1. Genetics

2. 1. What is a chromosome? 2. Where are chromosomes located? A threadlike structure of DNA and protein that contains genetic information. In eukaryotes chromosomes are found in the nucleus; in prokaryotes, they are found in the cytoplasm Chromosomes Genetics

3. 3. What are genes? 4. Where are genes found? Genetics Special sequences of DNA that codes for a protein and thus determines a trait. Genes are found on chromosomes.

4. 5. What is genetics? 6. Who is considered the father of genetics? father of genetics? Genetics Genetics is the scientific study of heredity. Gregor Mendel, an Austrian monk Mendel’s paper on genetics 1865

5. 7. What kind of organism did Mendel study? 8. What are some of the traits that Mendel studied? traits that Mendel studied? Genetics Mendel studied pea plants Seed color and shape; Pod color and shape; Flower color and position

6. 9. What is an allele? Genetics An allele is one of a number of different forms of a gene. For example, the gene for flower color in peas has two alleles— purple (P) and white (p). And the gene for seed pod color has two alleles—Green (G) and yellow (g). Green Seed Pod allele Yellow Seed Pod allele Purple flower allele White flower allele

7. 10. What is meant by Mendelian Genetics? Genetics? Genetics Any traits that are controlled by a single gene. For example, flower color is controlled by a single gene that has two alleles. Locus for Flower Color Gene Locus for Pod Color Gene 11. What is a locus? The specific location of a gene on a chromosome.

8. 12. What is a true breeding plant? Genetics True breeding plants always make offspring identical to themselves. For example, white flower plants always produce white flower offspring. ParentsOffspring And purple flower plants always produce purple flower offspring. ParentsOffspring

9. P P P P Parents Offspring Alleles 14. How many alleles for a single gene can an organism have? gene can an organism have? Genetics Two. Offspring inherit one allele from the male parent and the other allele from the female parent. 13. What is the universal symbol for a male and female? and female? MaleFemale PP PP Click once for animation

10. 15. State Mendel’s Principle of Dominance? Genetics This principle states that some alleles are dominant and others are recessive. For example, a plant that has a purple allele (P) and a white allele (p) will have purple flowers. This is because the purple allele is dominant over the white allele. p P Recessive allele (white) Dominant allele (purple) Dominant color (purple)

11. 17. Define phenotype? Genetics 16. Define genotype? The phenotype is the physical characteristic of an organism. For example, the phenotype of the flower shown at right is white. The genotype is the genetic makeup of an organism. For example, the possible genotypes for a purple flower could be PP or Pp.

12. 19. What is the phenotype of each flower? Genetics 18. Identify the genotype for each flower shown below? PpPpPpPp PPpp PurplePurpleWhite Genotypes = Phenotypes =

13. 21. Which of the following is a hybrid? Genetics A hybrid is an organism that has two different alleles for a particular gene. PpPpPpPp 20. What is a hybrid? PP pp Hybrid plant True breeding plants

14. Genetics Homo- means “same” and -zygous means “pair.” Homozygous refers to the fact that two alleles for a gene are the same. For example PP or pp PP or pp 22. What does homozygous mean Hetero- means “different. Heterozygous refers to the fact that two alleles for a gene are different. For example, Pp. 23. What does heterozygous mean

15. PpPpPpPp PP pp Genetics 24. Match the flower genotypes on the left to the terms on the right. terms on the right. Homozygous recessive Heterozygous Homozygous dominant

16. 25. How do the alleles get from parents to offspring? Genetics The chromosomes the alleles reside on are packaged in gametes (sex cells), like egg and sperm. Egg Sperm When egg and sperm meet, fertilization occurs, making a new cell called a zygote. Fertilization The zygote will divide by mitosis and develop into an embryo. Embryo

17. Genetics Pp x Pp a. Since this is a monohybrid cross, you should have cross, you should have drawn a 2 x 2 Punnett square. drawn a 2 x 2 Punnett square. 26. Draw a Punnett square for the following hybrid cross: the following hybrid cross:

18. Genetics b. Next, you should have written the parent written the parent genotypes above the genotypes above the Punnett square. Punnett square. Pp x Pp 26. Draw a Punnett square for the following hybrid cross: the following hybrid cross:

19. Genetics c. Then you should have placed the sex symbols placed the sex symbols on the Punnett square. on the Punnett square. 26. Draw a Punnett square for the following hybrid cross: the following hybrid cross: Pp x Pp

20. Genetics d. After the sex symbols, you were to determine the were to determine the alleles for the sperm and eggs. alleles for the sperm and eggs. 26. Draw a Punnett square for the following hybrid cross: the following hybrid cross: Pp x Pp P p p P

21. Genetics 26. Draw a Punnett square for the following hybrid cross: the following hybrid cross: e. Finally, you should have combined the alleles of the combined the alleles of the gametes to form zygotes gametes to form zygotes Pp x Pp P p p P PP PpPpPpPp PpPpPpPppp

22. Genetics 28. Draw ovals around those alleles found in sperm alleles found in sperm Pp x Pp P p p P PpPpPpPp PpPpPpPp PP pp 29. Draw circles around those alleles found in eggs. alleles found in eggs. 30. Draw diamonds around the alleles of the offspring. alleles of the offspring. 27. Draw squares around the alleles of the parents alleles of the parents Punnett Square Review

23. Genetics 32. Put squares around the heterozygous offspring. heterozygous offspring. Pp x Pp P p p P PpPpPpPp PpPpPpPp PP pp 33. Draw a diamond around the homozygous recessive the homozygous recessive offspring. offspring. 31. Circle the homozygous dominant offspring. dominant offspring. Punnett Square Review

24. Genetics 35. Put diamonds around the hybrid offspring. the hybrid offspring. Pp x Pp P p p P PpPpPpPp PpPpPpPp PP pp 36. Why is this called a monohybrid cross? monohybrid cross? 34. Circle the purebred offspring. offspring. Punnett Square Review Mono- means “one.” Hybrid refers to having different alleles for the same gene. Since the cross deals with only one character (mono-) and each parent is a hybrid, the cross is described as monohybrid.

25. Genetics 38. What is the phenotypic ratio of the offspring? ratio of the offspring? Pp x Pp P p p P PpPpPpPp PpPpPpPp PP pp 37. What is the genotypic ratio of the offspring? of the offspring? Punnett Square Review PP : Pp : pp 1 : 2 : 1 1 : 2 : 1 Purple : White 3 : 1 3 : 1

26. Genetics 39. State Mendel’s Principle of Segregation. Allele pairs separate during gamete formation. Meiosis Germ cell Gametes

27. Genetics 40. State Mendel’s Principle of Independent Assortment. Assortment. Allele pairs for different traits separate independently during gamete formation. Germ cell Gametes Chromosome alignment A Chromosome alignment B or Four different types of gametes 1 2 3 4

28. Genetics 41. Study the table below for a pattern. What number do you think goes in the last space? (Assume genes are on do you think goes in the last space? (Assume genes are on separate chromosomes and sort independently) separate chromosomes and sort independently) Genotype Possible number of unique gametes Aa AaBb AaBbCc AaBbCcDd AaBbCcDdEe 24816 1 gene 2 genes 3 genes 4 genes 5 genes 32 The formula for calculating the number of possible gametes is 2 n, where 2 equals the number of different alleles and n is the number of genes.

29. Genetics 42. Humans have 23 sets of chromosomes. How many different ways could these chromosomes sort different ways could these chromosomes sort independently? independently? Hint: You would use the same formula as was done for alleles and genes (2 n ). However, this time n represents the number of chromosome sets. 2 n = 2 23 = 8,388,608 different combinations

30. Genetics AaRr x AaRr 43. Draw a Punnett square for the following dihybrid cross: the following dihybrid cross: Since this is a dihybrid cross, you should have drawn a 4 x 4 Punnett square. Each parent will also be able to produce 4 different kinds of gametes. ARARARAR ArArArAr aRaRaRaR arararar ARARARAR ArArArAr aRaRaRaR arararar AARR AARr AaRr AARr AArr AaRr AArr AaRR AaRr aaRR aaRr AaRr Aarr aaRr aarr

31. Genetics AaRr x AaRr 44. What is the genotypic frequency of this dihybrid cross? cross? ARARARAR ArArArAr aRaRaRaR arararar ARARARAR ArArArAr aRaRaRaR arararar AARR AARr AaRr AARr AArr AaRr AArr AaRR AaRr aaRR aaRr AaRr Aarr aaRr aarr Genotype Frequency AARR AARr AArr AaRR AaRr Aarr aaRR aaRr aarr 1/162/162/161/165/161/161/162/161/16

32. Genetics AaRr x AaRr 45. What is the phenotypic frequency of this dihybrid cross? cross? ARARARAR ArArArAr aRaRaRaR arararar ARARARAR ArArArAr aRaRaRaR arararar AARR AARr AaRr AARr AArr AaRr AArr AaRR AaRr aaRR aaRr AaRr Aarr aaRr aarr Phenotype Frequency Axial, Round Axial, Wrinkled Terminal, Round Terminal, Wrinkled 9/163/163/161/16 A = Axial flowers A = Terminal flowers R = Round seeds r = Wrinkled seeds