Ch 10 Meiosis and Heredity Vocab

alternation of generations

A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae.

asexual reproduction

The generation of offspring from a single parent that occurs without the fusion of gametes. In most cases, the offspring are genetically identical to the parent.

autosome

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

chiasmata

The X shaped, microscopically visible region where crossing over has occurred earlier in prophase I between homologous nonsister chromatids. Chiasmata become visible after synapsis ends, with the two homologs remaining associated due to sister chromatid cohesion.

clone

A group of genetically identical individuals or cells. (2) In popular usage, an individual that is genetically identical to another individual. (3) As a verb, to make one or more genetic replicas of an individual or cell. See also gene cloning.

Crossing over

The reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis.

Diploid cell

A cell containing two sets of chromosomes (2n), one set inherited from each parent.

fertilization

The union of haploid gametes to produce a diploid zygote.

gamete

A haploid reproductive cell, such as an egg or sperm, that is formed by meiosis or is the descendant of cells formed by meiosis. Gametes unite during sexual reproduction to produce a diploid zygote.

gene

A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses).

genetics

The scientific study of heredity and hereditary variation.

Haploid cell

A cell containing only one set of chromosomes (n).

heredity

The transmission of traits from one generation to the next.

Homologous chromosomes/homologs/homologous pair.

A pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci. One homologous chromosome is inherited from the organism's father, the other from the mother.

karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

Life cycle

The generation to generation sequence of stages in the reproductive history of an organism.

locus

A specific place along the length of a chromosome where a given gene is located.

meiosis

A modified type of cell division in sexually reproducing organisms consisting of two rounds of cell division but only one round of DNA replication. It results in cells with half the number of chromosome sets as the original cell.

Meiosis l

The first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the number of chromosome sets as the original cell.

Meiosis II

The second division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the number of chromosome sets as the original cell.

Recombinant chromosome

A chromosome created when crossing over combines DNA from two parents into a single chromosome.

Sex chromosome

A chromosome responsible for determining the sex of an individual.

Sexual reproduction

Reproduction arising from fusion of two gametes

Somatic cell

Any cell in a multicellular organism except a sperm or egg or their precursors.

synapsis

The pairing and physical connection of one duplicated chromosome to its homolog during prophase I of meiosis.

Synaptonemal complex

A zipper-like structure composed of proteins, which connects a chromosome to its homolog tightly along their lengths during part of prophase I of meiosis.

variation

Differences between members of the same species.

zygote

The diploid cell produced by the union of haploid gametes during fertilization; a fertilized egg.