Genetics

Chromosomes Autosomes: chromosomes that do not contain genes that determine the sex of an individual Sex chromosomes: chromosomes that contain genes that determine the sex of an individual

Sex Determination Sex determination: one sex chromosome determines the sex of the organism In humans eggs have an X chromosome and sperm have either an X or a Y chromosome

Fruit Fly Karyotype

Chicken Karyotype

Dog Karyotype

Chromosome mapping Chromosome mapping: a diagram that shows where genes are located on each chromosome

Genes Gene: a section of DNA that codes information for making proteins. Genes are located on Chromosomes

Alleles Allele- an alternative form of a gene Represented by letters of the alphabet Dominant-masks the other traits Capital letters Recessive-hidden by dominant trait Lower case letters

Traits Trait: a characteristic that is determined by what genes an organism has

Traits and Heredity Dominant trait: masks the other traits Capital letters Recessive trait: hidden by dominant trait Lower case letters Homozygous: has 2 of the same allele for a gene (AA or aa) Heterozygous: has 2 different alleles for the same gene (Aa)

Heredity Heredity: the passing of traits from parent to offspring

Traits and Heredity Genotype: an organisms genetic makeup (alleles that are on our chromosomes) Phenotype: an organisms appearance (traits that are expressed)

Gregor Mendel The father of genetics Austrian monk who worked on genetics with pea plants

Mendel’s Laws 1. The Law of Segregation: during the formation of gametes (sperm and egg) the two copies of each hereditary factor separate so that offspring acquire one factor from each parent 2. The Law of Independent Assortment: the hereditary factors separate randomly during the formation of gametes 3. The Law of Dominance: one factor in a pair of traits dominates the other in inheritance

Vocabulary True-breeding: pure, always produces offspring with the same traits Self-pollination: sperm pollinates egg in the same plants Cross-pollination: sperm pollinates egg in a different plant

Vocabulary Hybrid Cross: Cross between parents with one differing trait P or P₁: Parental Generation F₁: First Generation offspring F₂: Second Generation offspring

Mendel’s Experiments

Punnett Squares Punnett Square: predicts the genetic probabilities of offspring

Punnett Squares

Punnett Squares

Dihybrid crosses Dihybrid cross: 2 traits are tracked because the genes move together R: round r: winkled Y: yellow y: green

Dihybrid crosses

Other forms of inheritance Incomplete Dominance: neither allele is completely dominant over the other

Other forms of Inheritance Co-dominance: both alleles are expressed

Sex-linked Traits Sex-linked: determined by the x chromosome Males will be affected more than females because males only have one X chromosome