Lecture 2

Question 1

how many genes are there in the human genome?

Answer 1

30000

Question 2

In a heavy chain and TCRbeta what is the V region encoded by?

Answer 2

V, D and J segments

Question 3

what segment is the largest?

Answer 3

V

Question 4

in the light chain and TCRalpha what is the V region encoded by?

Answer 4

V and J

Question 5

what happens when DNA is broken in B cells?

Answer 5

rearranged to assemble a gene that encodes for the variable region

Question 6

when is DNA broken on B cells?

Answer 6

during development in the bone marrow

Question 7

how do B cells and T cell generate random antibodies?

Answer 7

by randomly breaking their DNA

Question 8

what are the two loci containing L chains?

Answer 8

lambda and kappa

Question 9

where does the transcript join on the antibody?

Answer 9

constant region

Question 10

what is the order of the B cell development for Ig arrangements?

Answer 10

heavy chains then light chains

Question 11

what is rearranged after D-J in the heavy chain?

Answer 11

V-DJ

Question 12

what segments rearranged first in the kappa light chain region?

Answer 12

V-J

Question 13

what happens if the kappa arrangement is unsuccessful in the light chain?

Answer 13

lambda segments start to rearrange

Question 14

on what chromosome is the heavy chain locus found on?

Answer 14

14

Question 15

on what chromosome is the kappa chain locus found on?

Answer 15

2

Question 16

on what chromosome is the lambda chain locus found on?

Answer 16

22

Question 17

what does a D and a J segment make on a B cell?

Answer 17

IgM

Question 18

how can IgM switch to IgG?

Answer 18

by class switching

Question 19

explain recombination signal sequences

Answer 19

Ig gene segments are rearranged by special sequences flanking each of the V,D,J segments

Question 20

what enzyme is involved?

Answer 20

V,D,J recombinase

Question 21

what do RAG-1 and RAG-2 do?

Answer 21

they are genes that encode lymphoid-specific components of the recombinase

Question 22

what do mutations of RAG genes result in?

Answer 22

immunodeficiency

Question 23

what is light chain isotope exclusion?

Answer 23

each B cell expresses wither a rearranged kappa or lambda light chain NEVER both

Question 24

what is each B cell compared to another B cell

Answer 24

unique, never the same as another

Question 25

what does junctional diversity do?

Answer 25

increases diversity further by imprecise joining and random addition of nucleotides

Question 26

what does terminal transferase do?

Answer 26

randomly adds in extra nucleotides

Question 27

what are two other examples of mechanisms for generation of antibody diversity?

Answer 27

somatic hypermutation (SHM)

Question 28

what does SHM occur?

Answer 28

in germinal centres

Question 29

what is SHM performed by?

Answer 29

any enzyme called AID (activation-induced deaminase)

Question 30

what do AIDs act on?

Answer 30

on DNA to de-aminate cytosine to uracil

Question 31

what are the membrane and secreted forms of each B cell produced by?

Answer 31

alternative RNA processing

Question 32

what does each secreted form made by a B cell lack?

Answer 32

a transmembrane region in the constant region

Question 33

what is released from the B cell as a secreted product?

Answer 33

RNA

Question 34

what heavy chain is IgM on?

Answer 34

Mu

Question 35

what heavy chain is IgD on?

Answer 35

delta

Question 36

what heavy chain is IgG on?

Answer 36

lambda

Question 37

what heavy chain is IgA on?

Answer 37

alpha

Question 38

what heavy chain is IgE on?

Answer 38

epsilon

Question 39

what does it mean when Cdelta is next to CMu?

Answer 39

IgD can be co-expressed with IgM