BIO 103: Ch. 15 Vocab - Chromosomes, Mapping, and Meiosis

Chromosomal Theory of Inheritance

a basic principle in biology stating that genes are located at specific positions on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns

Autosome

A chromosome that is not directly involved in determining sex; not a sex chromosome.

Sex Chromosome

A chromosome responsible for determining the sex of an individual

Y Chromosome

One of two sex chromosomes; in mammals and in Drosophila, male individuals have a Y chromosome and an X chromosome; the Y determines maleness

X Chromosome

One of two sex chromosomes; in mammals and in Drosophila, female individuals have two X chromosomes

X-linked Gene

A gene located on the X chromosome; such genes show a distinctive pattern of inheritance. Sex-linked traits are determined by a gene carried on the X chromosome and absent on the Y chromosome

X Chromosome Inactivation

Developmental shutdown of one of the two X chromosomes in the cells of female mammals

Law of Independent Assortment

Formally part of Mendel's second law.... phenomenon where each pair of alleles (=gene copies) segregates, or assorts, independently of each other pair during gamete formation (meiosis); applies when genes for two characters are located on different pairs of homologous chromosomes or when they are far enough apart on the same chromosome to behave as though they are on different chromosomes (separate due to crossing over)

Linked Genes

Genes located close enough together on a chromosome that they tend to be inherited together

Genetic Recombination

General term for the production of offspring with combinations of traits that differ from those found in either parent

Crossing Over

The reciprocal exchange of genetic material between non-sister chromatids during prophase I of meiosis

Parental Type

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

Recombinant Type

An offspring whose phenotype differs from that of the true-breeding P generation parents; also refers to the phenotype itself

Genetic Map

An ordered list of genetic loci (genes or other genetic markers) along a chromosome

Nondisjunction

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

Maternal Inheritance

A module of uniparental inheritance from the female parent; for example, in human’s mitochondria and their genomes are inherited from the mother

Genomic Imprinting

A phenomenon in which expression of an allele in offspring depends on whether the allele is inherited from the male or female parent

Epigenetic Inheritance

Cell-t0-cell and organism-to-organism inheritance of a trait that does not involve alterations to DNA. This is thought to be mediated by changes in chromatin structure that do not alter the DNA itself

Genetic Counseling

The process of evaluating the risk of genetic defects occurring in offspring, testing for these defects in unborn children, and providing the parents with information about these risks and conditions