Question 12 1 point From a threepoint testcross mapping expe

Question 12 (1 point)

From a three-point testcross mapping experiment, the following gamete data is obtained:

ABC 365; abc 367

aBc 110; AbC 105

aBC 4; Abc 3

ABc 25; abC 21

From the above data, what can be said of the genes?

Question 12 options:

All the genes are unlinked

The gene order is ABC

The gene order is ACB

The gene order is CAB

2 of the genes are linked, and one of the genes is independently assorting

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Question 13 (1 point)

From a three-point testcross mapping experiment, the following gamete data is obtained:

ABC 365; abc 367

aBc 110; AbC 105

aBC 4; Abc 3

ABc 25; abC 21

From the above data, what is the distance between gene A and gene B?

Question 13 options:

21.5 mu

4.6 mu

22.2 mu

5.3 mu

27.5 mu

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	All the genes are unlinked
	The gene order is ABC
	The gene order is ACB
	The gene order is CAB
	2 of the genes are linked, and one of the genes is independently assorting

Solution

Answer:

12). The gene order is CAB

13). 22.2 mu

Explanation:

Imagine the order of genes is ABC/abc

1. If single cross over (SCO) occurs between A&B

Normal order= A---------B & a-----b

After cross over= A-----b & a------B

A-----b recombinants are 105+3= 108

a------B recombinants are 110+4 = 114

Total recombinants = 222

RF = (222/1000)*100 =22.2%

2. If single cross over (SCO) occurs between B & C

Normal order= B---------C & b----c

After cross over= B-----c & b------C

B-----c recombinants are 110+25=135

b------C recombinants are 105+21=126

Total recombinants = 261

RF = (261/1000)*100 = 26.1%

3. If single cross over (SCO) occurs between A & C

Normal order= A---------C & a------c

After cross over= A-----c & a------C

A-----c recombinants are 25+3=28

a------C recombinants are 21+4=25

Total recombinants = 53

RF = (53/1000)*100 =5.3%

% RF = Map unit distance

The order of genes is -----

B---------22.2 m.u.---------A----5.3m.u.----C