Lecture 5

Question 1

How are H and L chains held together?

Answer 1

disulphide bonds

Question 2

What is the structure of the two globular domains in the L chain, and the 3 or 4 globular domains in the H chain?

Answer 2

anti-parallel beta sheets

Question 3

What is the HV/CDR? What is their function

Answer 3

area in the gene that has higher variability in amino acids, antigen binding site (determines antigen specificity)

Question 4

What are the conserved regions of the gene (non CDR) for?

Answer 4

framework regions to create beta sheets (3d structure)

Question 5

Where is the DNA for the CDR1, 2 and 3?

Answer 5

CDR 1 and 2: in the V region
CDR 3: at the VDJ joint (or VJ joint for the L chain)

Question 6

How is a TCR like a BCR?

Answer 6

TCR is like one arm of the BCR

Question 7

What are the two cell types in the Tonegawa experiment?

Answer 7

Myeloma: all derived from one B cell– has the same V(D)J segments
embryonic cell: healthy liver cell

Question 8

What are the steps in the Tonegawa experiment

Answer 8

1) digest both cells DNA with RE
2) denature the dsDNA to ssDNA
3) isolate mRNA of myeloma cell and label with radioactive isotope 32p
4) transfer fragments to nitrocellulose paper
5) watch as mRNA binds to DNA
6) observe 2 bands in the embryonic DNA, only 1 in myeloma DNA