Download CELL CYCLE and Mitosis AP

CELL CYCLE
The events in the life of a cell
Interphase
• The time between cell divisions where the cell grows to
full size, duplicates its DNA and rests
• Cells live a “normal” life in Interphase
• Interphase is broken into three different sub-phases
G1, (G0), S and G2
Interstate highway
BETWEEN States
Cell Cycle Diagram
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G1 Phase – (Gap)
Occurs just after cell division
• Cell must re-grow to normal size
• Proteins are made
Cyklins mediate process
G0 Phase – Resting Phase
• Most of an adult’s cells are in
Interphase, stopping in G0
• Cell undergoes normal cell functions
while resting
• A cell that skips this phase can
become cancerous, growing
uncontrollably
• Humourous cell cycle video 3.5 mins
Check points
• Places where cell checks itself for damage
before proceeding
• Cancer bypasses check points
S Phase - Synthesis
• DNA is synthesized or copied in
preparation for cell division
Point of no return
Once a cell enters this S phase it is
committed to go through cell
division
A cell must divide or self destruct
upon entering
G2 Phase – Gap 2
• Cell grows larger in preparation for
cell division
• Organelles, Centrosomes, enzymes
and proteins are replicated
M Phase - Mitosis
• Division of cell Nucleus
• DNA forms into chromosomes
• Chromosomes separate with identical
pairs moving to opposite sides of the cell
• New nuclear membrane forms around
each set of chromosomes
Chromosomes = colored bodies
Only appear during Mitosis
Chromosomes
• Sister chromatids = identical DNA
• Homologous chromosomes = same type
chromosome in pairs (paternal/maternal)
• Centromere – connects chromatids
• Kineticore – winds up spindle fibers to
separate chromatids
overview
• 24 hour cycle
Cell cycle animation
Binary Fission - Cell division in
Prokaryotes
• NO nucleus
• No mitosis
• Origen of replication
is where DNA
replicated first
Regulation of the cell cycle
• Cyclin – a protein that controls the cell
cycle
• CDK – (Cyclin Dependant Kinase) binds to
cyclin to form MPF
A Kinase is an enzyme that activates
proteins
• MPF – (Maturation Promoting Factor)
helps start M phase
Formation of MPF brings past G2
checkpoint
Control of the Cell
Cycle
Control of cell cycle you tube video
Growth factor
• Protein released by certain body cells that
stimulate other cells to divide
Density-dependant inhibition
• Crowded cells stop dividing
Anchorage dependence
• To divide, most cells must be attached to
something
CANCER – Cells mutate and grow
• Normally a mutant cell is
destroyed or self
destructs.
• Called Apoptosis
• This does not occur in
cancer cell
• Cancer cells are not
inhibited by density or lack
of anchorage
Tumors – Mass of abnormal cells
• Benign tumor – remains at original site
• Malignant tumor – becomes invasive and
impairs function of other cells
• Metastasis – The spread of cancer cells
Interphase (again)
• Each daughter cell enters
interphase, so it can regrow, rest
and be a normal cell
Mitosis
Interphase
• The non dividing portion of the cell cycle
• Most of the time a cell is in interphase
Prophase
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Chromosomes become visible
Spindle fibers form
Nuclear envelope breaks down
Centrioles are replicated (Animal cells only)
Metaphase
• Chromosomes are aligned at the metaphase plate.
• Polar microtubules vs. Kinetochore microtubules.
Anaphase
• Each Kinetochore “eats” the spindle fiber and the sister
chromatids are moved apart.
• The polar microtubules push the poles apart.
Telophase
• The nucleus reforms
• The chromosomes become chromatin
• Cytokinesis begins
CytoKinesis
• The complete separation of daughter cells.
• Membrane sides connect
Cytokinesis Plant vs Animal
• Animal - Cleavage furrow
• Plant – Cell Plate
Interphase (again)
• Each daughter cell enters
interphase, so it can regrow, rest
and be a normal cell
Onion cell mitosis
Animal cells
Interphase
Prophase
Anaphase
Metaphase
Telophase
Plant cells
• Prophase
• Anaphase
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Metaphase
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• Telophase
Interphase
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Metaphase
Interphase
Interphase
Prophase
• Cytokinesis
• Anaphase
• interphase