Genetics Study of Inheritance

Reproduction Asexual – Cell divides, creating an identical daughter cell Sexual – Exchange of genetic material, both parents contribute to fertilization of egg/ovary – Increases diversity – In Animals  Egg & Sperm – In Plants  Pollen & Ovary

Heredity We share many similarities with our parents & siblings, but we are not genetically identical due to the mixing of genes

Chromosomes A chromosome is a rod-shaped bundle of DNA In sexual reproduction, each “parent” contributes ½ of the offspring’s genetic info – ½ from “mom’s egg” & ½ from “dad’s sperm” The physical characteristics that show are due to “genetics”

Genes vs Alleles A gene is a section of a chromosome that codes for a specific trait – EX: Eye Color An allele is a variation of that instruction – EX: Brown vs blue eyes Every gene has 2 alleles, which we represent with a single letter (capital or lowercase) – BB or Bb or bb

Genotype vs Phenotype Genotype  the Genetic code – BB Phenotype  the Physical trait – Brown eyes

Dominant vs Recessive Alleles A dominant allele (represented by a capital letter), if present, shows that specific trait – BB or Bb = Brown Eyes A recessive allele (represented by a lowercase letter), must have both alleles to show a trait – bb = Blue eyes

If both letters are the same, BB or bb, we say it is HOMOZYGOUS (dominant or recessive) If both letters are different, Bb, we say it is HETEROZYGOUS

Look at this… HH = Does not have trait Hh = Does not show trait, but is a carrier hh = shows trait Trait could be anything inheritable, such as baldness or albinism

Let’s watch this video… zq1fFUEA zq1fFUEA

Punnett Squares We can predict the outcome of offspring by using a PUNNETT SQUARE

Let’s Practice…