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Do now:

1) Put these in order from which is the largest to the smallest:

gene

nucleus

chromosome

cell

DNA

Friday, April 21, 2023

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Do now:

1) Put these in order from which is the largest to the smallest:

cell

nucleus

chromosome

gene

DNA

Friday, April 21, 2023

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1) Explain what is meant by dominant and recessive

2) Explain what an allele is

2) Use a Punnett Square

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X

X

X

Y

Male

Female

XX

XY

XX

XY

Copy!

Tongue rolling

How many people in the class could roll their tongues?

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R

R

r

r

Male

Female

RR

r r

Rr

Rr

Roller gene (R) is dominantNon-roller gene (r) is

recessive

Probabilities

Homozygous dominant and

recessive

Heterozygous

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B

B

b

b

Male

Female

BB

bb

Bb

Bb

Brown eyes (B) are dominant

Blue eyes are recessive (b)

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An allele is just a type of gene e.g. B=Brown eyes, b = blue eyes

The allele which will always be expressed is called the Dominant allele.

The allele which may be hidden is called the Recessive allele.

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In mice, pointed ears (E) are

dominant over round ears (e)

Draw the Punnett square for offspring of a “pure-breed” male with pointed ears (EE) and a female with round ears (ee).

What is the probability the offspring has round ears?

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In mice, pointed ears (E) are

dominant over round ears (e)

Draw the Punnett square for offspring of a “cross-breed” male with pointed ears (Ee) and a female with round ears (ee).

What is the probability the offspring has round ears?

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Hypertrichosis

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