11/26

1. 11/26 • Pick Up Applications of Genetics Notes Packet • Pick Up Practice Problems Worksheet. • HAPPY Tuesday!!! 

2. Applications of Genetics

3. Incomplete dominance and Codominance • When one allele is NOT completely dominant over another (they blend) – incomplete dominance Example: In carnations the color red (R) is incompletely dominant over white (r). The hybrid color is pink. Give the genotypic and phenotypic ratio from a cross between 2 pink flowers. RrX Rr R r R r Genotypic = 1 RR : 2 Rr : 1 rr Phenotypic = 1 red : 2 pink : 1 white

5. When both alleles are expressed – Codominance Example: In certain species of chickens black feathers (FB) are codominant with white feathers (FW). Heterozygous chickens have black and white speckled feathers. Show the F1 from crossing 2 hybrid chickens. Give the genotypic and phenotypic ratio.

6. FBFB = black FWFW = white FBFW = speckled FB FW FBFW X FBFW FBFB FBFW FB FW FBFW FWFW Genotypic =1 FBFB : 2 FBFW : 1 FWFW Phenotypic = 1 black : 2 speckled: 1 white

8. Sex – linked Traits • Genes for these traits are located only on the X chromosome (NOT on the Y chromosome) • X linked alleles always show up in males whether dominant or recessive because males have only one X chromosome

9. Examples of recessive sex-linked disorders: • colorblindness – inability to distinguish between certain colors (most common red/green) You should see 58 (upper left), 18 (upper right), E (lower left) and 17 (lower right). Color blindness is the inability to distinguish the differences between certain colors. The most common type is red-green color blindness, where red and green are seen as the same color.

10. 2. hemophilia – blood won’t clot (blood clotting factor VIII defective)

11. 3. Duchenne muscular dystrophy – wasting away of skeletal muscles

12. Example: A female that has normal vision but is a carrier for colorblindness marries a male with normalvision. Give the expected phenotypes of their children. N = normal vision n = colorblindness XNXnXXN Y XN Xn XN Phenotype: 1normal vision female 1 normal vision female (carrier) 1 normal vision male 1 colorblind male Y

13. HW: PROBLEMS 1-5 • Have a great Thanksgiving Break !!

14. 12/2 • Get out your practice problems • Get out a spare sheet of paper for Warm-UP. • Get out your Genetics Applications Notes Packet. • TEST CORRECTIONS – NEXT THREE DAYS • IF YOU MISSED THE TEST COME SEE ME!

15. Warm - UP • Define Codominance and Incomplete Dominance and give an example of each. • Name the three recessive sex-linked disorders discussed last Tuesday. • Which gender is most affected by sex-linked disorders and why?

16. Pedigrees • Graphic representation of how a trait is passed from parents to offspring • Tips for making a pedigree • Circles are for females • Squares are for males • Horizontal lines connecting a male and a female represent a marriage • Vertical line and brackets connect parent to offspring • A shaded circle or square indicates a person has the trait • A circle or square NOT shaded represents an individual who does NOT have the trait • Partial shade indicates a carrier – someone who is heterozygous for the trait

17. Example: Make a pedigree chart for the following couple. Dana is color blind; her husband Jeff is not. They have two boys and two girls. HINT: Colorblindness is a recessive sex-linked trait. • XnXn XNY Has trait Can pass trait to offspring

18. Multiple Alleles • 3 or more alleles of the same gene that code for a single trait • In humans, blood type is determined by 3 alleles – IA, IB, and iO BUT genes come in pairs, so each human can only inherit2 alleles • Codominant – IA, IB Recessive –iO • 2.Blood type – A = IAIA or IAiO B = IBIB or IBiO AB = IAIB • O =iOiO

19. Example: A woman homozygous for type B blood marries a man who is heterozygous type A. What will be the possible genotypes and phenotypes of their children? • IBIB X IAiO IB IB IA IAIB IAIB iO IBiO IBiO Genotypic = 2 IAIB : 2 IBiO Phenotypic = 2 AB : 2 B

20. Polygenic Inheritance • Effect of 2 or more geneson a single phenotypic characteristic • Examples: eye color, skin color, height, body mass

21. Skin color: dark is dominant to light, genes are not linked • Ex: aabbcc = very light • AABBCC = very dark • AaBbCc = medium color – 3 dominant, 3 recessive • AABbcc = medium color – 3 dominant, 3 recessive • Disorders that are polygenic: autism, diabetes, cancer

22. 12/4 • Get out your Practice Problems Worksheet + Notes • Reminder all test corrections need to be completed by today. • Quiz tomorrow • Grab worksheets from my desk • Get out a blank sheet of paper for Warm-UP

23. 12/5 • Turn in “Sex Linked Traits” worksheet to Alpha Sorter. • Grab plastic sleeve and lab procedure • Place procedure in sleeve. • Clear off your desk! • Get ready for quiz! • Turn in Quiz to alpha sorter and begin reading pages 322-324 in the textbook!

24. Warm - UP • List the possible genotypes for members 1-8 on the following Pedigree.

25. Mutations • Mutation – sudden genetic change (change in base pair sequence of DNA) • Can be : Harmful mutations – organism less able to survive:genetic disorders, cancer, death 5 – 8 genes in humans results in death – lethal mutation Beneficial mutations – allows organism to better survive: provides genetic variation Neutral mutations – neither harmful nor helpful to organism • Mutations can occur in 2 ways: chromosomal mutation or gene/point mutation • Only mutations in sex cells are passed from parent to offspring

26. Chromosomal mutation: • less common than a gene mutation • more drastic – affects entire chromosome, so affects many genes rather than just one • caused by failure of the homologous chromosomes to separate normally during meiosis (nondisjunction) • chromosome pairs no longer look the same – too few or too many genes, different shape

27. Examples: Down’s syndrome – (Trisomy 21) 47 chromosomes, extra chromosome at pair #21

28. Turner’ssyndrome – only 45 chromosomes, missing a sex chromosome (X)

29. Klinefelter’s syndrome – 47 chromosomes, extra X chromosomes (XXY)

30. Gene or Point Mutation • most common and least drastic • usuallyonly one gene is altered

31. Examples: Recessive gene mutations: Sickle cell anemia – red blood cells are sickle shaped instead of round and get stuck in the blood vessels – can cut off blood supply to organs – heterozygous condition protects people from malaria

32. Cystic fibrosis– mucusclogs lungs, liver and pancreas • Tay-Sachs Disease – deterioration of the nervous system – early death

33. Phenylketonuria (PKU) –an amino acid common in milk cannot be broken down and as it builds up it causes mental retardation – newborns are tested for this • Dominant gene mutations: • Huntington’s disease –gradual deterioration of brain tissue, shows up in middle age and is fatal • Dwarfism – variety of skeletal abnormalities

34. 12/6 • Place all books, bags, etc…by overhead projector. • DO NOT TOUCH ANYTHING ON YOUR DESKS • Grab “Rainbow DNA Lab” if you haven’t already. • 1-2nd: Grab “DNA Fingerprinting” article • Start reading procedure!

35. Gel Electrophoresis