Question

Explain the structure of antibodies, mention different types and one property of each... (15 marks)...

NEED VERY URGENTLY...NO SPAMMING ALLOWED...​

Answer 1

Answer:

Antibodies are immune system-related proteins called immunoglobulins. Each antibody consists of four polypeptides– two heavy chains and two light chains joined to form a "Y" shaped molecule. The amino acid sequence in the tips of the "Y" varies greatly among different antibodies.

An antibody has a Y-shaped structure, made up of four polypeptide subunits.  The N-terminus of each heavy chain forms an antigen-binding domain with a light chain. There are two antigen-binding domains forming the arms of the “Y” shape.

Explanation:

Answer 2

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What are Antibodies ?

Antibody (Ab) is also known as an immunoglobulin(Ig). These are large, Y-shaped blood proteins produced by plasma cells. They bind to foreign particles and invade them. These particles are foreign bodies that get attacked by Antibody.

Antigens are foreign pathogens that invade the body and have the capability to give rise to a response from our immunity system either by grouping up with a larger molecule or alone after binding with antibodies for a particular immune response. Hence, antigens stimulate the production of antibodies by the immune system.

Types Of Antibodies

Antibodies or immunoglobulins(Ig) are of five different isotypes. This classification is on the basis of their H chains. The different types of antibodies are:

IgM

IgM is the first antibody produced in response to a microbial attack by B cells.

It is the largest antibody and is found in a pentameric form.

IgG

Most abundant isotype in the plasma, and comprises 80% of the total antibody content in the serum. It detoxifies substances that are harmful and recognizes the antibody-antigen complex.

It is transferred to the placenta through the foetus and protects the infant until its birth.

IgA

Usually found in liquids such as breast milk, serum, saliva, fluids of the intestine. IgA in breast milk protects an infant’s gastrointestinal tract from microbial activity.

It constitutes 13% of the total antibody content in the serum and is divided into 2 sub-classes- IgA1 and IgA2. Among these, IgA1 is highly found in the secretions and is also called the secretory immunoglobulin.

IgD

It is involved in the production of the antibody by B cells.

It is present as a monomer and weighs around 1,80,000 dalton.

IgE

IgE is present in the least amounts, around 0.02% of the antibody content in the serum.

These are present in the linings of the respiratory and intestinal tracts and respond to allergic reactions.