Q. A male human is heterozygous for autosomal genes A and B .He is also hemizyous for hameophilic gene g. what prolportion of sperms will carry abg

Options

A. a) `1//8`
B. b) `1//32`
C. c) `1//4`
D. d) `1//16`

Answer

To solve the question regarding the proportion of sperm that will carry the alleles A, B, and G, we can follow these steps:

### Step 1: Understand the Genotype
The male is heterozygous for the autosomal genes A and B, meaning he has one dominant and one recessive allele for each gene. His genotype for these genes can be represented as:
- A = A (dominant)
- a = a (recessive)
- B = B (dominant)
- b = b (recessive)

Additionally, he is hemizygous for the hemophilic gene G, which is located on the X chromosome. Since males have one X and one Y chromosome, his genotype for the hemophilic gene can be represented as:
- X^G (hemophilic allele on X)
- Y (no corresponding allele on Y)

Thus, the complete genotype of the male is:
- A/a, B/b, X^G/Y

### Step 2: Determine Possible Gametes
To find the gametes produced by this male, we need to consider the combinations of alleles he can pass on. The male can produce gametes with combinations of the alleles from the autosomal genes and the sex chromosomes.

1. From the heterozygous genes A and B, the possible combinations are:
- A B
- A b
- a B
- a b

2. From the sex chromosomes, the possible combinations are:
- X^G (carrying the hemophilic gene)
- Y (not carrying the hemophilic gene)

### Step 3: Combine Gametes
Now, we combine the autosomal gametes with the sex chromosome gametes:

- From A B:
- A B X^G
- A B Y

- From A b:
- A b X^G
- A b Y

- From a B:
- a B X^G
- a B Y

- From a b:
- a b X^G
- a b Y

This gives us a total of 8 possible combinations of gametes:
1. A B X^G
2. A B Y
3. A b X^G
4. A b Y
5. a B X^G
6. a B Y
7. a b X^G
8. a b Y

### Step 4: Identify Gametes Carrying A, B, and G
We need to find the proportion of gametes that carry A, B, and G. From the combinations above, only the gametes that include A, B, and X^G will carry all three traits.

The relevant gametes are:
1. A B X^G
2. A b X^G
3. a B X^G
4. a b X^G

Out of the 8 gametes, only 2 (A B X^G and A b X^G) carry both A and B along with G.

### Step 5: Calculate the Proportion
The proportion of sperm that carry A, B, and G is:
- Number of gametes carrying A, B, and G = 2
- Total number of gametes = 8

Thus, the proportion is:
\[ \text{Proportion} = \frac{2}{8} = \frac{1}{4} \]

### Final Answer
The proportion of sperm that will carry A, B, and G is **1:4**.

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