Biology Genetics 9th grade

Chromosomes

threadlike structures made of DNA molecules that contain the genes.

Genes

Sequence of DNA that codes for protein and thus determines a trait.

DNA

(biochemistry) a long linear polymer found in the nucleus of a cell and formed from nucleotides and shaped like a double helix

Mitosis

Part of eukaryotic cell division during which the cell's nucleus divides.

Gametes

Sex cells

Egg

animal reproductive body consisting of an ovum or embryo together with nutritive and protective envelopes

Sperm

Male reproductive organ.

Zygote

Feritilized egg.

Meiosis

Process by which the number of chromosomes per cell is cut in half through the seperation of homologous chromosomes in a diploid cell.

Spermatogenesis

development of spermatozoa

Oogenesis

development of ova

Testes

The male gonads, which produce sperm and secrete male sex hormones.

Ovary

produces eggs

Homologous Chromosome

one of a matching pair of chromosomes, one inherited from each parent

Diploid

Term used to refer to a cell that contains both sets of homologous chromosomes.

Haploid

Term used to refer to a cell that contains only a single set of chromosmes and therfore only a single set of genes.

Genetics

Scientific study of heredity.

Gregor Mendel

Father of Genetics

Heredity

the biological process whereby genetic factors are transmitted from one generation to the next

Stamens

Male part of the flower; made up of an anther and a filament.

Pollen

the fine spores that contain male gametes and that are borne by an anther in a flowering plant

Pistie

the female ovule-bearing part of a flower composed of ovary and style and stigma

Self pollination

when sperm cells in pollen fertilize the egg cells in the same flower; seeds that are produced inherit all of their characteristics from the single plant that bore them

Cross pollination

pollen from one flower transfered to the sticky stigma of another flower

Principle of dominant and recessiveness

States some alleles are dominant and others are recessive.

Dominant

The trait that is most likely to appear in the next generation

Recessive

The trait that is less likely to appear in the next generation

Hybrid

A mixed gene (Gg)

Pure

100% same (GG)

Law of segragation

states that the two alleles for a character segragate when gametes are formed

Genotype

different combinations of alleles

Phenotype

what an organism looks like as a consequence of its genotype

Homozygous

having identical alleles at corresponding chromosomal loci

Heterozygous

having dissimilar alleles at corresponding chromosomal loci

Contrasting traits

Traits that differ from eachother, or do not favor each other.

Law of independant assortment

the law that states that genes seperate independantly of one another in meiosis

Alleles

different forms of a gene

Monohybrid cross

hybridization using a single trait with two alleles (as in Mendel's experiments with garden peas)

Dihybrid cross

hybridization using two traits with two alleles each

Incomplete dominance

Traits that are not fully dominant, nor fully recessive