Genetic problems

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Question #2D

W w

w Ww ww

w Ww ww

phenotypes: 1:1 ratio

genotypes: 1:1 ratio

Slide 13

Question #3

In snapdragons, red flower (R) color is incompletely dominant over white flower (r) color.

The heterozygous (Rr) plants have pink flowers.

RR - red flowers

Rr - pink flowers

rr - white flowers

Slide 14

Question #3A

If a red-flowered plant is crossed with a white-flowered plant, what are the genotypes and phenotypes of the plants F1 generation?

RR x rr

Slide 15

Question #3A

R R

r Rr Rr F1 generation

r Rr Rr

phenotypes: 100% pink genotypes: 100% heterozygous

Slide 16

Question #3B

What genotypes and phenotypes will be produced in the F2 generation?

Rr x Rr

Slide 17

Question #3B

R r

R RR Rr F2 generation

r Rr rr

phenotypes: 1:2:1 ratio

genotypes: 1:2:1 ratio

Slide 18

Question #3C

What kinds of offspring can be produced if a red-flowered plant is crossed with a pink-flowered plant?

RR x Rr

Slide 19

Question #3C

R R

R RR RR

r Rr Rr

50%: red flowered

50%: pink flowered

Slide 20

Question #3D

What kind of offspring is/are produced if a pink-flowered plant is crossed with a white-flowered plant?

Rr x rr

Slide 21

Question #3D

R r

r Rr rr

r Rr rr

50%: white flowered

50%: pink flowered

Slide 22

Question #4

In humans, colorblindness (cc) is a recessive sex-linked trait.

Remember: XX - female

XY - male

Slide 23

Question #4A

Two normal people have a colorblind son.

What are the genotypes of the parents?

XCX_? x XCY

What are the genotypes and phenotypes possible among their other children?

Slide 24

Question #4A

XC Y  parents

XC XCXC XCY

Xc XCXc XcY

50%: female (one normal, one a carrier)