Question

4.Explain X-linked inheritance, and name other genetic diseases that are known to be X- linked? 5.What are the five classes of antibody? 6.What are the means by which antibody molecules exert a protective effect? 7.What are the basic differences between active and passive immunity?

Answer 1

4. X-linked inheritance means that the gene causing the trait or the disorder is located on the X chromosome. Females have two X chromosomes; males have one X and one Y. Genes on the X chromosome can be recessive or dominant. Their expression in females and males is not the same. Genes on the Y chromosome do not exactly pair up with the genes on the X chromosome. X-linked recessive genes are expressed in females only if there are two copies of the gene (one on each X chromosome). However, for males, there needs to be only one copy of an X-linked recessive gene in order for the trait or disorder to be expressed.

Red-green colour blindness and hemophilia B are other diseases that are X-linked.

5. IgA (immunoglobin A)

IgD (immunoglobin D)

IgE (immunoglobin E)

IgG (immunoglobin G)

IgM (immunoglobin M)

6.Antibodies are produced in large quantities by plasma cells which are derived from activated B-lymphocytes (part of the Adaptive Immune System). The production of a large number of these immune cells with a specific antibody to target a specific antigen allow the immune system to generate a massive attack on the foreign invader. Antibodies enable the immune cells to attach to the antigen/invader, thus helping the immune system to kill large numbers of invading organisms.

7.Active Immunity:

The active immunity is the direct response of your body against the pathogens. It is induced by the exposure to a foreign antigen such as the antigen of microbes. It is an adaptive response of the individual after contact with specific pathogen or antigen.

Passive Immunity:

The passive immunity is the immunity conferred to an individual by the transfer of serum or lymphocytes from a specifically immunized individual. Passive immunity is a useful method for conferring resistance without waiting for the development of the active immune response.