Unit 1 & 2 FRQ's

Q: Block of cell cycle in T cells

(a) Chemical Z is a large, polar molecule. Describe the process by which chemical Z moves across the plasma membrane without an input of cellular energy. Explain why the amount of DNA in a cell indicates whether the cell is in G1, S, or G2.

(b) Identify a dependent variable in the experiment. Justify the use of untreated cells in the experiment. Justify the use of both chemicals B and C in the experiment.

(c) Based on the data in Figure 2, identify the phase in interphase at which chemical Z treatment blocks the cell cycle. Describe the trends in the data that support your identification. Based on the mean values shown in Figure 2, calculate the difference in the number of cells in G1 between the sample treated with chemical Z and the untreated sample if a total of 600 cells are counted for each sample.

(d) Cancerous T cells result from genetic mutations and lack normal cell cycle controls. Scientists tested whether chemical Z blocks the cell cycle of cancerous T cells. State the null hypothesis for their experiment. Individuals with cancerous T cells also have normal T cells. Scientists find that chemical Z is an effective treatment against cancerous T cells. However, they claim that using chemical Z can have a negative effect on a patient’s ability to fight off an infection. Provide reasoning to justify their claim.

Q: Capsaicin-Activated TRPV1 Signaling

(a) Low extracellular pH activates TRPV1 through the binding of H+ ions to TRPV1. Describe the properties, including the location, of the site of TRPV1 that allow H+ ions to bind. Describe the specific location in the cell where ATF3 protein is produced.

(b) The pGoG protein is known to block the G1 to S transition in the cell cycle. Explain why this prevents mitosis from happening in the cell.

(c) Before treating melanoma cells with capsaicin, researchers pretreated the cells with an inhibitor of calcineurin. Predict the effect of this pretreatment on the ability of capsaicin to induce apoptosis by the pathway shown in Figure 2. Provide reasoning to justify your prediction.

(d) Researchers claim that many cancers include a mutation in the gene encoding pGoG. Support the researchers' claim.

Q: Cellular response to infection

(a) Describe the effect of inhibiting step 3 on the formation of pores AND on the release of interleukin from the cell

(b) Make a claim about how cleaving inactive caspase-1 results in activation of caspase-1. A student claims that preinfection production of inactive precursors shortens the response time of a cell to a bacterial infection. Provide ONE reason to support the student’s claim.