Alleles
an alternative form of a single gene may have for a particular trait passed from generation to generation.
Dominant
the form of the trait that appeared.
Dihybrid Cross
generation that is heterozygous for both traits. (uses two alleles each.).
F1 Generation
first filial generation, offspring of the parent cross.
F2 Generation
second filial generation; offspring from the F1 cross.
Gene
DNA on chromosomes that is arranged in segments that control the production of proteinds. (functional unit that controls inherited trait expression that is passed on from one generation to another generation.).
Genetics
science of heredity.
Genetic Recombination
new combination of genes produced by crossing over and independent assortment.
Genotype
an organism's allele pairs. (ex. Tt.).
Genotypic Ratio
the proportions of genotypes found in individuals after cross. (ex. Aa X Aa ratio : 1:2:1 ratio.).
Gregor Mendel
Austrian monk and plant breeder, made findings on the method and the mathematics of inheritance in the garden through pea plants. called the father of genetics.
Complete Dominance
a kind of dominance wherein the dominant gene completely masks the effect of the recessive gee in heterozygous condition.
Heterozygous
organism with two different alleles for a specific trait. (ex. Tt.).
Homologous Chromosomes
one of two paired chromosomes, one from each parent, that carries genes for a specific trait at the same location.
Homozygous
organism with two of the dame alleles for a specific trait. (ex. TT.).
Hybrids
organism heterozygous for a specific trait. (offspring of genetically dissimilar parents of stock.).
Monohybrid Cross
a cross that involves hybrids for a single trait. ( genetic cross between 2 genetically identical individuals, a cross between two individuals that are heterozygous for a single trait or gene.).
P1 generation
parent generation; the first set of parents crossed in which their genotype is the basis for predicting the genotype of their offspring, which in turn, may be crossed. (filial generation.).
Law of Independent Assortment
Mendelian law stating that a random distribution of alleles occurs during the formation of gametes.
Law of Segregation
Mendelian law stating that two alleles for each trait separate during meiosis.
Punnett Square
in genetics, a type of grid used to show the gametes of each parent and their possible offspring; a type of grid that can indicate all the possible outcomes of a genetic cross; also called a checkerboard.
Recessive
Mendal's name for a specific trait hidden or masked in the F1 generation.
Phenotype
observable characteristics that is expressed as a result of an allele pair.
Phenotypic ratio
ration that shows varied outcomes that result from a genetic cross and is based on physical appearance alone.
Probability
a number expressing the likelihood of the occurrence of a given event.
Carrier
individual heterozygous for a recessive disorder such as cystic fibrosis or Tay-Sams disease. (has the recessive trait for the disease, but does not have the disease.).
Codominance
complex inheritance pattern that occurs when niether allele is dominant and both alleles are expressed.
Incomplete Dominance
complex inheritance pattern in which the heterozygous phenotype is intermediate between those of the two homozygous parent organism.
Multiple Alleles
having more that two alleles for a specific trait.
Nondisjunction
cell division in which the sister chromatids do not separate correctly, resulting in gametes with abnormal number of chromosomes.
Polygenic Trait
characteristic, such as eye color or skin color, that results from the interaction of multiple gene pairs.
Sex-Linked Trait
characteristic, such as re-green colorblindness, controlled by the henes on the x chromosome; also called an X-linked trait.
Cross- Pollination
transferring a male gamete from a flower to the female reproductive organ in a flower of another plant. (transfer pollen of flower to have a different genetic construction.).
Heredity
the transmission of genetic characteristics from parent to offspring (dependent on segragtion and recombination of genes, resulting in genesis of new individuals.).
Self- Fertilization
common in flowering plants, when , the fusion of sperm and egg that are produced by the same individual organism, usually in flowering plants when a male gmaete within a flower combines with a female gamete in the same flower.
Purebred
PARENTS HAVE THE SAME ALLELES. of or pertaining to an animal, all of whose ancestors derive over many generations from a recongnized bred., an organism that always produces offspring with the same form of a trait as the parent
Self- Pollination
transfer of pollen from the anther to the stigma of the same flower, another flower of the same plant, or the flower of a plant of the same clone.
Testcross
A METHOD FOR DETERMINING WHETHER AN ORGANISM THAT SHOWS A DOMINANT TRAIT IS PURE DOMINANT FOR THAT TRAIT OF WHETHER IT IS HETEROZYGOUS.a cross between an organism whose genotype for a certain trait is unknown and an organism that is homozygous recessive f
True-Breeding
homozygous for the true breeding traits. (sometimes called purebred, is an organism haing certain biological traits which are passed on to all generations.).
Trait
a genetically determined characteristic or condition.
Walter Sutton
American geneticist and physician whose most significant contribution to biology today was his theory that the Mendelian laws of inheritance could be applied to chromosomes at the cellular level of living organisms (Boveri- Sutton Chromosome Theory.).