Meiosis Vocabulary

asexual reproduction
A type of reproduction involving only one parent that produces genetically identical offspring by budding or by the division of a single cell or the entire organism into two or more parts.
autosome
A chromosome that is not directly involved in determining sex, as opposed to a sex chromosome.
centromere
The centralized region joining two sister chromatids.
chiasma
(plural, chiasmata) The X-shaped, microscopically visible region representing homologous chromatids that have exchanged genetic material through crossing over during meiosis.
crossing over
The reciprocal exchange of genetic material between nonsister chromatids during synapsis of meiosis I.
diploid cell
A cell containing two sets of chromosomes (2n), one set inherited from each parent.
Down syndrome
A human genetic disease resulting from having an extra chromosome 21, characterized by mental retardation and heart and respiratory defects.
fertilization
The union of haploid gametes to produce a diploid zygote.
gamete
A haploid cell such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.
genetic recombination
The general term for the production of offspring with new combinations of traits inherited from the two parents.
genome
The complete complement of an organism's genes; an organism's genetic material.
haploid
A cell containing only one set of chromosomes (n).
homologous chromosomes
Chromosome pairs 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 method of organizing the chromosomes of a cell in relation to number, size, and type.
meiosis
A two-stage type of cell division in sexually reproducing organisms that results in cells with half the chromosome number of the original cell.
nondisjunction
An accident of meiosis or mitosis, in which the members of a pair of homologous chromosomes or sister chromatids fail to move apart properly.
polyploid
Cells that contain more than two complete sets of homologous chromosomes in each somatic cell.
sexual reproduction
A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the two parents.
sister chromatids
Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II.
somatic cell
Any cell in a multicellular organism except a sperm or egg cell.
trisomy 21
A condition in which there are three number-21 chromosomes, which can cause Down syndrome.
zygote
The diploid product of the union of haploid gametes in conception; a fertilized egg.