1 / 94

GENETICS

This chapter covers the basics of genetics, including vocabulary terms, Mendel's experiments, predicting traits using Punnett squares, and an introduction to human genetics, including sex-linked disorders.

lroberto
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 Chapters 11, 12-4 & 14

  2. INTRO TO GENETICS Chapter 11

  3. I. Genetics Vocabulary A. GENETICS = STUDY of howtraits are passed from parent to offspring B. HEREDITY = passing of traits from parents to offspring C. TRAIT=inherited characteristic

  4. D. GENE – located on chromosomes, control traits. E. ALLELE – different forms of same gene/trait Ex: Trait = hair color Alleles = black, brown, blonde, red

  5. 1) Dominant = masks/hides recessive trait • use CAPITAL letters 2) Recessive–ishidden if dominant allele is present; can only be seen when both are present • use lowercase letters

  6. Ex: Brown hair (B) is dominant over blonde hair (b) • Bb_______ • bb_______

  7. F. Genotype = genetic makeup of organism • usually have 2 alleles • Ex: Bb, Tt, Gg, Hh

  8. 1) Homozygous = both alleles are alike (Purebred) Ex: CC, aa 2) Heterozygous = alleles are different (Hybrid) Ex: Tt, Bb

  9. G. Phenotype = physical appearance determined by genotype Ex: Brown hair, tall, green eyes, curly hair.

  10. II. History of Genetics A. GregorMendel = “Father of Genetics” (1850’s)

  11. 1) Mendel’s Conclusions Bb a. Every trait has 2 factors. b. Law of Segregation 1. Genes are separated during the formation of gametes Example B b

  12. c. Law of Independent Assortment = Genes for different traits are distributed to gametes independently

  13. III. Predicting the Traits of Offspring A. Punnett Square = predicts probability of inheriting certain traits

  14. To do Punnett Square problems, there are 4 major steps. You must show all 4 steps to get full credit!!!

  15. Example 1) In fruit flies, long wings (L) are dominant to short wings (l). Two heterozygous long-winged fruit flies (both Ll) are crossed. What are the possible genotypes of their offspring? What are the phenotypes?

  16. 1. Make a key: L = long wings l = short wings 2. Show the cross between the parents: Ll x Ll

  17. 3. Draw the Punnett Square: L l L LL Ll Ll ll l

  18. 4. Answer the question: Genotypes = Phenotypes =

  19. Example 2) In peas, the color yellow is dominant to the color green. A homozygous yellow pea plant is crossed with green plant. What will the genotypes and the phenotypes of all the possible offspring be?

  20. 1. Make a key: Y = yellow pea plant y = green pea plant 2. Show the cross between the parents: YY x yy

  21. 3. Draw the Punnett Square: Y Y y Yy Yy y Yy Yy

  22. 4. Answer the question: Genotypes = _______ Phenotypes = ________

  23. IV. Other Genetic Possibilities A. Incomplete dominance = 2 alleles influence phenotype • neither allele is dom. • 2 alleles BLEND

  24. Ex: Red flowers (RR) crossed with white flowers (rr) make pink flowers (Rr). What percent of the offspring would be red, white and pink when you cross two pink flowers?

  25. Key: RR = red rr = white Rr = pink Cross: Rr x Rr

  26. Punnett Square: R r RR Rr R rr Rr r

  27. Answer: 25% = red (RR) 50% = pink (Rr) 25% = white (rr)

  28. B. Codominance – both alleles are expressed in phenotype • neither allele is dom. • NOBLENDING of alleles Ex: red x white ---> red & white spottedflowers

  29. C. Multiple Alleles = traits controlled by 3 or more alleles of the same gene Ex: Human blood types • 3 diff. alleles: A, B & O • 4 blood types: A, B, AB & O • A & B codominant; both dominant over O

  30. D. Polygenic Trait = trait controlled by more than one gene and therefore more than two alleles. Can change over life time • Most traits are polygenic • Ex: skin color, eye color, hair color, height, etc.

  31. Dihybrid Crosses A. Def: cross between 2 pairs of contrasting traits * Use a 16-box Punnett Square!!

  32. Ex: In pea plants, the color yellow (Y) is dominant to green (y) and round texture (R) is dominant to wrinkled (r). Give the phenotype ratios when you cross two plants with YyRr genotypes.

  33. Key: Y = yellow y = green R = round r = wrinkled Cross: YyRr x YyRr

  34. Before you do the Punnett square, you need to determine the gametes 1st to put across the top/down the side! DO NOT PUT ONE LETTER PER ROW/COLUMN!

  35. yR yr YR Yr YYRR YYRr YyRR YyRr YR YYRr YYrr YyRr Yyrr Yr YyRR YyRr yyRR yyRr yR yr YyRr Yyrr yyRr yyrr

  36. Answer: 9 Yellow & Round pea plants 3 Yellow & Wrinkled pea plants 3 Green & Round pea plants 1 Green & Wrinkled pea plant

  37. Human Genetics

  38. I. Vocab: A. Genes on chromosomes #1-22 = AUTOSOMAL B. Pair #23- Genes on sex chromosomes = SEX-LINKED

  39. II. Human Genome Project A. Completed in 2003 • International scientific project • Identified over 92% of our genes • HUGE science advancement

  40. HUMAN GENOME PROJECT • VIDEO CLIP

  41. III. Sex Linkage A. If sex-linked, it is X-linked (on X chr.) or Y-linked(on Y chr.) B. X chr. much LARGER than Y chr., so it carries more genes.

  42. IV. Sex-linked Disorders A. Colorblindness = cannot distinguish certain colors (red-green most common) • recessive X-linked • males more likely to be colorblind

  43. WHY? • males only need 1 recessiveX to be colorblind • females must have 2recessiveX to be colorblind

  44. B. Hemophilia = disorder where blood does not clot • recessive X-linked • men more likely to have hemophilia

  45. SEX LINKED DISORDERS • VIDEO CLIP- Hemophilia

More Related