AP Bio Chapter 12 Vocab

Mendelian inheritance

The concept that genes are inherited according to Mendel's laws, which involves dominant and recessive traits.

Chromosome theory of inheritance

The theory that genes are located on chromosomes and that chromosome behavior during meiosis explains Mendel's laws.

Sex-linked genes

Genes that are located on sex chromosomes, mainly affecting traits linked to the X chromosome.

Barr body

The inactivated X chromosome in female mammals, which is highly condensed.

Aneuploidy

An abnormal number of chromosomes resulting from nondisjunction during meiosis.

Trisomy

A condition where an individual has three copies of a particular chromosome (2n + 1).

Monosomy

A condition in which an individual is missing one copy of a chromosome (2n - 1).

Recombination frequency

The proportion of offspring that exhibit new combinations of traits due to crossing over during meiosis.

Linkage map

A genetic map based on recombination frequencies that shows the relative positions of genes on a chromosome.

Linked genes

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

Crossing over

The exchange of genetic material between homologous chromosomes during meiosis, which can create recombinant chromosomes.

Polyploidy

A condition where a cell has more than two complete sets of chromosomes, often resulting from complete nondisjunction.

Parental type

An offspring with a phenotype that matches one of the true-breeding parental (P generation) phenotypes; also refers to the phenotype itself.

Nondisjunction

An error in meiosis or mitosis in which members of a pair of homologous chromosomes or sister chromatids fail to separate properly from each other.

Duplications

An aberration in chromosome structure due to fusion with a fragment from a homologous chromosome, such that a portion of a chromosome is duplicated.

Inversions

An aberration in chromosome structure resulting from reattachment of a chromosomal fragment in a reverse orientation to the chromosome from which it originated.

Translocations

An aberration in chromosome structure resulting from attachment of a chromosomal fragment to a nonhomologous chromosome.