alternation of generations
A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte
asexual reproduction
The generation of offspring from a single parent that occurs without the fusion of gametes
Autosome
A chromosome that is not directly involved in determining sex; not a sex chromosome
chiasma
The X-shaped, microscopically visible region where crossing over has occurred earlier in prophase I between homologous nonsister chromatids.
clone
A lineage of genetically identical individuals or cells. In popular usage, an individual that is genetically identical to another individual. As a verb, to make one or more genetic replicas of an individual or cell.
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.
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
A pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci.
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.
meiosis I
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
A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from both parents via the gametes
somatic cell
Any cell in a multicellular organism except a sperm or egg or their precursors.
Synapsis
The pairing and physical connection of duplicated homologous chromosomes during prophase I of meiosis.
synaptonemal complex
A zipper-like structure composed of proteins, which connects two homologous chromosomes tightly along their lengths.
variation
Differences between members of the same species.
Zygote
The diploid cell produced by the union of haploid gametes during fertilization; a fertilized egg.
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