Unit 6 Test Retake: The Human Genome - 1st Period

Front

What is Lesch-Nyhan syndrome?

Back

Lesch-Nyhan syndrome is an X-linked recessive genetic disorder characterized by self-mutilating behaviors, neurological problems, and gout due to the absence of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT).

Front

How do X-linked recessive traits affect males and females differently?

Back

Males with one copy of the allele for an X-linked recessive trait will express the trait, while females need two copies to express it; thus, females can be carriers with one copy.

Front

What is a Punnett Square used for?

Back

A Punnett Square is a diagram used to predict the genetic makeup of offspring from a cross between two parents, showing the probability of inheriting specific traits.

Front

What is the probability of a son inheriting Hemophilia if his mother is a carrier and his father is unaffected?

Back

If the mother is a carrier (X^H X^h) and the father is unaffected (X^H Y), the son has a 0% chance of inheriting Hemophilia.

Front

What does it mean for a trait to be X-linked recessive?

Back

An X-linked recessive trait is one that is located on the X chromosome and requires two copies of the allele for females to express the trait, while males only need one.

Front

What is a point mutation?

Back

A point mutation is a change in a single nucleotide in the DNA sequence, which can result in a different amino acid in a protein or no change at all.

Front

What is androgenetic alopecia?

Back

Androgenetic alopecia is a common form of hair loss in both men and women, often referred to as male or female pattern baldness.

Front

What is the significance of the dominant and recessive alleles in genetic traits?

Back

Dominant alleles mask the effects of recessive alleles; an individual only needs one dominant allele to express the dominant trait.

Front

What is the expected phenotype of a male with one copy of the allele for an X-linked recessive trait?

Back

A male with one copy of the allele for an X-linked recessive trait will express the trait.

Front

What does it mean for a female to be a carrier of an X-linked recessive trait?

Back

A female carrier has one normal allele and one recessive allele for an X-linked trait, meaning she does not express the trait but can pass the recessive allele to her offspring.