LINKED & SEX-LINKED GENES + HUMAN GENOME

What are linked genes?

Genes located close together on the same chromosome that tend to be inherited together.

In regards to linkage, how does distance from one gene to another affect how closely linked two genes are?

The closer they are, the less likely crossing over will separate them.

Explain this process and why this is the case.

Genes close together rarely recombine because crossing over is less likely to occur between them.

What is a sex-linked gene?

A gene located on a sex chromosome (usually the X chromosome).

Why are sex-linked genes different from autosomal genes?

Males have only one X chromosome, so recessive traits show up more easily.

What unique properties would you look for if a gene is X-linked or Y-linked?

X-linked: appears mostly in males; Y-linked: passed father to son only.

What is the Human Genome Project?

An international effort to map all human genes and their base pair sequences.

What does the project tell us about genetic variation?

Humans are 99.9% genetically similar; small differences explain traits and diseases.

What does this tell us about the composition of our genome?

Most DNA is noncoding; only about 1–2% codes for proteins.

Why might humans want to sequence DNA?

To understand genetic diseases, develop treatments, and study evolution.