Questions and Answers

Use the Figure 1 data to calculate the ratio between the amount of Sepin‑1 required to kill 50% of the cells in the cell line that is most sensitive to the compound and the cell line that is least sensitive to the compound

1:3 Math Type ratio between the amount of Sepin-1 required to kill A, the most sensitive cell line, 10 μM kills 50% of the cells and D, the least sensitive cell line, 30 μM kills 50% of the cells

D) Based on Figure 1, explain how a mutation to p53 may lead to an increased risk of cancer.

A mutation to p53 may inhibit its ability to slow the cell cycle and inhibit abnormal cell division. This leads to an increased risk of cancer because if a mutated cell begins to uncontrollably divide, the p53 won't be able to stop it, and it may lead to cancer.

D) Explain how the arrangement of cellular components during the step of mitosis portrayed by cell D in Sample 2 facilitates the proper distribution of chromosomes to the two daughter cells.

Cell D is an example of metaphase. Some of the cellular components shown are spindle fibers that will eventually split the sister chromatids if the cell passes the spindle checkpoint. The spindle checkpoint makes sure the chromosomes are lined up correctly and that everything is good to go before splitting. One of the irreversible steps is the separation of sister chromatids, so this step is crucial to make sure that each daughter cell gets properly distributed chromosomes.

C) Draw an X on the template in the space provided for your response to indicate the phase during which the replication of damaged DNA would occur.

Draw the X on the S phase.

C) Refine the model in the space provided for your response by using the letters from four of the cell labels of Sample 2 to represent the sequential steps of mitosis

E, D, B, C

A) Describe the role of mitosis in the growth of a plant.

Mitosis helps the plant grow by creating genetically identical daughter cells. More cells mean more plant growth.

Propose 3 features of a model to connect the genetic mutation you predicted with the activity of a signaling pathway involving the LDS2B gene product

Mutation causes a structural change in polypeptide Change in sequence decreases signaling pathway An altered protein could change other components of the signaling pathway Lack of ATP

identify a control that shows that Sepin‑1 rather than something else in the culture medium is inhibiting the growth of the cancer cells

Sepin-1 is responsible for inhibiting the growth of the cancer cells that all cells are 100% viable at a very low concentration

Explain how the progression of cells past sequential cell cycle checkpoints and the activity of enzymes such as separase is controlled by interactions between two major groups of regulatory proteins.

The combinations of cyclin and cdk cause the cells to move to different stages of cell cycle

Identify an independent variable in the experiment graphed in Figure 1

The concentrations of Sepin-1

A) A skin cell completes one round of the cell cycle. Describe the products.

The products are two genetically identical diploid daughter cells.

B) Explain why there are more cells observed in mitosis in the root tip than the woody stem.

The root tip shows more cells undergoing mitosis because the root tip needs to grow more than the woody stem. Thus, the root tip cells divide more frequently. It's like how some parts of the human body like muscles and the brain never divide, but skin cells are frequently dividing.

B) Based on Figure 1, explain how p53 regulates the ell cycle in the presence of damaged DNA.

When DNA gets damaged, p53 comes in to activate a CDK inhibitor which will slow the cell cycle if the division gets out of control.

Based on the data in Table 1, describe the general relationship between the sensitivity of cells to Sepin‑1 and the concentration of separase in the cells

the greater the concentration of separase in the cells, the more sensitive the cells are to Sepin-1

The scientists hope to test Sepin‑1 in clinical trials with human cancer patients. The scientists claim that one way to test the efficacy of the Sepin‑1 treatment will be to obtain periodic samples of the patients' cancer cells and determine the percent of cells in metaphase. Provide reasoning to support the scientists' claim

the rate at which the cells are cycling should decrease because Sepin-1 should decrease the amount of active separase in the cells