Question

Codominant expression of polygenic and polymorphic MHC genes allows: O your cells to present more diverse peptides O you to mount an immune response to diverse pathogens you to make 1018 different MHC clefts a and b all of the above Question 35 (2 points) Ab diversity generation: occurs through shifts in the reading frame occurs through irreversible recombination events at the S regions occurs through repeated exposure to Ag a and c

Answer 1

1)option D is the correct answer.Codominant expression occurs when two different alleles are inherited at the same genetic location and the products of both of the alleles are expressed.Polygenic traits are controlled by more than one gene.The MHC genes are highly polymorphic,ie there are many different alleles in the different individuals inside a population.The MHC molecules have broad specificity,because they can bind many types of possible peptides,so the cells present more diverse peptides.The genes encoding the major histocmpatibility molecules play an importanat role in the induction of immune responses.This polymorphism is due to selection for increased protection of hosts against pathogens.

2)optio D is the correct answer.Antibody diversity is the phenomenon of immense variability characteristics of antibodies,which enables the immune system to react specifically against the unlimited kinds of antigens it encounters.After repeated exposure by antigens,antibodies are generated by B cells that bind their antigen with much higher affinity through the process called affinity maturation.Antigen stimulation greatly increases the antibody arsenal.It may causes deletion and addition of nucleotides which result in the shift of the reading frame of the coding sequence.