I. History• Gregor Mendel conducted the earliest genetic research and is known as the “Father or Genetics” for his discoveries of genes and inheritance• He found organisms closely resembled their parents with slight variations and characteristics are influenced by heredity and the environment
II. Genetics• The branch of biology that studies HEREDITY, which is the passing on of characteristics from parent to offspring during sexual reproduction
III. Conclusions Made by Mendel1. _TRAITS or physical characteristics are influenced by GENES on chromosomes o _GENE: Segment of DNA -1 or more genes can determine a hereditary trait
o There are two types of chromosomes, all having different genes a. _NON-SEX chromosomes(autosomes) b. _SEX chromosomes: X AND YLook at theKaryotype…Which are theautosomes? Which are thesex chromosomes?What is the gender?
2. Genes have alternative forms called ALLELES a. Offspring receives 1 allele from mom and dad (One from each parent) b. _TWO alleles determine how a trait is expressed
Allele combinations on each homologous pair:A. HOMOZYGOUS: HAS IDENTICAL alleles thatresult in a dominant or recessive trait Tall Pea Plant TT Short Pea Plant tt
Allele combinations on each homologous pair:A. HETEROZYGOUS: HAS DIFFERENT alleles thatresult in a dominant or recessive trait • One allele is dominant and one Tall Pea Plant Tt is recessive • DOMINANT: observed or expressed trait (Capital Letter) • RECESSIVE: Weaker or hidden trait (Lower Case Letter)
Skip to Bottom of next page…A. GENOTYPE: The allele combinations of an individual (genetic makeup)Ex. Trait: Flower Color RR Rr rr red red white
B. PHENOTYPE: The physical appearance of anindividualEx. Trait: Eye ColorYou can “see” the phenotype, but you may not besure what alleles are exactly present.