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Cell Cycle
Based on what you already know:
What is Diffusion?
Does Rate of Diffusion effect if a cell will grow?
• Remember, the cell membrane allows nutrients
(ex. Glucose, oxygen, etc.) in and wastes out
(diffusion)
• Diffusion is fast over short distances but slow over
long distances
• So, b/c of slow rate of diffusion, cells can’t be
giants b/c they would starve to death or be
poisoned from the build up of wastes!!
So what must happen?
• Before the cells become to large it must divide
into 2 “daughter cells”
•
http://www.youtube.com/watch?v=Q6ucKWIIFmg
WHY DON’T CELLS GROW
INDEFINENTLY?
The larger a cell becomes, the harder it gets to move
nutrients & waste throughout the cell.
Cells abide by a certain volume to surface area ratio.
If the cell is too big in volume, then there is not
enough surface area to meet the cell's
requirements.
A certain surface area is needed so that materials
can pass through the cells membrane and sustain
the volume of the cell.
Types of cell division
•
Prokaryotes
• Binary fission
•
Eukaryotes
• Mitosis: (Asexual Reproduction)
• Growth, development & repair
• Asexual reproduction (yields genetically
identical cells)
• Occurs in somatic (body) cells
• Meiosis: (Sexual Reproduction)
• Sexual reproduction (yields genetically
different cells with half the # of chromosomes)
• Occurs in specific reproductive cells
• Yields gametes (e.g., eggs & sperm) or spores
Why Do Cells Divide?
Cells must divide for:
• Growth
• Repair
• Reproduction
Important Facts to know before we begin…
•
Completed in 2003, the Human Genome Project (HGP)
•
13-year project coordinated by the U.S. Department of Energy and the National
Institutes of Health.
•
To identify all the approximately 20,000-25,000 genes in human DNA,
•
To determine the sequences of the 3 billion chemical base pairs that make up
human DNA,
•
To store this information in databases,
•
To improve tools for data analysis,
•
To transfer related technologies to the private sector, and
•
To address the ethical, legal, and social issues (ELSI) that may arise from the
project.
• Genome-the total complement of an
organism’s genes
• Chromatin-network of DNA and
fibrils in a nucleus that is NOT
dividing
• Chromosome-structure of DNA that
transmits genetic information to the
next generation
• Chromatids-two copies of the same
chromosome attached together
• Centromere-constriction where
sister chromatids of a chromosome
are held together.
• Sister
chromatids
Homologous Chromosomes
1.In body cells, chromosomes occur as pairs.
2.Each set of chromosomes is a homologous pair
3.One member of each homologous pair is inherited from
the male parent, the other member from the female
parent.
What is the
picture below?
www.treachercollins.co.uk
(Mader 2007)
• All living things grow and
reproduce
• The cell cycle has two parts—
growth (interphase) and
reproduction (mitosis)
• B. Controlled by enzymes called CYCLINS
• 1. These enzymes, produced with instructions
from the cell's DNA (genes), control when the
cell undergoes mitosis.
• 2. When DNA (genes) are damaged, the enzymes
controlling mitosis may not be produced,
• a. resulting in cell death.
Apoptosis
•Apoptosis is programmed cell death
•Apoptosis and cell division are balancing processes
that maintain the normal level of somatic (body) cells.
•Death by apoptosis prevents a tumor from developing.
• b. Damaged DNA (genes) could also cause
the enzymes that control mitosis to be
produced in excess amounts, resulting in
uncontrolled cell growth (cancer).
• Brain Tumor
Section 10-2
Cell Cycle
includes
G1 phase
Go to
Section:
Interphase
M phase
(Mitosis)
is divided into
is divided into
S phase
G2 phase
Prophase
Metaphase
Anaphase
Telophase
Eukaryotic Cell Cycle
The eukaryotic cell cycle has 5 main phases: (cell cycle:
Series of events a cell goes through as they grow and
divide)
1. G1 (gap phase 1)
2. S (synthesis)
3. G2 (gap phase 2)
Interphase
Cells spend 90% of their time in this phase
4. M (mitosis) (M) phase (mitosis and cytokinesis)
5. C (cytokinesis)
The length of a complete cell cycle varies greatly among cell
types.
17
G1 Phase
a. grows and develops
b. makes new proteins
S Phase-Replication
•
Synthesis
•
chromosomes replicate in the
nucleus
•
Chromosomes form an EXACT
copy so daughter cell will have a
the correct number of identical
chromosomes
• When Chromatin have
replicated, we call them Sister
Chromatides
G2 Phase
•
preparing for mitosis by making RNA and
proteins needed for cell division
•
During G2 the chromosomes undergo
condensation, becoming tightly coiled and are
called chromosomes.
•
Centrioles (microtubule-organizing centers)
replicate and one centriole moves to each pole.
20
Interphase Diagram
Interphase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Mitosis
Asexual Reproduction
Prophase, Metaphase, Anaphase,
Telophase
Which type of Cells Go Through
Mitosis?
• Somatic Cells (Body Cells):
• Skin, hair, muscle, etc.
• Each human body cell has 46
chromosomes
Prophase (1st stage of cell division)
The cell prepares for
nuclear division
a.) Sister Chromatids condense and
shorten, become distinguishable
b.) Nuclear membrane disintegrates,
nucleolus disappears
c.) Centrioles separate, migrate to
the poles
d.) Spindle fibers form between
centrioles and attach to the
centromere on the sister
chromatids
e.)
Prophase
Early prophase
Late prophase
Prophase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Metaphase- 2nd stage (shortest)
a.) chromosomes line up in
pairs at equator (center of
cell)
b.) centromere of each
chromosome is attached
to a separate spindle fiber
Metaphase
The cell prepares chromosomes for division
Sister Chromatids line up across the middle of the cell.
• Animal Cell
• Plant Cell
• Chromosomes line up at
the center of the cell
• Chromosomes line up at
the center of the cell
• Spindle fibers attach from
daughter cells to
chromosomes at the
centromere
• Spindle fibers attach from
daughter cells to
chromosomes at the
centromere
Metaphase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Metaphase
Anaphase- 3rd stage
a.) Centromere of each
chromosome divides (separates)
b.) Separation of the chromatids in
each pair
c.) Spindle fibers appear to shorten,
pulling the chromatids apart at
the centromere (now called
chromosomes)
d.) migration of the chromosomes
ends with the arrival at the poles
and the formation of clusters
Anaphase
Anaphase
The chromosomes divide
• Animal Cell
• Plant Cell
• Spindle fibers pull
chromosomes apart
• Spindle fibers pull
chromosomes apart
• ½ of each chromosome
(called chromotid) moves
to each daughter cell
• ½ of each chromosome
(called chromotid) moves
to each daughter cell
Anaphase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Telophase – 4th stage
a.) Cleavage furrow forms b/w 2
cells and spindle fibers disappear
b.) Nuclear membrane forms
around each set of chromosomes
(forms 2 new nuclei)
c.) Chromosomes uncoil to form
chromatin net (getting ready for
interphase)
d.) Nucleoli reorganized
Telophase
Telophase
The cytoplasm divides
• Animal Cell
• Plant Cell
• DNA spreads out
• DNA spreads out
• 2 nuclei form
• 2 nuclei form
• Cell wall pinches in to
form the 2 new daughter
cells
• New cell wall forms
between to nuclei to form
the 2 new daughter cells
Telophase
Animal Cell
Plant Cell
Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm
Last phase of Cell Cycle
Cytokinesis
• Cytokinesis- division of the cytoplasm-the
cytoplasm divides to form 2 new, identical
cells.
• In animal cells- cell membrane pinches
together, furrow forms along the equator.
• In plant cells- cell plate forms in the middle of
the dividing cell
Picture of cytokinesis
*Image courtesy Indigo Instruments. Visit indigo.com for more original content like this. Reprint permission is
granted with this footer included.*
Mitosis Animation
http://www.cellsalive.com/mitosis.htm
Animal Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
Plant Mitosis -- Review
Interphase
Prophase
Metaphase
Anaphase
Telophase
Interphase
MITOSIS SUMMARY
•After Interphase, Mitosis,
and Cytokinesis, 1 cell has
become 2 new, identical
cells – each containing the
same genetic information.
•Mitosis is a form of
asexual reproduction
•A single parent cell
divides once to form 2
daughter cells identical to
themselves and to the
parent cell.
Figure 12.5x Mitosis
Figure 12.9 Mitosis in a plant cell
Figure 12-09x Mitosis in an onion root
Uncontrolled Cellular Division Causes
CANCER…
Chemicals, radiation, and some viruses & bacteria
can cause mutations to your cells that make
mitosis uncontrollable!
How cancer forms in the body…
Abnormal Cell Growth
Abnormal Cell Growth
Cancer
• Occasionally, cells lose control of the cell cycle
• Cancer is a malignant growth resulting from
uncontrolled cell division
• Malignant =dangerous to health; marked by uncontrolled
growth
• This results from:
• failure to produce certain enzymes,
• the overproduction of enzymes
• Or the production of enzymes at the wrong time.
Tumors
• Tumors are abnormal growth of cells
• Benign tumors are non cancerous and and only
grow locally
• Malignant tumors are cancerous and spread to
other areas of the body
A Large Abdominal Tumor
Surgical Removal of Tumor
Body without Tumor
Number of deaths for leading causes of death
according to the CDC
• Heart disease: 599,413
• Cancer: 567,628
• Chronic lower respiratory diseases:
137,353
• Stroke: 128,842
• Accidents (unintentional injuries):
118,021
• Alzheimer's disease: 79,003
• Diabetes: 68,705
• Influenza and Pneumonia: 53,692
• Nephritis, nephrotic syndrome, and
nephrosis: 48,935
• Intentional self-harm (suicide):
36,909
• Cancer is the second
leading cause of
death in the U.S.
• Lung, colon,
breast, and
prostate cancers
are the most
prevalent types
•
Genetics
Environmental Factors
• Cigarette smoke
• Air and water pollution
• Exposure to UV radiation
• Certain food products
• industrial chemicals
• viruses are some of the MANY
substances implicated in DNA
damage.
Cancer prevention
• Healthy Lifestyle
• Low fat, high fiber diet
• Exercise
• Not smoking
• Taking daily vitamins and minerals
• Carotenoids, Vitamins A, C, E, and calcium
Cancer
• Cancer is difficult to treat in later stages because
the cancer may have spread to vital organs and
damaged them beyond repair.
• Cancer staging is the process of finding out how
advanced and widespread a cancer has become.
• http://www.youtube.com/watch?v=LEpTTolebqo