Meiosis and Sexual Life Cycles
Terms
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- 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
- 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
- chiasma
- The X-shaped, microscopically visible region representing homologous chromatids that have exchanged genetic material through crossing over during meiosis
- clone
- (1) A lineage of genetically identical individuals or cells. (2) In popular usage, a single individual organism that is genetically identical to another individual. (3) 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 synapsis of meiosis I
- 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 cell such as an egg or sperm
- gametophyte
- The multicellular haploid form in organisms undergoing alternation of generations that mitotically produces haploid gametes that unite and grow into the sporophyte generation
- 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
- Chromosome pairs of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci
- karyotype
- A method of organizing the chromosomes of a cell in relation to number, size, and type
- life cycle
- The generation-to-generation sequence of stages in the reproductive history of an organism
- locus
- A particular place along the length of a certain chromosome where a given gene is located
- 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
- meiosis I
- The first division of a two-stage process of cell division in sexually reproducing organisms that results in cells with half the chromosome number of 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 chromosome number of the original cell
- recombinant chromosomes
- Chromosomes created when crossing over combines the DNA from two parents into a single chromosome
- sex chromosomes
- One of the pair of chromosomes 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 the gametes of the two parents
- somatic cell
- Any cell in a multicellular organism except a sperm or egg cell
- spore
- In the life cycle of a plant or alga undergoing alternation of generations, a meiotically produced haploid cell that divides mitotically, generating a multicellular individual, the gametophyte, without fusing with another cell
- sporophyte
- The multicellular diploid form in organisms undergoing alternation of generations that results from a union of gametes and that meiotically produces haploid spores that grow into the gametophyte generation
- synapsis
- The pairing of replicated homologous chromosomes during prophase I of meiosis
- syngamy
- The process of cellular union during fertilization
- tetrad
- A paired set of homologous chromosomes, each composed of two sister chromatids
- variation
- Differences between members of the same species
- zygote
- The diploid product of the union of haploid gametes in conception; a fertilized egg