1. Chapter 8
Cell Growth

2. In most cases, a living thing grows because it produces more and more cells

3. Limits of Cell Growth

4. Number 1
Cell membrane- food oxygen and water enter and wastes leave

5. How fast things enter and leave depends on the surface area
How fast products are used up and waste is produced depends on the volume

6. Fig 8-2
Surface Area and volume do not increase at the same rate so this is a problem

8. Number 2
All the information a cell needs to survive and function is stored in the DNA
When a cell is small enough RNA is made to make all the proteins a cell needs

10. As a cell gets bigger it does not make more RNA so there is an information crisis
As the cell grows there is not enough RNA to support its growth
The cell becomes inefficient

11. The Solution: Cell Division
The process where by the cell divides into two daughter cells
Draw picture in notes

12. Rates of Cell Growth E. coli – divides every 30 minutes
1 day – 14kg mass
3 days – mass of earth
Ideal conditions do not last long

13. Controls on Cell Growth
Cell behavior – cell growth and cell division are carefully controlled
Heart and nervous system – cells rarely divide

14. Skin and digestive tract – cells divide through life

15. When cells come in contact with other cells they stop growing
Scientists are still working on why this is true

16. Cell growth can be turned on
Example – a cut, broken bone
Cell growth stops when fixed

17. Uncontrolled Cell Growth
Results are severe
Cancer – disorder where cells have lost the ability to control their own growth

18. 8-2 Cell Division: Mitosis and Cytokinesis

19. Eukaryotic Cells Nucleus and membrane bound organelles
Eukaryotic cells divide in two steps

20. 1. Mitosis – the process by which the nucleus of a cell is divided into 2 nuclei, each with the same number and kinds of chromosomes as the parent cell

22. 2. Cytokinesis – process of the cytoplasm dividing to form 2 new cells

23. The process is complex
Large amounts of DNA need to be separated.
Each cell needs one copy of a chromosome

24. Chromosomes
Structures in the cell that contain the genetic information that is passed from one generation to the next

25. The cells of different organisms contain different numbers of chromosomes
Humans – 46
Goldfish – 94
Dog – 78
Cat – 32

26. Chromosomes are made of chromatin.
Chromatin is made of DNA and proteins.

27. When a cell is not dividing chromatin is lose and spread out
When a cell is going to divide chromatin condenses and chromosomes become visible

28. The proteins in chromatin help in the folding of DNA.
Helps it fit and keeps it organized.
Total length of DNA 10,000x the length of a chromosome

29. Histones
Circular proteins that the DNA is wrapped around

30. Nucleosome
Bead like structures of DNA wrapped around a few histones

31. Chromosome Structure Ready to divide DNA replicated
Chromosomes become visible by condensing

32. Section 8.2 Summary – pages 201 - 210
The structure of eukaryotic chromosomes
Centromere
Sister chromatids
Supercoil within chromosome
Chromosome
Continued coiling within supercoil
Histone H1
Nucleosome
DNA
Section 8.2 Summary – pages

33. The chromosome has two identical parts – 2 Chromatids

34. The two chromatids are often called sister chromatids
Centromere – holds sister chromatids together

35. The Cell Cycle

36. The period of time from one mitosis to the next
A cell grows, prepares for division, and divides to form two daughter cells
Includes mitosis

39.                                `
Mitosis – M phase

40. Interphase
G1 – growth and activity
S- DNA replication
G2 – growth and activity

41. Some cells in the body go through the cell cycle every 6 hours
Some cells never do (nerve and muscle)

42. Interphase
Long
Period between cell divisions
3 phases – G1, S, G2
G1 – (gap1) – growth and development

43. S (DNA synthesis phase) – replication
Proteins associated with chromosomes are also made
G2- gap 2 – shortest phase
Synthesis of materials needed for cell division

44. During interphase the cell is active
Proteins are made
DNA is copied
ATP is made and used
Cells that are specialized do their thing
Example - secretion

46. Do Now What are the 2 phases of the cell cycle? What happens in g1?
What happens in S phase?
What happens in the g2 phase?
What is chromatin?
What are histones and nucleosomes?
What do uncopied chromosome s look like?
What do copied chromosomes look like?
How many chromosomes do humans have?

47. Mitosis is divided into 4 stages.

48. Prophase (Ready)
Metaphase (Middle)
Anaphase (away)
Telophase (two)

49. Prophase
Longest phase
50-60% of total mitosis time
Chromosomes become visible – coil tightly
Centrioles separate and move to opposite sides

50. Chromosomes attach to the spindle
Nucleolus disappears
Nuclear envelope breaks down

51. Spindle
Meshlike structure that develops from the centrioles
Helps chromosomes move

52. Metaphase
Shortest – few minutes
Chromosomes line up at the center of the cell

53. Anaphase Centromeres that join sister chromatids split
Sister chromatids separates into individual chromosomes
Chromosomes separate into two groups near the poles

54. Over when chromosomes separate

55. Telophase
Chromosomes loosen up – go back to chromatin
Occurs in the area where the nucleus will form
Nuclear envelope reforms
Nucleolus becomes visible
Mitosis is over

58. Cytokinesis
Last step in cell division
Two nuclei form – each with a set of chromosomes
Cytokinesis – division of the cytoplasm

59. Animal Cells – cell membrane pinches in
Plant cells – cell plate forms down the middle
The cell wall forms in the cell plate

60. Plant Cell undergoing Mitosis

63. Mitosis Movie

65. 9-3 Meiosis
A type of cell division that gametes (eggs and sperm) undergo

66. A cell has two copies of each chromosome.
Humans have 46 chromosomes or 23 pairs.

67. Homologous Chromosomes
Two chromosomes that make up a pair
Carry the same types of information
One originally came from mom and one originally came from dad

68. Diploid A cell with pairs of chromosomes One from mom and one from dad
Diploid number for humans is 46

69. Haploid
A single set of chromosomes 1N

70. Autosomes
Body cell chromosomes
Humans have 22 pairs

71. Sex Chromosomes X and Y Humans have two Females have 2 X chromosomes
Males have an X and Y chromosome

72. Karyotype A picture of all of the chromosomes found in one cell.
Can be used to determine gender and genetic diseases.

74. Meiosis
2N produces 1N
Process of reduction division in which the number of chromosomes per cell is cut in half
2 rounds of cell division
Meiosis I and Meiosis II
Produces gametes (eggs and sperm)

77. Meiosis I
Prophase I
Metaphse I
Anaphase I
Telophase I
Tetrad

78. `

81. Meiosis II Prophase II Metaphase II Anaphase II Telophase II
Telophase II produces gametes (IN) (eggs or sperm)