How many of the male offspring of parents 1 and 2 were normal?

Question

ScanSolve AI Tutor · Accepted Answer

A person with one recessive allele for colour-blindness (X^c) may not be colour-blind if they are female. Step 1: Females have two X chromosomes (XX). Step 2: A female can be heterozygous: X^N X^c, where X^N is the dominant allele for normal vision. Step 3: The dominant X^N allele masks the recessive X^c allele, so she has normal colour vision. Males with a similar allele are colour-blind. Step 1: Males have one X and one Y chromosome (XY). Step 2: A male with the recessive allele has genotype X^c Y. Step 3: There is no second X chromosome with a dominant X^N allele to mask X^c. Step 4: The recessive allele is expressed, so he is colour-blind. The trait is X-linked recessive.

How many of the male offspring of parents 1 and 2 were normal?

Answer

Step-by-step solution

Females have two X chromosomes (XX).

A female can be heterozygous

The dominant $X^N$ allele masks the recessive $X^c$ allele, so she has normal colour vision.

Males have one X and one Y chromosome (XY).

A male with the recessive allele has genotype $X^c Y$ .

There is no second X chromosome with a dominant $X^N$ allele to mask $X^c$ .

The recessive allele is expressed, so he is colour-blind.

Still stuck on this one?

More Biology Questions

How many of the male offspring of parents 1 and 2 were normal?

Answer

Step-by-step solution

Females have two X chromosomes (XX).

A female can be heterozygous

The dominant XNX^NXN allele masks the recessive XcX^cXc allele, so she has normal colour vision.

Males have one X and one Y chromosome (XY).

A male with the recessive allele has genotype XcYX^c YXcY.

There is no second X chromosome with a dominant XNX^NXN allele to mask XcX^cXc.

The recessive allele is expressed, so he is colour-blind.

Still stuck on this one?

More Biology Questions

The dominant $X^N$ allele masks the recessive $X^c$ allele, so she has normal colour vision.

A male with the recessive allele has genotype $X^c Y$ .

There is no second X chromosome with a dominant $X^N$ allele to mask $X^c$ .