Quiz 4 Part 1 Flashcards
name similarities that T cells have to B cells
express highly variable ANTIGEN SPECIFIC receptors
receptors are produced by gene rearrangements (like somatic recombination)
express only a single type of receptor on each cell
the receptor on the T cell resembles the fab fragments
which are more diverse — T cells or B cells?
T cells.
Do T cells and B cells differ in the antigens that they recognize?
yes!
T cells recognize small peptides while B cells recognize structural components
Is there a secreted form of a T cell?
no — only receptor
does somatic hypermutation and isotype switching happen in T cells?
no
thoroughly explain the structure of a T cell receptor
very similar to a fab fragment
there is a variable region, constant region, and a transmembrane region. There is a cytoplasmic tail that branches off from the transmembrane region and sticks into the cytoplasm
there is an alpha chain and a beta chain.
hypervariable loops that serve as the antigen binding site
the alpha chain of a T cell receptor is similar to the ____ chain of an antibody
the beta chain of a T cell receptor is similar to the ____ chain of an antibody (B cell receptor)
alpha chain = light chain. undergoes a SINGLE somatic recombination event (VJ recombination)
beta chain = heavy chain. Undergoes TWO somatic recombination events. (dj, then vdj
What enzyme carries out recombination in T cells?
same as B cell — RAG complex and DNA recombinases
Does junctional diversity also exist in T cells?
yes! (P and N nucleotides)
What is the name of the disease in which the person has NO RAG PROTEINS
SCID (severe combined immunodeficiency disease)
What is the name of the syndrome in which the person has PARTIAL RAG activity
Omenn syndrome
is somatic recombination happening on DNA or RNA
DNA
T cells undergo virtually the same somatic recombination as B cells. However, what is the difference
T cells have more distinct gene segments
Which have more diversity —– T cells or immunoglobulins?
T cells
Which has more variability for the “J” (joining) segments —– alpha chain or beta chain?
alpha chain has more variability for the joining segments
Can T cell receptors be expressed on the cell surface without help?
NO – it needs help
what “helpers” aid the T cell receptor in being expressed on the surface
the T cell receptor associates with 4 invariant membrane proteins
3 in CD3 complex, called CD3Y (gamma), CD3delta, and CD3 epsilon
the TCR complex is assembled from how many polypeptides?
break it down
8 polypeptides
alpha and beta chains (2)
2 CD3episolon (2)
1 CD3delta (1)
1 CD3gamma (1)
2 zeta chains (2)
what are the functions of:
a.) the alpha and beta chains
b.) CD3epsilon, CD3delta, CD3gamma, and the zeta chain
the alpha and beta chains bring about antigen recognition
the others bring about signal transduction
TCR’s can either have alpha and beta chains or __ and ___ chains
gamma and delta
which are made more:
alpha and beta chains
or
gamma and delta chains
alpha and beta
alpha matches with _____ and beta matches with ____
alpha —> gamma
beta —> delta
Can a t cell express alpha and delta?
NO
it’s either alpha and beta OR gamma and delta
cant be both
which is more diverse (has more gene segments)
alpha and beta or gamma and delta
alpha and beta are more diverse
