1. Power point presentation/notes
Unit 3 – Genetics
I can explain the relationships between DNA and chromosomes and explain how traits are passed from parents to offspring
Today’s agenda:
Warm up
Practice correction
Power point presentation/notes
Use a model to illustrate the role of cellular division (mitosis) and differentiation in producing and maintaining complex organisms

2. Warm up
A woman with type O blood is claiming that a man with type AB blood is the father of her child who is type O. Could this man be the father of the child?
Based on the information in this table, which man could not be the father of the baby? Justify your answer.

3. Warm up
3. What is mitosis? 4. What types of cells go through mitosis?

4. What do you notice about these siblings?

5. Sometimes siblings don’t look alike: why?

6. Prior knowledge
What is fertilization?

7. Fertilization n=23 egg 2n=46 zygote
The fusion of sperm and egg to form a zygote.
A zygote is a fertilized egg
n=23
egg
n=23??
sperm
n=23
2n=46
zygote

8. Zygote develops into embryo and finally adult organism by mitosis23 46
Fertilized egg – zygote
Fertilization – process by which an egg and sperm unite
Zygote – fertilized egg
Embryo – organism in early stage of development

9. Think Pair Share
Mitosis produces genetically identical cells… so why are we different from our siblings (given the same biological parents)?

10. Warm up – molecular genetics
1. Use the genetic code to solve this problem

11. Warm up – molecular genetics
2. Where do replication, transcription and translation take place? 3. What are the differences between RNA and DNA (3 differences)? 4. What is the cell cycle?

14. Meiosis Using scientific language, describe each phase
Write down questions that come to mind
Make copies of this page for students so they can work on it
Ask students to focus on number of chromosomes and the concept of haploid and diploid

15. How is this process (meiosis) different or similar to mitosis?

16. Review: watch the video clip and be ready to solve the problem

17. Warm up – molecular genetics
1. Use the genetic code to solve this problem: you need to give the DNA sequence, the tRNA anticodon, and the amino acid

19. Translation Overview Defined: Process of making proteins
Step 1: mRNA enters ribosome
Step 2: Ribosome reads one mRNA codon at a time
Step 3: tRNA delivers amino acids until a protein is created

20. Warm up
Translate the following DNA sequence into a protein TTA GCG ACA

21. mRNA codes

22. 1. What is Arlene's genotype?
2. What is George's genotype?
3. What are Ann & Michael's genotypes?  
4. Most likely, Sandra's genotype is .
5. List three people from the chart (other than George) who are most likely carriers of Falconi anemia.

23. What questions come to mind?

24. Meiosis
Process in which diploid cells undergo two cell divisions that result in haploid cells.
Produces genetically unique cells
Results in haploid cells
Involved in sexual reproduction
What does the term “diploid” mean?
What’s the difference between sexual and asexual reproduction?

25. Describing Meiosis

26. Prophase I - Synapsis sister chromatids maternal paternal
Homologous chromosomes
sister chromatids
Tetrad

27. Crossing Over M/P P/M chiasmata: site of crossing over Tetrad
nonsister chromatids P M M P
M/P
P/M
chiasmata: site of crossing over
variation

28. Crossing Over
Crossing over occurs between non-sister chromatids of homologous chromosomes at the chiasmata (points of crossing over)
Segments of non-sister chromatids break and reattach to the other chromatid

29. Think
Why is crossing over important?

30. Crossing Over Generates Genetic Variation
Tetrad
nonsister chromatids P M M P
M/P
P/M
chiasmata: site of crossing over
variation

31. Telophase II/Cytokinesis
Meiosis II results in four non-identical haploid cells.

32. Video analysis
As you watch the video clip, identify steps of meiosis: write down the time, example - 0:11 DNA replication (interphase)

33. Gametogenesis is the production of gametes
Any difference between gametogenesis in males and females?

34. Gametogenesis differs between females and males
Sperm primarily contribute DNA to an embryo
Eggs contribute DNA, cytoplasm, and organelles to an embryo
During meiosis, the egg gets most of the contents; the other cells form polar bodies
List some of the organelles found in a cell

35. Watch the video clip and take notes

36. Answer the following questions
Why is meiosis called the reduction division?
What is interphase?
If you have 46 chromosomes, how many chromatides do you have?
What does it mean that meiosis produces “variety”?

37. Review questions How many chromosomes do germ cells have?
What do the terms “diploid” and ”haploid” mean?
If a cell with 16 chromosomes goes through mitosis, how many chromosomes will the daughter cells have?

38. More practice

39. 1. Which of these is accomplished by meiosis? Choose all that apply.
It allows multicellular organisms to get bigger in size.
It produces gametes.
It ensures even distribution of chromosomes.
It allows organisms to replace worn out cells.
It allows unicellular organisms to reproduce.

40. 2.
Meiosis 1 separates the ___.
Meiosis 2 separate the ___.

41. 3. How many total chromosomes are in a human somatic cell?

42. 4. If a somatic cell contains 50 chromosomes,
How many chromosomes are in a diploid cell?
What is the 2n number?
What is the 1n number?
How many chromosomes are in a gamete?

43. 5. How do homologous chromosomes differ from sister chromatids?

44. 6. If a haploid cell contains 30 chromosomes,
how many pairs of homologous chromosomes are there?
how many pairs of sister chromatids are there after Telophase 1?
how many pairs of sister chromatids are there after Telophase 2?

45. 7. Which of the following are true about mitosis & meiosis
7. Which of the following are true about mitosis & meiosis? Choose all that apply.
Mitosis makes identical cells; meiosis makes unique cells.
Mitosis makes haploid cells; meiosis makes diploid cells.
Mitosis makes gametes; meiosis makes somatic cells.
Mitosis makes 1 cell; meiosis makes 2 cells.
Mitosis makes cells w/ homologous chromosomes; meiosis does not.

46. 8. When & why does crossing over take place?

47. 9. What makes sexual reproduction biologically advantageous?

48. Sexual vs asexual reproduction

49. Check for understanding
What the advantages or disadvantages of sexual reproduction?

50. Mitosis & Meiosis Compared
Location all tissues ovary/testis
Products diploid somatic cells haploid egg/sperm
DNA replication one round one round
Cell division one round two rounds
Gene recombination rare & abnormal yes (at least once
per chromosome arm)
Relationship between genetically identical different

51. Check for understanding
Germ cells are found in ova and testes. They are
Haploid cells (n)
2. Diploid cells (2n)

52. Check for understanding
Gametogenesis is the term for
The production of gametes
The fertilization of eggs
The development of polar bodies
The movement of sperm

53. Meiosis Mitosis One diploid (2n) --> Four haploid (1n) cells
Reduces chromosome # from
46 --> 23
Reduces the DNA content from
2n --> n
Mitosis
One diploid (2n) cell --> two diploid daughter cells
Maintains chromosome #
46 --> 46
Maintains DNA content
2n --> 2n

54. Comparing mitosis and meiosis

55. Is this right or wrong? Why?