A mutation that inserts or deletes one or two nucleotides is usually more harmful than a mutation that substitutes one base for another because -

A It changes one amino acid in the sequence of a protein

B it shifts the reading frame for the rest of the code causing many errors

C The codon consists of three nucleotides coding for an amino acid

D the chromosomes fail to separate resulting in trisomy 21

Imagine a self-reactive t cell that has not undergone clonal deletion in the thymus (that is to say, it has escaped central tolerance). if it encounters self antigen in the absence of an infection or inflammation, what will happen to this self-reactive t cell? (select two answers) (a) the t cell undergoes clonal expansion. (b) the t cell gains effector functions. (c) the t cell undergoes apoptosis. (d) the t cell becomes activated. (e) the t cell becomes anergic.