Antibody, Lymphocytes & Generation of Diversity (#1) Flashcards
Give an adv + disadv of adaptive immunity
- adv: not as fast
- disadv: more specific with memory
What is the limitation of innate immunity?
pathogens can still enter, divide + mutate
What would happen if you didn’t have adaptive immunity?
we die
What are the cells of the adaptive immune system?
- B cell
- T cell
Describe the T cell receptor
- heterodimer of alpha + beta chain
- 1 binding site for antigen
- unique to each cell
Describe the B cell receptor
- an antibody
- 2 identical heavy chains
- 2 identical light chains
- 2 sites for antigen
How does the adaptive system roughly work?
- depends on cells that are indiv + recognise their own unique antigenic shapes
- also on diversity of lymphocyte receptors that can match antigenic shapes body might be threatened by
What is adv of constant migration of lymphocytes with diverse receptors through blood + lymphoid tissues?
inc probab that they will encounter specific antigens
How are pathogens entering the system recognised?
- recognised by lymphocytes with complementary shape
- these cells div + eventually antigen overpowered so cells with complementary receptor inc + become memory cells - more abundant + can respond rapidly
What happens when the immune system encounters the same antigen it has before?
- freq of receptors specific to antigen inc + so antigen overpowered more quickly
Summarise how memory works for B + T cells
- higher freq of specific cells
- respond more rapidly + efficiency
What system is memory only specific to?
adaptive
Compare the timing of responses between innate + adaptive system
- innate: mins to hrs
- adaptive: 1st exposure (primary response) - 12 days
booster (secondary response) - 5-7 days
What are the 2 main parts of the lymphocyte receptor and their location?
- variable region: tip of receptor
- constant: rest of receptor
What is the issue of having receptors dependant on being encoded in our DNA?
- total no. of human genes in genome approx 25k
- but microbe diversity exceeds millions + can mutate + adapt
- so wouldn’t have enough variability to match microbes
What process generates unique lymphocyte receptor specificity + diversity?
Gene rearrangement
What 3 segments is the variable region of the heavy chain composed of?
- Variable
- Diversity
- Joining
Where is the antibody heavy chain found?
on chr 14 of every cell in the body
What are the number of options that human DNA encodes approx for V, D + J segments?
- V: 48 different options
- D: 23 diff options
- J: 6 diff options
How do the diff options for the V, D + J segment differ?-
- differ in seq but all have same functions
How many diff combos of V, D + J segments are there for immunoglob heavy chain variable region?
776
How exactly are the V, D + J segments selected?
- D + J segments taken at random from options available
- rearranged V segment joins D + J
- intervening DNA removed as a loop
What segments are the variable regions of antibody light chain made up of?
- variable
- joining
How many diff combos of V + J segments are there for immunoglob light chain variable region?
340
