Ch. 7 - Cellular Basis of Inheritance

alternation of generations

a life-cycle type in which the diploid and haploid stages alternate

aneuploid

an individual with an error in chromosome number

autosome

any of the non-sex chromosomes

chiasmata (singular = chiasma)

the structure that forms at the crossover points after genetic material is exchanged

chromosome inversion

the detachment, 180° rotation, and reinsertion of a chromosome arm

crossing over (also, recombination)

the exchange of genetic material between homologous chromosomes resulting in chromosomes that incorporate genes from both parents of the organism forming reproductive cells

diploid-dominant

a life-cycle type in which the multicellular diploid stage is prevalent

euploid

an individual with the appropriate number of chromosomes for their species

fertilization

the union of two haploid cells typically from two individual organisms

gametophyte

a multicellular haploid life-cycle stage that produces gametes

germ cell

a specialized cell that produces gametes, such as eggs or sperm

haploid-dominant

a life-cycle type in which the multicellular haploid stage is prevalent

interkinesis

a period of rest that may occur between meiosis I and meiosis II

karyogram

the photographic image of a karyotype

karyotype

the number and appearance of an individuals chromosomes, including the size, banding patterns, and centromere position

life cycle

the sequence of events in the development of an organism and the production of cells that produce offspring

meiosis

a nuclear division process that results in four haploid cells

meiosis I

the first round of meiotic cell division

meiosis II

the second round of meiotic cell division following meiosis I

monosomy

an otherwise diploid genotype in which one chromosome is missing

nondisjunction

the failure of synapsed homologs to completely separate and migrate to separate poles during the first cell division of meiosis

polyploid

an individual with an incorrect number of chromosome sets

recombinant

describing something composed of genetic material from two sources, such as a chromosome with both maternal and paternal segments of DNA

reduction division

a nuclear division that produces daughter nuclei each having one-half as many chromosome sets as the parental nucleus

somatic cell

all the cells of a multicellular organism except the gamete-forming cells

sporophyte

a multicellular diploid life-cycle stage that produces spores

synapsis

the formation of a close association between homologous chromosomes during prophase I

tetrad

two duplicated homologous chromosomes (four chromatids) bound together by chiasmata during prophase I

translocation

the process by which one segment of a chromosome dissociates and reattaches to a different, nonhomologous chromosome

trisomy

an otherwise diploid genotype in which one entire chromosome is duplicated

X inactivation

the condensation of X chromosomes into Barr bodies during embryonic development in females to compensate for the double genetic dose