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TRUE/FALSE: 01. CD8 T cells recognize 13-amino acid peptides presented on MHC cl

ID: 59658 • Letter: T

Question

TRUE/FALSE:

01. CD8 T cells recognize 13-amino acid peptides presented on MHC class I molecules.

02. MHC class II molecules are loaded with peptides which originate from the cytosol.

03. The MHC class I molecule is composed of two polymorphic chains the a chain (composed of the a1-a2-a3 domain) and a smaller b2microglobulin chain.

04. TAP1 and TAP2 molecules form a transporter, which shunts partially degraded peptides from the cytosol into the endoplasmic reticulum.

05. The a2 and a3 domains of MHC class I bind to peptides.

06. The proteasome degrades proteins found in the cytoplasm and is a stable structure composed of subunits which are not replaceable.

07. HLA-DM binds to MHC class I molecule, releasing CLIP and allowing other peptides to bind within the endosome.

08. Cross-presentation is a process whereby phagocytosed material which normally would be loaded onto MHC class II molecules are loaded onto MHC class I molecules.

09. _____    MHC class I and MHC class II proteins once loaded with peptide are indefinitely express on the surface of the cell.

10. _____    MHC class II molecules are constitutively express by every cell of the body.

Explanation / Answer

1. False...

The CD8 T cells recognise 8-10 amino acid peptides presented on MHC class I molecule. The MHC class I molecule accomodates small proteins in its groove , which is narrow at the ends.

On the other hand 13-17 amino acid long peptides are accomodated in MHC class II molecule, whose groove is not narrow at the ends.