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Genetics

Genetics. Solving Punnett Squares. Vocabulary. Heredity – parent traits appear in offspring Allele – One version of a gene Gene – DNA code for a protein  a trait. Dominant trait – Trait appears even with only one copy of the gene.

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Genetics

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  1. Genetics Solving Punnett Squares

  2. Vocabulary • Heredity – parent traits appear in offspring • Allele – One version of a gene • Gene – DNA code for a protein  a trait

  3. Dominant trait – Trait appears even with only one copy of the gene. • Recessive trait – Trait appears only with two recessive alleles • Homozygous – (Purebred) – two of the same alleles (AA or aa) • Heterozygous – (Hybrid) – two different alleles (Aa)

  4.  Genotype – the DNA for a trait i.e. R or r. •  Phenotype – the appearance of a trait determined by a genotype, i.e. round or wrinkled peas.

  5. Try these possibilities in HW

  6. Now use two letters from above to fill in 2 genes for each of the following individuals

  7. Cross a hybrid white flower with a homozygous purple flower The heterozygote (hybrid) trait must be dominating the recessive trait Ex. If Hh is hybrid. Then hybrid means one of each. If the Dominant is expressed then white is dominant because white is the trait that is expressed.

  8. Seven Steps to Solve The heterozygote (hybrid) trait must be dominating the recessive trait 1. Dom = white Rec= purple 2. Dom= H rec=h 3. Ma= Hh Pa= hh 4. 5/6. 7. Genotypes = 50% Hh and 50% hhPhenotypes = 50% White 50% Purple Pa H h h h

  9. Try This • In a certain plant, tall stems are dominant to short stems. A farmer crosses a short-stemmed flower with a homozygous long-stemmed flower. Complete each of the steps.

  10. 1. Dom = T Rec =t 2. T = Tall t = short 3. Ma: TT Pa: tt 4. Pa T T t t • Genotypes: 100% T t • Phenotypes: 100% Tall

  11. CoDominance • There are many different ways that we type blood. Today, we’ll look at two systems, ABO and the Rh- factor. ABO Typing: • Each red blood cell has proteins on its surface that let the body identify it as belonging to yourself. Genes “A” and “B” are Co-Dominant genes. Gene “o” is the recessive gene.

  12. Sample Problem for Blood Type:Mom is hybrid type B blood, Dad is hybrid type A blood. 5/6. 7. Genotypes = 25% AB, 25% Ao, 25% Bo, 25% ooPhenotypes = 25% AB, 25% A, 25% B, 25% O 1. Dom = A & B Rec= o 2. A or B o 3. Ma= Bo Pa= Ao 4. B o A o

  13. Rh Factor - is a protein found in blood Rh + means the protein is present. Rh – means it is not.Example: Dad is heterozygous Rh+ factor and mom is homozygous for Rh- factor blood. 1. Dom = + Rec= - 2. + - 3. Ma= - - Pa= + - 4. 5/6. 7. Genotypes = 50% - - 50% + -Phenotypes = 50% Rh + 50% Rh- - - + -

  14. What are sex-linked traits? • Traits on the Y or X chromosomes Females are XX Males are XY Which sex chromosome is home of the most sex-linked traits? • X…much, much larger and if any essential gene were on the Y females would not live.

  15. Male Karyotypes:Is this a male or female?

  16. What are examples of traits that are sex-linked? What are examples of traits that are sex-linked? 1)Color blindness – (red-green) 2) Hemophilia 3) Muscular Dystrophy 4) Male pattern baldness

  17. Fill in this table of phenotypes with the correct genotype B = normal b = color blind H = normal h = hemophilia M = normal m = muscular dystrophy How should we write these genotypes to help us remember they are sex-linked? XmXm or XMY M = Normal m = muscular dystrophy

  18. Colorblindness Test

  19. Should See • Circle, Square, star,

  20. Colorblindness

  21. Should see • Square, circle

  22. Try to find in the next picture

  23. Dog, Sailboat, balloon, car

  24. Should have seen • Faint Brown boat, colorblind individuals would have seen nothing.

  25. Try to see.

  26. Should see • Colorblind individuals should see a yellow square. • Normal sight should see circle and square.

  27. Ishihara Test • http://www.toledo-bend.com/colorblind/Ishihara.html

  28. Hemophilia – blood doesn’t clot Czar Nicholas II of Russia and his family, photographed c. 1916, showing his wife Alexandra (who was a carrier of hemophilia), his four daughters, and (in the foreground) his son Alexis, perhaps the most famous European royal with hemophilia. http://www.humanillnesses.com/original/Gas-Hep/Hemophilia.html

  29. Muscular Dystrophy • Muscles form incorrectly, including heart and lungs, slowly deteriorate •  death by early 30’s

  30. Male Pattern Baldness • Some evidence hints at X linked status Androgens (male sex hormones) play a key role in balding--castrated men don't go bald--and the AR gene helps them do their work. The researchers found the balding men were much more likely to have a particular version of the AR gene than the non-balding men, which they took to mean they'd found a genetic variant that triggers baldness. http://www.straightdope.com/columns/050819.html

  31. Sample Problems: • Genotypes and Phenotypes XHXh XhY XBXB XMY XMXm Woman carrier of hemophilia Man with hemophilia Normal Vision Girl Normal boy Woman carrier of muscular dystophy

  32. Color Vision Phenotypes XBXb XbY XBXB XBY Woman carrier of color blindness Man with color blindness Normal Vision Girl Normal boy

  33. Sex Linked traits: Cross a normal male with a female whocarrier for hemophilia. 5/6. 7. Genotypes = 1/4 XH Xh 1/4 Xh Xh 1/4 XhY 1/4 XHY Phenotypes = 50% girls with hemophilia 50% carrier for hemophilia girls, 50% boys have hemophilia 50% boys normal 1. Dom = healthy Rec= hemophilia 2. XH Xh 3. Ma= XHXh Pa=XHY 4. XH Xh XH Y

  34. Incomplete Dominance • Sometimes, depending on the way the different proteins from each allele interact genes don’t completely dominate the alternate allele • Mendel studying 4 o’clocks (flowers) gave up genetic research because of this fact.

  35. Seven Steps to SolveCross an incompletely dominant White flower with a red flower. 1. Dom = Red and White Inc. = Pink 2. R or W or RW 3. Ma=WW Pa=RR 4. • 5/6. • Genotypes = 100% RWPhenotypes = • 100% Pink W W R R

  36. Pedigrees • Looking at ancestor’s traits to predict the genotypes of individuals in a family

  37. Symbols

  38. Add P1, F1, and F2 and genotypes • Decide if disorder is dominant or recessive • Assign disease letters • Fill in only remaining letters you can guarantee • Be brave…use ? If you don’t know

  39. Complete:

  40. Dihybrid Problems • Definition – Genetics Problems with two traits tracked at the same time Try This: • Given B = brown hair, b = blond hair AND T = Tall while t = short. • BbTt = ____________phenotype • Bbtt = ____________ phenotype • bbTT = ____________ phenotype • bbtt = ____________ phenotype

  41. Dihybrids continued • When drawing your sperm and egg for the 7 steps in this type of problem each: • Sperm contains ____ genes? • Egg contains ____ genes? • Predict the sperm or eggs possible for a critter of BbTt. Arrow Rule B b T t = BT & Bt Then B b T t = bT & bt

  42. What sex cells could be obtained from the genotypes below? • Bbtt: ___________, ___________, ___________, ___________ • bbtt: ___________, ___________, ___________, ___________ • BBTT: ___________, ___________, ___________, ___________ • BbTt: ___________, ___________, ___________, ___________ • Hint: repeated sperm or eggs can be crossed out. Bt Bt bt bt bt bt bt bt BT BT BT BT BT Bt bT bt

  43. Dihybrid:Cross a totally heterozygous brown eyed tall girl with a heterozygous brown eyed homozygous tall guy. • Dom =Brown & Tall Rec= blue & Short 2. B & T b & t 3. Pa= BbTT ma=BbTt 4. 5/6. BT BT Bt bT bt bT

  44. Genotypes: 1/8 BBTT 2/8 BbTT 1/8 BBTt 2/8 BbTt 1/8 bbTt 1/8 bbTT Phenotypes: 6/8 Brown eyed and tall 2/8 blue eyes and Tall

  45. Multiple Genes • Much like dihybrids, but more capital letter alleles contribute to more of the specific trait • Ex. RRSS would be very dark red (4 caps) RRSs is dark red (any 3 caps) RrSs would be medium red (any 2 caps) Rrss would be light red (only 1 cap) rrss would be albino (no caps)

  46. 1. Dom = dark rec = light 2. R or S r or s 3. Ma: RrSs Dad: RrSS RS rS RS Rs rS rs

  47. Geno: 1/8 RRSS 2/8 RrSS 1/8 RRSs 2/8 RrSs 1/8 rrSS 1/8 rrSs Pheno: 1/8 Very dark red 3/8 dark red 3/8 medium 1/8 light red

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