2018 Exam Question 2

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

By inhibiting step 3, the cleaving of gasdermin by capase - 1 will prevent the combining of gasdermin proteins and formation of pores in the cell membrane. This will not impact the release of interlukin, given that interlukin does not require the pores to leave 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.

Cleaving inactive capase - 1 leads to active capase - 1 because it withdraws repressor proteins that maintain the inactive form of capase - 1. Preinfection production of inactive precursors shortens response time because it reduces the number of steps required to initiate cellular response. Therefore, it's unnecessary to transcribe and translate the inactive precursors if they are already present.

E) Explain how gasdermin pore formation AND interleukin release contribute to an organism's defense against a bacterial pathogen.

Gasdermin pore formation leads to the flow of water into the cell, which can cause the infected cell to burst. Due to phagocytes digesting the compounds of the cell along with other pathogens, this would prevent the spread of infection. Interlukin release activates the adaptive immune response through the stimulation of B and T leukocytes to divide and produce antibodies or, to kill infected cells.

D) Describe the most likely effect of gasdermin pore formation on water balance in the cell in a hypotonic environment.

In a hypotonic environment, gasdermin pore formation would allow water to move into the cell in a net amount. This is bc the cell would have a higher solute concentration compared to the surrounding environment. Better known as osmosis, the diffusion of water involves moving towards higher solute concentration.

C) A student claims that the NF-kB protein is located in the cytoplasm until the protein is needed for transcription. Justify the student's claim with evidence. Identify TWO fractions where N-terminal gasdermin would be found in cells infected with pathogenic bacteria.

The student's claim is correct bc fraction 2 and 3 tested positive for NF-kB. Fraction 2 is evidently the nucleus bc it has DNA polymerase, an enzyme found only in the nucleus where DNA replication occurs. The protein NF-kB would be needed to regulate transcription. Fraction 3 is the cytoplasm bc it tested positive for glyolitic proteins. Glycolytic proteins aid in glycolysis, a process perfmormed in the cytoplasm. N terminal gasdermin would be found in fractions 3 and 4 bc they are closest to the cellular membrane.