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What do we need to do to make new cell?
An old one
What are the requirements for cell divison?
- 1. Grow: build new macromolecular structures
- 2. Duplicate genetic material (DNA replication)
- 3. Partition/segregate genetic material (mitosis)
- 4. Divide content of cytoplasm (cytokinesis)
Describe Bacterial Cell Division
- Simple process produces two cell from one
- Call process binary fission
- Actually more complex than we usually talk about
- Proteins involved are similar to eukaryotic proteins
- Process is distinct and different from mitosis
What are the key feature of bacterial division
- Replication and segregation concerted process-Chromosome is "pushed" to poles during replications
- -Chromosome finish replication at opposite poles
What is the exact mechanism of segregation of bacterial division?
- Not Known
- Appears to be under controll by cell
- Appears to use cellular proteins (not passive)
What's the difference between bacterial and eukaryotic cell division?
- More complex genome, multiple chromosomes
- Genome inside nucleous
- More complex cytoplasmic contents
What are the key feature of Eukaryotic cell division?
- Keep products of replication together (protein glue)
- Temporal separation and replication/segregation
Describe the cell cycle
- G1: Gap 1 prepares for DNA replication
- S: During synthesis DNA is replicated
- G2: Gap 2 prepares for mitosis
- M: Mitosis segregate chromosomes
What is the interphase in cell division?
G1, S, G2
What is the M phase in cell division?
Mitosis and Cytokinesis
What is G0?
Cells have left the cycle: noncycling
- Linear structure that contain single DNA molecule
- DNA molecule is alwways packaged into chromosomes
- -1st DNA wrapped around protein is Nucleosomes
- Amount of condesation changes during cell cycle
- Chromosome has visible constriction call centromere
- Site where replicated chromosomes held together
- Site of kinetochore: functional element of centromere
What are the phases of mitosis?
What is the function of mitosis?
- Segregate chromosomes
- -Each cell gets 1 copy each chromsome
How do cells gets entire genome?
- Keep chromosome together after replication
- Align them together in the center of cell
- Pull apart copies at the same time
What do the cell use to separate chromosomes?
Spindle - microtubules
chromosome condense; nucleus breaks down, spindle forms (microtubles)
Chromosomes move to center of cell, attached to spindle at equator (metaphase plate)
What happens in Anaphase?
Chromosomes are pulled to poles
What happens in telophase?
reverse of prophase; spindle breaks down, nucleuos reform
What happens in cytokinesis?
- Cell is actually divided
- -contrictile ring of microfilaments
Events in the cell cycle that are irreversible
How do cell insure accuracy?
monitors process with mechanisms of control
Positive regulators that drive cell cycle
- Cyclin proteins are produced in synchrony with cell cycle
- Cycclin dependent kinases (cdk) drive cell cycle
1st Checkpoint of cell cycle
- G1/S - also called START
- -Decision to replicate DNA
- -Check for chromosome integrity
2nd Checkpoint of cell cycle
- -Replication complete?
3rd Checkpoint of cell cycle
- Metaphase/Anaphase: decision to separate chromosomes
- -All chromosome align properly
- -Connected to both poles