CD4 and CD 8 are molecules present on the surface of T cells where they interact with major histocompatibility (MHC) Molecules.
CD4 and CD8 improve T cell signalling by attaching to MHC class II (CD4) or MHC class I (CD8) molecules on APCs.
- The association of CD4 with MHC class II significantly decreases the number of antigenic peptides necessary for T cell activation (5) and significantly boosts cytokine output by helper T cells.
The MHC molecules' wide polymorphism is their distinguishing trait.
- This polymorphism is crucial for T cell antigen recognition.
- A T cell detects antigen as a peptide bound by a specific allelic variation of an MHC molecule and will not identify the identical peptide bound by other MHC molecules.
- This type of T cell activity is known as MHC limitation.
Hence, the correct answer is option C
Learn more about MHC here,
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# SPJ4
C. Bats and dolphins probably share an ancestor from millions of years ago
Answer: I am not totally sure but I would say the answer would be (D)
Explanation: Exposure to Diborane will not kill you or anything like that but it will most likely cause you to have a cough, shortness of breath (but not to bad), and eye/skin irritation.
Answer:
It helps organisms survive.
Explanation:
To elaborate, adaptive traits and behavior is learned because of a necessity to <em>survive</em>.
A good example might be vaccinations and your immune system. Your body needs exposure to a pathogen to learn what it does, then adapts to fight off the pathogen. It adapts to survive.
In a constantly changing world, if you can't adapt, you simply won't survive long enough.
