-What are antibody molecules? -What is their structure? - What is the difference

Question

-What are antibody molecules? -What is their structure? - What is the difference between IgG, IgA, IgM, IgD, and IgE? - What are the Fab and Fc fragments? -Where does antigen binding occur? -What are some of the functions of antibodies? -How do they clear antigens? -What is a neutralizing antibody?
Need help with all parts confused . Thanks -What are antibody molecules? -What is their structure? - What is the difference between IgG, IgA, IgM, IgD, and IgE? - What are the Fab and Fc fragments? -Where does antigen binding occur? -What are some of the functions of antibodies? -How do they clear antigens? -What is a neutralizing antibody?
Need help with all parts confused . Thanks -What is their structure? - What is the difference between IgG, IgA, IgM, IgD, and IgE? - What are the Fab and Fc fragments? -Where does antigen binding occur? -What are some of the functions of antibodies? -How do they clear antigens? -What is a neutralizing antibody?
Need help with all parts confused . Thanks

Explanation / Answer

1. What are antibody molecules?

An antibody (Ab) is as an immunoglobulin (Ig) is a large, Y-shaped protein produced mainly by plasma cells. it is used by the immune system to neutralize pathogens such as pathogenic bacteria and viruses.

2. What is their structure?

Antibodies are heavy (~150 kDa) globular plasma proteins. They have sugar chains (glycans) added to conserved amino acid residues. The attached glycans are critically important to the structure and function of the antibody. Among other things the expressed glycans can modulate an antibody's affinity for its corresponding FcR(s). The basic functional unit of each antibody is an immunoglobulin (Ig) monomer (containing only one Ig unit); secreted antibodies can also be dimeric with two Ig units as with IgA, tetrameric with four Ig units like teleost fish IgM, or pentameric with five Ig units, like mammalian IgM.

Although different immunoglobulins can differ structurally, they all are built from the same basic units.

A. Heavy and Light Chains

All immunoglobulins have a four chain structure as their basic unit. They are composed of two identical light chains (23kD) and two identical heavy chains (50-70kD)

B. Disulfide bonds

1. Inter-chain disulfide bonds - The heavy and light chains and the two heavy chains are held together by inter-chain disulfide bonds and by non-covalent interactions The number of inter-chain disulfide bonds varies among different immunoglobulin molecules.

2. Intra-chain disulfide binds - Within each of the polypeptide chains there are also intra-chain disulfide bonds.

C. Variable (V) and Constant (C) Regions- When the amino acid sequences of many different heavy chains and light chains were compared, it became clear that both the heavy and light chain could be divided into two regions based on variability in the amino acid sequences. These are the:

1. Light Chain - VL (110 amino acids) and CL (110 amino acids)

2. Heavy Chain - VH (110 amino acids) and CH (330-440 amino acids)

D. Hinge Region: This is the region at which the arms of the antibody molecule forms a Y. It is called the hinge region because there is some flexibility in the molecule at this point.

3. What are the Fab and Fc fragments?

Fab (fragment): The arms of the Y contain the sites that can bind to antigens and recognize specific foreign objects. This region of the antibody is called the Fab (fragment, antigen-binding) region. It is composed of one constant and one variable domain from each heavy and light chain of the antibody. The paratope is shaped at the amino terminal end of the antibody monomer by the variable domains from the heavy and light chains.

Fc fragments: The base of the Y plays a role in modulating immune cell activity. This region is called the Fc (Fragment, crystallizable) region. it is composed of two heavy chains that contribute two or three constant domains depending on the class of the antibody. the Fc region ensures that each antibody generates an appropriate immune response for a given antigen, by binding to a specific class of Fc receptors, and other immune molecules, such as complement proteins. it mediates different physiological effects including recognition of opsonized particles (binding to FcR), lysis of cells (binding to complement), and degranulation of mast cells, basophils, and eosinophils (binding to FcR).

4.  What is the difference between IgG, IgA, IgM, IgD, and IgE?

5. Where does antigen binding occur?

A. antigen binding site is paratope.

6.  What are some of the functions of antibodies? -How do they clear antigens?

7. What is a neutralizing antibody?

A. Neutralizing antibody (NAb) is an antibody that defends a cell from an antigen or infectious body by neutralizing any effect it has biologically.

example of neutralizing antibody: diphtheria antitoxin, which can neutralize the biological effects of diphtheria toxin.

Class Subclass difference IgD 1 Functions mainly as an antigen receptor on B cells that have not been exposed to antigens. It activates basophils and mast cells to produce antimicrobial factors IgE 1 binds to allergens and triggers histamine release from mast cells and basophils, and is involved in allergy. Also protects against parasitic worms. IgM 1 Expressed on the surface of B cells (monomer) and in a secreted form (pentamer) with very high avidity. Eliminates pathogens in the early stages of B cell-mediated (humoral) immunity before there is sufficient IgG. IgA 2 Found in mucosal areas, such as the gut, respiratory tract and urogenital tract, and prevents colonization by pathogens. Also found in saliva, tears, and breast milk. IgG 4 In its four forms, provides the majority of antibody-based immunity against invading pathogens. The only antibody capable of crossing the placenta to give passive immunity to the fetus.

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.