Lecture 30

Question 1

what part of the omicron spike protein is mutated to evade the immune system?

Answer 1

N-terminal domain and receptor-binding domain

Question 2

hematopoietic tree

Answer 2

starting in BM, immune cells derive from hematopoeitic stem cell

then split into common lymphoid progenitor (adaptive) or common myeloid progenitor (innate)

Question 3

humoral vs cellular immunity

Answer 3

humoral = B cells producing Ab
cellular = T cells bind Ag

Question 4

development of humoral immunity

Answer 4

1. lymphocytes originate from stem cells in BM
2. B cells mature in BM
3. B cells encounter Ag and mature into plasma cells that make Ab

Question 5

development of cellular immunity

Answer 5

1. lymphocytes originate from stem cells in BM
2. T cells mature in thymus and enter circulation
3. T cells use TCR to fight infection

Question 6

clonal selection of B cell

Answer 6

B cell binds its antigen to cause B cell division

Question 7

clonal expansion of selected B cell

Answer 7

B cell division = proliferation –> primary immune response

creates 1st wave: Ab-secreting plasma cells and memory cells that stay in circulation

2nd wave: if antigen encountered again

Question 8

3 types of active agents of a vaccine

Answer 8

1. inactivated
2. attenuated
3. purified components of pathogen

Question 9

what does a successful vaccine rely on? why?

Answer 9

memory!

vaccine induces the primary immune response and generates memory cells that are active when the infection occurs

Question 10

why are next generation vaccines better?

Answer 10

ex. RNA vaccine –> uses host cells to produce antigen which is much faster

Question 11

how many types of light chains are there? what are they?

Answer 11

2: kappa and lambda

Question 12

gene segments of light chains

Answer 12

V, J, and C

Question 13

2 possible light chains

Answer 13

kappa/kappa OR lambda/lambda

Question 14

how many types of heavy chains are there? what are they?

Answer 14

5: alpha, delta, gamma, epsilon, or mu

Question 15

gene segments of heavy chains

Answer 15

V, D, J, and C

Question 16

how many Ab can be produced with different specificities?

Answer 16

10^11

Question 17

3 ways of generating Ab diversity?

Answer 17

1. somatic recombination
2. junctional diversity
3. somatic hypermutation

Question 18

describe somatic recombination of light chain (DNA –> pre-mRNA –> mature mRNA)

Answer 18

1. RAG1/2 cuts at 3’ end of a variable region and 5’ end of a joining region to join random V and J segments (at level of DNA)
2. transcription begins at the selected V region to make pre-mRNA with joint V and J and other J regions
3. pre-mRNA is spliced to remove remaining J regions and mature mRNA with only 1 V, J, and C region is transplated

Question 19

does a B cell always make the same Ab? why?

Answer 19

yes

because somatic recombination occurs at the DNA level

Question 20

how much of Ab diversity is due to somatic recombination?

Answer 20

4.5x10^6

Question 21

which Ab segment does NOT contribute to Ab specificity?

Answer 21

constant region

Question 22

what is junctional diversity?

Answer 22

a few random nucleotides are lost or gained (may lead to frameshift that produces nonfunctional gene)

Question 23

what is somatic hypermutation?

Answer 23

immunoglobulin genes have high mutation rate

Question 24

example of point mutation created in somatic hypermutation

Answer 24

cytosine deaminated to uracil –> DNA repair mechanisms replace the uracil with another base to make a point mutation

Question 25

2 chains of TCR?

Answer 25

1. alpha
2. beta

Question 26

what gene segments are in the alpha chain?

Answer 26

V, J, C

Question 27

what gene segments are in the beta chain?

Answer 27

V, J, D, C

Question 28

what are the mechanisms for generating TCR diversity?

Answer 28

somatic recombination and junction diversity