Biology Unit 9: Genetics - Vocabulary

allele

allele

one of a number of different forms of a gene

chromatid

one of two identical "sister" parts of a duplicated chromosome

codominance

situation in which the phenotypes produced by both alleles are completely expressed

crossing over

process in which homologous chromosomes exchange portions of their chromatids during meiosis

dominant trait

a trait that appears more frequently than another trait, resulting from interactions between gene alleles

hybrid

offspring of crosses between parents with different traits

diploid

term used to refer to a cell that contains two sets of homologous chromosomes

gamete

sex cell

gene

sequence of DNA that codes for a protein and thus determines a trait; factor that is passed from parent to offspring

genotype

genetic makeup of an organism

haploid

term used to refer to a cell that contains only a single set of genes

heterozygous

having two different alleles for a particular gene

homologous chromosome pair

a pair of homologous chromosomes, or homologs, are a set of one maternal and one paternal chromosome that pair up with each other inside a cell during fertilization

homozygous

having two identical alleles for a particular gene

incomplete dominance

situation in which one allele is not completely dominant over another allele

inherited trait

a trait or variants encoded in DNA and passed from parent to offspring during reproduction

karyotype

micrograph of the complete diploid set of chromosomes grouped together in pairs, arranged in order of decreasing size

meiosis

process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell

chromosomal mutation

involve changes in the number or structure of chromosomes

mendel's laws of inheritance

paired inherited units that control the expression of a character (as height or seed color) separate during germ cell formation so that each sperm or egg receives only one member of each pair, include the Law of Dominance and Uniformity, the Law of Segregation, and the Law of Independent Assortment

non-mendelian inheritance

any pattern in which traits do not segregate in accordance with Mendel's laws

offspring

the product of the reproductive processes of a person, animal, or plant

punnet square

diagram that can be used to predict the genotype and phenotype combinations of a genetic cross

phenotype

physical characteristics of an organism

recessive (trait)

a trait that is expressed only when genotype is homozygous

variation

any difference between the individuals in a species or groups of organisms of any species