1 / 14

Heredity and Genetics

Heredity and Genetics. PRINCIPLES OF GENETICS. OVERVIEW “ Like produces like, but not *exactly* like ”. REVIEW: Sexual reproduction → variation due to chromosomes. *HEREDITY: transmission of traits from parents to offspring *GENETICS: science of heredity. A History Lesson.

cosima
Télécharger la présentation

Heredity and Genetics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Heredity and Genetics

  2. PRINCIPLES OF GENETICS • OVERVIEW • “Like produces like, but not *exactly* like” REVIEW: Sexual reproduction → variation due to chromosomes *HEREDITY: transmission of traits from parents to offspring *GENETICS: science of heredity

  3. A History Lesson *Gregor Mendel: 1822-1884 *monk in monastery @ Czechoslovakia *Vienna- studied science and math- became a teacher *2 yrs later- returned to monastery; plant experiments *1866- published data from 8 years of experiments *1900- finally genetics recognized as major development *Mendel’s Experiments: *Studied pea plants (b/c clearly express traits like flower color, seed shape, seed color, and plant height) *large sample sizes- help ensure actual ratios present in population

  4. *crossed “different” plants → ex. Purple flowers x white flowers *offspring of parental cross = first filial generation (F1) *offspring of 2nd cross = 2nd filial generation (F2) *Mendel produced 929 offspring– 705 were purple (3:1 ratio) *DOMINANT TRAIT: form of a trait that dominates another trait; (prevents expression of another trait) (ex. Purple flowers) *appears in F1 generation *RECESSIVE TRAIT: hidden in F1 generation

  5. *MENDEL’S HYPOTHESIS: *Mendel’s experiments saw recessive trait disappear in F1 generation but reappear in F2 generation *ASSUMPTION: for each trait, there must be a pair of factors- 1 comes from egg; 1 from sperm * “Factors” = GENES: contain information for every trait *Represented by symbols or letters *Capitals = dominant *lowercase = recessive EX. W= purple, w= white

  6. *ASSUMPTION: 2 genes segregate during gamete formation *offspring = ratio depending on genes present EX. WW x ww parents Ww Ww Ww Ww F1 Ww x Ww WW Ww Ww ww F2 RESULTS: 1WW : 2Ww: 1ww 3 purple: 1 white (similar to 705: 929)

  7. *EASIER TO SEE WITH PUNNETT SQUARES: *Chart used to determine possible combinations of genes among offspring Gametes of 1 parent Gametes of 1 parent W w EX: Ww x Ww W w

  8. *TEST OF SEGREGATION: 3:1 ratio 1st time but what if Ww x ww??? MAKE YOUR PUNNETT SQUARE: W w w Ww ww *****50% white: 50% purple!!! w Ww ww

  9. GENETICS TERMINOLOGY *ALLELE: either of 2 alternative forms of gene for particular trait ex. W or w *GENOTYPE: combo. of alleles for certain trait ex. WW, Ww, or ww *PHENOTYPE: appearance of trait ex. “purple” or “white” *HOMOZYGOUS: 2 of same alleles for given trait ex. RR, rr (deals w/ seed shape) or WW or ww *HOMOZYGOUS DOMINANT: 2 dominant alleles (WW) *HOMOZYGOUS RECESSIVE: 2 recessive alleles (ww) *HETEROZYGOUS: 2 different alleles for a trait ex. Rr or Ww

  10. Pedigree charts *are used to help determine the possible genotypes of parents and offspring

  11. karyotypes *are used to analyze the chromosomes present in a person

  12. TIME TO PRACTICE PUNNETT SQUARES!!

More Related