Quiz on Immunoglobulin Structure and Function

Immunoglobulins or antibodies are blood proteins, which are found to be defensive only against the specific microorganisms, or their toxins that evoked that particular antibody. Immunoglobulins are glycoproteins, made up of 4 polypeptide chains (linked by disulphide bonds). There are two long chains, called heavy or H chains, and two short chains, called light or L chains. The four polypeptide chains are held together to form Y shaped molecule. The top two tips of this  shaped molecule bind to the specific antigens in a lock and key fashion, forming an antigen antibody complex. In humans there are five chemically and physically distinct classes of antibodies (IgG, IgA, IgM, IgD, IgE). Read more>>

1. The most effective Ig is
IgM
IgA
IgE
IgG
2. Cleavage of an IgG molecule by the protease, papain, produces:
an antigen-binding site and two constant regions
two Fab fragments and one Fc fragment
two heavy chain-light chain dimers.
an antibody without its N-linked oligosaccharide
3. The Ig that mediates allergic reaction is
IgM
IgG
IgE
IgA
4. Antibodies of the IgG class
consist of four subunits
are glycoproteins
have inter- and intra-chain disulfide crosslinks.
all of the above
5. The Ig involved in host defence against parasitic infection (helminths)
IgM
IgG
IgE
IgA
6. The immunoglobulin fold is
a b-barrel composed of a three- and a four-stranded antiparallel b-sheet.
found only in IgG molecules.
composed of two antiparallel b-strands folded into a globular domain.
found six times in the IgG molecule.
7. IgM is a
pentamer with 10 antigen binding sites
monomer with 2 antigen binding sites
dimer with 4 antigen binding sites
tetramer with 8 antigen binding sites
8. Antibodies in the human immune system can identify approximately 108 different molecules. Which one of the following is true?
Most of these antibodies recognize proteins.
This diversity is generated from 108 different immunoglobin genes.
Most of these antibodies recognize small organic molecules.
There are really just a small number of antibodies, each of which can bind to many different antigens.
9. Antigenic determinants bind to which portions of an antibody?
constant regions
variable regions
only heavy chains
the effector region
10. Monoclonal antibodies produced in the laboratory
lack the constant regions of IgG.
derive from human cancer patients.
can be selected to bind to almost any known molecule.
cannot be used for disease diagnosis yet.
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Correct answers: