The Hardy-Weinberg Principle: Watch your Ps and Qs

The Hardy-Weinberg Principle states that allele and genotype frequencies in populations remain stable over time, given certain assumptions. What assumptions? What does the principle mean? And how do you SOLVE those Hardy-Weinberg PROBLEMS? Everything shall be revealed in this video - with some penguins of course. They make everything go down easier.
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Links to Videos Mentioned:
Mendelian Genetics: • Mendelian Genetics - F...
How to Solve Genetics Problems: • Solving Genetics Problems
Solution for the additional problem I showed at the end:
Allele Frequencies:
q = 0.04
p = 0.96
Genotype Frequencies:
homozygous dominant: 0.92
Heterozygous: 0.08
Homozygous recessive: 0.002
Answer to the additional problem step-by-step: www.penguinprof.com/uploads/8/...
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Video Details:
Population Genetics:
The Hardy-Weinberg Principle
You need to know:
gene vs. allele
gentoype vs. phenotype
understanding probabilities (and vs. or)
Punnett Square
Hardy-Weinberg Principle
Timeline of Discoveries
Darwin, Mendel, DeVries, Correns
Hardy, Weinberg, Castle
Mendelian Genetics Gets HOT
Particles are inherited!
Traits aren't blended!
Cambridge opens a department of Genetics
So What's it All About?
It's about frequencies
When talking about population genetics, we are interested in the prevalence of a particular allele or genotype in a population
The Hardy-Weinberg Principle States:
Frequencies of alleles and genotypes in a population will remain constant over time in the absence of other evolutionary influences
Assumptions
Organisms are diploid
Generations are non-overlapping
Population must be large
No immigration or emigration
No mutation in the gene of interest
No natural selection occurs (individuals reproduce at equal rates)
Mating is random
Alleles and Allele Frequency
Penguin Prof Helpful Hints
The Sum of All Possible Outcomes MUST Equal 1
p+q = 1
ALLELE FREQUENCY
2 Alleles = Genotype
p2 + 2pq + p2 = 1
What if There are Three Alleles?
(p, q and r)
Sample Problem
In a population of 1,000 penguins, 12 have blue feet. Find the frequency of the blue allele, the yellow allele and the frequencies of the three possible genotypes in this population.
Solving Hardy-Weinberg Problems
Assign the alleles
Frequency of the dominant allele is 'p'
Frequency of the recessive allele is 'q'
Calculate q by taking the square root of the number of homozygous recessive individuals
Calculate p (the allele frequencies must equal 1, so p = 1 − q)
Use p and q to calculate the other genotype frequencies:
frequency of homozygous dominant individuals = p2
frequency of heterozygous individuals = 2pq
frequency of homozygous recessives = q2
This may help:
Hardy-Weinberg Punnett Square
Try Another One...
In a population of 130,000 magical mice, green fur is dominant over orange. If there are 300 orange mice in a population of 130,000, find the following (assume population is in Hardy-Weinberg equilibrium):
1. Frequency of dominant (green) allele
2. Frequency of recessive (orange) allele
3. Frequency of each genotype

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Et ce ratio il l’a bien compris ce principe ?

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[@Penguinprof]

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+ThePenguinProf how do you convert a frequency into population

[@totallymcmylastname9077]

With proportions. The same stuff you do with stochiochemistry or mathematics. but you'll need to know the numbers of the guys you're interested in first ex. there are 13 brown rats out of 41 so its [13/41] so if you're asked for numbers of brown rats in a den of 1000 rats you just need to set up [13/41] = [x/1000] since frequency = specimens/total population. You can just set up the ratios for that.

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[@shriyasrivaz3369]

@@nyevs21 so question says that - phenotype =orange recessive mice are 300 Phenotype =2 alleles =q×q(recessive pheno) Or p×p(domint pheno) So orange mice out of total =300/130000 = 0.0025= q×q Recesv allele? = q = sqroot(0.0025)=0.0479 Dominant allele? =p We know, tot allele =1 therefore p=1-q =0.0.952

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Thank you for watching and for sharing this VERY important message... you should NEVER be made to feel stupid!!! No one is born with knowledge about how to solve these problems (or how to do differential equations or how to dance a Waltz or anything else for that matter) but we all have the potential to learn these things - and it is essential, in my opinion, that we have safe, encouraging learning environments in which to explore, to question and to be wrong. If I can create that kind of environment through these videos, well, that is my career goal. And I thank you from the bottom of my penguin heart for letting me know that you understand what I am trying to do. Best of luck to you in your studies - keep in touch!!!

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Excellent video! Just have to remember that after assigning p and q alleles, I have to square root the homozygous recessive genotypes to get q. After obtaining q, everything is golden.

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While the content past four minutes was incredibly useful for biology students wanting to solve hardy-Weinberg problems, the first four minutes contain history which is not necessarily applicable to H-W problems, and the individuals who down-voted may have felt that ThePenguinProf wasted 4 minutes unnecessarily.

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+Jabeen Thaz You are so welcome!!

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Very well explained. You can also check if you have calculated the frequencies correctly (10:58) in the table, because the total should also = 1 (0.79+0.2+0.01 =1).

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Yes, thank you!

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