Bio- Intro to Genetics

Early Ideas

• theory of blending

  • mother and father’s traits are blended in the offspring

• Deeper experimentation show complex heredity

Gregor Mendel

• born in 1822 in Czech Republic

• entered monastery at 21 in Brno

  • originally wanted to do physics

• worked in the garden and did pea experiments

• published work in 1866

Flower Structure

• Pistil- female reproductive structure

• ovules- eggs

• ovary- female gonad that makes eggs

• stigma- where pollen enters

• style- connects stigma to ovary

• stamen- male reproductive structure

• Anther- male gonad

• pollen- plant sperm

• filament- holds the anther

• sepal- protects developing bud

• pedicle- attaches flower to stem

• petal- attracts pollinators

Pollination

• self pollination

  • flower pollinates itself

• cross pollination

  • when 2 flowers pollinate each other

Mendel’s Peas

• contrasting traits

  • either/or, not blended

  • ex: tall/short, yellow/green

• pure breeding

  • when self pollinated all offspring looks like parents

Cross Pollinated Plants

• round X wrinkled

• yellow X green

• called original P generation

• called first gen F1

• called second gen F2

Results

• P- round X wrinkled

• F1- all round

• F2- ¾ round, ¼ wrinkled

Explanations

1. First explanation

   • individual factors that don’t blend control each trait- Gene

   • genes occur in contrasting forms- alleles

2. Principle of dominance

   • dominant allele will be expressed even if present with recessive

   • recessive allele will only be expressed without dominant present

3. Principle of Segregation

   • 2 alleles per trait

   • when gametes are formed alleles separate- 1 allele per trait

   • fertilization restores the pair of alleles

4. Principle of Independent Assortment

   • alleles for one trait segregate independently from the alleles of any other trait

Punnett Squares

• way to look at different alleles

• pure breeding

  • round must be round, RR

  • wrinkled must be wrinkled, rr

• used to predict possible gamete combos

Vocab

• Monohybrid- differing in one trait

• Di- 2

• tri- 3

• genotype- the genetic makeup of something

• Homozygous- both alleles are the same

• Heterozygous- has different alleles for a trait

• Phenotype- physical characteristic of an organism