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FD1 > Adaptive Immunity I > Flashcards

Adaptive Immunity I Flashcards

1
Q

Describe the purpose of the innate immune system

A
  • first line of defence- fast, nonspecific
  • humoral and cell mediated
  • activated within mins
  • buying time for adaptive immune system to kick it
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2
Q

What do Primitive T cells do?

A
  • recognise antigens similarly to the innate immune system
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3
Q

Describe the role of the adaptive immune system

A
  • humoral and cell mediated (using B an T cells)
  • slower to develop (5-6 days)
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4
Q

Which recognition molecules does the innate immune response use?

A
  • germ line encoded pattern recognition receptors
  • these bind to pathogen - and damage-associated molecular patters- generic molecules found on many different types of pathogen (e.g. LPS) or released in response to stess/ tissue damage
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5
Q

Which recognition receptors does the adaptive immune system use?

A
  • randomly generated B and T cell receptors
  • highly specific to individual antigen molecules, rather than generic molecules found on many pathogens
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6
Q

What cell produces antibodies?

A
  • B cells
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7
Q

How can antibodies provide passive immunity?

A
  • transferred between individuals
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8
Q

What is the difference between humoral immunity and cell-mediated immunity?

A
  • humoral - antibodies
  • cell mediated - involved primarily T cells
    • these eradicate pathogens, clear infected self-cells, or aif other cells in inducing immunity
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9
Q

Fill in the gaps and describe the process

A
  • only naive cells should be released into circulation
  • continually circulate through body
  • go into secondary lymphoid organs looking for their specific antigen
  • if it encounters its antigen - clonally proliferates so more effective
  • these cells will eliminate pathogen
  • effector cells die
  • left with memory cells
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10
Q

How do the innate and adaptive immune systems work together?

A
  • dendritic cell key - initiates adaptive IS
  • need the innate immune cells to sense the danger and to become APCs
  • helper cells then produce cytokines that can help B cells and NK to form a better antibody response
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11
Q

What is happening here?

A
  • primary response initiated upon first exposure to antigen
  • memory lymphocytes left behind
  • a second exposure to same antigen - stimulates memory cells
  • reactivation yields a faster/ more effective reponse
  • memory NOT present in innate immunity
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12
Q

Why are memory cells more effective?

A
  • more of them
  • more easily activated
  • more effective
  • reside in/ home back into the tissue where first infection occured
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13
Q

What forms may an antigen be in?

A
  • protein, lipid, carb, nucleic acid or any combo of these
  • foreign or altered self molecules
  • soluble or particulate
  • simple or complex
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14
Q

What is an antigen?

A
  • a processed peptide derived from a foreign or alter self protein and presented by MHC I or II molecules
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15
Q

What do CD8/ CD4 T cells recognise peptides presented by?

A
  • CD8 - MHC I
  • CD4 - MHC II
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16
Q

What is the antigen receptor on B cells?

A
  • membrane-bound form of IG secreted upon stimulation
17
Q

Membrane bound IG =

Secreted IG =

A
  • BCR
  • antibody
18
Q

Describe the structure of an antibody

A
  • 2 heavy chains
  • 2 light chains
  • held together by intra/interchain disulfide covalent bonds
19
Q

Label this

A
20
Q

What is the function pf CH1 and CL domains?

A
  • extend arms of the antibody away from hinge region
21
Q

What is the function of the VH and VL domains?

A
  • variable regions are made of Ig folds
  • contain 3 hypervariable loops called CDRs
  • produce ability of Ab to bind to its specific antigen
  • each Ab can bind to 2 antigens
22
Q

What is the function of the carboxyl-terminal domains?

A
  • confers the effector activity of the Ab
  • membrane-bound Ab has a hydrophobic tansmembrane segment and very short cytoplasmic tail
  • secreted Ab is formed by alternative RNA splicing mechanisms that remove/ replace these regions
23
Q

What is the process of signal transduction in B cells?

A
  • BcR has v little cytoplasmic domain and cannot signal
  • but complexes with 2 Igalpha and 2 Igbeta chains (CD79a + CD79b)
  • Igalpha and Igbeta have signaling motifs in their cytoplasmic chains
  • phosphorylation of the ITAMs triggers signaling cascades
  • CD19 acts as a co-receptor further initiating the signaling pathways
24
Q

What are TCRs?

A
  • T cell receptors
  • not Ig
  • belong to the Ig superfamily
  • possess V and C domains
  • CDRs (complementary determining regions) are found on the variable regions of each chain- bind to MHC
  • heterodimers (alpha and beta chain)
25
Q

How do T cells signal?

A
  • TCR cannot signal
  • transduction is initiated through ITAMs expressed by chains of the CD3 complex
  • T cell co-receptors CD4 and CD8 also bind to MHC to aid signal transduction
  • CD28 involved
26
Q

How can a limited amount of DNA genetic info produce an extensive variety of antibodies?

A
  • B cells use groups of PARTS of genes to create different possible antibodies using recombination
27
Q

Name the different gene segments used.

A
  • Variable
  • diversity
  • joining
  • constant
28
Q

Which segment is used in antibody heavy chains only?

A
  • D
29
Q

What are the 2 types of light chains?

A
  • kappa
  • lambda
30
Q

What happens if you change the heavy constant gene segment?

A
  • change tail of antibody
  • change the functional properties
  • greater diversity of constant gene segment
31
Q

Describe the mechanism of V(D)J recombination

A
  • recombination is directed by signal sequences (RSSs) flanking each antibody gene segment
  • gene segments joinedby the recombo activating gene recombinases RAG1/2
  • RAG1 forms a complex with RSSs stabilized by binding RAG2
  • +other proteins required
  • V(D)J proteins results in functional Ig variable region gene
  • RAG proteins bind and cleave the DNA
  • other proteins process tha hairpin loops that form after RAG has done its job
  • products include a recombines coding joint and a leftover signal joint that is later degraded
32
Q

What are the 4 mechanisms that generate antibody diversity in naive B cells?

A
  1. Multiple gene segments
  2. nucleotides can be inserted between joints
  3. exonuclease trimming
  4. combinatorial diversity (which heavy chains pair with light chains)
33
Q

What are the 2 receptors that thymocytes can express?

A
34
Q

Which thymocyte receptor is more common in fetal development and how does this change?

A
  • TCRygamma are more common
  • but decrease after birth in mice
  • (retained as a major pop in ruminants, pigs and chickens)
35
Q
A
36
Q
A

FD1 (31 decks)

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