1 / 14

Dihybrid Crosses

Dihybrid Crosses. Figuring out the probability of passing on 2 separate genes at the same time. Monohybrid Cross. Looking at a single gene. H = widow’s peak h = no widow’s peak Cross Hh x Hh. Results = 75% Widow’s, 25% none. Dihybrid Cross.

alize
Télécharger la présentation

Dihybrid Crosses

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. Dihybrid Crosses Figuring out the probability of passing on 2 separate genes at the same time.

  2. Monohybrid Cross • Looking at a single gene. • H = widow’s peak • h = no widow’s peak Cross Hh x Hh Results = 75% Widow’s, 25% none

  3. Dihybrid Cross • A cross between two individuals looking at 2 different genes at the same time. • For example: • H = widow’s, h = none • L = long 2nd toe, l = short 2nd toe • Cross 2 people heterozygous for both HhLl x HhLl

  4. 1. Figure out Gametes Using FOIL method HhLl x HhLl • First • Outside • Inside • Last HL HL D/D Hl Hl D/r hL hL r/D hl hl r/r

  5. 2. Plug Gametes into outside of 16 box Punnett Square

  6. 3. Figure out the genotypes

  7. 4. Figure out phenotype #s • D/D – Widow/Long = 9 • D/r – Widow/Short = 3 • r/D – None/Long = 3 • r/r – None/Short = 1

  8. Pedigrees • Shows a pattern of inheritance in a family for a specific trait (phenotype) • Genotypes can usually be determined • Why would we want to use a pedigree in genetics?

  9. Track the occurrence of diseases such as: • Hemophilia– sex-linked recessive – causes person to bleed • Huntington’s– simple dominant – lethal allele – causes breakdown of the brain • Cystic fibrosis – 1/2500 – mucus accumulates (white North Amer.) • Tay-Sachs disease – lipids accumulate in CNS (Jewish)

  10. Huntington’s – Lethal Dominant

  11. Pedigree of Queen Victoria AKA: family tree Graphic representation of family inheritance. Pedigree Analysis

  12. The Symbols used:

  13. Inheritance patterns: • The disease is never passed from father to son. • Males are much more likely to be affected than females. • Trait or disease is typically passed from an affected grandfather, through his carrier daughters, to half of his grandsons. Sex-linked recessive • Examples: • Color-blindness • Duchenne Muscular Dystrophy

  14. Most Confusing Pedigree • I’m my own grandpa…

More Related