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Cell Division
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Requirements for cell division
1. Grow; build new macromolecular structures
2. Duplicate genetic material (DNA replication)
3. Partition/Segregate gentic material (mitosis)
4. Divide content of cytoplams (cytokinesis)
Batterial Cell Divison
Simple process produces two cell from one
Made easier by single circular chromosome
Binary fission
Proteins involved similar to eukaryotic proteins
Process is distinct and different from mitosis
Key Feature of Bacterial Division
Replication and segregation
concerted process (simultaneous process)
-chromosome is "pushed" to poles during replication
-chromosome finish replication at opposite poles
Exact mechanism of segregation not known
Eukaryotic Cell Division
More complex genome, mutiple chromosomes
Genome inside nucleus
More complex cytoplasmic contents
How does cell keep track of chromosomes?
Keep products of replication together (protein glue)
Temporal separation and replication/segregation
Cell Cycle
G
1
Gap 1 prepares for DNA replication
Cell Cycle
S
During synthesis DNA is replicated
Cell Cycle
G
2
Gap 2 prepares for mitosis
Cell Cycle
M
Mitosis segragate chromosomes
Interphase
G
1
S
G
2
M Phase
Mitosis
Cytokinesis
G
0
Cells have left the cycle: noncycling
Eukaryotic Chromosomes
Linear structure that contain single DNA molcule
DNA molecule is always packaged into chromosomes
Amount of dondensation changes during cell cycle
Chromosome has visible contriction called centromere
Nucleosomes
1st DNA wrapped around protein
Centromere
Visible contriction
-Site where replicated chromosomes held together
-Site of
kinetochore:
functional element of centromere
Phases of Mitosis
Divide into 5 phases
-Prophase
-(Prometaphase)
-Metaphase
-Anaphase
-Telophase
What is the function of mitosis
To segregate chromosomes
-Each cell gets 1 copy each chromosome
Does cell count or mark chromosomes?
No!
How do we ensure new cells gets entire genome?
Keep chromosomes together after replication
Align them together in the center of cell
Pull apart copies at the same time
Completely rearranging microtubles
-Construct
spindle
to separate chromosome
Prophase
Chromosome condense; nucleus breaks down, spindle forms (microtubles)
Metaphase
Chromosomes move to center of cell, attached to spindle at equator
Anaphase
Chromosome are pulled to poles
Telophase
Reverse of prophase
Cytokinesis
Cell is actually divided
-Centractile ring of microfilaments
Control of cell cycle
Cancer
: uncontrolled cell division
Irreversible events
-DNA replication
-Anaphase
To insure accuracy cell monitors process
MOC: Positive regulators that drive cell cycle
Cyclin
proteins are produced in synchrony with cycle
Cyclin dependent kinases (cdk)
drive cycle
MOC: Checkpoints
Are points the cell assess accuracy
Allows cell to stop if process is faulty
Can even lead to cell death when process goes wrong
CP: G
1
/s
Decision to replicate DNA
Check for chromosome integrity
CP: G
2
/M
Is replication complete?
Are the chromosomes damaged:
Metaphase/Anaphase
Decision to separate chromosomes
-All chromosomes align properly
-Connected to both poles
Author
skyy22
ID
36858
Card Set
Cell Division
Description
Cell division flashcards
Updated
2010-09-23T17:53:03Z
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