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What do we need to do to make new cell?
An old one
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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)
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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
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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
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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)
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What's the difference between bacterial and eukaryotic cell division?
- More complex genome, multiple chromosomes
- Genome inside nucleous
- More complex cytoplasmic contents
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What are the key feature of Eukaryotic cell division?
- Keep products of replication together (protein glue)
- Temporal separation and replication/segregation
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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
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What is the interphase in cell division?
G1, S, G2
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What is the M phase in cell division?
Mitosis and Cytokinesis
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What is G0?
Cells have left the cycle: noncycling
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Eukaryotic Chromosomes
- 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
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Centromere
- Site where replicated chromosomes held together
- Site of kinetochore: functional element of centromere
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What are the phases of mitosis?
- Prophase
- (Prometaphase)
- Metaphase
- Anaphase
- Telophase
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What is the function of mitosis?
- Segregate chromosomes
- -Each cell gets 1 copy each chromsome
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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
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What do the cell use to separate chromosomes?
Spindle - microtubules
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Describe prophase
chromosome condense; nucleus breaks down, spindle forms (microtubles)
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Describe metaphase
Chromosomes move to center of cell, attached to spindle at equator (metaphase plate)
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What happens in Anaphase?
Chromosomes are pulled to poles
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What happens in telophase?
reverse of prophase; spindle breaks down, nucleuos reform
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What happens in cytokinesis?
- Cell is actually divided
- -contrictile ring of microfilaments
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Events in the cell cycle that are irreversible
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How do cell insure accuracy?
monitors process with mechanisms of control
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Positive regulators that drive cell cycle
- Cyclin proteins are produced in synchrony with cell cycle
- Cycclin dependent kinases (cdk) drive cell cycle
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1st Checkpoint of cell cycle
- G1/S - also called START
- -Decision to replicate DNA
- -Check for chromosome integrity
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2nd Checkpoint of cell cycle
- G2/M
- -Replication complete?
- -Damaged?
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3rd Checkpoint of cell cycle
- Metaphase/Anaphase: decision to separate chromosomes
- -All chromosome align properly
- -Connected to both poles
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