing the cell from entering the S-phase. In many cases of breast cancer, there are reduced levels of p27 found in the tumor cells. Explain why this reduced level of p27 could cause tumor cell growth.
11. Many cancer medications work by attacking all cells in the body that are actively dividing. This includes normal cells that divide regularly, such as hair cells and cells in the stomach, leading to side effects like hair loss and nausea.
a) Why are these medications useful in treating cancer despite their side effects?
b) Methotrexate is a medication that prevents cells from making nucleotides. Explain how this could help fight a cancerous tumor.
c) Taxol is a cancer medication that makes the structures in the cytoskeleton more stable. This makes it harder for cells to form mitotic spindles. Why would this be effective when fighting a tumor?