The Cell Cycle

1
The Cell Cycle
Ch 3b
2
Reproduction of Cells
3
The DNA Molecule
4
Chromosome Structure

• Rod shaped structure
• Made of a single DNA molecule and proteins called
  histones
• Histones maintain shape of chromosomes
• Aids in tight packing of DNA
• Seen during cell division
• Coiled and compact

5
DNA and Chromosomes
double-stranded DNA molecule
6
A Pair of Homologous
Chromosomes
7
DNA Replication
8
Chromosome Structure

• Chromosome consists of two identical halves
• Each half is a chromatid
• Formed when DNA makes a copy of itself before
  cell division
• Each new cell will receive one chromatid from
  each chromosome
• Chromatids are held together by a centromere

9
Chromosomal Replication
10
Human Chromosomes
11
Human Chromosomal Pairs
23 pairs
autosomes
Sex chromosomes
12
Cell Cycle
13
Cell Cycle
14
Cell Cycle

• Interphase- 75 of cell life cycle
• G1 rapid growth
• S DNA replicates centrioles replicate.
• G2 cell prepares for cell division
  microtubular structures form.

15
Cell Cycle

• Cell Division
• Mitosis cell divides its nuclear components
  (chromosomes).
• Cytokinesis cell divides its cytoplasmic
  components.

16
Stages of Mitosis

• Prophase
• Metaphase
• Anaphase
• Telophase

17
Interphase
18
Prophase

• Chromosomes shorten and become visible (early
  prophase)
• Chromosomes made up of 2 identical chromatin
  threads called chromatids
• Centrioles migrate toward opposite pole pulled by
  kinetochore
• Nuclear envelope disintegrates (late prophase).

19
Prophase
centrioles
20
Prophase
21
Centrioles during Prophase
22
Metaphase

• Chromosomes lined up in the middle
• Mitotic spindle complete.

23
Metaphase
24
Metaphase
25
Chromosome at Metaphase
26
Anaphase

• Sister chromatids ( identical strands of DNA)
  split from each other to form divided identical
  chromosomes.
• Kinetochore fibers shorten and pull divided
  identical chromosomes to opposite sides of the
  dividing cell.
• Polar microtubules slide past each other,
  lengthening and pushing the cell apart

27
Anaphase
28
Model for the
Movement of
Chromosomes
29
Telophase

• Divided chromosomes reach opposite sides of cell
  and begin to disperse as chromatin.
• Nuclear envelopes reforms around separated
  collections of chromosomes to form two nuclei.
• Cytokinesis- completion of cell division

30
Telophase

• Spindle apparatus disintegrates.
• Cytokinesis usually begins near the end of
  telophase.

31
Telophase
32
Cytokinesis

• Separation of cytoplasmic components to yield two
  daughter cells
• Microfilaments form a contracting ring that
  pinches the plasma membrane inward between the
  forming daughter cells

33
Cytokinesis
cleavage furrow
34
Cytokinesis
35
RNA
Protein Synthesis
36
Contrasting RNA with DNA
DNA
RNA

• Single-stranded
• Ribose
• Bases
• Adenine
• Uracil
• Guanine
• Cytosine

• Double-stranded
• Deoxyribose
• Bases
• Adenine
• Thymine
• Guanine
• Cytosine

37
Protein Synthesis

• mRNA- copies DNA and directs protein synthesis
• rRNA- joins with ribosomal proteins to make
  ribosomes
• tRNA- transfers amino acids to ribosomes to make
  protein

38
Protein Synthesis

• Transcription-occurs in nucleus
• mRNA copies DNA nucleotide sequence
• 2. Translation
• nucleotide sequence in mRNA is uncoded
• mRNA binds to rRNA
• tRNA brings appropriate amino acid to mRNA
• Polypeptide is manufactured

39
Protein Synthesis
40
Transcription
DNA Sense Strand
mRNA Transcript
41
Transcription
Transcription begins here
enzyme
mRNA
42
Transcription
mRNA
43
Translation
tRNA
anticodon
codon
44
Translation
Amino Acid
Ribosome
tRNA
mRNA
Anticodon
Codon
45
Translation
AA
Binding sites
Ribosome
Anticodon
mRNA
Initiator codon
46
Translation
47
Translation
48
Translation
49
Translation
u
50
Translation
u
51
Translation
AA
AA
AA
AA
Complete protein
1
2
U A G A U C
Stop codon
http//www.youtube.com/watch?v983lhh20rGY
52
Cancer
Rapid and uncontrollable development and
production of cells.
53
Development of Cancer Cells

• Inheritance may increase risk
• Proto-oncogenes and tumor suppressor genes mutate
  or become damaged by carcinogens
• Known carcinogens
• Viruses and bacteria
• Environmental chemicals
• Tobacco
• Radiation
• Dietary factors

54
Conversion

• Conversion begins with a mutation (a change in
  DNA) by
• Chemical
• Physical
• Biological

Conversion
55
Production of Cancer Cells
Development and Progression
56
Development Progression of Cancer

• Begins when a chemical substance stimulates
  growth of a mutated cell
• Those chemical substances influence a 2nd stage
  of carcinogens called promoters.
• Promoters stimulate cell to divide uncontrollably
• Metastasis- cancer traveling to other sites like
  a forest fire

57
Development of a Benign Tumor
58
Development of a Malignant Tumor
59
Overview of
Cancer Development
60
Ultraviolet Radiation
Skin Cancer
ozone
61
Ozone

• Screens out 99 of harmful UV light
• Ozone produced by lightening
• 1 in ozone will result in a 2 in skin
  cancer
• Holes in ozone
• Dupont- CFCs hairspray, refrigerators, air
  conditioning
• Which country has the highest rate of skin cancer?

62
Skin Cancer

• Avoid sun between 10am to 4pm.
• Wear sunscreen w/ SPF 40.
• Wear appropriate clothing.

63
Testing

• Genetic testing
• Biopsy
• Blood test
• X-rays, PET, MRI
• Visual tactile observation

64
Treatments

• Surgery
• Radiation
• Chemotherapy
• Homeopathy

65
Prevention

• Know family history
• Get regular medical screenings
• Learn self-exam techniques
• Avoid direct sunlight
• Watch your diet and weight
• Dont smoke
• Drink alcohol in moderation (alcohol decrease
  heart disease, but increases risk of certain
  cancers)
• Become educated

66
INQUIRY

• What do CFCs do?
• What is a proto-oncogene?
• Name 3 carcinogens.
• What are the ABCDs of skin cancer?
• What is the function of ozone?
• Who is Henrietta Lacks?

67
INQUIRY

• Which cells in the body are diploid and which are
  haploid?
• During which stage does DNA replication occur?
• Which stage of mitosis is seen in this picture?
• At which stage is the cell binuclear?
• In which phase do chromosomes line up in the
  center of the cell?
• Where does the kinetochore attach?