Final: Immune System Part 1 Flashcards Preview

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Flashcards in Final: Immune System Part 1 Deck (46)
1

the immune consists cells that occur mainly within....

the circulatory system

collectively called white blood cells

2

innate immunity

cells part of a rapid response

3

adaptive immunity

cells part of a slow response

4

where are WBC formed?

in bone barrow

5

lymphocytes

B cells and T cells

brains of adaptive immunity

6

antigen

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

7

antibody

proteins that can bind two identical antigens

mark antigens for destruction

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

8

problem targeting antigens

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

9

what happens when an antibody binds an antigen

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

10

basic structure of an antibody

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

11

variable regions

parts of the antibody that contact the antigen

different shapes like a pocket or groove

12

constant regions

parts below the variable regions

13

how is an antibody held together

disulfide bridges

14

hypervariable regions

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

15

how is antibody diversity created?

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

16

how many antibodies do b cells make?

~100 billion

essentially infinate

17

how many protein coding genes are in the human genome

20,000-25,000

18

keys to antibody diversity

alternative splicing

more importantly, gene rearrangement

antibody genes are put together from separate DNA regions

19

gene rearrangement

antibody genes are kits with alternative components

different kit for heavy and light chains

we inherit the pieces of each kit

20

heavy chain kit chromosome

14

21

light chain kit chromosomes

2, 22

22

parts of heavy chain proteins

V, D, J, C

23

parts of light chain proteins

V, J, C

24

what does VDJC stand for heavy chain

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

25

how many heavy chain genes do we have

~30,000

26

what does VJC stand for light chain

V: varible ~100 alternative variable regions

J: joining ~5 alternative joining regions

C: constant 2 alternative types of constant region

27

how many light chain genes do we have?

~ 500

28

heavy chain + light chain combination number

about 15 million combinations

far from 100 billion so how?

DNA splicing

29

sloppy splicing

VJ and VDJ splice-junctions are sloppy

bases are gained or lost b/c uses NHEJ

30

inserted nucleotides

in sloppy splicing a few more bases are inserted at junctions

this increases diversity of coding in spliced segments

31

sloppy splicing and inserted nucleotides make many...

frameshift mutations: make non-functional antibody genes

these b-cells just apoptose b/c nonfunctional

32

can you pass antibody genes onto children?

no, they are not in germline cells

33

new antibodies are expressed...

on the b-cell surface

34

how many antibodies does each b cell make?

just one

only uses one allele (allelic exclusion)

35

clonal deletion

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

36

each b cells waits....

for an antigen that will bind its unique surface antibody

could live for 20 years or longer just waiting

37

b cells work with...

t cells

38

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

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

39

structure of a t cell receptor (TCR)

protein dimer has alpha and beta chain

each chain has a constant region and variable region

gene kits like antibodies

40

constant region attaches TCR to the

membrane

41

variable region of TCR

alpha-beta dimer forms single antigen binding site

42

t cells are derived from

arise in bone marrow

mature in the thymus

43

b cells are derived from

arise and mature in bone marrow

44

do t cells undergo a stage of somatic hypermutation?

no

45

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

yes

46

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

no, only expressed on the membrane