Transcript How to Solve Hardy-Weinberg

How to Solve Hardy-Weinberg
• What is the percentage of any genotype and
of any gene in a population?
– ? % of Dominant Genes
– ? % of Heterozygous Genotype
– ? % of Recessive Genes
Step by Step
• For those students who prefer to
approach these problems in a linear
manner, I have outlined a few steps to
follow . . .
Step 1 – The Formula
• 1. Be able to write out the formula from
memory!
• p2 + 2pq + q2 = 1
• Remember:
% + % + % = 100%
• BB + Bb + bb = 100%
• The % will be expressed as a decimal
(e.g. 14% = 0.140)
Step 2 - % with recessive trait
• 2. I will give you the % of the population that
has the recessive trait!
•
Or . . . . . You’ll be able to count it ! !
• # of rec/ total population
• Since % will be expressed as a decimal, be
sure to convert it! (e.g. 14% = 0.140)
• The % = q2
Step 3 – The Value of ‘q’
• 3. Figure out q.
• q = the Square Root of the % given
above (i.e. the Square Root of 0.140)
• Example q = .374 (round it to 3 decimal
places)
Step 4 – The Value of ‘p’
• 4. Figure out p.
• p+q=1
therefore . . . . .
• p=1-q
• Example
• p = 1 - .374 = .626 (p = .626)
Step 5 - % of Dominant trait
• 5. Figure out:
• A) p2
– p2 = p x p
– Example p2 = .626 x .626 = .391 (p2 = .391)
(round it to 3 decimal places)
Step 5 - % of Heterozygous
• 5. Figure out Con’t.
• B) 2pq
– 2pq = 2(p x q)
– 2(.626 x . 374) = 2(.234) (round it to 23decimal
places) = .468
Step 6 – Complete the Formula
• 6. Write the numbers out underneath
the formula!
• p2 + 2pq + q2 = 1
• .391 + .468 + .140 = 1
• That’s all there is to it!