1. Mitosis
and
Meiosis
Cell Division:

2. Objectives:
 To distinguish between
chromatin and chromosome
 To define homologous
chromosomes
 To distinguish between
diploid and haploid

3. Chromatin found in the
nucleus of a nondividing cell
 made of DNA and protein

7. DNA in chromatin replicates
before cell division
Chromatin becomes highly
coiled and condensed
Becomes visible as
a chromosome

8. A Chromosome consists
of 2 identical chromatids
Centromere – point at which each
pair of chromatids is attached
centromere

11. Homologous Chromosomes
pair of chromosomes that
have same size and shape
 found in
sexually
reproducing
organisms
 human body
cells have
23 homologous
pairs

13. Diploid (2N) – cell that contains
both chromosomes
of a homologous pair
human body
cells 46

14. Haploid # (N) – cell that has
only one
chromosome
of each
homologous
pair
egg &
sperm
human sex
cells 23

16. Objectives:
 To describe the cell cycle
 To define mitosis
 To list and describe the
stages of mitosis

17. Cell Cycle – period from
beginning of one mitosis
to beginning of next
Cell cycle consists of three stages:
I. Interphase
II. Mitosis
III. Cytokinesis

20. Interphase
cell growth
and
development
DNA replication

21. Interphase
Plant cell
Animal cell

22. Mitosis – division of
the cell nucleus
 number of chromosomes
remains the same
 occurs in body cells and unicellular
organisms
 produces identical daughter
cells

23. Mitosis in Human Body
Cells
46
(2N)
46
(2N)
46
(2N)

24. Stages of Mitosis
P M A T
r
o
p
h
a
s
e
e
t
a
p
h
a
s
e
e
l
o
p
h
a
s
e
n
a
p
h
a
s
e

25. 1) Prophase
 chromosomes become visible
 nuclear membrane disappears
 centrioles move to opposite ends
of cell and form the spindle

26. 2) Metaphase
 chromosomes line up along
the equator of the cell

27. 3) Anaphase
 chromatids separate
and are pulled to
opposite ends of the
cell

28. 4)
Telophase
 chromosomes
become
threadlike
forming
chromatin
 nucleus forms
in each cell

30. Plant cell mitosis Animal cell mitosis

31. Cytokinesis - division of the
cytoplasm

35. Objectives:
 To define meiosis
 To list and describe
the stages of meiosis

36. Meiosis – division of the
nucleus that reduces the
number of chromosomes
by half
 involved in sexual reproduction
 produces sex cells

37. Overview of Meiosis
46
(2N)
23
(N)
23
(N)
23
(N)
23
(N)
23
(N)
23
(N)
Meiosis I (PMAT I)
Meiosis II
(PMAT II)

38. Meiosis I
Prophase I
• homologous
chromosomes pair
up during synapsis
forming tetrads
• spindle appears
• crossing over may occur

39. tetrad
tetrad

40. Crossing Over
Between Homologous Chromosomes

41. Metaphase I
 homologous pairs of chromosomes
line up along the equator of the cell

42. Anaphase I
 homologous pairs of
chromosomes separate

43. Telophase I
 cytoplasm divides forming
2 new daughter cells

44. Meiosis II
 similar to the stages of mitosis
 chromosomes line up in the center
of each cell
 chromatids separate
 4 cells are produced

45. Prophase II

46. Metaphase II

47. Anaphase II

48. Telophase II

49. Products of
Meiosis

50. Objectives:
 To define gametes
 To define zygote
 To define genetic
recombination

51. Gametes
sex cells (sperm and egg)
human sperm cells
human egg cell

53. cell that results from
the fusion of gametes
 forms when
sperm
fertilizes
the egg
Zygote

54. process that results in genes
being combined in new ways
during meiosis
 introduces variation between
parents and offspring
 gives survival advantage to
sexually reproducing
organisms
Genetic Recombination

57. Objectives:
 To define cancer
 To describe the role
of gene expression in
cancer
 To describe the
causes of cancer

58. abnormal, uncontrolled growth
of cells that can spread from
one part of the body to another
Cancer

60. Tumor – abnormal proliferation of
cells that results from uncontrolled,
abnormal cell division
Types of Tumors
benign – cells remain within a
mass and do not spread
malignant – cells may invade and
destroy healthy tissues elsewhere
in the body

62. spread of cancer cells beyond the
original site of growth
cells grow as malignant
tumor in epithelium
Metastasis

64. Types of Genes Implicated in
Cancer Development
1. Oncogenes
2. Tumor-Suppressor
Genes
3. DNA Repair Genes

65. proto-oncogene –
a gene which
regulates normal
cell growth
Oncogene – mutated proto-
oncogene that can cause
uncontrolled cell growth
and proliferation

67. inhibits cell division and
prevents tumor formation
Tumor-Suppressor Gene
mutations in tumor
suppressor genes
promote cell division
and allow genetically
damaged cells to
grow out of control

68. repairs mutations in cellular
DNA before a cell enters
mitosis
• mutations in repair
genes leads to
continued transcription
of mutated DNA
sequences and affects
normal cell functioning
DNA Repair Gene

70. Breast Cancer Cell Line Karyotype

71. any substance that can
induce or promote cancer
Carcinogen