Genetics
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Transcript of Genetics
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 traitP or P₁: Parental GenerationF₁: First Generation offspringF₂: 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: roundr: winkledY: yellowy: 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