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Mendelelian Genetics

This informative text explains Gregor Mendel's findings in Mendelian genetics, including the laws of dominance and segregation. It also introduces the concept of meiosis and discusses the importance of genetic variability. Punnett squares are used to illustrate genetic crosses and the inheritance of traits.

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Mendelelian Genetics

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  1. I CAN: TELL THE ROLE OF MEIOSIS IN GENETIC VARIABILITY. Mendelelian Genetics

  2. Gregor Mendel(1822-1884) • Studied the inheritance of traits in pea plants • Developed the laws of genetics • aka “Father of Genetics”

  3. Mendel stated that physical traits are inherited as “particles” Mendel did not know that the “particles” were actually GENES Particulate Inheritance

  4. Genetic Terminology • Trait - any characteristic that can be passed from parent to offspring • Heredity - passing of traits from parent to offspring • Genetics - study of heredity

  5. Punnett Square A diagram used to show the probability of a trait being present in offspring.

  6. “Genes” • Alleles - two forms of a gene (dominant & recessive) • Dominant - stronger of two genes. Expressed in a cross; represented byacapital letter (R) • Recessive - gene that shows up less often in a cross; is dominated or overpowered by the dominant gene; represented by alowercase letter (r)

  7. More Terminology • Genotype – genetic makeup orgene combination for a trait(e.g. RR, Rr, rr) • Phenotype - the physical feature resulting from a genotype(e.g. red, white)

  8. Genotypes • Homozygousgenotype - gene combination where both alleles are alike (e.g. RR or rr); also calledpure bred  • Heterozygousgenotype - gene combination where the alleles are different (e.g. Rr); also calledhybrid

  9. Mendel’s Laws

  10. Law of Dominance • Some alleles are dominant and some are recessive. • When combined in a hybrid, the dominant overpowers the recessive.Like  Rr • The dominant form of the trait ALWAYS shows in the phenotype if ONE dominant gene is present.

  11. Law of Dominance

  12. Law of Segregation During meiosis, the two alleles responsible for a trait separate from each other. (when the homologous chromosomes separate) Alleles for a trait are "recombined" at fertilization Study diagram!!!

  13. Law of Segregation

  14. Assignments For Today!! Begin Spongebob Practice Sheet Watch Video to Better Understand How to use Punnett Squares. Practice Doing Punnett Squares – Spongebob Worksheet. Complete Lecture Quiz Paper Pet Genetics Power Notes Let’s Practice Using SpongeBob!!!

  15. Female Parent Meiosis M E I O S I s Male Gametes Female Gametes Male Parent DOING PROBABILITY!!

  16. GENOTYPE vs. PHENOTYPE B – brown eyes (dominant) b – blue eyes (recessive) What are the possible genotypes for brown eyes? What are the possible genotypes for blue eyes? W – widow’s peak ( ? ) w – no widow’s peak ( ? ) Possible genotypes for having a widow’s peak: Possible genotypes for not having a widow’s peak:

  17. HETEROZYGOUS vs. HOMOZYGOUS F – free earlobe (dominant) f – attached earlobe (recessive) FF – homozygous Ff – ff - H – hitchhiker’s thumb ( ? ) h – no hitchhiker’s thumb ( ? ) HH – hh – Hh -

  18. PUNNETT SQUARES

  19. Trait: Seed Shape Alleles: R – Round r – Wrinkled Cross:Homozygous Roundseeds x HeterozygousRound seeds Genotype: Phenotype:GenotypicRatio: PhenotypicRatio:

  20. Female Parent Meiosis M E I O S I s Male Gametes Female Gametes Male Parent

  21. Female Parent Meiosis M E I O S I s Male Gametes Female Gametes Male Parent

  22. TRAITS FOR THE MALE…

  23. TRAITS FOR THE FEMALE…

  24. Complete at least 2 Punnett Squares Using Parents Genotypes…Show the Percents. Female Parent Meiosis M E I O S I s Male Gametes Female Gametes Male Parent

  25. Last Part of Project • Pick a DIPLOID # for your ORGANISMS and Draw a Karotype like the one on page 168 • Be sure the last pair gives THE sex of each organism. • Lastly, write or type a one page paper that explains the following: • ITS NICHE (TOTAL WAY OF LIFE • TYPE OF REPRODUCTION, ADAPTATIONS) • DIET (CARNIVORE, HERBIVORE OR OMNIVORE) • HABITAT..(NAME THE BIOME ) DESCRIBE THE CLIMATE • YOUR HYPOTHESIS ABOUT HOW IT WENT EXTINCT • ANY OTHER INTERESTING BIOLOGY STUFF YOU WOULD LIKE TO ADD TO SHOW THE TEACHER YOU ARE LEARNING 

  26. Types of Genetic Crosses • Punnett Square - cross involving a single traite.g. flower color • AKA Monohybrid cross • Dihybrid cross - cross involving two traits e.g. flower color & plant height

  27. Seed color Seed shape • Examines the cross of 2 different traits Y = Yellow (dominant) y = green (recessive) R = Round (dominant) r = wrinkled (recessive) Cross 2 heterozygous yellow, heterozygous round plants: what are the genotypes?

  28. Law of Independent Assortment Alleles for differenttraits are distributed to the gametes independently of one another. This law can be illustrated using dihybrid crosses.

  29. Y = Yellow y = green R = Round r = wrinkled YyRr YyRr

  30. LAW PARENT CROSS OFFSPRING DOMINANCE TT x tttall x short Tt 100% tall SEGREGATION Tt x Tttall x tall 75% tall 25% short INDEPENDENT ASSORTMENT RrGg x RrGground & green x round & green 9/16 round seeds & green pods 3/16 round seeds & yellow pods 3/16 wrinkled seeds & green pods 1/16 wrinkled seeds & yellow pods Summary of Mendel’s laws

  31. Non-Mendelian Inheritance

  32. + Incomplete Dominance One trait is not dominant over the other. The offspring’s trait is a MIXTURE of the 2 parents.

  33. Codominance One trait is not dominant over the other. BOTH alleles are expressed in the offspring. = + WW BB WB

  34. + Homozygous Red Homozygous White = Roan

  35. Human Blood type AA or AO BB or BO AB OO

  36. EXIT TICKET……. • COMPLETE ALL PARTS OF THE MONSTERS GENETICS WORKSHEET • BE SURE TO DRAW AND COLOR MIKE… • YOU WILL NEED GREEN AND YELLOW

  37. GENETICS WITH A SMILE • EACH PARENT CREATE YOUR OWN BABY BASED ON IT’S TRAITS.. • INCLUDE THE FOLLOWING ON YOUR BABY’S PICTURE: • BABY’S NAME & PARENT’S NAME • BIRTHDAY • CUTE HAIR BOW IF A GIRL! • NICE NECK-TIE IF A BOY!

  38. SEX LINKED TRAITS • Genes located on sex chromosomes are called sex-linked genes. • Y chromosome genes in mammals are responsible for male characteristics. • X chromosome genes in mammals affect many traits.

  39. SEX LINKED TRAITS * Most sex linked (X-linked) disorders are recessive and show up only in males. * Females are carriers of sex linked disorders

  40. Order of dominance: brown > green > blue. POLYGENETIC TRAIT • Trait produced by 2 or more genes that interact • Human skin color • Human eye color

  41. -Male without trait -Male with trait -Male carrier -Female without trait -Female with trait -Female carrier PEDIGREES • A pedigree is a chart for tracing genes in a family • Trace phenotypes to infer the genotypes Autosomal genes: widow’s peak -Male carrier

  42. M – normal color vision m - colorblind Sex Linked genes: colorblindness -Male without trait -Male with trait -Male carrier -Female without trait -Female with trait -Female carrier

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