Genetics Exam 2

Semiconservative replication

Each new DNA molecule contains one old and one new strand.

DNA polymerase

Adds nucleotides to the growing DNA strand.

Nucleosomes

DNA wrapped around histones.

Telomerase

Adds repeating DNA sequences to chromosome ends.

Hydrogen bonds

The type of bond that holds the two strands of DNA together.

SRY gene

Triggers the formation of testes in embryos.

Dosage compensation

Only one X chromosome is active in each female somatic cell.

Barr body

An inactivated X chromosome.

Complete androgen insensitivity

A syndrome caused in an XY individual.

Anti-Müllerian hormone (AMH)

Responsible for causing degeneration of female ducts in male embryos.

Metacentric chromosome

A chromosome with a centromere at the center.

Karyotype

A visual display of chromosomes arranged by size and shape.

Trisomy

A condition characterized by the presence of an extra chromosome.

Nondisjunction

The failure of chromosomes to separate properly during meiosis.

Amniocentesis

A test for genetic and developmental defects in a fetus.

Complex trait

A trait involving multiple genes and environmental factors.

Discontinuous trait

A trait that falls into distinct categories.

Continuous variation

Phenotypic traits that show a range of values.

Polygenic traits

Traits controlled by two or more genes.

Regression to the mean

Offspring of extreme phenotypes tend to have average traits.

Heritability

Measures how much of a trait's variation is due to genetics.

Epigenetics

Involves reversible changes that affect gene expression.

Monozygotic twins

Genetically identical twins.

High concordance rate in MZ twins

Suggests a genetic component to the trait.

Correlation coefficient

Used to measure the degree of similarity between traits.