Oral biology - Cell cycle Flashcards
Definition of cell proliferation
An increase in the number of cells; as a result of cell growth and cell division
Definition of Growth factors
Polypeptides that control animal cell growth and differentiation
Definition of Transcription factor
a protein that regulates the activity of RNA polymerase
Definition of cell signalling
phosphorylation of residues
How cell divides?
A cell reproduces by preforming an orderly sequence pf events in which it duplicates its content and then divides in two
Mitosis is followed by what?
In most cases followed by cytokinesis
Cell division in eukaryotic cells: What occurs during G1 phase?
This is one of the longest phases.
A cell has one centrosome consisting of two centrioles.
Cell division in eukaryotic cells: What occurs during S phase?
S phase is completed within 8 hours.
Transition, centrosomes duplicate. Daughter centrioles arise from each centriole
Cell division in eukaryotic cells: What occurs at the end of G2 phase?
G2 phase completes in about 4 hours.
The centrosomes complete duplication and each centriole is fully assembled
Cell division in eukaryotic cells: What occurs in G0 phase?
Some cells stop dividing occasionally and leave G1 phase and enter the G0 where cells are metabolically active, however there is no appropriate extracellular signals that allows for re-entry to the cell cycle
What is the shortest phase of cell cycle?
Mitotic phase
Define mitosis
Its a division of the nucleus of a eukaryotic cell, involving condensation of DNA into visible chromosomes and separation of the duplicated chromosomes to form two identical sets.
What are the phases of mitosis?
- Interphase
- Prophase/Prometaphase
- Metaphase
- Anaphase
- Telophase
- Cytokinesis
What happens at interphase?
The nucleus and the nuclear envelope are distinct and the chromosomes are in the from of threadlike chromatin
What happens at prophase and prometaphase?
The chromosomes appear condensed, and the nuclear envelope is not apparent
What happens at metaphase?
Thick,coiled chromosomes. Each lined up at the equator.
What happens at anaphase?
The sister chromatids are separated to form two daughter chromosomes. Each pulled towards the pole
What happens at telophase?
The chromosomes are at the poles and begin to decondense.
A new nuclear envelope is reforming. The cytoplasm may be dividing
What happens at cytokinesis?
The cytoplasm is divided into two by contractiole ring - creating two daughter cells, each with one nucleus
Control of cell cycle depend on?
- Timer
- Events in correct order
- Events takes place once per cycle
- On/Off switch trigger events in complete and irreversible fashion
- Robustness
- Adaptability
What are cyclin dependent kinase (Cdk) controlled by?
Cyclins
What do Cdk need for protein kinase activity?
Cyclins
What does cyclin undergo during cell cycle?
Cycle of synthesis
How many cyclin-Cdk controllers are there?
4
What are the cyclin-cdk controllers?
- G1/S-cyclins bind at end G1: commit cell to DNA replication
- S-cyclins bind Cdks during S phase initiate DNA replication
- M-cyclins promote events of mitosis
- G1 cyclins promote passage through restriction point
Points to remember for cell cycle control systems..
- Cyclin does not activate the Cdk but directs it
- Different proteins phosphorylated
- Accessibility
