Which mutations can interfere with the proper insertion of a protein in the plasma membrane?

Question

A.  A polar amino acid to a non-polar amino acid within a transmembrane domain
B.  A non-polar amino acid to a polar amino acid within a transmembrane domain
C.  A polar amino acid to a non-polar amino acid within a cytoplasmic domain
D.  A non-polar amino acid to a polar amino acid within a cytoplasmic domain

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?

Gather Content
· What do you know about the amino acids found in a transmembrane domain? What other information is related to the question?

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

B.  A non-polar amino acid to a polar amino acid within a transmembrane domain

Clarify Question
· What is the key concept addressed by the question?
        o The question asks about the amino acids found in a transmembrane domain.
· What type of thinking is required?
        o You are being asked to apply your knowledge about the amino acids found in a transmembrane domain.

Gather Content
· What do you know about the amino acids found in a transmembrane domain? What other information is related to the question?
        o Transmembrane domains contain non-polar amino acids because the membrane itself is non-polar. Polar amino acids are found more on the cytoplasmic portions of a protein that interact with water.

Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o If a non-polar amino acid was changed to a polar amino acid in a transmembrane domain it would interfere with the insertion of a protein into a membrane. Changes in the cytoplasmic domain would not affect this process and non-polar amino acids will interact better than the polar amino acids with the membrane.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked you to apply your knowledge about the amino acids found in a transmembrane domain. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you think that polar amino acids would be found on a membrane? Did you think that the inside of a membrane was polar?