Bits and Bytes of Biology

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1)IMMUNOLOGY (ISOTYPE, ALLOTYPE AND IDIOTYPE) 
1. Ig idiotypes are found:

 A  In the constant region of the heavy chain.
 B  In the constant region of the light chain.
 C  In the hinge region.
 D  In the variable region of both heavy and light chains.

Ans. D  Idiotypes are the collection of epitopes on the variable region of an immunoglobulin which are recognized by a collection of antibodies directed against them (the so-called anti-idiotypic serum).

2.A given Ig isotype is:

 A  A heavy chain variant encoded by allelic genes.
 B  A light chain constant region encoded by allelic genes.
 C  Present in all normal individuals.
 D  A collection of hypervariable region epitopes recognized by an anti-idiotype.

Ans. C Isotypes are the immunoglobulin classes and subclasses expressed in all normal individuals.

2)IMMUNOLOGY (TYPE-1 HYPERSENSITIVITY REACTION)
1.Mast cells have receptor for (June 2006) 

a) IgE 
b) IgA 
c) IgG 
d) IgM

Ans.a
2. A polymorphonuclear neutrophil (PMN):

 A  Is a bone marrow stem cell.
 B  Is closely similar to a mast cell.
 C  Contains microbicidal cytoplasmic granules.
 D Has granules which stain with eosin.

Ans. C The granules contain a wide spectrum of microbicidal agents.

3. Eosinophils do not:

 A  Stain with basic dyes.
B  Contain a major basic protein.
 C  Contain peroxidase.
 D  Give a respiratory burst on activation.

Ans. A They do stain with acidic dyes.

4.  Acute inflammation can be initiated by:

 A  Mast cell activation.
 B  Influx of neutrophils.

 C  An increase in vascular permeability.
 D.  Lysozyme.

Ans. A  Activation of mast cells releases chemotactic factors for neutrophils and also vasoactive mediators such as histamine.

5. An immune response against grass pollen often involves:

 A  Pathogen-associated molecular patterns
 B  Breakdown of self tolerance
 C  A hypersensitivity reaction
 D  Reaction against MHC

Ans. C  Hypersensitivty to otherwise innocuous antigens can lead to tissue damage.

6. IgM:

 A  Is usually of high affinity.
 B  Is most commonly tetrameric.
 C  Is a weak bacterial agglutinator.
 D  Is the main class of the 'natural antibodies'.

Ans. D The natural antibodies which include many anti-bacterial antibodies, arise largely without external antigenic stimulation. In the mouse they are made by the CD5+ B1 subset.

7. IgE:

 A  Is abundant in saliva.
 B  Binds strongly to mast cells.
C  Cannot bind to macrophages.
D  Activates the complement cascade.

Ans. B The Fc epsilon receptor on mast cells, Fc epsilon RI, binds IgE very strongly and cross-linking by antigen leads to mast cell activation and initiation of an inflammatory reaction.

3)IMMUNOLOGY(VIDEO-3)

4)IMMUNOLOGY (VIDEO-4)

5)IMMUNOLOGY(VIDEO-5)

6)IMMUNOLOGY(VIDEO-6)

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