Genetics questionse PDF

Preview

Summary

reewere...

Description

SHOKOOH MANSOURI

Genetics Questions

1

K1816634

SHOKOOH MANSOURI

Genetics Questions

K1816634

Q1: PLAN S – allele for straight fur long ears

L – allele for

s – allele for curly fur short ears

l – allele for

Possible allele combinations: Male

Female

Straight fur, long ears ears

SsLI SSLL SsLL SSLl

Straight fur, short

×

Ssll SSLL when crossed with Ssll or SSll produces all straight fur and long ears offspring which is incorrect.

SsLL when crossed with Ssll produces straight and curly fur and long ears but no short ears. With SSll, it produces all straight fur, with some short ears and most long ears.

SSLl when crossed with Ssll or SSll produces all straight fur, (no curly) with long ears and short ears.

2

SSll

This is the correct genotype for both genders because it produces a combination of all the genotypes within the offspring including curly, straight, long or short. Whereas others don’t include all of them.

SHOKOOH MANSOURI

Genetics Questions

3

K1816634

SHOKOOH MANSOURI

Genetics Questions

K1816634

Q1: GENETIC DIAGRAM S – allele for straight fur long ears

L – allele for

s – allele for curly fur short ears

l – allele for

Parental phenotype fur,

Straight fur,

Straight

Long ears

Short ears

SsLl

Parental genotype

Ssll

Meiosis Gametes

SL

Sl

sL sl

Sl

×

Sl

sl

sl

Fertilisation

Male Gametes Sl Female Gametes

Sl

sl

sl

SL

Sl

sL

sl

SSLl

SSll

SsLl

Ssll

Straight, Long

Straight, Short

Straight, Long

Straight, Short

SSLl

SSll

SsLl

Ssll

Straight, Long

Straight, Short

Straight, Long

Straight, Short

SsLl

Ssll

ssLl

ssll

Straight, Long

Straight, Short

Curly, Long

Curly, Short

SsLl

Ssll

ssLl

ssll

4

SHOKOOH MANSOURI

Genetics Questions

Straight, Long

Straight, Short

5

K1816634

Curly, Long

Curly, Short

SHOKOOH MANSOURI

Offspring Genotypic ratio: ssLl : 2 ssll

Genetics Questions

K1816634

2 SSLl : 2 SSll : 4 SsLI : 4 Ssll : 2 ~ 2:2:4:4:2:2 ⟹ 1:1:2:2:1:1

Offspring Phenotypic ratio: 2 curly, Long : 6 Straight, Long : 6 Straight, Short : 2 Curly, Short

~ 2:6:6:2 ⟹ 1:3:3:1 Calculations

83 =5.19 16

11 + 31 + 32 + 9 = 83

5.19× 2=¿ 10.38 ~ 10

2 + 6 + 6 + 2 = 16

5.19× 6=¿

Curly fur and short ears = 11 Curly fur and long ears = 9 Straight fur and long ears = 31

These two are roughly very close values to 10 and the ratios are the same for both of them. 32 is roughly close to 31 and the ratios are the same for both of them.

Straight fur and short ears = 32

6

31.14 ~ 31

SHOKOOH MANSOURI

Genetics Questions

K1816634

Q2: PLAN This unknown male is XBY and NOT XGY Because the offspring that it produces has a mixture of all black, ginger and tortoiseshell. If it is XGY, then the offspring will be 100% all ginger which is incorrect.

XGXG

×

Two possible outcomes: it could be XGY or XBY.

Key: G

X X

G

-

all ginger female

X? Y

-

unknown male

X? X?

-

unknown female

XBXB

-

X? X ?

XBXB

all black female

XBY

-

all black male

XG Y

-

all ginger male

7

X? Y

×

+

XBY

+

XGY

SHOKOOH MANSOURI

Genetics Questions

K1816634

Q2: GENETIC DIAGRAM For F1 XG – allele for ginger coat colour XB – allele for black coat colour

Parental phenotype

Ginger coat

Black coat

(homozygous dominant)

Parental genotype

XGXG

XgY

Meiosis XG

Gametes

XG

XB

×

Y

Male Gametes XB

Y

XG

XBXG

XGY

XG

XBXG

XGY

Female Gametes

Fertilisation Offspring (F1) genotype

2:2 ⟹ 1:1 X BXG:XGY

Offspring (F1) phenotype

Tortoiseshell female : Ginger male 8

SHOKOOH MANSOURI

Genetics Questions

K1816634

Q2: PLAN Working out: X?Y could be XGY or XBY

This cannot be correct – because it only produces correct male offspring with all black and all ginger fur and NOT all black female. Therefore, XGY is incorrect.

This is correct – because it produces correct offspring with the right fur colours. This also includes all black female. Therefore, XBY is correct.

XBXG

with

Male Gametes XG

Y

XB

XBXG

XBY

XG

XGXG

XGY

Female Gametes

Male Gametes XB

Y

XB

XBXB

XBY

XG

XBXG

XGY

Female Gametes

9

SHOKOOH MANSOURI

Genetics Questions

K1816634

Q2: GENETIC DIAGRAM FOR F2 Parental phenotype (F2) coat

Tortoiseshell coat

Black

(heterozygous)

XBXG

Parental genotype (F2)

XBY

Meiosis XB

Gametes

XG

×

XB

Y

Fertilisation

Male Gametes Female Gametes XB XG Offspring (F2) genotype

XB

Y

XBXB

XBY

XBXG

XGY 1:1:1:1 X BXB:XBXG:XBY:XGY

Offspring (F2) phenotype Black female:Tortoiseshell female: Black male: Ginger male

10...