Transcript CH # 3C
CHAPTER 3C Section 1 • HEREDITY – The passing of traits from parent to offspring FATHER OF GENETICS… • Gregor Mendel--born 1822 *Austrian monk *(21)bad test taker *returned to work in lab Unraveling the Mystery… • Why did he choose to work with the Pea Plant? • Fast Growing • Self-Pollinating – can fertilized it’s own eggs Eggs- produced by an ovule on Stigma Sperm-produced by Anther Cross-Pollinating – can fertilize another plant Mendel only worked with ONE characteristic at a time • Characteristicfeature that has different forms in a population • Trait – different forms of a characteristic Mendel’s st 1 Experiment….. • Work with all 7 characteristics, but did them separately • Cross True-breeding dominant plants with true-breeding recessive plants for the same characteristic • Ex) Pure Purple Flowers x Pure White Flowers • First generation had all one color (PURPLE) • Dominant – one that appears most often • Recessive – on that appears least often Mendel’s Second Experiment….. • He then self-pollinated these 1st generation plants • Results - some had PURPLE (DOMINANT) and some were recessive (white) • Ratio – 3:1 in second generation Section 2 • Genes – instructions for an inherited trait • Alleles – different forms of a gene – Dominant (capital letters) – Recessive (lowercase letters) Genotypes….. Types of genes that are present • PP • Pp • pp Phenotype….. The physical appearance of the organism • Ex) PP-----Purple Pp-----Purple pp-----white • PP - Pure Purple Pure Dominant True Purple True Dominant Homozygous Purple Homozygous Dominant • Pp - Heterozygous • pp - - Pure White - Pure Recessive - True White - True Recessive - Homozygous White - Homozygous Recessive Punnett Squares….. • Used to organize all the possible outcomes of the offspring from a particular set of parents Probability…. • The chance that something will occur Ex) Flip of a coin Boy or girl Roll of the die Paper/rock/scissors Genotype Probability….. Rr rr • PP x PP 100% PP • PP x Pp 50% PP, 50% Pp • PP x pp 100% Pp • Pp x Pp 25% PP, 50% Pp, 25% pp • Pp x pp 50% Pp, 50% pp • pp x pp 100% pp Incomplete Dominance….. • Snapdragons- Red x white = Pink • Both show their affect One Gene….Many Traits Many Genes, One Trait….. Section 3 • Meiosis…..process used to make the sex cells • Male Sex Cell – Sperm • Female Sex Cell - Egg Sperm….. Egg….. • Meiosis…. • REDUCTION • DIVISION • Process to make sex cells Meiosis Video: 60131.mov Sex Chromosomes….. Sex-Linked Disorders….. • Carried on the Xchromosome • Males are more likely to get this disease Pedigrees….. Selective Breeding….. • WHY ???? • Examples: Horses Dogs Humans