Hardy-Weinberg

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Transcript Hardy-Weinberg

Hardy-Weinberg

It’s Not That Hard!

Foothill High School Science Department

What You Will Learn • • • •

Who were Hardy & Weinberg?

The nomenclature

what do the words mean?

How to calculate

It really is not that hard.

How you can use it.

Foothill High School Science Department

Who Were They?

Professor Godfrey Harold Hardy Mathematician 1877-1947 Foothill High School Science Department

Who Were They?

Dr. Wilhelm Weinberg Physician Geneticist 1862-1937 Foothill High School Science Department

What Did They Figure Out?

Hardy & Weinberg did not know each other, but they were both interested in population genetics.

They independently figured out how field observations could be used to calculate the frequency ( how many ) of alleles in populations of organisms Foothill High School Science Department

Remember the Punnett Square?

TT,Tt Let’s Review Remember Mendel’s Peas?

Remember Some Were Tall & Some Were Short?

Controlled By “Alleles” in “Genes”?

tt

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Remember the Punnett Square?

Remember the old F

1

Cross?

And Then P

1

P

1

P

2

= Tt = Tt and P

2

Got Married And Then They Had Baby Peas!

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Remember the Punnett Square?

P

1

P

2

= Tt t

What Does This Have To Do With Hardy-Weinberg?

TT Tt

Actually – Everything It Is Hardy-Weinberg!

Tt tt

Here is how it works!

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Hardy-Weinberg The Hardy-Weinberg Equation Calculates Allele Frequencies In POPULATIONS OF ORGANISMS.

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Hardy-Weinberg Language Could We Convert The Language of the Punnett Square into Mathematical Language?

Watch!

T

2

t

2 Foothill High School Science Department

Hardy-Weinberg Language We used Tall and Short Pea plants (TT, Tt, tt) But We could have been demonstrating color, smoothness, locations, or any other trait TT Tt Tt tt That would require different letters for each trait.

However, Hardy-Weinberg applies to all traits!

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Hardy-Weinberg Language

To Solve This Problem, Hardy-Weinberg Assigns A Single Letter To Represent Each Different Allele

p = The Dominant Allele TT Tt Tt tt q = The Recessive Allele

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Hardy-Weinberg Language Let’s Recode Our Punnett Square to Hardy-Weinberg Notation p

2

q

2 Foothill High School Science Department

Hardy-Weinberg Equation TT Tt Tt tt = pp pq pq qq

p 2 + 2pq + q 2 = 1 Foothill High School Science Department

Calculating Hardy-Weinberg 1.

2.

Therefore: All The “p” alleles + All The “q” alleles = ALL THE ALLELES!

Therefore:

pp pq pq

Key Equations

qq

Therefore: The Genotypes of the Offspring = ALL the Possible Genotypes!

Therefore: p + q = 1 p 2 + 2pq +q 2 = 1

You Already Know This Punnett Square represents the Whole Population Therefore, It Represents ALL the Alleles in the Population

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Calculating Hardy-Weinberg w w

Sheep White

is Dominant Black is Recessive

10

Number of BLACK Sheep =

2 Foothill High School Science Department

w Calculating Hardy-Weinberg

q

q

2 w

0.2

OK Hardy Weinberg Formula

p 2 + 2pq + q 2 = 1 ww = qq = q 2

q

q

2

q

 0 .

2

Calculating Hardy-Weinberg

q = 0.447

p + q = 1.000

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Calculating Hardy-Weinberg

q = 0.447

p = 0.553

p 2 pq = 0.247

q 2

pp pq

+ 0.247

1.000

pq qq