Question

calculate the probability of the albino trait appearing in the offspring if the following cousins and second cousins should marry and reproduce.

IV-1 x III-16, IV-1 x IV-2, and III-4 x III-7

80 II IIII OOOO OUTOCO TO OS clce&E°Cele do | de & HEAT

Answer 1

Answer :

As 2 and 4 are not affected its not x linked recessive. Of II generation.

Its not X linked dominant then 14 could not have affected. So is autosomal dominant.

Hence the inheritance is autosomal recessive.

Let diseased be c and dominant normal be C.

So 1, of Ist 5 of II ,14 and 6 of III are cc.

Cc are 2 of I generation and 1,3,7 of II generation.

2, 6 of II generation are CC.

4 and 8 of II generation are Cc.

1,2,3,4 of III generation are

	C	c
C	CC	Cc
C	CC	Cc

50% chance Cc that is normal carrier or 50% normal dominant.

6 of third generation is cc.

5, 7, 8 of III generation could be

	C	c
C	CC	Cc
c	Cc	cc

2/3 chances to become Cc heterozygous normal or 1/3 chances to become CC homozygous normal.

11,12,13 of III generation could be all Cc heterozygous normal.

14,15,16,17 could be 2/3 Cc heterozygous normal or 1/3 CC homozygous normal. As seen in previous punnet square.

9,10 of generation III is not cc. Can be Cc or CC.

8 is 33% CC or 66% Cc So 75% C gamete or 25% c gamete.

9 is 50% CC or Cc here also 75% C and 25 % c

So 1 of IV th generation is

	C	C	C	c
C	CC	CC	CC	Cc
C	CC	CC	CC	Cc
C	CC	CC	CC	Cc
c	Cc	Cc	Cc	cc

9/16 chance CC homozygous normal or 6/16 Cc heterozygous normal.

11 of III generation is Cc and 10 could be 50% cC or 50% CC.

So gametes are C or c and 75% C and 25% c

So 2 of IV th generation is

	C	c
C	CC	Cc
C	CC	Cc
C	CC	Cc
c	Cc	cc

4/8 Cc heterozygous normal or 3/8 CC homozygous normal.