Transcript Cell Division and The Cell Cycle

Cell Division and The Cell Cycle
MITOSIS ANIMATION
Process of Cell Division
Cell Life Cycle
•G1 phase
•S phase
•G2 phase
•Mitotic Phase
Interphase
Cell division
Think of interphase as the active life of the cell, towards the
middle of the phase, it copies its DNA and prepares to divide……
INTERPHASE
• active period in life of a
cell
–
–
–
–
biochemical reactions
protein synthesis
cellular differentiation
preparation for division
•muscle cells work as muscle cells
• nerve cells as nerve cells
•liver cells as liver cells…
Parts of Interphase
• G1
• S
• G2
Parts of Interphase
G1 “Growth phase”
• cells are performing
their assigned tasks,
metabolizing,
synthesizing etc
Parts of Interphase
G1 “Growth phase”
S “synthesis phase”
• DNA molecules are
copied or replicated
• Result: two copies of
the cell’s DNA
Parts of Interphase
G1 “Growth phase”
S “synthesis phase”
G2 “Growth Phase 2”
• cell is preparing for
the actual division
events (much protein
synthesis).
Interphase Summary
• Cell performing its job
• Preparing for division
• DNA not tightly
packaged into
chromosomes
(WHY?)
MITOTIC PHASES
•
•
•
•
Prophase
Metaphase
Anaphase
Telophase
Prophase
• What’s happening to
the DNA?
– Condensing into
chromosomes
Metaphase
• What’s happening to
the DNA?
– Chromosomes lining
up in the center of the
cell
– Spindle fibers attach to
centromeres
Anaphase
• What’s happening to
the DNA?
– Spindle fibers are
pulling chromosomes
apart to opposite sides
of the cell (towards
centrioles)
Telophase / Cytokinesis
• What’s happening to
the DNA?
– Chromosomes are
pulled to separate
sides of the cell
– Cell membrane forms
between 2 daughter
cells
Animal Cell Cytokinesis
• plasma membrane at
the equator is pulled
inwards until it meets
in the center of the
cell
• process guided by
actin microfilaments
Cell Division in Plants
• Plant cells have no
centrioles
• Cytokinesis
Plant Cell Cytokinesis
• CELL PLATE:
– formed by vesicles from
Golgi fusing at equator of
cell (composition of cell
wall??)
– Cell membrane is formed
by the membrane of the
vesicles (composition of
membrane??)
MITOSIS IN A PLANT CELL
MITOSIS IN AN ANIMAL CELL
DNA in Mitosis
• Copy chromosomes
to form sister
chromatids
DNA in Mitosis
• Copy chromosomes
to form sister
chromatids
• Chromosomes line up
single-file at median
DNA in Mitosis
• Copy chromosomes
to form sister
chromatids
• Chromosomes line up
single-file at median
• Sister chromatids
pulled apart
Mitosis Animation
Chromosomes
Phases of Mitosis Identification
Stopping Cell Division
• Anchorage-dependent:
needs to be attached to a
surface
• Density dependent: stop
dividing when they hit other
cells
Cell Cycle Checkpoints
Growth factor
Plasma membrane
Receptor
protein
Signal
transduction
pathway
Relay
proteins
G1 checkpoint
Control
system
G1
M
S
G2
Consequences of Mitotic
Mistakes
Cancer
• Uncontrolled cell division
BENIGN
MALIGNANT
METASTASIZED
Lymph
vessels
Tumor
Blood
vessel
Glandular
tissue
A tumor grows from a
single cancer cell.
Cancer cells invade
Neighboring tissue.
Cancer cells spread through
lymph and blood vessels to
other parts of the body.
HeLa Cells
Mitosis Review
• Growth
• Replacement of cells
• Asexual Reproduction
• Identical Cells