GENETICGENETICPROBLEMSPROBLEMS

Question #1Question #1How many different kinds of gametesgametes could

the following individuals produce?

1.1. aaBbaaBb2.2. CCDdeeCCDdee3.3. AABbCcDDAABbCcDD4.4. MmNnOoPpQqMmNnOoPpQq5.5. UUVVWWXXYYZzUUVVWWXXYYZz

Answer #1Answer #1Remember the formula Remember the formula 22nn

Where Where n = # of heterozygousn = # of heterozygous

1.1. aaaaBbBb = 2= 22.2. CCCCDdDdeeee = 2= 23.3. AAAABbCcBbCcDDDD = 4= 44.4. MmNnOoPpQqMmNnOoPpQq = 32= 325.5. UUVVWWXXYYUUVVWWXXYYZzZz = 2= 2

Question #2Question #2In dogs, In dogs, wire-hairedwire-haired is due to a is due to a

dominant gene dominant gene (W),(W), smooth-hairedsmooth-haired is is due to its recessive allele due to its recessive allele (w)(w)

WW, Ww WW, Ww = wire haired= wire hairedwwww = smooth haired= smooth haired

Answer #2AAnswer #2AIf a If a homozygous wire-hairedhomozygous wire-haired dog is mated with a dog is mated with a smooth-haired dogsmooth-haired dog, what type of offspring could , what type of offspring could

be producedbe produced

WWww

WWww WWww

WWwwFF11 generation generation

all heterozygousall heterozygous

W WW W

ww

ww

Question #2BQuestion #2B What type(s) of offspring could be produced in the What type(s) of offspring could be produced in the FF22

generationgeneration??

Must breed the Must breed the FF11 generation generation to get the to get the FF22..

Ww x WwWw x Ww

Answer #2BAnswer #2B W wW w

W WW WwW WW Ww FF22 generation generation

w Ww www Ww ww

genotype: 1:2:1 ratiogenotype: 1:2:1 ratiophenotype: 3:1 ratiophenotype: 3:1 ratio

Question #2CQuestion #2C Two Two wire-haired dogswire-haired dogs are mated. Among the are mated. Among the

offspring of their first litter is a offspring of their first litter is a smooth-haired pupsmooth-haired pup..

If these, two If these, two wire-haired dogswire-haired dogs mate again, what are mate again, what are the chances that they will produce another the chances that they will produce another smooth-smooth-haired puphaired pup??

What are the chances that the pup will What are the chances that the pup will wire-hairedwire-haired??

Answer #2CAnswer #2C W wW w

W WW WwW WW Ww FF22 generation generation

w Ww www Ww ww

-- 1/4 or 25% chance for smooth-haired1/4 or 25% chance for smooth-haired- 3/4 or 75% chance for wire-haired- 3/4 or 75% chance for wire-haired

Question #2DQuestion #2DA A wire-hairedwire-haired male is mated with a male is mated with a

smooth-hairedsmooth-haired female. The mother of the female. The mother of the wire-hairedwire-haired male was male was smooth-hairedsmooth-haired..

What are the What are the phenotypesphenotypes and and genotypesgenotypes of the pups they could produce?of the pups they could produce?

Breed: Ww x wwBreed: Ww x ww

Answer #2DAnswer #2D W wW w

w Ww www Ww ww

w Ww www Ww ww

phenotypes: 2:2 ratiophenotypes: 2:2 ratiogenotypes:genotypes: 2:2 ratio2:2 ratio

Question #3Question #3 In snapdragons, In snapdragons, red flower (R)red flower (R) color is incompletely color is incompletely

dominant over dominant over white flower (r)white flower (r) color. color.

The The heterozygous (Rr)heterozygous (Rr) plants have plants have pinkpink flowers. flowers.

RR RR - red flowers- red flowers

Rr Rr - pink flowers- pink flowers

rr rr - white flowers- white flowers

Question #3AQuestion #3A If a If a red-flowered plantred-flowered plant is crossed with a is crossed with a white-white-

flowered plantflowered plant, what are the , what are the genotypesgenotypes and and phenotypesphenotypes of the plants of the plants FF11 generation generation??

RRRR x x rr rr

Answer #3AAnswer #3A R RR R

rr Rr RrRr Rr FF11 generationgeneration

r r Rr RrRr Rr

phenotypes:phenotypes: 100% 100% pinkpinkgenotypes:genotypes: 100% 100% heterozygousheterozygous

Question #3BQuestion #3B What What genotypesgenotypes and and phenotypesphenotypes will be will be

produced in the produced in the FF22 generation generation??

Rr Rr x x RrRr

Answer #3BAnswer #3B R rR r

RR RRRR Rr Rr FF22 generationgeneration

rr RrRr rrrr

phenotypes: 1:2:1 ratiophenotypes: 1:2:1 ratiogenotypes: 1:2:1 ratiogenotypes: 1:2:1 ratio

Question #3CQuestion #3C What kinds of offspring can be produced if a What kinds of offspring can be produced if a red-red-

flowered plantflowered plant is crossed with a is crossed with a pink-flowered pink-flowered plantplant??

RRRR x x RrRr

Answer #3CAnswer #3C R R

R RR RR

r Rr Rr

50%: red flowered50%: pink flowered

Question #3DQuestion #3D What kind of offspring is/are produced if a What kind of offspring is/are produced if a pink-pink-

flowered plantflowered plant is crossed with a is crossed with a white-flowered white-flowered plantplant??

Rr Rr x x rr rr

Answer #3DAnswer #3D R r

r Rr rr

r Rr rr

50%: white flowered50%: pink flowered

Question #4Question #4 In humans, In humans, colorblindness (cc)colorblindness (cc) is a recessive is a recessive

sex-linked traitsex-linked trait..

Remember:Remember: XX - femaleXX - female

XY - maleXY - male

Question #4AQuestion #4ATwo Two normal peoplenormal people have a have a colorblind soncolorblind son..

What are the What are the genotypesgenotypes of the parents? of the parents?

XXCCXX_?_? x x X XCCYY

What are the What are the genotypesgenotypes and and phenotypesphenotypes possible among their other children?possible among their other children?

Answer #4AAnswer #4A XXCC Y Y parents parents

XXCC X XCCXXCC X XCCYY

XXcc X XCCXXcc XXccYY

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

Question #4BQuestion #4B A couple has a A couple has a colorblindcolorblind daughter. daughter.

What are the possible What are the possible genotypesgenotypes and and phenotypesphenotypes of of the parents and the daughter?the parents and the daughter?

Answer #4BAnswer #4B XXcc Y Y

XXCC X XCCXXcc X XCCYY

XXcc XXccXXcc XXccYY

parents: parents: XXccYY and and XXCCXXcc or or XXccXXcc

father father colorblindcolorblind

mother mother carriercarrier or or colorblindcolorblind

daughter: daughter: XXccXXcc - colorblind - colorblind

Question #5Question #5 In humans, the presence of In humans, the presence of frecklesfreckles is due to a is due to a

dominant gene dominant gene (F)(F) and the and the non-frecklednon-freckled condition is condition is due to its recessive allele due to its recessive allele (f).(f).

Dimpled cheeks (D)Dimpled cheeks (D) are dominant to are dominant to non-dimpled non-dimpled cheeks (d).cheeks (d).

Question #5AQuestion #5A Two persons with Two persons with frecklesfreckles and and dimpleddimpled cheekscheeks have have

two children: one has two children: one has frecklesfreckles but but no dimplesno dimples and and one has one has dimplesdimples but but no frecklesno freckles..

What are the What are the genotypesgenotypes of the parents? of the parents?

Parents:Parents: FF__DD__ x F x F__DD__

Children: F_Children: F_dd dd x x ffffD_D_

ff ffd d dd

Question #5BQuestion #5B What are the possible What are the possible phenotypesphenotypes and and genotypesgenotypes of of

the children that they could produce?the children that they could produce?

Breed:Breed: FfDd x FfDd FfDd x FfDd

This is a This is a dihybrid crossdihybrid cross

Answer #5BAnswer #5B Possible gametes for both: FD Fd fD fdPossible gametes for both: FD Fd fD fd

FD FD Fd fD fd Fd fD fd

FD FD FFDD FFDd FfDD FfDdFFDD FFDd FfDD FfDd

Fd Fd FFDd FFDd FFddFFdd FfDd FfDd FfddFfdd

fD fD FfDD FfDd FfDD FfDd ffDD ffDdffDD ffDd

fd fd FfDd FfDd FfddFfdd ffDdffDd ffddffdd

Answer #5BAnswer #5BPhenotypePhenotype :: Freckles/Dimples:Freckles/Dimples: 99

Freckles/no dimples:Freckles/no dimples: 33

no freckles/Dimples:no freckles/Dimples: 33

no freckles/no dimples:no freckles/no dimples: 11

Phenotypic ratio will always been 9:3:3:1 for Phenotypic ratio will always been 9:3:3:1 for all dihybrid crosses.all dihybrid crosses.

Answer #5BAnswer #5BGenotypic ratio:Genotypic ratio: FFDDFFDD - 1- 1

FFDdFFDd - 2- 2FFddFFdd - 1- 1FfDDFfDD - 2- 2FfDdFfDd - 4- 4FfddFfdd - 2- 2ffDDffDD - 1- 1ffDdffDd - 2- 2ffddffdd - 1- 1

Question #5CQuestion #5C What are the chances that they would have a What are the chances that they would have a

child whom lacks both child whom lacks both frecklesfreckles and and dimplesdimples??

This child will have a genotype of This child will have a genotype of ffddffdd

Answer:Answer: 1/161/16

Question #5DQuestion #5D A person with A person with frecklesfreckles and and dimplesdimples whose mother whose mother

lacked both lacked both frecklesfreckles and and dimplesdimples marries a person marries a person with with frecklesfreckles but not but not dimplesdimples whose father did not whose father did not have have frecklesfreckles or or dimplesdimples..

Breed:Breed: FfDdFfDd x x FfddFfdd

Possible gametesPossible gametes: : FD Fd fD fdFD Fd fD fd x x Fd fdFd fd

Question #6Question #6 In dogs, the inheritance of hair color involves a In dogs, the inheritance of hair color involves a gene gene

BB for for black hairblack hair and and gene bgene b for for brown hair bbrown hair b..

A A dominant Cdominant C is also involved. It must be present is also involved. It must be present for the for the colorcolor to be synthesized. to be synthesized.

If this gene is not present, a If this gene is not present, a blondblond condition results. condition results.

BB, Bb - black hairBB, Bb - black hair CC, Cc - colorCC, Cc - color

bbbb - brown hair - brown hair cccc - blond - blond

Question #6AQuestion #6AA A brownbrown haired male, whose father was a haired male, whose father was a

blondblond, is mated with a , is mated with a blackblack haired female, haired female, whose mother was whose mother was brownbrown haired and her haired and her father was father was blondblond..

Male: Male: bbCc (gametes: bC bc)bbCc (gametes: bC bc)

Female: Female: BbCc (gametes: BC Bc bC bc)BbCc (gametes: BC Bc bC bc)

What is the expected ratios of their puppies?What is the expected ratios of their puppies?

Answer #6AAnswer #6ABCBC Bc Bc bC bC bcbc

bCbC BbCC BbCc bbCC bbCc BbCC BbCc bbCC bbCc

bcbc BbCc Bbcc bbCc bbcc BbCc Bbcc bbCc bbcc

Offspring ratios:Offspring ratios:Black:Black: 3/83/8Brown:Brown: 3/83/8Blond:Blond: 2/8 or 1/42/8 or 1/4

Question #7Question #7 Charlie Chaplin, a film star, was involved in a Charlie Chaplin, a film star, was involved in a

paternitypaternity case. The woman bringing suit had two case. The woman bringing suit had two children, on whose children, on whose blood type blood type waswas A A and the other and the other whose whose blood type blood type waswas B B..

Her Her blood typeblood type was was OO, the same as Charlie ’s!, the same as Charlie ’s!

The judge in the case awarded damages to the woman, The judge in the case awarded damages to the woman, saying that Charlie had to be the father of at least one saying that Charlie had to be the father of at least one of the children.of the children.

Answer #7AAnswer #7A Obviously, the judge should be sentenced to Obviously, the judge should be sentenced to BiologyBiology. .

For Charlie to have been the father of both children, For Charlie to have been the father of both children, his his blood typeblood type would have had to be what? would have had to be what?

IIAA I IBB Answer Answer

ii IIAAi i I IBBii

ii IIAAi Ii IBBii