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Genetics

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Genetics

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  1. Genetics Ch 9 p164 – 178 Ch 12 p221 - 232

  2. History • Gregor Mendel 1850s “Father of Genetics” • Garden Peas • 7 traits • Height, flower position, pod color, pod appearance, seed texture, seed color, flower color • Selectively self and cross pollinated the plants • Obtained pure stains • P generation – parents • F1 generation – the kids • Conclusions: • Traits don’t get inherited together • Every organism gets two copies of a trait • Some are dominant, some are recessive

  3. Genotype- • What the genes say • Rr, homozygous recessive, “big big” • Can’t see it • Phenotype- • What the organism looks or pheels like • Fuzzy, brown, tall • Can see it

  4. Vocab Double check • Allele • Trait • Dominant • Recessive • Cross-Pollination • Self-Pollination • Pure • F1 Generation • P Generation • Law of Independent Assortment • Law of Segregation • Genotype • Phenotype • Homozygous • Heterozygous

  5. Probability • - the likelyhood that something will occur • Everytime, doesn’t matter what happened last time • What are the chances of flipping a coin and getting tails? • 1 out of 2 sides = 50% • What if I just flipped a tail? Does that mean next time I WILL get a head? NO WAY!

  6. Study Pages 174 and 175 • Monohybrid cross- • Using a punnett square to predict the chance that an offspring will have a certain trait • 4 boxes • Dihybrid Cross- • Looking at TWO traits at the same time • 16 boxes • Punnett Square- • A tool used to predict offspring • One parent goes on the side, other goes on top • A Test Cross- • Used to determine the genotype of an organism

  7. Practice • Homozygous Recessive X Heterozygous Red (red is dominant to white) • Step one: Choose letter based on dominant trait • Hetero = Rr homo recessive = rr • Step two: draw box, fill in parents • 1st named parent or Female goes on TOP • Step three: fill in offspring (kids) always put capital first • Step four: Interpret • 50% are white • 0% are homo dom • 50% are heterozygous

  8. Test Cross • Take an unknown organism and breed it with a pure recessive. Outcome tells you what the unknown parent was.

  9. You do Practice • Homozygous Dominant Purple X White (Purple is dominant to White) • Heterozygous Fuzzy X Heterozygous Fuzzy (Fuzzy is dominant to smooth) • Homozygous Recessive Short X Heterozygous Tall • Heterozygous Inflated X Homozygous Recessive Constricted • Black Rabbit X Brown Rabbit (hint p175) Black is dominant

  10. Homozygous Dominant Purple X White • Heterozygous Fuzzy X Heterozygous Fuzzy • Homozygous Recessive Short X Heterozygous Tall

  11. Hetero Inflated X Homo Recessive Constricted • Black Rabbit X Brown Rabbit

  12. Types of inheritance • Complete Dominance- • One trait totally over powers the other • Red + White = Red • Incomplete Dominance- • Traits will blend in the heterozygous state • Red + White = Pink • Codominance- • BOTH Traits show up • Red + White = Red + White • Sex-Linked- • Inheritence depends on offsprings sex

  13. incomplete dominance • There isn’t a true dominant phenotype so what letter you use isn’t as important • Homozygous Dominant will be one phenotype • Homozygous Recessive will be another phenotype • Heterozygous will be a phenotype between the first two • RR = Red rr = White Rr = Pink • TT = Tall tt = Short Tt = Medium • BB = Blue bb = Red Bb = Purple

  14. codominance • In this type of inheritance BOTH phenotypes are dominant and BOTH show up • Homozygous Dominant will be one phenotype • Homozygous Recessive will be another phenotype • Heterozygous will show both possibilities • PP = Purple P’P’ = White PP’ = One Purple petal, one White petal • BB = Blue B’B’ = Red BB’ = One Blue feather, one Red feather • RR = Red R’R’ = White RR’ = One Red hair, One white hair (this color is found commonly in horses and is known as Roan)

  15. Sex-linked • The genes for a sex-linked trait are found on the X or Y chromosome. • For Females, XX, it works like complete dominance and they need two recessive copies to have that trait. • For Males, XY, since they only get one copy, a single recessive will cause them to have the trait. • Two common conditions are color blindness and hemophilia

  16. Chances of boys and girls

  17. Can a color blind dad give it to his sons? • NO! The gene is on the X and Dad gives Y’s to his sons