cell bio8
TRANSCRIPT
Advanced Cell Biology
2014 1nd Semester
Department of Animal Science
Chungbuk National University
8th Lecture
1st week : Introduction
3rd week :Research Strategies For Cell Biology
5nd week : Nucleus, Transcription and Splicing
7nd week : Membrane and Channel
9nd week : Membrane Trafficking
11nd week : Cell Signaling
13nd week : Cytoskeleton
15nd week : Cell Cycle
Cell Cycle
G1: originally described as a gap between mitosis and DNA replication; now appreciated to be the time when cells grow and check for DNA damage and sample the environment to make the pivotal decision to replicate their genomes and progress through the cell cycle.
S: phase when the genome is replicated.
G2: originally described as a gap between DNA replication and mitosis; now appreciated to be the time when cells check for completion of DNA replication before entering mitosis.
M: Mitosis and cytokinesis separate the replicated genome into two daughter cells.
G0: Most differentiated cells in higher eukaryotes withdraw from the cell cycle into this stage.
G1 restriction point: Monitors cell size, environmental conditions, and interactions with neighbors and matrix.
G1/S DNA damage checkpoint: Stops the cell cycle if DNA damage is detected.
G2/M DNA damage checkpoint: A protein kinase cascade stops the cell cycle until all DNA is replicated.
Metaphase spindle assembly checkpoint: Delays separation of daughter chromatids until all are attached to the mitotic spindle.
Checkpoints control transitions between the cell cycle phases
Cyclin and Cyclin Dependent Protein Kinase
Discovery of Cyclin and Regulators
- Temperature Sensitive Yeast mutant defective in Cell Cycle
- Isolations of cdc mutants
Xenopus embryo as model system for Cell Cycle Research
Xenopus egg extract as in vitro model forCell Cycle Research
Maturation Promoting Factor (MPF)
Some protein(?) factors inducing Nuclear Membrane Breakdown and spindle Formation
Purification of MPF reveals the identity of MPF..
MPF = Cyclin B + CDK1
Cdc2
Mitotic entry(Cell Division)
Mitotic Delay(Cell Growth)
No divisionInfinite growth
Premature division
Inactive MPFHyperactive MPF
Role of Protein Destruction in Cell-Cycle Control
Role of APC/C in Cell Cycle Control
G1 Phase
Divide or not? That is question
Growth Control
Cell should be reached at the specific size to divideUncontrolled division leads cancer
Integrity of Cellular DNA Monitored by a G1 Checkpoint
S-Phase and DNA Replication
Metaphase
Spindle Checkpoint
If there is unattached kinetocore, stop cell cycle progress