Problem 7 - AP Psychology Premium Prep 2021

Question

A researcher uses molecular biology techniques to insert a human lysosomal membrane protein into bacterial cells to produce large quantities of this protein for later study. However, only small quantities of this protein result in these cells. What is a possible explanation for this result? (A) The membrane protein requires processing in the ER and Golgi, which are missing in the bacterial cells. (B) Bacteria do not make membrane proteins. (C) Bacteria do not use different transcription factors than humans, so the gene was not expressed. (D) Bacteria do not have enough tRNAs to make this protein sequence.

Step-by-Step Solution

Answer

The correct answer is (A) The membrane protein requires processing in the ER and Golgi, which are missing in the bacterial cells. This is because bacterial cells lack the ER and Golgi apparatus present in eukaryotic cells, which are necessary for proper processing and modification of membrane proteins.

Step 1: Evaluate answer choice (A)

Consider if the membrane protein requires processing in the ER and Golgi, which are missing in the bacterial cells. In eukaryotic cells, membrane proteins are synthesized in the endoplasmic reticulum (ER) and then transported to the Golgi apparatus for further processing and modification. Bacterial cells are prokaryotic cells and do not have the ER or Golgi apparatus. Therefore, the absence of these organelles could explain the low protein production.

Step 2: Evaluate answer choice (B)

Consider if bacteria do not make membrane proteins. This statement is incorrect as bacteria do have membrane proteins involved in various functions, such as transport and cell signaling.

Step 3: Evaluate answer choice (C)

Consider if bacteria do not use different transcription factors than humans, so the gene was not expressed. This statement is incorrect as bacteria and humans do use different transcription factors. However, this difference alone would not completely prevent the expression of the gene in bacteria as various techniques can be employed to overcome this issue.

Step 4: Evaluate answer choice (D)

Consider if bacteria do not have enough tRNAs to make this protein sequence. This statement is incorrect as bacteria have a sufficient number of tRNAs to make proteins, including those from human cells. The genetic code is universal, so tRNAs from bacteria should recognize the codons in the human gene.

Step 5: Choose the correct answer

Based on the evaluation of each answer choice, the correct answer is (A) The membrane protein requires processing in the ER and Golgi, which are missing in the bacterial cells. This is because bacterial cells lack the ER and Golgi apparatus present in eukaryotic cells, which are necessary for proper processing and modification of membrane proteins.