Which of the following is a difference between class I and class II major histocompatibility complex (MHC) proteins?
A) Class I MHC proteins can be found on most cell types, whereas both class I and II MHC proteins are found on the antigen-presenting cells of the immune system
B) Class I MHC proteins are added to antigens in the cytoplasm, whereas class II proteins are added to antigens in the Golgi apparatus.
C) Class I MHC proteins signal the immune system to activate the cell displaying the message, whereas class II proteins signal the immune system to destroy a particular cell.
D) Class I and class II MHC proteins have the same basic role, but individuals with particularly strong immune systems will have both types, whereas most individuals have just one or the other.

Question

Quizplus · Accepted Answer

Class I MHC proteins can be found on most cell types, whereas both class I and II MHC proteins are found on the antigen-presenting cells of the immune system. This is a key difference between the two classes of MHC proteins.

B, C, and D are incorrect:
B: Both class I and II MHC proteins are added to antigens in the endoplasmic reticulum, not the cytoplasm or Golgi apparatus.
C: Both class I and II MHC proteins play a role in signaling the immune system, but the specific signals are different, and neither signal necessarily indicates destruction of a cell. 
D: Most individuals have both class I and class II MHC proteins, although some individuals may have certain variations or mutations that affect their MHC protein expression.

Which of the Following Is a Difference Between Class I