1 / 17

Understanding Mendel's Laws of Genetics: Homozygous, Heterozygous, Alleles, and More!

Explore Mendel's 3 laws of genetics, dihybrid crosses, and traits inheritance through homozygous, heterozygous, alleles, genotypes, and phenotypes. Learn about dominant/recessive traits, monohybrid crosses, and the contributions of Gregor Mendel, the "Father of Genetics."

pollock
Download Presentation

Understanding Mendel's Laws of Genetics: Homozygous, Heterozygous, Alleles, and More!

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! Chapter 9

  2. Objectives • Define homozygous, heterozygous, allele, genotype, phenotype. • Understand Mendel’s 3 laws • Perform a Dihybrid cross.

  3. What we already know… • Dominant/Recessive • Alleles • Genotypes • Phenotypes • Heterozygous/Homozygous • Monohybrid Crosses (Punnett Squares with 1 trait!)

  4. Gregor Mendel • “Father of Genetics” • Austrian Monk that studied pea plants • Pure breeds • Self Fertilization • Cross Polination • Discovered how traits were inherited in a population

  5. W w Sperm Mendel’s 3 Laws • 1. Law of Segregation • Each allele a person has separates into different gametes • Ex. Ww – one W goes in one sperm and the other w goes into another sperm w W

  6. 2. Law of Independent Assortment Gene pairs (homologous) will separate randomly into gametes Mendel’s 3 Laws

  7. Mendel’s 3 Laws • 3. Law of Dominance • Traits exist in two possible forms (dominant and recessive) • The dominant forms hides the recessive trait in the heterozygous condition

  8. Mendel’s Crosses • P Generation: • F1 Generation: • F2 Generation:

  9. Monohybrid Cross • If Fred Flintstone is heterozygous for black hair. • (B=Black, b=blonde) • What is Fred’s genotype? • What is Fred’s phenotype? • Tweety bird is yy. (Y= yellow feathers, y=brown feathers) • 1. What is his genotype? • 2. What is his phenotype? • 3. Is he heterozygous or homozygous? Explain.

  10. Dihybrid Crosses • Set up: • 1. Determine parent genotypes • 2. Determine alleles to be passed down • 3. Set up punnet square • 4. Determine outcome • Phenotype Ratio • Genotype Ratio

  11. Dihybrid Crosses • Looking at two different traits • Ex. Hair color and eye color • B=brown eyes • b=blue eyes • R=Brown hair • r=blonde hair • Mother is heterozygous for both traits • Father is heterozygous for eye color and homozygous dominant for hair color

  12. Incomplete Dominance • Heterozygous phenotype is an intermediate phenotype between the two homozygous phenotypes. • Two alleles are blended • Ex) Four O’clock Flowers • Red + White = Pink

  13. Codominance • Neither trait is dominant instead, both traits are shown (No Blending) • Ex) Roan Cows • Red + White = REDANDWHITE

  14. Traits determined by more than 2 alleles Ex. Blood Typing (3 alleles ABO) A and B are dominant to O Multiple Alleles

  15. Sex Linked Traits • Traits located on the sex chromosomes (X or Y) • X linked: gene is located on the X chromosomes • Y linked: gene is located on the Y chromosome

  16. Example Sex-Linked Problem • In humans, normal vision (XC) is dominant to colorblindness (Xc) and is sex-linked.  A normal-visioned man, whose father was colorblind, marries a colorblind woman.  What are the chances that a son will be colorblind.  A daughter? 

  17. Homework! • Inheritance problems worksheet. Due Friday/Monday (whenever I see you!)

More Related