Chapter 13 - Genetics Notes Gregor Mendel

UNIT 6 GENETICS

DNA = Genes Genes vs. Alleles Genes are characteristics passed down from the parental generation to the next. Alleles – the different forms of genes. Example: The forms for genes for Tall plant & Short plant - the different forms of the genes are the alleles

Law of Segregation This occurs during meiosis when gametes form, the chromosomes get separated.

Law of Independent Assortment The chromosomes are separated from each other randomly.

Genes Principle of Dominance – when one allele (trait) is expressed over another allele. Example if the organism has a gene for black hair and a gene for brown hair, but the “SEEN” gene is black hair. Which one is dominant?

Dominant vs. Recessive The dominant trait is expressed over the recessive gene. Genotype = the genetic makeup = BB or Bb Phenotype = the “SEEN” trait = black or brown hair color. The recessive trait is the gene that is only “SEEN” if the dominant gene is not there. Example: bb = brown rabbit

Punnett Square A simple way to predict the results of crossing two different genotypes: Rr x Rr

Pedigree