Lecture 7

Question 1

What are antigens and what are they?

Answer 1

Foreign agents; often biomolecules of a virus, bacteria, parasite, or cancer cell - result in the production of antibodies

Question 2

What is the bodys immune response

Answer 2

the body’s primary defense against foreign pathogens (infection) and cancer

Question 3

What are the two types of immune response

Answer 3

Innate and adaptive

Question 4

Compare innate vs adaptive immune responses

Answer 4

uses different system of biomolecules; includes humoral and cellular components

Question 5

What are B cells for in immune response

Answer 5

stimulated to proliferate and secrete the antibody, which binds the antigen, marking it for destruction by macrophages

Question 6

What do T lymphocytes do in immune response?

Answer 6

recognize and kill infected or cancerous cells

Question 7

What do B-lymphocytes do in humoral immune response

Answer 7

displays on its surface an antibody to a particular antigen.

Question 8

Describe the structure of antibodies and how they are bonded

Answer 8

a pair of heavy and a pair of light chains. Each heavy chain is covalently bonded to its light chain and the other heavy chain by disulfide bonds between pairs of cysteine side chains

Question 9

Amino acid sequences in constant vs. variable domains

Answer 9

These are identical in amino acid sequence in all class members; Amino acid sequence of variation in these domains is what lets different antibodies bind different targets

Question 10

Describe the tandem repeats of the immunoglobulin fold

Answer 10

Four Ig folds in each heavy chain, Two Ig folds in each light chain, Will have an identical folding pattern

Question 11

Describe the structure of an immunoglobulin fold

Answer 11

Composed of two antiparallel B sheets stacked face to face, with a minor amount of alpha helix

Question 12

Where do antigen binding sites occur?

Answer 12

at the variable regions on an antigen

Question 13

What do constant regions of the heavy chain do

Answer 13

interact with other effectors of the immune system

Question 14

What do Fab fragments do?

Answer 14

retain the specificity for binding to particular antigens

Question 15

What do Fc fragments do?

Answer 15

corresponds to the remainder of the constant region of the antibody, and does not bind antigen

Question 16

What does the antigen binding region contain?

Answer 16

This part of the structure contains the complementarity determining regions (CDRs) that determine antibody specificity

Question 17

True or false: CDRs are complementary in charge and shape to their antigen

Answer 17

true

Question 18

Are interaction surfaces between epitope of the antigen and antibody complementary?

Answer 18

Yes, with respect to shape, charge, and polarity

Question 19

What do complementary interactions between biomolecules do? (overall, broad)

Answer 19

Mediate interactions between cells, they are Foundations of multicellular life itself

Question 20

What is an epitope?

Answer 20

specific part of the antigen that binds to the antibody

Question 21

What is a polyclonal antibody mixture?

Answer 21

a population of antibodies that recognizes the same antigen, but different epitopes of it

Question 22

What can the binding of two epitopes by each antibody form?
What happens to this formation?

Answer 22

can form a crosslinked networks which precipitates as an aggregate. This aggregate becomes a target for phagocytosis by immune cells such as macrophages

Question 23

Describe what happens when a TCR binds to an MHC that is presenting a viral peptide

Answer 23

Binding of the TCR triggers a response in the T-cell that causes it to release proteins that disrupt the membrane of the virally-infected cell, Without host cells to propagate the virus, the viral infection is cleared from the host

Question 24

how do virally-infected cells flag themselves for destruction?

Answer 24

An infected cell will present peptides derived from virus proteins on its cell surface by means of its major histocompatibility complex (MHC) proteins

Question 25

What are Killer T-cells and do they have Ig folds?

Answer 25

cells that kill the virally-infected cells - have on their cell surface proteins that also use tandem repeats of the Ig fold (TCR - T-cell receptors)

Question 26

Why does HIV present a challenge as a viral disease (2)

Answer 26

HIV mutates at a high rate that changes the nature of its proteins that could as antigens, HIV targets a class of T-cells than typically enhances antibody production by B-cells

Question 27

Explain the six steps on how to prepare polyclonal antibodies

Answer 27

1. Inject host with antigen 2. Host begins to raise antibodies against the antigen 3. Repeat antigen injection several weeks later to boost antibody production 4. Withdraw some blood from host; centrifuge to obtain serum 5. Isolate antibodies from serum by affinity chromatography using the antigen linked to the column matrix 6. Keep the host alive so further polyclonal antibody can be obtained later

Question 28

What can antibodies against specific molecules of interest be used for? (overall what do antibodies do, broadly)

Answer 28

1. To quantify these molecules within biological samples 2. To detect their location 3. To detect protein-protein interactions within cells