1 / 22

GENETICS

GENETICS. Why do you look like that?!?. A little background…. Gregor Mendel- “Father of Genetics” Austrian monk and biologist in the mid-1800s Used pea plants to figure out how traits were inherited (passed down). Vocabulary. Genetics : the study of heredity, or how genes are inherited.

tab
Download Presentation

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. GENETICS Why do you look like that?!?

  2. A little background… • Gregor Mendel- “Father of Genetics” • Austrian monk and biologist in the mid-1800s • Used pea plants to figure out how traits were inherited (passed down)

  3. Vocabulary Genetics: the study of heredity, or how genes are inherited

  4. Allele: variation of a trait; form of a gene ex. Trait- pod color / Alleles- yellow, green

  5. Dominant: allele that can mask the other (uppercase letters- A) • Recessive: allele that can be masked by the other (lowercase letters- a)

  6. Homozygous: both alleles in the pair are the same (AA or aa) • Heterozygous: both alleles in the pair are different (Aa)

  7. Genotype: genetic make-up (the genes) of an organism Ex. Uu or UU • Phenotype: physical appearance expressed by the genes Ex. Unibrow

  8. G – green pea pods g – yellow pea pods (Dominant) (Recessive) Genotypes  GG Gg gg Terms  Phenotypes  Homozygous dominant Heterozygous Homozygous recessive Green pea pods Green pea pods Yellow pea pods

  9. Mendel’s Work

  10. Laws of Heredity • Law of Segregation: Two alleles for a trait separate during gamete formation

  11. Laws of Heredity • Law of Independent Assortment: • Alleles from different genes separate independently of one another during gamete formation

  12. Punnett Squares • Used to figure out the possible genotypes and phenotypes (ratios) • Monohybrid cross: one trait of an individual is crossed with the same trait of another individual

  13. Monohybrid Cross Example Let’s look at pea pod color: • Green is dominant (G) and yellow is recessive (g) • Example: Homozygous dominant (GG) crossed with homozygous recessive (gg) G G Genotype ratio 4 Gg: 0 GG: 0 gg 100% Gg g Gg Gg Phenotype ratio 4 green: 0 yellow 100% green g Gg Gg

  14. Punnett Squares • Dihybrid cross: two traits of an individual are crossed with the same two traits of another individual

  15. Dihybrid Cross Example Must find all possible allele combinations: Traits - seed shape and seed color Alleles: R = Round r = Wrinkled Y = Yellow y = green Female: RrYy Male: RrYy both are round and yellow All combinations for each: Female: RY, Ry, rY, ry Male: RY, Ry, rY, ry

  16. Dihybrid Cross Example Cross these combinations to find possible genotypes/phenotypes of offspring: RY Ry rY ry RY RRYY RRYy RrYY RrYy Ry RRYy RRyy RrYy Rryy rY RrYY RrYy rrYY rrYy ry RrYy Rryy rrYy rryy

  17. Dihybrid Cross Example Cross these combinations to find possible genotypes/phenotypes of offspring: Genotype ratio: RRYY 1/16 RRYy 2/16 RrYY 2/16 RrYy 4/16 Rryy 1/16 Rryy 2/16 rrYY 1/16 rrYy 2/16 rryy 1/16 Phenotype ratio: Round and Yellow 9/16 Round and Green 3/16 Wrinkled and Yellow 3/16 Wrinkled and Green 1/16

  18. Types of Dominance: • 1) Complete Dominance- One allele can completely mask another RR- RedRr- Redrr- white

  19. Types of Dominance • Incomplete Dominance: one allele is partially covered by another RR- REDRR’- PINKR’R’- WHITE

  20. Types of Dominance • Co-dominance: Both alleles are dominant, so they both show through RR- REDRW- Red & WhiteWW- White

  21. Types of Dominance • 4) Multiple Alleles- when a trait has more than two alleles • Ex. Blood Type • IA- Type A • IB- Type B • i- Type O • Both complete and co-dominance are shown in creating phenotypes • Type A- IAIA, IAi • Type B- IBIB, IBi • Type AB- IAIB • Type O- ii

  22. Types of Dominance 5) Sex-linked- Allele for trait is found on a sex chromosome • Ex. Hemophilia • Normal- XH • Hemophilia- Xh • Nothing at all- Y

More Related