| A | B |
|---|
| heredity | transmission of traits from one generation to the next |
| variation | differences between members of the same species |
| genes | a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA |
| gametes | reproductive cells that are the vehicles that transmit genes from one generation to the next; egg and sperm |
| sexual reproduction | two parents give rise to offspring that have unique combinations of genes inherited from the two parents |
| somatic cell | any cell other than those involved in gamete formation (have 46 chromosomes in humans) |
| karyotype | display of the chromosome pairs of a cell arranged by size and shape |
| homologous chromosome | two chromosomes that are have the same length, centromere position, and straining pattern |
| sex chromosome | distinct chromosomes referred to as X and Y that determine the sex of the organism |
| autosomes | other chromosomes that are not sex-determining chromosomes |
| genetics | scientific study of heredity and hereditary variation |
| diploid cells | any cell with two chromosome sets; number of chromosomes are abbreviated as 2n |
| haploid cells | cells that have a haploid number of chromosomes abbreviated as n |
| fertilization | the union of gametes, culminating in fusion of their nuclei |
| zygote | fertilized egg; diploid because it contains the sperm and the egg, which are diploid; mitosis of the zygote and its decendants generate all the somatic cells of the body |
| alternation of generations | both diploid and haploid stages are multicellular; exhibited by plants and some algae |
| sporophyte | found in organisms that have alternation of generations; the multicellular diploid form that results in the union of gametes; produces haploid spores by meiosis that develop into gametophytes |
| gametophyte | found in organisms that have alternation of generations; the multicellular haploid form that produces haploid gametes by mitosis; haploid gametes unite and develop into sporophytes |
| meiosis I | first division of a two-stage process of cell division in sexually reproducting organisms that results in cells with half the number of chromosome sets as the original cell |
| meiosis II | 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 |
| 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; results in cells with half the number of chromosome sets as the original cell |
| crossing over | genetic rearrangement between nonsister chromatids; reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis |
| synapsis | pairing and physical connection of replicated homologous chromosomes during prophase I of meiosis |
| independent assortment | the first meiotic division results in each pair sorting its maternal and paternal homologs into daughter cells independently of every other pair |
| recombinant chromosomes | individual chromosomes that carry genes (DNA) derived from two different parents |
| character | heritable feature that varies among individuals, such as flower color |
| trait | each variant of character, such as purple or white color for flowers |
| true-breeding | reffering to plants that produce offspring of the same variety when they self-pollinate |
| hybridization | mating or crossing of two-true breeding varieties |
| alleles | alternative versions of a gene |
| dominant allele | determines the organism's appearance |
| recessive allele | has no noticeable effect on the organism's appearance |
| homozygous | an organism that has a pair of identical alleles for a character |
| heterozygous | an organism that has two different alleles for a gene |
| phenotype | organisms appearance or observable traits |
| genotype | the genetic make up of an organism |
| law of independent assortment | each pair of alleles segregates independently of each other pair of alleles during gamete formation |
| complete dominance | situation in which the phenotypes of the heterozygote and dominant homozygote are indistinguishable |
| incomplete dominance | situation in which the phenotype of heterozygotes is intermediate between the phenotypes of individuals homozygous for either allele |
| codominance | situation in which the phenotypes of both alleles are exhibited in the heterozygote because both alleles affect the phenotype in separate, distinguishable ways |
