Mendelian Genetics PPT Notes Answers


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Mendelian Genetics PPT Notes Answers

  1. 1. Mendelian Genetics PowerPoint Questions All Materials © cmassengale Gregor Mendel 1. Who is responsible for our laws of inheritance? Gregor Mendel 2. What organism did Mendel study? pea plants 3. When was Mendel's work recognized? 20 century th 4. When did Mendel perform his experiments & how many plants did he grow? Between 1856 and 1863, Mendel cultivated and tested some 28,000 pea plants 5. What did Mendel notice about offspring traits? retained traits of the parents 6. How is Mendel referred to today? “Father of Genetics" 7. In what country did Mendel do his research on peas? Czech Republic and austria 8. Mendel stated that physical traits were inherited as __“particles”__. 9. Today we know that particles are actually what? “particles” are actually Chromosomes & DNA Terminology 10. Define these three terms: a. Trait - any characteristic that can be passed from parent to offspring b. Heredity - passing of traits from parent to offspring c. Genetics - study of heredity 11. Name & describe two types of genetic crosses. Monohybrid cross - cross involving a single trait e.g. flower color Dihybrid cross - cross involving two traits e.g. flower color & plant height 12. What is used to solve genetic crosses? Punnet squares help solve genetics problems 13. Sketch a Punnet square & show how they are used to solve a genetics problems.
  2. 2. 14. Use a Punnet square to solve a cross between two parents that both have the genotype Yy. 15. What are alleles & what are the two forms? alleles are two forms of a gene (dominant & recessive) 16. Explain the difference between dominant & recessive alleles. Dominant - stronger of two genes expressed in the hybrid; represented by a capital letter (R) Recessive - gene that shows up less often in a cross; represented by a lowercase letter (r) 17. Using a letter of the alphabet, show how each allele would be represented. A- dominant a- recessive 18. What is a genotype and write 3 possible genotypes? Genotype - gene combination for a trait (e.g. RR, Rr, rr) 19. What is a phenotype and write possible phenotypes for your genotypes in question 18?
  3. 3. Phenotype - the physical feature resulting from a genotype (e.g. red, white) 20. Using these alleles, R = red flower and r = yellow flowers; write all possible genotypes & phenotypes. Genotype of alleles: R = red flower r = yellow flower All genes occur in pairs, so 2 alleles affect a characteristic Genotypes RR Rr rr Phenotypes RED RED YELLOW STOPPING POINT 11/24/09 21. What are homozygous genotypes? gene combination involving 2 dominant or 2 recessive genes (e.g. RR or rr); also called pure 22. Write a homozygous dominant genotype. RR 23. Write a homozygous recessive genotype. rr 24. What is meant by a heterozygous genotype? gene combination of one dominant & one recessive allele (e.g. Rr) 25. Write a heterozygous genotype. Rr 26. Heterozygous genotypes are also called _ hybrid____. 27. What two things actually determine an organism's characteristics? Genes and Environment Pea Experiments 28. Give 4 reasons that Mendel used garden peas, Pisum sativum, for his experiments. 1) Can be grown in a small area 2) Produce lots of offspring 3) Produce pure plants when allowed to self-pollinate several generations 4) Can be artificially cross-pollinated 29. Name the male and female parts of a flowering plant and explain how pollination occurs. Pollen contains sperm and is produced by the stamen
  4. 4. Ovary contains eggs and is found inside the flower 30. What is the difference between self and cross pollination? Pollen carries sperm to the eggs for fertilization Self-fertilization can occur in the same flower Cross-fertilization can occur between flowers 31. Explain how Mendel cross pollinated his pea plants. Mendel hand-pollinated flowers using a paintbrush, He could snip the stamens to prevent self-pollination, then covered each flower with a cloth bag He traced traits through the several generations 32. How did Mendel get pure plants? produced pure strains by allowing the plants to self-pollinate for several generations 33. Name 8 pea plant traits and give the dominant & recessive form of each. Seed shape --- Round (R) or Wrinkled (r) Seed Color ---- Yellow (Y) or Green (y) Pod Shape --- Smooth (S) or wrinkled (s) Pod Color --- Green (G) or Yellow (g) Seed Coat Color ---Gray (G) or White (g) Flower position---Axial (A) or Terminal (a) Plant Height --- Tall (T) or Short (t) Flower color --- Purple (P) or white (p) 34. How did Mendel's experimental results compare to the theoretical genotypic ratios? Explain. The theoretical or expected ratio of plants producing round or wrinkled seeds is 3 round :1 wrinkled Mendel’s observed ratio was 2.96:1 The discrepancy is due to statistical error The larger the sample the more nearly the results approximate to the theoretical ratio
  5. 5. 35. What does P1 mean? Parental P1 Generation = the parental generation in a breeding experiment. 36. What is the F1 generation? F1 generation = the first-generation offspring in a breeding experiment. (1st filial generation) From breeding individuals from the P1 generation 37. What is the F2 generation? F2 generation = the second-generation offspring in a breeding experiment. (2nd filial generation) From breeding individuals from the F1 generation 38. What results from this cross --- TT x tt? All hybrids (Tt) 39. What results do you get from crossing two hybrids (Tt x Tt)? you would get the following genotypes TT, Tt, tt Assuming T represents tall and t represents short; you would get 3 tall and 1 short 40. Show all your work for solving a P1 monohybrid cross for seed shape. Trait: Seed Shape Alleles: R – Round r – Wrinkled Cross: Round seeds x Wrinkled seeds P1 cross: __RR___ x _ rr __ Rr Rr Rr Rr Genotype __ Rr ____ Phenotype __Round _ G. Ratio _ All alike _ P. Ratio _ All alike _ 41. The offspring of the above cross are called the _F1____ generation. 42. Show all your work for solving a F1 monohybrid cross for seed shape. Trait: Seed Shape
  6. 6. Alleles: R – Round r – Wrinkled Cross: Round seeds x Round seeds F1 cross: _ Rr _ x _ Rr _ RR Rr Rr rr Genotype: RR, Rr, rr Phenotype: Round & wrinkled G. Ratio: 1:2:1 P. Ratio: 3:1 43. Show all your work for solving both F2 monohybrid crosses for seed shape. Trait: cross 1: Round, Round cross 2: wrinkled round Alleles: cross 1 RR, Rr cross 2: rr, Rr F2 cross: __ RR ______ x ___ Rr _____ F2 cross: __ rr ______ x ___ Rr _____ R r R r RR Rr rr R Rr r R RR Rr r Rr rr Genotype: RR, Rr Genotype: Rr, rr
  7. 7. Phenotype: Round & Wrinkled Phenotype: Round Genotypic Ratio: 1:1 G. Ratio: 1:1 Phenotypic Ratio: All alike P. Ratio: 1:1 Mendel's Laws Complete the following question: 44. __genes_______ are responsible for inherited traits. 45. Phenotype is based on __genotype_____________. 46. Each trait requires _2__ genes, one from each _parent__. 47. State the Law of Dominance and give an example. In a cross of parents that are pure for contrasting traits, only one form of the trait will appear in the next generation. All the offspring will be heterozygous and express only the dominant trait. RR x rr yields all Rr (round seeds) 3 genotypes yields 3 phenotypes 48. State the Law of Segregation and tell when alleles are "recombined". During the formation of gametes (eggs or sperm), the two alleles responsible for a trait separate from each other. Alleles for a trait are then "recombined" at fertilization, producing the genotype for the traits of the offspring. 49. State the Law of Independent assortment & tell what type of crosses show this. Alleles for different traits are distributed to sex cells (& offspring) independently of one another. This law can be illustrated using dihybrid crosses. 50. Using the formula 2n where n = the number of heterozygotes, tell how many gametes will be produced by each of the following allele combinations: a. RrYy = 22 = 4 b. AaBbCCDd = 23 = 8 c. MmNnOoPPQQRrssTtQq = 26 = 64 51. What are the possible allele combinations in the egg and sperm from the following cross --- RrYy x RrYy.
  8. 8. RY Ry rY ry from egg RY Ry rY ry from sperm 52. Show how to work an F1 dihybrid cross for seed shape & seed color. Traits: Seed shape & Seed color Alleles: R round r wrinkled Y yellow y green F1 cross _RrYy _______ x _RrYy _________
  9. 9. RRYY RRYy RrYY RrYy RRYy RRyy RrYy Rryy RrYY RrYy rrYY rrYy RrYy Rryy rrYy rryy
  10. 10. PARENT LAW OFFSPRI CROSS DOMINANCE TT x tt tall x 100% Tt short SEGREGATION Tt x Tt tall x 75% tall 25