What is Hereditary?

Vocabulary• Hereditary: passing physical

characteristics from parent to offspring• Trait: specific characteristic• Genetics: scientific study hereditary• Fertilization: new organism forms when

egg, sperm cells join• Purebred: offspring many generations

have same form of trait• Gene: factors control trait• Alleles: different forms genes• Dominant allele: trait always shows up in

organism when allele present

Vocabulary• Recessive allele: hidden whenever dominant allele

present• Hydrid: organism with 2 different alleles

Gregor Mendel• Why did different pea plants have different

characteristics?• Same tall, some short• Some green seeds, some yellow seeds• Traits similar to parents

Experiments

• pistil produces female sex cell-egg

• Stamen produces pollen• Male sex cell- sperm• Egg, sperm cell join into

fertilization• Pollen reaches pistil pea• Pollination• Pea plants self pollinating• Mendel crosses pollinated

pea plants• Contrasting traits- short, tall

F1, F 2 Offspring

• Purebred tall crossed with purebred short

• F1- parent• F-2 fillal- daughter, son• Outcome all tall• Short trait disappear• Self pollinated• 2nd generation- ¾ tall• ¼ short

Other Traits

• Flower color• Seed shape• Only 1 form trait 1st generation• F2 lost trait• Reappeared ¼ plants

Alleles

• Set genetic info• Controls inheritance• Female contributes 1st trait• Male contributes 2nd trait• 1 factor masked

Alleles

• Traits controlled by alleles inherited

• Some dominant• Some recessive• Purebred tall- 2 tall• Purebred short- 2 short• F1- one short, one tall• Hybrid• All tall- short allele masked

Symbols alleles

• Dominant- CAPITAL LETTER• Recessive- lowercase letter• T- TALL• T- short• 2 dominant- TT• Two recessive- tt• Tt- Tall- recessive trait

masked