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Ap Biology Ch. 13
Meiosis and Sexual Life Cycles
Question | Answer |
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heredity | the transmission of traits from one generation to the next |
variation | differences between members of the same species |
genetics | the scientific study of heredity and hereditary variation |
gene | A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA in domr viruses) |
gamete | A haploid cell, such as an egg or sperm. gametes unite during sexual reproduction to produce a diploid zygote |
locus | A specific place along the length of a chromosome where a given gene is located |
asexual reproduction | A type of reproduction involving only one parent that produces genetically identical off spring by budding or by the division of a single cell or the entire organism into two or more parts |
clone | A liniage of genetically identical individuals or cells |
sexual reproduction | A type of reproduction in which two parents give rise to off spring that have unigue combinations of genes inherited from the gametes of the two parents |
life cycle | The generation-to-generation sequence of stages in the reproductive history of an organism |
somatic cell | Any cell in a multicellular organism except a sperm or egg cell |
karyotype | A display of the chromosome pairs of a cell arranged by size and shape |
homologous chromosomes | Chromosome pairs of the same length, centromere position, and staining pattern that possess alleles of the same genes at corresponding loci. One homologous chromosome is inherited from the organism's father, the other from the mother |
sex chromosome | One of the pair of chromosomes responsible for determining the sex of an individual |
autosome | A chromosome that is not directly involved in determining sex, as opposed to a sex chromosome |
diploid cell | A cell containing two sets of chromosomes (2n), one set inherited from each parent |
haploid cell | a cell containing only one set of chromosomes (n) |
fertilization | The union of haploid gametes to produce a diploid zygote |
zygote | The diploid product of the union of haploid gametes in conception; a fertilized egg |
meiosis | A two-stage type of cell division in sexually reproducing organisms that result in cells with half the chromosome number of the original cell |
meiosis I | The first division of a two-stage process of cell divsion 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 divsion in sexually reproducing organisms that results in cells with half the chromosome number of the original cell |
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 |
sporophyte | In organisms undergoing alternation of generations, the multicellular diploid from that results from a union of gametes that meiotically produces haploid spores that grow into the gametophyte generation |
spore | In the life cycle, of a plant or alga undergoing alteration of generations, a meiotically produced haploid cell that divides mitotically, generating a multicellular individual, the gametophyte, without fusing with another cell |
gametophyte | In organisms undergoing alternation of generations, the multicellular haploid form that mitotically produces gametes that unite and grow into the sporophyte genration |
synapsis | The pairing of replicated homologous chromosomes during prohase I of meiosis |
crossing over | The reciprocal exchange of genetic material between nonsister chromatids during prohase I of meiosis |
tetrad | A paired set of homologous chromosomes, each composed of two sister chromatids. Tetrads form during prophase I of meiosis |
chiasma | The X-shaped, microscopically visible region representing homologous chromatids that have exchanged genetic material through crossing over during meiosis |
recombinant chromosome | A chromosome created when crossing over combines the DNA from teo parents into a single chromosome |