Biology Ch12 Review - Intro to Genetics

genetics

The scientific study of heredity

complete dominance

a relationship in which one allele is completely dominant over another

incomplete dominance

Situation in which one allele is not completely dominant over another allele - they BLEND

codominance

A condition in which both alleles for a gene are fully expressed

genotype

genetic makeup of an organism (allele combinations, e.g. Bb)

phenotype

An organism's physical appearance, or visible traits. (physically what trait does an organism have, e.g. black fur)

allele

Different forms of a gene

heterozygous

having two different alleles for a trait

homozygous

having two identical alleles for a trait

trait

A characteristic that an organism can pass on to its offspring through its genes. (e.g. fur color)

gamete

sex cell, sperm or egg

hybrid

Offspring of crosses between parents with different traits

Punnett Square

A chart that shows all the possible combinations of alleles that can result from a genetic cross

Multiple alleles

three or more forms of a gene that code for a single trait (e.g. blood type ABO)

meiosis

Cell division that produces reproductive cells in sexually reproducing organisms

diploid

2n - containing two complete sets of chromosomes, one from each parent.

haploid

n - having a single set of unpaired chromosomes

crossing-over

Exchange of genetic material between homologous chromosomes during Prophase I of meiosis