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…

• https://www.youtube.com/watch?v=CBezq1fFUEA

Punnett Squares

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

Let’s Practice…