hardy-weinberg equilibrium
DESCRIPTION
Hardy-Weinberg Equilibrium. What Darwin didn’t Get . Darwin couldn’t figure out why there was so much GENETIC VARIATION in natural populations. . Darwin thought that selection should ALWAYS favor the optimal form and eliminate vaiation…… hmmm…. But……. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/1.jpg)
HARDY-WEINBERG EQUILIBRIUM
![Page 2: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/2.jpg)
What Darwin didn’t Get
Darwin couldn’t figure out why there was so much GENETIC VARIATION in natural populations.
![Page 3: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/3.jpg)
Darwin thought that selection should ALWAYS favor the optimal form and eliminate vaiation…… hmmm…. But…….
![Page 4: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/4.jpg)
The reality is, there is A LOT of variation in populations
So how could this be?
![Page 5: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/5.jpg)
Hardy and Weinberg (1908) Independently solved
WHY this genetic variation exists
Hardy was a mathematician
Weinberg was a physician
![Page 6: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/6.jpg)
They showed that the frequency of genotypes in a population will stay the same from one generation to the next.
That is if : SEVEN conditions are met
We call this HARDY-WEINBERG EQUILIBRIUM
![Page 7: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/7.jpg)
THE BIG SEVEN1. Mutation is not occurring
2. Natural selection is not occurring
3. The population is very large
4. All members of a population breed
5. All mating is totally random
6. Everyone produces the same number of offspring
7. There is no immigration or emigration happening in the population
![Page 8: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/8.jpg)
Ok, so how realistic is this???
Not very, but we can use an equation as a model for population genetics
First you need to know that:
•ALLELES represent GENES
•Individuals receive one allele from each parent
•This makes up an individuals genes
•The genes determine the phenotype
![Page 9: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/9.jpg)
Therefore an individual will receive a combination of alleles in the form of :
Dominant Dominant
Recessive Recessive
Dominant Recessive
The alleles are represented as letters
Capital letter = DominantLowercase Letter = Recessive
AAaaAa
![Page 10: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/10.jpg)
AA is called: HOMOZYGOUS DOMINANT
Aa is called: HETEROZYGOUS DOMINANT
aa is called: HOMOZYGOUS RECESSIVE
![Page 11: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/11.jpg)
The HARDY- WEINBERG Equation (s)
p + q = 1 p2 + 2pq +
q2 = 1
BREATH DEEP….here we go……
These equations figure out:
•ALLELE FREQUENCY
•GENOTYPE FREQUENCY
![Page 12: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/12.jpg)
AA + Aa + aa = 1
p2 + 2pq + q2
= 1
Formula for GENOTYPE Frequency
![Page 13: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/13.jpg)
A + a = 1 p + q = 1
Formula for ALLELE frequency
![Page 14: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/14.jpg)
Now that we know what each formula represents, figuring out each problem is easy!!!!!!
![Page 15: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/15.jpg)
You will ALWAYS be given
That the characteristic is either DOMINANT or RECESSIVE
Example: the problem will tell you that
RED = RWHITE = r
![Page 16: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/16.jpg)
THEN you will be GIVEN
A VALUE of one of these:
A a AA aa
And you already know that:
A = p a = q AA = p2 Aa = 2pq aa = q2
![Page 17: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/17.jpg)
NOW all you have to do is..
Plug the values in!!!
But it’s kind of like a maze
Sooooooooo
![Page 18: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/18.jpg)
STEP 1: write out both formulas
AA + Aa + aa = 1p2 + 2pq + q2 = 1
AND
A + a = 1 p + q = 1
![Page 19: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/19.jpg)
Step 2: Figure out what you’ve been given and plug it in
![Page 20: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/20.jpg)
Example: if you are given the value of aa as 50% or .5o
Plug .50 into the q2 spot
AA + Aa + aa = 1p2 + 2pq + q2 = 1p2 + 2pq + .50 = 1
Now you can figure out q
.50 = .71
![Page 21: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/21.jpg)
A + a = 1p+ q = 1
P + .71 = 1.29 + .71 = 1
AA + Aa + aa = 1p2 + 2pq + q2 = 1
.084 + 2 (.29)(.71) + .50 = 1.084 + .41 + .50 = 1
![Page 22: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/22.jpg)
Lets look at a problem
The gene for an intelligent dolphin is dominant to a gene for an aggressive dolphin. In a population there are 25% that have the gene for homozygous recessive aggressiveness. Figure out the gene frequency for the heterozygous intelligent.
![Page 23: Hardy-Weinberg Equilibrium](https://reader036.vdocuments.site/reader036/viewer/2022081507/56815faf550346895dcea9b8/html5/thumbnails/23.jpg)
OK, so we know that:We’re looking or GENE FREQUENCY
Intelligent = A
Aggressive = a
Homozygous recessive = aa = 25% = .25
Heterozygous = Aa