B cells: antibodies and diversity

Question 1

antibodies are??

Answer 1

targeted effector proteins

Question 2

what are the three sources of antigen diversity?

Answer 2

genetic recombination
junctional diversity
somatic hypermutation

Question 3

after negative and positive selection the B cells is considered

Answer 3

mature and leave the bone marrow and head to secondary lymphoid tissues

Question 4

where do antibodies bind on antigens?

Answer 4

on the epitope of the antigen

1 antibody to 1 epitope

Question 5

effector functions of antibodies

Answer 5

receptors in B cells and Granulocytes
neutralize
opsonize
signaling

Question 6

the heavy chain determines what?

Answer 6

the isotype and thus the antibody class

Question 7

what are the five antibody classes?

Answer 7

IgA
IgG
IgM
IgD
IgE

Question 8

the heavy chain has a proportionally small or large variable region?

Answer 8

small because there is no hypermutation that occurs here

Question 9

what are the two isotypes of the small chains?

Answer 9

kappa and lambda

Question 10

heavy chain characterisitics

Answer 10

determines class
receptor interaction (Fc portion)
proportionally small variable region
binds antigen

Question 11

light chain characteristics

Answer 11

binds antigen
proportionally large variable region
two isotypes

Question 12

T/F each isotype can bind the same antigen and the same epitope

Answer 12

true because the variable region doesn’t change in class switching

Question 13

what antibodies interact with j chians

Answer 13

IgM pentameric

IgA dimeric

Question 14

what antibody is good at neutralization and diffusion and opsonization into extravascular tissues?

Answer 14

IgGs

also cross placenta

Question 15

what antibody is good at activating the complement?

Answer 15

IgM (mostly in the blood) and IgG

Question 16

what antibody sensitizes basophils

Answer 16

IgD

Question 17

what antibody is good at transporting across epithelium?

Answer 17

IgA

Question 18

what antibody is good at sensitizing mast cells?

Answer 18

IgE

Question 19

antibody variable regions do what?

Answer 19

bind antigens

Question 20

antibodies can bind to what?

Answer 20

polysaccharides, globular proteins, lipids

Question 21

what is the difference between linear and discontinuous epitopes?

Answer 21

linear the recognition site is one after another

• discontinuous the recognition sites are separated but due to structure are close
• linear are used for antigen testing

Question 22

T/F antigens can different epitopes on their surface as well as repeated copies of epitopes on their surface?

Answer 22

true

Question 23

antibody structure facilitates what?

Answer 23

function

Question 24

what is the first antibody to be expression on a B cell?

Answer 24

IgM then an IgD

Question 25

Gene rearrangement occurs where?

Answer 25

bone marrow | *as well as junctional diversity

Question 26

once the B cell is in the secondary lymphoid tissue what happens?

Answer 26

somatic hypermutation and isotype switching

Question 27

what are the three portions of the variable region of the heavy chain?

Answer 27

variable diversity joining

Question 28

what are the two portions of the variable region of the light chain?

Answer 28

variable and joining

Question 29

T/F each loci for the light chain and heavy chain are located on different chromosomes?

Answer 29

true kappa light is on chrom 2 lambda light is on chrom 22 heavy is on chrom 14

Question 30

what is the sequence of recombination?

Answer 30

the joining and diversity region are spliced together - the the DJ region is spliced to variable region * segments are randomly paired

Question 31

what does the RAG complex do?

Answer 31

randomly pairs gene segments

Question 32

order of pair gene segmentation

Answer 32

1. Vh-Dh-Jh-> Vh-DJh 2. Vh-DJh-> VDJh (heavy chain) 3. VL-JL-> VJL * remember heavy chain is first

Question 33

what is junctional diversity? | 2nd place of antibody diversity

Answer 33

* *-when you are pairing a junctional with a diversity region you are adding nucleotides to the sequence and thus altering the DNA sequence thus changing protein structure - this occurs on light and heavy chains between the variable, diverse, and junction or joining regions

Question 34

Can a single B cell express all antibody isotypes?

Answer 34

yes

Question 35

is isotype switching permanent

Answer 35

yes with the acception of IgM and IgD

Question 36

why is isotype swithcing not permanent with IgM and IgD?

Answer 36

because the termination sequence is after the conserved regions of both IgM and IgD -this means that at an mRNA step either IgM or IgD conserved regions are cut giving both IgM and IgD due to alternate splicing

Question 37

why are IgD important in B cell development?

Answer 37

they bind with Igalpha and Igbeta which allows for signaling

Question 38

upon antigen activation of the B cell what happens?

Answer 38

antibody secretion somatic hypermutation and class switching **only in mature B cells

Question 39

what are the three sources of antibody diversity?

Answer 39

Genetic recombination Junctional diversity Somatic hypermutation

Question 40

what does polyclonal mean?

Answer 40

multiple antibodies targeted against the same antigen

Question 41

what does monoclonal mean?

Answer 41

a single antibody targeted against a single antigen

Question 42

isotype switching occurs within the light or heavy chain?

Answer 42

heavy chain | *remember the heavy chain determines isotype*****