Download Cell cycle and mitosis 2014

The Cell Cycle
Mrs. Taktak and
Mrs. Storey
Bell Work: 1. Label the phase of the
cell cycle that is missing. 2. What
happens during this time of the
???
cycle?
The Cell Cycle Consists of Two
Major Parts….
A.) Cell Growth
(Interphase)
B.) Cell Division
(Mitosis)
Interphase: Cell Growth

G1 Phase: Cells increase in Size, Increases
in Number of Proteins, and Increases in the
Number of Organelles
What Does This
Phase Compare
To In Our Cycle?
Interphase: Cell Growth
S Phase: (S=Synthesis) DNA Synthesis
(replication) Occurs in this Phase
Interphase: Cell Growth
G2 Phase: The Cell Continues to
Grow and Produces Proteins
Required for Cell Division (It
prepares for Cell Division)
Interphase= G1 + S + G2
What Does This Phase
Compare To In Our
Cycle?
Cell Division: Mitosis
M Phase (M= Mitosis) Less Than 10% of
the Cell Cycle, Mitosis is the Process of
Cell Division
Mitosis Animation
Why do cells divide?
• Growth
• Development
• Repair
• Keep cells small (more surface
area to volume)
Essential Features of Cell Division
1. Transmit a complete copy of
genetic information (DNA)
2. Transmit materials necessary for
cell to survive and use genetic
information (cytoplasm and organelles)
DNA- TWO DIFFERENT
FORMS?
During INTERPHASE of cell cycle:
• DNA
molecules are
in extended,
uncondensed
form =
Chromatin
During division phase of cell cycle:
• DNA molecules condense to form
chromosomes.
– each chromosome is a single
molecule of DNA
– easier to sort and
organize DNA into
daughter cells
Structure of a eukaryotic chromosome
• Unreplicated chromosome (CHROMATID)
arm
arm
centromere
Prior to cell division:
• chromosomes (DNA) are replicated
(duplicated)
• duplicated chromosome
– attached at their centromeres
– as long as attached, known as
sister chromatids
duplicated
chromosome
sister
chromatids
daughter
chromosomes
Each species has a characteristic
number of chromosomes:
Prokaryotes – one chromosome
Crayfish – 200 chromosomes
Human – 46 chromosomes
=> 23 pairs of chromosomes
What is Mitotic Cell Division?
• Division of somatic cells
(body cells) in
eukaryotic organisms
• A single cell divides into two
identical daughter cells
(cellular reproduction)
Mitotic Cell Division
2 major processes:
• mitosis – divides the nucleus and
chromosomes
• cytokinesis – cytoplasmic division
=> cell divides into two daughter
cells
Mitosis
4 phases:
1st – Prophase (4 major events)
2nd – Metaphase
3rd – Anaphase
4th – Telophase and Cytokinesis
Prophase
4 major events
i) Chromatin condenses (coils up)
ii) spindle fibers form
iii) chromosomes are captured by
spindle
iv) The nuclear envelope breaks down
Centrioles
producing
spindle
fibers
Nuclear
envelope
(membrane)
breaks
down
Chromatin
coils up
forming
chromosomes
chromatin
nucleus
nucleolus
centrioles
condensing
chromosomes
Metaphase
Chromosomes align along
equator of the cell
centrioles
chromosomes
spindle fibers
Anaphase
• Sister chromatids separate
• Spindle fibers attached to
centromeres and shorten and pull
chromatids toward opposite poles
• free spindle fibers lengthen and push
poles of cell apart
V-shaped chromatid
free spindle fibers
Telophase
• Spindle fibers disintegrate
• Nuclear envelopes form around both
groups of chromosomes
• Chromosomes revert to their extended
state (chromatin)
• Cytokinesis occurs, enclosing each
daughter nucleus into a separate cell
chromosomes
decondensing
pinching of cell
membrane at equator
nuclear envelope
reforming
nucleolus reappears
cytokinesis
Cytokinesis
• Animal cells:
Cytoplasm pinches around the equator
Plant Cell: cell plate forms to
become the new cell wall.
Cell
Plate
“Wheel decide”- Be ready to come up and
point out a cell and name the phase it is in!