Cell Growth and Revision

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CHAPTER 5
Cell Growth and Revision
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Why do cells reproduce?
GROWTH
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REPAIR
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Stomach lining cells 2 days
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Life Spans of Body Cells
Platelets 10 days
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Skin Cells 20 days
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Red Blood Cells 120 days
Brain cells 30-50 years
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Intestinal lining cells 3 days
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Chromosomes

• DNA plus proteins is called chromatin.

• One half of a duplicated chromosome is a
  chromatid.
• Sister chromatids are held together at the
  centromere.
• Telomeres protect DNA and do not include genes.

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The Cell Cycle

• The four stages of the cell cycle are gap 1,
  synthesis, gap 2, and mitosis.

1) Gap 1 (G1) cell growth and normal functions
2) DNA synthesis (S) copies DNA
3) Gap 2 (G2) additional growth
4) Mitosis (M) includes division of the cell
nucleus (mitosis) and division of the cell
cytoplasm (cytokinesis)

• Mitosis occurs only if the cell is large enough
  and the DNA undamaged.

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Mitosis
Mitosis and cytokinesis produce two genetically
identical daughter cells.

• Interphase prepares the cell to divide.
• During interphase, the DNA is duplicated.

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Steps of Mitosis

• Prophase
• Metaphase
• Anaphase
• Telophase

_______________________________________ _________
______________________________ __________________
_____________________ ___________________________
____________
PMAT
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PROPHASE
Sister Chromatids Nuclear Membrane Centrioles Fibers

Shorten and Thicken
Begins to break down
Move apart from one another
Form between centrioles
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METAPHASE
Sister Chromatids Nuclear Membrane Centrioles Fibers

Become attached to the fibers. Are pulled to
middle of cell
Are stretched between the two ends of cell
Move to opposite ends of cells
Remains dissolved
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ANAPHASE
Sister Chromatids Nuclear Membrane Centrioles Fibers

Pulled apart by fibers. Each chromatid is
separate from its sister
Still at cells poles
Pull each chromatid toward opposite ends of cell
Remains dissolved
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TELOPHASE
Sister Chromatids Nuclear Membrane Cell Membrane Fibers

Each end of cell has a complete set of
chromosomes.
Begins to pinch, forming two new cells
Begin to disappear
Begins to reform
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Mitosis

• Cytokinesis differs in animal and plant cells.

• In animal cells, the membrane pinches closed.
• In plant cells, a cell plate forms.

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The Point of Mitosis
Result in two IDENTICAL daughter cells
Each cell will have the SAME number of
chromosomes as the original cell.
Each cell will have the SAME job as the original
cell.
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Understanding Mitosis
Starting with prophase, draw a cell undergoing
mitosis. Your original cell has 8 chromosomes.
Make sure to include the cell membrane, nuclear
membrane, chromosome, centrioles, and fibers.
PROPHASE
ANAPHASE
METAPHASE
TELOPHASE
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• Cells Life Cycle
• Interphase
• Prophase
• Metaphase
• Anaphase
• Telophase
• Interphase

• Mitosis
• Prophase
• Metaphase
• Anaphase
• Telophase

INTERPHASE
__________________________________________________
__________
PROPHASE
METAPHASE
ANAPHASE
TELOPHASE
__________________________________________________
__________
__________________________________________________
__________
__________________________________________________
__________
__________________________________________________
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Plant Mitosis
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MITOSIS
Plant Cell vs. Animal Cell

• The process is VERY SIMILAR in each type of cell.
• There are only 2 differences
• Plant cells do not have centrioles
• A cell wall is laid down at the end of the cell
  division.

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Can You Put These Cells In The Correct Sequence
Of Mitosis?
??So What Is This??
3. Anaphase
2. Metaphase
___________________
___________________
___________________
??So What Is This??
1. Prophase
4. Telophase
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___________________
___________________
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Mitosis is only a small part of a cell's
"LIFE CYCLE"
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(Just like you You will only spend a short time
of your life actually reproducing!")
At least...LET'S HOPE SO!
INTERPHASE
The cell spends most of its life in
_____________________________
(The phase IN-BETWEEN mitosis)
Life Cycle Animation
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Can You Put These Cells In The Correct Sequence
Of Mitosis?
3. Anaphase
Interphase
2. Metaphase
___________________
___________________
___________________
1. Prophase
4. Telophase
Interphase
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___________________
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Rates of Mitosis
An organism's cells are in different parts of
their life's cycle.
Can you identify the phases of this plant's cells?
__________
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__________
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Changes in the Rate of Mitosis
Changes often occur in the growth rate of cells.
Faster Rate of Mitosis
CANCER
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Slower Rate of Mitosis
AGING
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Cancer
Cell division is uncontrolled in cancer.

• Cancer cells form disorganized clumps called
  tumors.

• Benign tumors remain clustered and can be
  removed.
• Malignant tumors metastasize, or break away, and
  can form more tumors.

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Cancer

• Cancer cells do not carry out necessary functions.

• Cancer cells come from normal cells with damage
  to genes involved in cell-cycle regulation.

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Cancer

• Carcinogens are substances known to promote
  cancer.

• Standard cancer treatments typically kill both
  cancerous and healthy cells.

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CANCER CAUSERS
SOME VIRUSES
RADIATION
2._________________________
1._________________________
Sun
X-Rays
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CHEMICALS
3._________________________
Chemicals used on household items and/or
pesticides
Nuclear Wastes
Drugs
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__________________ ____________________
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CHROMOSOMES OF ORGANISMS
ORGANISM GUESSTIMATE ACTUAL CHROMOSOME
CAT
DOG
CHIMPANZEE
EARTHWORM
GOLDFISH
CARROT
LETTUCE
ONION
CHICKEN
GUINEA PIG
HUMAN
MOSQUITO
PEA
PENICILLIN
CORN
FROG





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78
48
36
94
18
18
16
78
64
46
6
14
1-4
20
26
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Chromosome Comparisons
If an organism has more chromosomes, does that
mean it is smarter?
NO
If an organism has more chromosomes, does that
mean it is larger?
NO
If an organism has more chromosomes, does that
mean it is more complex or evolved?
NO
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Stem Cells
Stem cells are unique body cells.

• Stem cells have the ability to
• divide and renew themselves
• remain undifferentiated in form
• develop into a variety of specialized cell types

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Stem Cells

• Stem cells are classified into three types.

• totipotent, or growing into any other cell type
• pluripotent, or growing into any cell type but a
  totipotent cell
• multipotent, or growing into cells of a closely
  related cell family

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Stem Cells

• Stem cells come from adults and embryos.

• Adult stem cells can be hard to isolate and grow.
• The use of adult stem cells may prevent
  transplant rejection.
• The use of embryonicstem cells raisesethical
  issues
• Embryonic stem cellsare pluripotent andcan be
  grown indefinitelyin culture.

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Stem Cells

• The use of stem cells offers many currently
  realized and potential benefits.

• Stem cells are used to treat leukemia and
  lymphoma.
• Stem cells may cure disease or replace damaged
  organs.
• Stem cells may revolutionize the drug development
  process.