Ch.4 Ab structure & B-cell diversity

Question 1

resting b cell

Answer 1

has membrane bound Ig

Question 2

stimulated b cell

Answer 2

b cell activated by Ag gives rise to Ab secreting plasma cells

Question 3

Ab structure

Answer 3

2Fab fragments

4Fc fragment

Question 4

Fab

Answer 4

ag binding fragment bind to exact same molecule

Question 5

Fc

Answer 5

crystallizable fragment. constant region made of only one protein, part of H chain

Question 6

hinge region

Answer 6

allows for flexibility of atoms (Fab)

Question 7

epitope

Answer 7

antigenic determinant- small part of ag that fits into ag binding site of ab molecule

Question 8

affinity

Answer 8

strength binding between receptor and ligand

Question 9

avidity

Answer 9

strength of binding when more than one receptor is binding to the same molecule

Question 10

valency

Answer 10

number of binding sites

Question 11

ab binding sites

Answer 11

2- divalent

Question 12

T cell receptor binding sites

Answer 12

1- monovalent

Question 13

polyvalent

Answer 13

more than two binding sites

Question 14

constant region

Answer 14

determines class and effector function

Question 15

effector function

Answer 15

how ab removes the antigen

Question 16

class/isotype

Answer 16

group ab with same constant region

Question 17

H chain of IgG

Answer 17

gamma

Question 18

H chain of IgM

Answer 18

mu

Question 19

H chain of IgD

Answer 19

delta

Question 20

H chain of IgA

Answer 20

alpha

Question 21

H chain of IgE

Answer 21

epsilon

Question 22

light chain constant region

Answer 22

lambda or kappa doesn’t influence effector function or name of ab

Question 23

Ig domain

Answer 23

origional gene replicated many times and is used in many membrane receptors

Question 24

Ig domain compostition

Answer 24

110 amino acids long
2 beta pleated sheets
1 intrachain disulfide bond

Question 25

Ig loops/HV/CDR

Answer 25

extend from end of variable region where ab binds to ag.

Question 26

hypervariable regions (HV)

Answer 26

have sequence of high variability in the amino acid sequence and DNA

Question 27

framework regions

Answer 27

relatively conserved b/c necessary for folding. part of V region

Question 28

complementary determining regions (CDR)

Answer 28

part of V region where ab comes into contact w/ag and binds to it

Question 29

naive cell composition

Answer 29

IgM and IgD

Question 30

IgM and IgD in naive cell

Answer 30

have different constant regions but same variable. Can become a memory cell with a different class but same v region

Question 31

germline DNA

Answer 31

as found in germ cells (sperm and egg). DNA inherited on chromosome

Question 32

sperm and egg produced by

Answer 32

meiosis-synapse- can have cross over and DNA exchange

Question 33

recombination

Answer 33

DNA exchange

Question 34

somatic cell

Answer 34

every cell that isn’t a germline cell

Question 35

somatic recombination

Answer 35

rearrangement/splicing of DNA in somatic cell (only occurs in Ig and TCR DNA)

Question 36

proteins (enzyme complex) that perform somatic recombination

Answer 36

recombination activating genes (RAG) produce RAG proteins. RAG only found in B & T cells

Question 37

steps somatic recombination in B&T cells

Answer 37

1) RAG binds to Rss
2) RAG brings 2 Rss together forming a loop
3) intervening between 2Rss is cut out and destroyed (DNA splicing and rearrangement)
4) p&h nucleotides formed on cut ends
5) DNA repair forms coding joint

Question 38

class switch

Answer 38

permanent change in DNA (can’t remake any spliced out C regions)

Question 39

for class switch to occur

Answer 39

• cell must respond to ag
• must receive T cell help (T cell signals cytokines)
• ag must be a protein

Question 40

production IgM and IgD requires

Answer 40

differential RNA splicing

Question 41

co receptor

Answer 41

any molecule needed for ag receptor to produce a signal transduction cascade

Question 42

allelic exclusion

Answer 42

during somatic recombination only one H and L can be used to make ab—only one ag binding site per cell (many identical copies)

Question 43

Somatic hyper mutation definition

Answer 43

mechanisms for increasing diversity

Question 44

somatic hyper mutation parameters

Answer 44

1) occurs after ag binding
2) only in B cells
3) only w/T cell help
4) only happens w/protein ag

Question 45

point mutations

Answer 45

one nucleotide is changed in v region of Ig that occurs at accelerated rate

Question 46

activation induced deaminase (AID)

Answer 46

enzyme that removes amino group from cytidine and is only active when bound to ag