Question

A sample of 2,000 individuals from a human population was scored for MN blood group.

The following genotypes were found:

• 1,600 MM
• 250 MN
• 150 NN

Calculate the observed genotype frequencies and expected genotype frequencies under Hardy–Weinberg equilibrium to fill in the blanks to the following questions.

Remember to put a zero in front of the decimal point (e.g. 0.47) and round to the significant digits suggested.

The observed genotype frequencies (use to 3 significant digits) are:

MM =

MN =

NN =

The observed allele frequencies (use 4 significant digits) are:

M = p =

N = q =

The expected genotype frequencies (use 3 significant digits) under Hardy Weinberg Equilibrium are:

MM =

MN =

NN =

The frequency of heterozygotes in the observed population is  than expected. (lower/higher)

Answer 1

Solution:

A population is said to be in Hardy-Weinberg equilibrium if the population is not evolving with respect to a certain gene, Hence the allelic and genotypic frequencies remain relatively constant over the cenrtain generations.

The allele and genotypic frequencies can be represented as follows:

• 
  • where = the frequency of the dominant allele and

= the frequency of the recessive allele

• 
  • where = the frequency of being homozygous for the dominant allele,

= the frequency of being heterozygous,

= the frequency of being homozygous recessive allele

Given data :

• No. of MM individual =1600
• No. of MN individual =250
• No. of NN individual =150
• Total population=2000

(i) The observed genotype frequencies

• Observed genotype frequency of MM
  
• Observed genotype frequency of MN
  
• Observed genotype frequency of NN
  

(ii) Calculating the allelic frequency :

• Observed frequency of M allele (p) =
• Observed frequency of N allele (q) =

First, determine the Expected frequency of the M allele (pp) and the N allele (qq):

• Frequency of M allele (p) =

• Frequency of N allele (q) =

(iii) The expected genotype frequencies from these allele frequencies:

• Frequency of MM genotype (p²):
• Frequency of MN genotype (2pq):
• Frequency of NN genotype (q²):

Hope this helps
Happy learning!