Genetics

1. Genetics

2. If molecule Y represents a DNA molecule, then molecule W represents what? • Glucose • Nucleotide • Amino Acid • RNA • Lipid

3. Where in the cell does transcription take place? • Cytoplasm • Mitochondria • Nucleus • Golgi Body • Vacuole

4. mRNA is synthesized in the nucleus and travels to the cytoplasm to meet up with which organelle? • Mitochondria • Ribosome • Golgi Body • Lysosome • Nucleus

5. Where in the cell does translation, the second part of protein synthesis, take place? • Mitochondria • Nucleus • Golgi body • Cytoplasm

6. If molecule Y represents a protein, then molecule W represents what? • Glucose • Nucleotide • Amino Acid • RNA • Lipid

7. Chromosomal Mutations

8. Mutations • Deletion • Occurs when part of a chromosome is left out • Most are lethal

9. Mutations • Insertion • Segment of a chromosome is removed and inserted into another one

10. Mutations • Duplication • Segment of DNA is copied twice

11. Mutations • Inversion • Occurs when part of a chromosome breaks off and is reinserted backwards

12. Mutations • Translocation • Occurs when segments of DNA on 2 chromosomes are rearranged

14. Genetics

15. Some Vocab first • Heredity • The passing on of characteristics from parents to offspring • Trait • Characteristic that is inherited

16. What is a gene? • A region of DNA that controls a hereditary characteristic • Give me an example: • Let’s take the gene for hair color • How many different genes are present in this room? • Different forms of genes are called • Alleles • For the gene for hair color how many different alleles do each of you have? • 2

17. Where did it all begin? • With Gregor Mendel

18. Mendel • Mendel used pea plants to study what genetics really was. • He would cross pollinate them to see what kind of products he would get and then make assumptions as to what was happening to the genes. • Let’s look at how a plant reproduces • http://www.dnaftb.org/dnaftb/1/concept/index.html

19. Mendel • What was Mendel seeing? • http://www2.edc.org/weblabs/Mendel/mendel.html

20. Let’s take a trip down history lane… • Mendel took two pea plants that were identical in every way except for their heights, one was short and one was tall. • He called these two plants the parent generation, which is some vocab that we still use today. It’s abbreviated – P1

21. History Trippin • He cross pollinated them and took a look at their offspring.

22. History Trippin • When he planted the seeds from the cross pollination the plants that were produced were all tall. • He called the offspring from this first cross between the parents – the F1 generation • Filial is latin for son or daughter

23. History Trippin • Next, Mendel allowed the tall plants in the F1 generation to self pollinate. He then planted these seeds and grew 1000 plants. • Mendel found in this F2 generation that ¾ of the plants grew tall and ¼ were short.

24. Why was this a big discovery for Mendel? • 1 trait of a pair seemed to disappear in the F1 generation, only to reappear unchanged in ¼ of the F2 plants.

25. Mendel’s Conclusions • Gregor Mendel didn’t know much if anything about DNA or what it was, and he didn’t even know how much you know…so what was Mendel’s big conclusion after seeing his offspring? • He figured out that each organism must have 2 factors that control each of its traits.

26. The Rule of Dominance • In Mendel’s F1 offspring plants, there were only tall plants even though one of the parents was a short plant. • 1 of the alleles is dominant over the other.

27. The Rule of Dominance • The observed trait is DOMINANT and the trait that disappeared is recessive. • In Mendel’s example which is the dominant trait and which is the recessive trait? • The allele for tallness is DOMINANT • The allele for shortness is recessive

28. What does it mean to be Dominant or Recessive?

29. How many of you have 6 fingers on each hand? • 6 fingers are dominant

30. How many of you have a widow’s peak? • Widow’s peak is dominant

31. How many of you have attached ear lobes? • Attached earlobes are recessive

32. How many of you have the ability to roll your tongue? • Rolling your tongue is dominant

33. How many of you have a straight thumb? • Straight thumb is recessive

34. How many of you have blue eyes? • Blue eyes are recessive

35. How many of you can taste PTC paper? • PTC tasting is dominant

36. How many of you have freckles? • Having freckles are dominant

37. How many of you have a cleft chin? • Having a cleft chin is recessive

38. How many of you have a second toe longer than your big toe? • Having a longer second toe is dominant

39. How many of you when clasping your hands together, the left thumb is on top of the right thumb? • Left thumb on top is dominant

40. How many of you have broad/fuller lips? • Full lips are dominant

41. How many of you have an immunity to poison ivy? • Poison ivy immunity is dominant

42. The Rule of Dominance • We label or designate alleles with letters. • (For example, a letter T for the trait of height) • An uppercase letter is used for the Dominant allele (T for tall) • A lowercase letter is used for the recessive allele (t for short)

43. The Rule of Dominance • Using the letter T what can you say about the possible alleles that the following people have on the genes on their chromosomes?

44. Mendel’s Law of Segregation What happens during Meiosis? Mendel’s law of segregation explains the results of his cross between F1 tall plants. He concluded that the 2 alleles for each trait must separate when sex cells are formed. A parent, therefore, passes on at random only one allele for each trait to each offspring.

45. Let’s Make Another Baby! • How many chromosomes do we have in our cells? • How many came from Mom? • How many from Dad? • How many alleles for hair color did you receive from your mother? • How many alleles for hair color did you receive from your father? • If you have 2 alleles for hair color how come half of my head isn’t blonde and half isn’t brown?

46. Genetics Vocabulary • Phenotype • The way an organism looks • Give me an example • Genotype • The gene combination an organism has • Give me an example • *Problem: You can’t always know an organism’s genotype simply by looking at its phenotype

47. Genotype • Homozygous • An organism’s 2 alleles are the same • 2 capital letters would be homozygous dominant • Give me an example • 2 lowercase letters would be homozygous recessive • Give me an example • Heterozygous • An organism’s 2 alleles for a trait are different • Give me an example

49. Let’s revisit Meiosis again • What happens in Metaphase 1 • The law of independent assortment • Genes for different traits (for example seed shape and seed color) are inherited independently of each other. • In our class example we used hair color, number of toes, and eye color • We saw depending on how they randomly lined up with each other that you could tons of different combinations.

50. Punnett Squares • In 1905, Reginald Punnett, an English biologist, devised a way of finding the expected proportions of possible genotypes in the offspring of a cross. • If you know the genotypes of the parents, you can use a Punnett square to predict the possible genotypes of their offspring.