Final: Immune System Part 1

Question 1

the immune consists cells that occur mainly within….

Answer 1

the circulatory system

collectively called white blood cells

Question 2

innate immunity

Answer 2

cells part of a rapid response

Question 3

adaptive immunity

Answer 3

cells part of a slow response

Question 4

where are WBC formed?

Answer 4

in bone barrow

Question 5

lymphocytes

Answer 5

B cells and T cells

brains of adaptive immunity

Question 6

antigen

Answer 6

foreign molecules that evoke an immune response and are targeted by antibodies

Question 7

antibody

Answer 7

proteins that can bind two identical antigens

mark antigens for destruction

found freely circulating in blood or mounted on B-cell surfaces

Question 8

problem targeting antigens

Answer 8

how to locate and target them?

must be one antibody that binds the antigen before it can be destroyed

if the body doesn’t have the right antibody it can’t fight off the invader

Question 9

what happens when an antibody binds an antigen

Answer 9

cross linking can occur forming antigen-antibody complexes

both binding sites of the antibody can interact with the same antigen

antigen labeled for destruction by macrophages

Question 10

basic structure of an antibody

Answer 10

protein with two identical halves shaped in a Y

heavy chain and light chain protein

at the tip of each branch on top, there is an antigen binding site

Question 11

variable regions

Answer 11

parts of the antibody that contact the antigen

different shapes like a pocket or groove

Question 12

constant regions

Answer 12

parts below the variable regions

Question 13

how is an antibody held together

Answer 13

disulfide bridges

Question 14

hypervariable regions

Answer 14

part of the heavy and light chains where the actual antigen binding surfaces are

Question 15

how is antibody diversity created?

Answer 15

antibodies are made by millions of b-cells

diversity comes from the variable regions

every b cell makes a single kind of antibody with a unique binding site

Question 16

how many antibodies do b cells make?

Answer 16

~100 billion

essentially infinate

Question 17

how many protein coding genes are in the human genome

Answer 17

20,000-25,000

Question 18

keys to antibody diversity

Answer 18

alternative splicing

more importantly, gene rearrangement

antibody genes are put together from separate DNA regions

Question 19

gene rearrangement

Answer 19

antibody genes are kits with alternative components

different kit for heavy and light chains

we inherit the pieces of each kit

Question 20

heavy chain kit chromosome

Answer 20

14

Question 21

light chain kit chromosomes

Answer 21

2, 22

Question 22

parts of heavy chain proteins

Answer 22

V, D, J, C

Question 23

parts of light chain proteins

Answer 23

V, J, C

Question 24

what does VDJC stand for heavy chain

Answer 24

V: varible ~120 alternative variable regions

D: diversity ~27 alternative diversity regions

J: joining ~9 alternative joining regions

C: constant 5 alternative types of constant region

Question 25

how many heavy chain genes do we have

Answer 25

~30,000

Question 26

what does VJC stand for light chain

Answer 26

V: varible ~100 alternative variable regions

J: joining ~5 alternative joining regions

C: constant 2 alternative types of constant region

Question 27

how many light chain genes do we have?

Answer 27

~ 500

Question 28

heavy chain + light chain combination number

Answer 28

about 15 million combinations

far from 100 billion so how?

DNA splicing

Question 29

sloppy splicing

Answer 29

VJ and VDJ splice-junctions are sloppy

bases are gained or lost b/c uses NHEJ

Question 30

inserted nucleotides

Answer 30

in sloppy splicing a few more bases are inserted at junctions

this increases diversity of coding in spliced segments

Question 31

sloppy splicing and inserted nucleotides make many…

Answer 31

frameshift mutations: make non-functional antibody genes

these b-cells just apoptose b/c nonfunctional

Question 32

can you pass antibody genes onto children?

Answer 32

no, they are not in germline cells

Question 33

new antibodies are expressed…

Answer 33

on the b-cell surface

Question 34

how many antibodies does each b cell make?

Answer 34

just one

only uses one allele (allelic exclusion)

Question 35

clonal deletion

Answer 35

young b cells die if they bind to an antigen

this is b/c whatever a young b cell binds to must be one of the body’s own molecules

clonal deletion prevents this young b cell from making an antibody that would attack the body

Question 36

each b cells waits….

Answer 36

for an antigen that will bind its unique surface antibody

could live for 20 years or longer just waiting

Question 37

b cells work with…

Answer 37

t cells

Question 38

what happens when a mature b cell has an antigen bind its antibody?

Answer 38

the antigen is engulfed and cut into pieces

the pieces are displaced on the b cell surface

this may lead to activation of the b cell by a helper T cell

the activated b cell differentiates into plasma cells, which further manufacture the antibody

Question 39

structure of a t cell receptor (TCR)

Answer 39

protein dimer has alpha and beta chain

each chain has a constant region and variable region

gene kits like antibodies

Question 40

constant region attaches TCR to the

Answer 40

membrane

Question 41

variable region of TCR

Answer 41

alpha-beta dimer forms single antigen binding site

Question 42

t cells are derived from

Answer 42

arise in bone marrow

mature in the thymus

Question 43

b cells are derived from

Answer 43

arise and mature in bone marrow

Question 44

do t cells undergo a stage of somatic hypermutation?

Answer 44

no

Question 45

are b cell receptors (antibodies) secreted in the blood and expressed on b cell membranes?

Answer 45

yes

Question 46

are TCRs expressed on t cell membranes and secreted in the blood?

Answer 46

no, only expressed on the membrane