Mutation breeding

Mutation breeding
Physical Mutagens
  • Physical mutagens include various types of radiation, viz X-rays, gamma rays, alpha particles, beta particles, fast and thermal (slow) neutrons and ultra violet rays.
  • A brief description of these mutagens is presented below:
The chemical mutagens can be divided into four groups, viz.
  1. Alkylating agents,
  2. Base analogues,
  3. Acridine dyes, and
  4. Others. A brief description of some commonly used chemicals of these groups is presented below.
  5. Variables
  • The Hardy-Weinberg model consists of two equations: one that calculates allele frequencies and one that calculates genotype frequencies. Because we are dealing with frequencies, both equations must add up to
1. The equation
p + q = 1
  • Describes allele frequencies for a gene with two alleles. (This is the simplest case, but the equation can also be modified and used in cases with three or more alleles.) If we know the frequency of one allele (p) we can easily calculate the frequency of the other allele (q) by 1 รณ p = q.
  • In a diploid organism with alleles A and a at a given locus, there are three possible genotypes: AA, Aa, and aa.
  • If we use p to represent the frequency of A and q to represent the frequency of a, we can write the genotype frequencies as (p)(p) or p2 for AA, (q)(q) or q2 for aa, and 2(p)(q) for Aa. The equation for genotype frequencies is
p2+ 2pq + q2 = 1.

Last modified: Monday, 2 April 2012, 9:32 PM