Sex linkage

Question 1

In humans, sex chromosomes are X and Y. What do human females present as in their chromosomes?

Answer 1

As females have two X chromosomes, all the gametes are the same in that they contain a single X chromosome

Question 2

In humans, sex chromosomes are X and Y. What do human males present as in their chromosomes?

Answer 2

As males have one X chromosome and one Y chromosome, they produce two different types of gamete

half have an X chromosome and half have a Y chromosome

Question 3

Which chromosome is longer, the X chromosome or the Y chromosome?

Answer 3

The X chromosome

Question 4

The X chromosome is much longer than the Y chromosome, what this result in when considering allele presentation?

Answer 4

For most of the length of the X chromosome, there is no equivalent homologous portion of the Y chromosome. These characteristics that are controlled by recessive alleles on the non homologous portion of the X chromosome will appear more frequently in the male.

Question 5

Why do certain characteristics appear more frequently in a male rather than a female.

Answer 5

This is because there tends to be no homologous portion on the Y chromosome that might have the dominant allele, so the recessive allele on the X chromosome cannot express itself

Question 6

What is an X linked genetic disorder?

Answer 6

An X linked genetic disorder is a disorder caused by a defective gene on the X chromosome