1. Chapter 9 Cell Reproduction

2. Review: What we know Cells have DNA / genetic information We pass on our info to our children All our cells contain DNA Chromosomes are bundles of DNA

3. What we need know How do our cells make new cells? What can go wrong? Do all cells get made the same? Can do bacteria and viruses make new cells?

4. In the beginning… You start life as a single cell Human Embryo Day 3 Human Embryo 20 Weeks

5. Until the end of time… New cells made throughout entire life Called cell reproduction

6. Cell Reproduction Goal: – Replace old or worn out cells – Growth & Development

7. Most cells are less than 100 micrometers –Smaller than a period. at the end of a sentence! Why? –To ensure that the needs of the cell are met. http://learn.genetics.utah.edu/content/begin/cells/scale/ Cell Size

8. Factors that influence cell size are: –Ratio of surface area to volume Surface area is the area covered by the plasma membrane (nutrients & wastes must pass through) SA = L x W x # sides Cell Size Continued:

9. Volume is the space taken by the inner contents of the cell (including organelles and nucleus) V = L x W x H Cell Size Continued:

10. As cell grows the ratio of surface area to volume will continue to decrease! Volume increases much more rapidly than the surface area! Cell has TROUBLE: - supplying nutrients - expelling waste products Cell Size Continued:

11. SMALL cells have a higher ratio & can sustain themselves! REMEMBER: How do substances move in a cell? Cell Size Continued:

12. Communication breaks down over long distances! Cell Size Continued:

13. Investigate Cell Size: Complete the Investigation of Cell Size by creating a table on your handout. Hypothetical Cells SAVSA:V Ratio 0.00002 m 0.001 m 2.5 m 30 cm 15 m

14. Investigation of Cell Size: So based on your calculations do cells become large? Are large organisms large because they contain extra large cells or just more standard – sized cells?

15. Cell Cycle AKA A Cell’s Life

16. Once cell reaches a certain size it must: –Stop growing or –Divide The cell cycle is a cell’s cycle of growing and dividing. One complete cycle produces two cells. Cell Cycle

17. When repeated continuously the result is a continuous production of NEW cells! Cell Cycle

18. Interphase –Cell grows, carries our cellular functions, & replicates (makes copies) of DNA Mitosis –Cell’s nucleus and nuclear material divide Cytokinesis –Cell’s cytoplasm divides creating a new cell 3 Main Phases of Cell Cycle:

19. Divided into 3 stages: –G1 Cell grows, carries out normal cell functions, prepares to replicate DNA. Checkpoint for size & nutrients! Interphase:

20. –S (aka the synthesis phase) Cell copies (replicates) its DNA to prepare for cell division Interphase continued:

21. –G2 Cell prepares for the division of its nucleus Checkpoint to make sure cell is ready for mitosis! Interphase continued:

23. M Phase of Cell Cycle a.k.a. Mitosis Result = two identical cells Forms all human body cells Ex: skin, blood, bones, stomach Slows with age

24. Different Forms of DNA: Remember DNA is found in the nucleus DNA  Deoxyribonucleic Acid In it’s normal state DNA is loosely coiled and in the form of chromatin.

25. Chromatin: Looks like loose spaghetti!

26. During what phase is DNA replicated? “S” phase of Interphase. Humans have 46 chromosomes or 23 pairs: –23 from mom –23 from dad Chromosomes:

27. Once copied the DNA will begin to coil tightly around proteins and is now called chromosomes. Chromosomes:

28. Chromatid (s): The chromosomes 1-23 from mom will then pair up with chromosome 1-23 from dad respectively!

29. Once chromosomes are paired they are now called sister chromatids. Each half is a chromatid but together they are sister chromatids. Chromatid (s):

30. Chromatid   Chromatid

31. Centromere: Each sister chromatid is held together by a centromere!

33. Remember Before Cells Divide DNA replication occurs  chromosomes double This stage of the cell cycle is called interphase

34. Interphase Longest stage of cell cycle Cell is preparing for mitosis Cell gets larger & centrioles double

35. Interphase

36. Interphase (cont.)

37. Plant Cells in Interphase

38. Plant Cell in Interphase (cont.)

39. Stages of Mitosis P – M – A – T

40. PROPHASE Chromosomes shorten & thicken (shaped like an X) –Each half = chromatid –Attached by centromere. Nuclear membrane breaks down Centrioles move apart Spindle fibers form between centrioles

41. Prophase

42. Plant Cell in Early Prophase

43. Plant Cell in Late Prophase

44. METAPHASE Centrioles move to opposite sides of cell Spindle fibers stretch between centrioles Chromosomes line up in the middle by fibers connected to the centromere

45. Sister chromatids are pulled to line up at center of cell “Meta-” Prefix meaning middle METAPHASE (cont.)

46. Centromere Part that holds chromosomes together

47. Plant Cell in Metaphase

49. ANAPHASE Sister chromatids are pulled apart Fibers pull chromatids toward centrioles

50. Anaphase

51. Plant Cell in Anaphase

53. TELOPHASE Fibers begin to disappear Nuclear membrane begins to reform Cell membrane pinches in

54. Plant Cell in Telophase

55. Cytokinesis Last stage of cell cycle Process of dividing the cytoplasm Starts during anaphase finishes after telophase

56. In the end… Each cell has a complete set of chromosomes Two identical daughter cells  formed from one parent cell

57. Mitosis Completed

60. http://www.edumedia-sciences.com/en/a70-mitosis

61. Changes in Rate of Mitosis Cancer: Cells divide at a fast rate  out of control Malignant: dangerous Benign: not dangerous

62. Abnormal Cell Division A tumor is a mass of tissue that results from excessive cell division

64. Apoptosis: Not every cell is destined to survive! Some cells go through programmed cell death called apoptosis. –Cell shrinks & shrivels All animal cells have a “death program” that can be activated.

65. Discovered in 1998 Unspecialized cells that can develop into specialized cells under the right conditions. Two types: –Embryonic stem cells –Adult stem cells Stem Cells

68. How other cells divide 1.Bacteria (Prokaryote) One cell splits into two  Asexual reproduction  Same genes as “parent”

69. Bacteria Cell Reproduction

70. How other cells divide (cont.) 2.Viruses – Inject their DNA into other cells  Not considered “living” cells

71. Viral Cell Reproduction Step 3 Step 2Step 1 Step 4