CMB2004 Exam Questions And Answers
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What are the 4 sources of infection? - answerBacteria, viruses, fungi, parasites
What does the immune system need to be able to do for an effective immune response? -
answer1- Be able to recognise and respond to any invading organism
2- Not ove...
What are the 4 sources of infection? - answer✔✔Bacteria, viruses, fungi, parasites
What does the immune system need to be able to do for an effective immune response? -
answer✔✔1- Be able to recognise and respond to any invading organism
2- Not over react to benign or self
3- Be able to direct different effector mechanisms against different pathogens
approximately how many bacteria are their and how many are named? - answer✔✔10^9 bacteria
and 30000 named
What is specific/adaptive immunity? - answer✔✔It is induced by exposure to a particular
infection, it shows a high degree of specificity and exhibits memory
How is specific immunity mediated? - answer✔✔BY B/T lymphocytes with clonally distributed
receptors, this is a large repertoire but low frequency of cells for one specific antigen
Is specific immunity slow or fast to develop? - answer✔✔Slow but quicker the second time
What is clonal selection theory? - answer✔✔The clonal selection theory is that one individual
cell is selected, by virtue of its ability to recognize an antigen, to make billions of clones of itself
to help the body rid itself of one particular pathogen. When B-cells undergo clonal selection,
most clones becomes plasma cells which will produce massive amounts of antibody against the
particular antigen invading the body, after the pathogens have been removed from the body, the
plasma cells will undergo apoptosis and die.
What happens when a B cell is activated? - answer✔✔After something has bound the the antigen
binding site, the membrane form of immunoglobulin is released and is known as an antibody
What do T cells recognise? - answer✔✔Only A short peptide fragment
What is the difference between TCR and BCR? - answer✔✔TCR is never secreted and it needs
the peptide fragments to be presented to it.
What do antibodies do? - answer✔✔Infection with encapsulated bacteria
Activation of complement by oponisation or classical and MAC pathways
What is the structure of antibodies? - answer✔✔Basic 4 chain structure
2 identical heavy and light chains held together by covalent and non covalent bonds
2 types of light chain A and K
Each chain has a variable and constant region
Antigen binding sites have a VH and VL regions
Different CH regions interact with complement and the Fc region binds to different FcRs
expressed by the effector cells.
What is responsible for the AB structure in antibodies? - answer✔✔The constant regions are
responsible for both AB structure and interacting with other molecules and cells of the innate
system
What are the 5 classes of Antibodies? - answer✔✔IgM D A G and E
What determines the isotype of an antibody? - answer✔✔Isotypes are determined by the heavy
chain
How does Antigen interaction work? - answer✔✔Through the variable region which is specific
for each given Ab with concentrated regions of variability. There is hypervariable regions and 6
hypervariable loops which lead to the antigen binding site. Both heavy and light chains
contribute. The Ag binds to an aa in CDRs.
What is an antigen epitope? - answer✔✔the part of an antigen that is recognised by the immune
system, if continuous it means it binds on a continuous part of the structure, they can also be non
linear and not be connected.
How does antigen recognition work? - answer✔✔Epitopes recognised by antivodies can be
continuous or conformational.
Ag can be almost any molecule
Antibody and Ag form non covalent interactions
Ag sequence may be manipulated in vaccine designs
Ag may be folded
DRs present in antibody V regions determine the specificity and the affinity of an antibody for
Ag
What does A T cell receptor do? - answer✔✔It doesn't bind to free antigen, binds to processed
antigen, presented in the cleft of MHC class I or class II molecules. It is never secreted
TCR structure - answer✔✔Heterodimer (TCR alpha and TCR beta) joined by a disulfide bond.
Each chain has a constant and a variable region. V domains interact with antigen.
What are the classes of MHC molecules and where are they expressed? - answer✔✔Class1-
Expressed by nearly all cell types
Class 2- Expression restricted to a specialised group of immune cells
What is the differences between MHC class 1 and 2. - answer✔✔Different structures, Class 1
has 3 alpha 1 beta class 2 has 2 of each.
Different expression patterns
Present peptides from different sources
Essential in transplant rejection
What are the three different MHC class 1 molecules? - answer✔✔HLA-1A HLA-B AND HLA-
C
How is MHC class 1 structures formed? - answer✔✔A 1 and A2 domains fold to form B sheet
known as peptide binding site.
DNA encoding a1 and a2 domains is very polymorphic
a3 domain fold into Ig like domains
How is MHC class 2 structures formed? - answer✔✔Expression limited to APC.
Heterodimers and the alpha and beta domains are a similar size
3 different molecules. More open than groove
What genes encode a single polypeptide chain? - answer✔✔H chain and TCRb, V region is
encodes by three gene segments V D and J with V as the biggest
L chain and TCRa, v region encoded by two gene segments V and J
Where are Ig genes found? - answer✔✔In the genome as families of gene segments
What happens in B cells regarding the Ig gene? - answer✔✔During development in the bone
marrow the DNA containing the Ig gene segments is deliberately broken and the gene segments
are rearranged. Each B cell performs the breakage and rearrangement randomly.
What joins after B cell DNA is broken produce a functional Ig gene? - answer✔✔A single V and
Single J gene segment are joined together to encode the V region of the light chain. A single
random V D and J gene segment are joined to encode the V region of the Heavy Chain. Leads to
a random heavy and light chain region
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