chapter 7 Flashcards
two chromosomes: one from mother, one from father; same length and general appearance
homologous chromosomes
chromosome pairs 1-22; genes not directly responsible for the sex of an organism
autosomes
X and Y; female: XX, male: XY
sex chromosomes
sex cells
gametes
nuclear division that divides one diploid cell into four haploid cells
meiosis
one half of a duplicated chromosome
chromatid
differences in the genetic material of individuals in a population
genetic variation
arrangement of any one homologous pair does not depend on the arrangement of any other homologous pair
independent assortment
the exchange of chromosome segments between homologous chromosomes
crossing over
distinguishing characteristics that are inherited
traits
the mating of two organisms
genetic cross
a piece of DNA that provides a set of instructions to a cell to make a certain protein
gene
any of the alternative forms or versions of a gene that may occur at a specific locus
allele
two of the same alleles at a specific locus
homozygous
two different alleles at the same locus
heterozygous
an organism’s actual genetic makeup
genotype
the actual physical characteristics or traits of an individual
phenotype
the allele that is expressed when two different alleles or two dominant alleles are present
dominant
the allele that is only expressed when two recessive copies occur together
recessive
heterozygous phenotype is somewhere between the two homozygous phenotypes
incomplete dominance
both alleles of a gene are equally expressed and appear in the phenotype
codominance
multiple genes contribute to the overall phenotype observed
polygenic trait
genes that modify other genes
epistasis
