Antibodies Immunoglobulins Short And Long Essays Question And Answers

Antibodies-Immunoglobulins Long Essays

Question 1. Define and classify antibodies and add a note on the structure and function of IgG.
Answer:

Antibodies  Definition:

• Antibodies are substances which are formed in the serum and tissue fluids in response to an antigen and react with that antigen specifically and in some observable manner.

Antibodies  Classification:

• Antibodies are named as immunoglobulins.
• There are five groups of immunoglobulins (Ig]

IgG:

IgG Structure:

• IgG consists of
  • Two identical heavy chains (H) chains
    • They are gamma chains.
    • Held together by disulphide bonds (S-S)
    • They are longer chains.
    • Consists of a smaller variable (V) region and a longer constant (C] region.
  • Two identical light (L) chains.
    • Present in two forms. Kappa (K) and Lambada (L)
    • Attached to heavy chains by disulphide bonds.
    • They are shorter chains.
    • The init variable and constant region are equal.
    • Variable regions are present at the amino terminus
    • The amino acid sequence here is highly variable.
    • Constant region is present at the carboxy terminus.

IgG Functions:

• Can be transported through the placenta
• Thus, provide natural passive immunity to the newborn.
• Participates in precipitation, complement fixation and neutralisation of toxins and viruses.
• Protects against active micro-organisms present in the blood and tissues.

Antibodies Immunoglobulins Short Essays

Question 1. Immunoglobulin

Answer:

Immunoglobulin

• Immunoglobulin is defined as a protein of animal origin endowed with known antibody activity.

Immunoglobulin Synthesis:

• They are synthesized by plasma cells and by lymphocytes.

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Immunoglobulin Structures:

• Immunoglobulin consists of
  • Two heavy chains
  • Two light chains.

• The variable region is present at the amino terminus while the constant region is present at the carboxy terminus.
• Based on the heavy chains. Immunoglobulins are classified into 5 classes.
• Light chains in all the classes are Kappa (K) and lambda (L)

Question 2. IgA/Secretory Immunoglobulin.
Answer:

IgA

IgA is the second major serum immunoglobulin

• It is the fast-moving alpha-globulin.

Serum Concentration:

• Normal serum concentration – 0.6 – 4.2 mg/ml.
• It is about 10 – 13% of total serum immunoglobulin.
• Half-life: 6 – 8 days

IgA  Forms:

• IgA is present in two forms.
  • Serum IgA
  • Secretory IgA

IgA  Structure:

• IgA is a dinner consisting of two monomer units.
• It consists of
  • Two alpha-heavy chains
    • Joined by disulphide bonds.
  • Two kappa (K) or lambda (L) light chains.
    • Attached to heavy chains by disulphide bonds
  • I Chains
    • It is glycoprotein
    • It joins the two monomer units of IgA
  • S (secretory) piece.
    • It is glycine -rich polypeptide.
    • It is produced by mucosal or glandular epithelial cells.
    • It protects IgA from denaturation by bacterial proteases.

IgA  Synthesis:

• Locally from plasma cells.
• In trace amount from serum.

IgA  Functions:

• IgA, is present in secretions such as milk, saliva, tears, sweat, nasal fluids, colostrums and in secretions of respiratory, intestinal and genital systems.
• Hence called secretory immunoglobulin.
• Protects mucous membranes against micro-organisms.

Antibodies Immunoglobulins Short Question And Answers

Question 1. Functions of antibodies.
Answer:

Functions of antibodies

Question 2. Structure of IgM
Answer:

IgM Structure:

• IgM is a pentamer consisting of 5 immunoglobulin subunits and one molecule of J chain.
• J chain joins the Fc region of basic subunits.
• Each subunits consists of
  • Two identical mu heavy (H) chains and
  • Two identical Kappa (K) or Lambda (L) light chains.
• These chains are held together by disulphide bonds.
• Both chains have a variable (V) region and a constant (C) region.