1. Day 5

2. Cell Division
Cell Cycle & Mitosis

3. Why Do Cells Divide? Cell growth Replace damaged or old cells
Larger cell is, the harder it is for cell to take in nutrients and eliminate waste.
Replace damaged or old cells
Form gametes (sex cells)

4. Cell Division

5. Cell Cycle
Beginning of one cell until time that one cell divides into two cells
Interphase – stage between divisions
Mitosis is division of the nucleus
Cytokinesis is division of cytoplasm and organelles
Often the whole cell cycle is called mitosis, although this is not technically accurate

6. Interphase

7. Interphase Longest stage of Cell’s life Time spent between divisions
Produces all materials required for growth (metabolism)
Preparation for division
Chromosomes aren’t visible, in form of chromatin
Centrioles(microtuble-organizing centers) replicate and one centriole moves to each pole.
3 phases: G1, S Phase, and G2

8. G1 Phase of the Cell Cycle
Growth Phase
Cell increases in size

9. S Phase
Synthesis Phase
DNA duplicates
Chromosomes duplicated

11. Mitosis G2 checkpoint to make sure the DNA is correct
Cell prepares to divide
Next step –
Mitosis

12. Interphase

13. Terms to Know Chromosome - DNA coiled with proteins.
Chromatid - one side of the two strands a chromosome.
Centromere - point at which the two chromatid attach.
Spindle – cell structures made up of centrioles and microtubules fibers that move chromosomes during cell division.
Homologous Chromosomes – pair of like chromosomes that code for same trait.

14. Homologous Chromosomes

15. Mitosis: Cell Division The last part of the Cell Cycle is Mitosis.
4 phases.
Takes place in somatic cells (body cells)

16. Phases of Mitosis

17. Cytokinesis

18. The Cell begins the division process
1.Prophase
The Cell begins the division process
Nucleolus disappears
Nuclear membrane breaks apart

19. Chromosomes become visible
Spindle apparatus forms from centrioles and attaches to centromeres.

20. Prophase Chromosomes consisting of 2 Sister Chromatids
Pair of Centrioles
Spindle Fibers

21. The Second Phase of Mitosis
2. Metaphase
The Second Phase of Mitosis
Nuclear Membrane completely gone
Duplicated chromosomes line up along the cell's equator.

23. Metaphase
Spindle Fibers
Equator, or Metaphase Plate
Chromosomes

24. 3. Anaphase The third phase of Mitosis
Diploid (pair) sets of daughter chromosomes separate
They are pushed and pulled toward opposite poles of the cell by the spindle fibers

25. Anaphase
Daughter Chromosomes
Chromatid
Chromosome

26. Spindle Fibers

27. 4. Telophase Separation of chromosomes completed
Cell Plate forms (plants)
Cleavage furrow forms(animals)
Nucleus & nucleolus reform
Chromosomes uncoil

28. Telophase
Cleavage Furrow

29. Cytokinesis – The final stage of Cell Cycle and Mitosis
The cytoplasm, organelles, and nuclear material are evenly split and two new cells are formed.
Cell Plate

30. Animals - cell pinches inward
Plants - a new cell wall forms between the two new cells

32. Cancer

33. What is Cancer?
Cancer - disease where cells grow out of control and invade, erode and destroy normal tissue
Cancer cells lack differentiation (not specialized)
Normal cells enter the cell cycle only about 50 times; cancer cells can enter the cell cycle repeatedly.
Normal cells undergo Apoptosis which is a programmed cell death to prevent overgrowth of cells.

34. Cancer Development Abnormal cell growth called neoplasm
Abnormal growth results from the mutation of genes that regulate the cell cycle
Carcinogenesis, the development of cancer is gradual—it may take decades before a cell has the characteristics of a cancer cell.

35. Origin of Cancer
Mutations in genes for repair enzymes of DNA can cause cancer.
If proteins that start cell cycle or inhibit cell cycle are changed (mutated) it can cause cancer.
Normal DNA segments have ends that shorten with each replication, eventually signaling the cell to end division; cancer cells have enzymes that keep their DNA segments at a constant length and thus the cells to continue dividing.

37. Characteristics of Cancer Cells
Have abnormal nuclei
Lack differentiation
Chromosomes mutated; may be duplicated or deleted.
Gene amplification, extra copies of genes
Do not undergo apoptosis

38. Characteristics cont. Do not have contact inhibition
Normal cells are anchored and stop dividing when in contact with other cells;
Growth not inhibited and will invade and destroy normal tissue
Cancer cells pile on top of each other to form a tumor.
Cancer cells undergo metastasis and angiogenesis
Metastasis – cancer spreads throughout body; new tumors away from primary tumor.
Angiogenesis - formation of new blood vessels to bring nutrients and oxygen to tumor.

39. Types of Tumors
Benign: slow growth, non-invasive, no metastasis (not cancerous)
Malignant: rapid growth, invasive, potential for metastasis (cancerous)

40. Types of Cancers

41. Is cancer a heritable disease?
There are heritable cancer syndromes but a majority are not.
Cancer is a genetic disease, but the majority of mutations that lead to cancer are somatic (body cell)

42. What causes the mutations that lead to cancer?
Viruses: HPV --> cervical cancer
Bacteria: H. pylori --> gastric cancer
Chemicals --> B[a]P --> lung cancer
UV and ionizing radiation --> skin cancer
What do these agents have in common? They are all Mutagens

43. Treatments Surgery Chemotherapy Radiation Therapy Targeted Therapy
Immunotherapy
Hyperhermia
Bone Marrow and Peripheral Blood Stem Cell Transplant
Laser Therapy
Molecular Targeted Therapy

44. 7 ways to Reduce Risk Don’t use tobacoco
Eat healthy diet – fruits, veggies, limit alcohol
Maintain healthy weight; physical activity
Protect yourself from the sun
Get immunized – Hepatitis B and HPV
Avoid Risky behaviors – safe sex and no shared needles
Take early detection seriously
Self exams
Regular doctor visits

45. Meiosis
Creating Cells for Sexual Reproduction

46. Meiosis Takes place in Gametes(sex cells)
Produces a haploid cell (represented by N)
People have 46 Chromosome or 23 pairs (2N)
When an egg joins a sperm the count must stay at 46 to remain human
egg can only have 23
sperm can only have 23
How does this happen?

47. Definitions
Diploid Cells- (2N)cells that have pairs of chromosomes. There are 2 of each chromosome in diploid cells.
Haploid Cells- (N)cells that have only one of each chromosome. Haploid cells are used for sexual reproduction.
Somatic Cells – body cells that are Diploid.
Gametes or germ cells – sex cells that are Haploid.

48. During Meiosis gamete (sex) cells undergo a “double division”, called Meiosis I and Meiosis II.
This maintains the DNA, but reducing the chromosomal count to 23. + =
Sperm (23) Egg (23) = Fertilized Cell (46)
Haploid Cells (N)
Haploid Cells (N)
Diploid Cells (2N)

49. Meiosis I

50. Prophase I Chromosomes already copied Centrioles separate
Nuclear membrane breaks down
Crossing over occurs here

51. Crossing Over Synapsis- Homologous Pairs line up = Tetrad
During synapsis the chromatids within a homologous pair may twist around each other and break off and attach to the other homologous pair = Crossing Over
Results in exchange of genetic material between maternal and paternal chromosomes = genetic recombination

52. Metaphase I
Chromosome pairs line up at equator

53. Anaphase I
Chromosome pairs split
Sister chromatids stay connected

54. Telophase I Cell starts to divide in two
Nuclear membranes start to form again

55. Meiosis II

56. Prophase II Chromosomes do not replicate again
Cells have one set of sister chromatids
Nuclear membrane breaks down
Centrioles separate

57. Metaphase II
Sister chromatids line up at the middle of the cell

58. Anaphase II
Sister chromatids divide

59. Telophase II Cells start to split in two
Each cell has one set of chromosomes—it is a haploid
4 cells form

60. Original Gamete Metaphase Anaphase Telophase Cytokinesis
2 Daughter Cells Metaphase 2 Anaphase 2 Telophase 2 Cytokinesis – 4 Gametes

61. OOGENESIS – Meiosis in females
SPERMATOGENESIS
- Meiosis in Males

62. Meiosis ensures that all living organisms maintain both Genetic Diversity and Genetic Integrity

63. Cell Division in Prokaryotes
Lack a nucleus
Have a single chromosome
Reproduce by binary fission
Include bacteria

64. Steps in Binary Fission
Cells increase their cell mass slightly
the single, circular bacterial chromosome is replicated
Each cell divides into 2 daughter cells

65. Mutations
Ch. 10. pg

66. Mutations Changes in nucleotide sequence of DNA
May occur in somatic cells (body cells)
not passed to offspring
May occur in gametes (eggs & sperm)
passed to offspring

67. Causes Mutations happen regularly
Any agent that causes a change in DNA is called a mutagen.
Mutagens include radiation, chemicals, and even high temperatures.
Ex. of radiation: X rays, cosmic rays, ultraviolet light, and nuclear radiation.
Chemicals: Benzene
Many mutations are repaired by enzymes.

68. Are Mutations Helpful or Harmful?
Some harmful - Skin cancers and some leukemias result from somatic mutations
Most mutations have no affect, some have detrimental affects and a few mutations may improve an organism’s survival (beneficial)

69. Types of Mutations 2-Types
1. Gene mutations - change in one DNA sequence of a gene.
2.Chromosomal mutations – change in structure or loss or gain of part of a chromosome.

70. Gene mutation- 2 types 1. Point Mutation
A change in a single base pair in DNA.
Changes the amino acid in the protein
Does not always cause a problem.
THE DOG BIT THE CAT
THE DOG BIT THE CAR

71. 2. Frameshift Mutation
A single base is added or deleted from the DNA causing all the other bases to be out of position.
More harmful than a regular point mutation.
THE DOG BIT THE CAT
THE DOB ITT HEC AT

72. Chromosome Mutations Five types exist: Deletion Inversion
Translocation
Nondisjunction
Duplication

73. Deletion Part of a chromosome is lost/deleted.
A B C D E F G H
A B C E F G H

74. Duplication/Insertion A part of the chromosome repeats
A B C D E F G H
A B C B C D E F G H

75. Inversion Part of a chromosome breaks off; reattaches backward
A B C D E F G H
H A D C B E F G

76. Translocation Part of a chromosome breaks off; attaches to a different chromosome that is not homologous A B C D E F G H W X A B C D E F G H W X Y Z Y Z W X Y Z Y Z
Translocation
Translocation

77. Chromosome Mutation Animation

80. Karyotyping
Ch. 6 pg

81. Some mutations that cause chromosomal abnormalities can be detected by analyzing a karyotype.
Karyotype – photo of the chromosomes in a dividing cell that shows the chromosomes arranged by size, number, and shape.
Identifies gender and genetic disorders

82. Amniocentesis – medical procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections
small amount of amniotic fluid, which has fetal tissues, is extracted from the amniotic sac surrounding a developing fetus
Autosomal abnormalities – abnormalities of chromosomes not directly involved in determining gender
Sex Chromosomal abnormalities – abnormalities that affect the gender of an individual

83. How Scientists Read Chromosomes?
To "read" a set of human chromosomes, scientists first use three key features to identify their similarities and differences:
Size. This is the easiest way to tell two different chromosomes apart.
Banding pattern. The size and location of Giemsa bands on chromosomes make each chromosome pair unique.
Centromere position. Centromeres are regions in chromosomes that appear as a constriction. They have a special role in the separation of chromosomes into daughter cells during mitosis cell division (mitosis and meiosis).
Image taken from:
Using these key features, scientists match up the 23 pairs –
one set from the mother and one set from the father.

84. Typical Karyotype

85. Typical Karyotype

87. Trisomy 21- Down’s Syndrome - Karyotype
47 Total Chromosomes
Three Chromosomes at the 21st Pair
Image taken from:

88. Monosomy X - Turner Syndrome - Karyotype
45 Total Chromosomes
One “X” Chromosome
Image taken from:

89. XYY Karyotype 47 Total Chromosomes One “X” and Two “Y” Chromosomes
Image taken from: