Sex-Linked Traits and Pedigrees LT Quiz

What is Sex-Linked Inheritance? Give an example.

Sex linked Inheritance is Inheritance form a gene located on one of the sex chromosomes, examples being hemophilia, pattern baldness, or hairy ears.

What is the difference between X-Linked Dominant, and X-linked recessive?

X-Linked Dominant is when only one dominant allele is needed for the trait to be expressed, X-Linked recessive is females who are x^n x^n, and males who are x^n y, as they express the recessive trait. A female who is X^N x^n is a carrier.

Why can only females be a carrier for a sex-linked trait.

If a person is a carrier, they would need to be heterozygous as they would carry the allele for the trait. Therefore a female can be a carrier. However, a man cannot be a carrier as they only have one X chromosome, therefore they cannot be a carrier.

What is a pedigree?

A family tree that records and traces the occurrence of a trait/ characteristic in a family.

Explain the symbols in a pedigree.

Roman numerals- represent each generation

numbers- represent each member of a generation

parents- connected by Horizontal lines

Darkened shapes- represent individuals who show a trait/ characteristic of interest

What are carriers and when are they present?

Carriers are individuals who do not express the trait but have one allele for a trait, and are only present if the trait is recessive.

How can you determine if the pedigree shows an autosomal or X-Linked disease?

If most of the males are affected, the disorder is most likely X-Linked

If it is 50/50 between men and women, the disease is most likely autosomal.

How can you determine if the disorder is dominant or recessive?

If the disorder is dominant, one of the parents must have the disorder

if the disorder is recessive, neither parent has to have the disorder (they might still have it)

How can the environment impact one’s genotype of phenotype?

The environment can impact one’s genotype as it may cause a