Exam 2: Humoral response 2 Flashcards
Naive B lymphocytes express which two classes of membrane bound antibodies that function as teh receptors for antigens?
IgM and IgD
One activated B cell can generate up to how many plasma cells?
4000 plasma cells
One activated B cell can generate up to how many antibody molecules?
10^12 antibody molecules per day
High affinity antibodies are characterized by:
regions that match epitopes with the antigen
What is the flow of B cells in the lymph node?
efferent blood vessel, high endothelial venule, b cells then get trapped in t cell zone- paracortex, primary focus forms, germinal centers form in the cortex, B cells proliferate, leave node via efferent lymph vessel
What are the effector mechanisms of antibodies?
neutralization, opsonizaiton, complement activation
Neutralization
bacterial toxins bind to cell with receptors for toxin, antibodies neutralize the toxin and is ingested by macrophage
Opsonization
bacteria in extracellular space, antibodies bind to bacteria, macrophage Fc receptor binds to antibodies on bacteria, macrophage ingests and lysis the bacteria
What information is needed to make all proteins, including antigen receptors?
the genome
Mammals can express up to how many different antigen binding receptors on B and T cells?
10^15
How many genes do mammals use to create antigen binding receptors?
fewer than 500 genes
How many genes code for the variable region of antigen binding receptors?
several genes
How many genes code for the constant region of the antigen binding receptor?
one gene
Somatic hypermutation
increased mutation rate in the region in and around rearranged Ig genes, occurs in germinal centers
Gene conversion
Process in which portions of one gene are change to another
Gene recombination
offspring cells with combinations of traits different than traits of their parental cell DNA
What accounts for antigen binding receptors gene diversity?
gene recombination, somatic mutation, gene conversion
Process of Gene recombination will results in:
The deletion of unwanted genes by excising a loop that is destroyed and a wanted V and J gene segment
Steps in Gene recombination of the Ig light chain
Desired DNA segment undergoes rearrangment, transcription, RNA splicing and translation
Steps in Gene recombination of the Ig heavy chain
Desired Gene segment, DNA rearrangment 1, rearrangment 2, Transcription, RNA splicing, Translation
Somatic mutation involves teh replacement:
of one nucleotide change from C to T
Somatic mutations undergo selection and require:
enhanced antigen binding
