Hardy-Weinberg Equation

Key Questions

• How can the hardy-weinberg equation be calculated?

  Answer:

  To calculate Hardy-Weinberg equation you need to have the proportion of the studied genotype in order to calculate their frequence in the population from which you will find theorical frequency and then check if it matches reality.

  Explanation:

  To start let's recall the Wardy Weinberg equation :
  #p^2+2pq+q^2=1#
  with p the frequency of an allele A1 and q the frequence of an allele A2.
  Let's try an example. In a population there are two alleles M and N with three possible genotypes:

  homozygote MM : 1787 individuals
  homozygot NN : 1303 individuals
  heterozygot NM : 3039 individuals

  Total population : 6129

  We can calculate the frequency of each genotype :

  F11 = frequency of MM #= 1787/6129=0.2915#
  F22= frequency of NN #= 1303/6129=0.2126#
  F12= frequency of NM#=3039/6129=0.4958#

  We then calculate the frequency p of M and q of N in the population:

  #p=F11+F12/2=0.2915+0.4958/2=0.54#
  #q=F22+F12/2=0.2126+0.4958/2=0.46#

  Now that we have the Hardy Weinberg frequency, we can calculate the theorical frequency of the genotype by multiplying the frequency by the total population:

  MM#=p^2=0.54^2=0.2916#
  theoretical frequency of MM#=0.2916*6129=1787.2#
  NN#=q^2=0.46^2=0.2116#
  theoretical frequency of NN#=0.2116*6129=1286.9#
  NM#=2pq=2*0.54*0.46=0.4968#
  theoretical frequency of NM#= 0.4968*0.6129=3044.9#

  Now that we have those theoretical frequencies, we can compare them to the real frequencies and check if the population is or isn't at the Hardy Weinberg equilibrium with, for instance, a #chi^2# test.

  
  

  Axel H. · 3 · Jul 31 2015
• What is an example hardy-weinberg equation practice problem?

  A question could look like:

  If #mathbf98# out of #mathbf200# individuals in a population express the recessive phenotype, what percent of the population would you predict would be heterozygotes?

  An explanation, walked through:

  The Hardy-Weinberg equilibrium is a mathematical relationship of the alleles and genotypes in a population that meets certain characteristics. The relationships are as follow:

  Alleles: #p+q=1#

  #p="frequency of the dominant allele"#
  #q="frequency of the recessive allele"#

  Genotypes: #p^2+2pq+p^2=1#

  #p^2="frequency of homozygous dominant genotype"#
  #2pq="frequency of heterozygous genotype"#
  #q^2="frequency of homozygous recessive genotype"#

  From the question, we know that #98# of #200# individuals express the recessive phenotype. This means that these #98# also have the homozygous recessive genotype, the frequency of which is equal to #q^2#.

  To determine what the actual frequency is, simply divide #98/200=0.49#. We now know that #q^2=0.49#.

  However, we wish to find the frequency of the population that is heterozygous, which is equal to #2pq#. So, we must find both #p# and #q#.

  Finding #mathbfq#:

  #q^2=0.49#

  Take the square root of both sides.

  #q=0.7#

  (This means that #70%# of the alleles in the system are recessive alleles.)

  Now that we've found the value of #q#, we can find the value of #p# using the allele equation.

  Finding #mathbfp#:

  Through the equation #p+q=1#, substitute in #q=0.7#.

  #p+0.7=1#

  Subtract #0.7# from both sides to see that

  #q=0.3#

  Finding the frequency of heterozygotes:

  #"frequency of heterozygous genotypes"=2pq#

  Substitute the known values for #p# and #q#:

  #"frequency of heterozygous genotypes"=2(0.3)(0.7)=0.42#

  Converting this into a percent, we see that #42%# of the population is heterozygous.

  mason m · 30 · Jan 22 2016
• What is the Hardy-Weinberg equation?

  Answer:

  This is an equation used to determine if a population is evolving or not.

  Explanation:

  The Hardy-Weinberg principle is not generally found in nature because it requires certain conditions in an environment. These conditions are the absence of the things that can cause evolution . In other words, if no mechanisms of evolution are acting on a population, evolution will not occur--the gene pool frequencies will remain unchanged. However, since it is highly unlikely that any of these seven conditions, let alone all of them, will happen in the real world, evolution is the inevitable result. The conditions are:

  a. No mutation
  b. No immigration or emigration
  c. Infinitely large population size
  d. No natural selection
  e. All members of the population breed
  f. All mating is totally random
  g. Everyone produces the same number of offspring.
  Hardy-Weinberg principle can be illustrated mathematically with the equation: p2+2pq+q2 = 1, where ‘p’ and ‘q’ represent the frequencies of alleles. P added to q always equals one (100%). The principle behind it is that, in a population where certain conditions are met (see below), the frequency of the alleles in the gene pool will be constant.

  To read more about the Hardy-Weinberg Theory and Equation, check out this page from Nature.

  Samantha C. · 1 · Nov 2 2014

• How can the hardy-weinberg equation be calculated?
• How can the hardy-weinberg equation be used to model selection?
• What is an example hardy-weinberg equation practice problem?
• What is the Hardy-Weinberg equation?
• What are the assumptions of the Hardy-Weinberg principle?
• A population of trout lives in a small lake. Some of the trout have a mutation that makes them more colorful. What are some reasons this population is not at Hardy-Weinberg equilibrium?
• Using the Hardy-Weinberg equation, if p = 0.23, what must q equal?
• In the Hardy Weinberg formula, what does 2pq represent?
• If a homozygous dominant genotype is 46% what is the dominant allele frequency?
• Approximately 1 out of every 2,500 Caucasians in the United States is born with the recessive disease cystic fibrosis. According to the Hardy-Weinberg equilibrium equation, approximately how many people are carriers?
• Sickle cell anemia is caused by a recessive allele. Roughly 1 out of every 500 african americans is afflicted with sickle cell anemia. How would you use the hardy weinberg equation to calculate the % of heterozygotes for sickle cell allele (.002=q^2)?
• Given the following information, how would you determine the allele frequencies for the B allele and the b allele? How would you determine the genotype frequencies for the BB, Bb, and bb genotypes?
• For an X-linked recessive trait, 9% of the females in the population are affected. What percent of the males would be affected? What percentage of the population is represented by the carriers?
• In a certain population, the dominant phenotype of a certain trait occurs 91% of the time. What is the frequency of the dominant allele?
• The allele for the hair pattern widow's peak is dominant. In a population of 1000 individuals, 510 show the dominant phenotype. How many individuals would you expect of each of the possible 3 genotypes for this trait? How do you answer this?
• If the frequency of a homozygous dominant genotype is 0.49, what is the frequency of the homozygous recessive genotype?
• What is the Hardy-Weinberg equation used for?
• Why is the Hardy-Weinberg equation important?
• What is 2pq in the Hardy-Weinberg equation?
• What does the Hardy-Weinberg equation predict?
• How do you use the Hardy-Weinberg principle?
• How is the Hardy-Weinberg equation used?
• Who discovered the Hardy-Weinberg equation?
• What is the Hardy-Weinberg equation and why it is used?
• What idea did Hardy and Weinberg disprove?
• What was the most important impact of Hardy Weinberg law of equilibrium?
• If the frequency of a dominant phenotype in a stable population is 75%, the frequency of recessive allele in that population would be how much? a. 0.375 b. 0.25 c. 0.75 d. 0.50
• Question #6d9ab
• Question #1ad13
• Hardy-Weinburg Equlibrium?
• In a population that is in Hardy-Weinberg equilibrium, 16% of the individuals show the recessive trait. What is the frequency of the dominant allele in the population?
• If p = 0.25, then q must equal ?