Cell Division Flashcards
How do unicellular organisms usually reproduce?
Through cell division, commonly binary fission.
What do multicellular organisms depend on cell division for?
- Development from a fertilized cell
- Growth
- Repair
How does cell division occur?
Mitosis and Meiosis.
Chromosome
A string like structure structure comprised of DNA.
Chromatin
DNA wrapped around histone proteins.
Sister chromatid pair
Replicated DNA connected at the centresome, forming the x like structure.
What are the 2 phases in the eukaryotic cell cycle?
Interphase (G1, S, and G2) Mitotic Phase (M)
What occurs during the M Phase of the eukaryotic cell cycle?
Mitosis, cytokensis (Division of cytoplasm)
What occurs during the interphase stage of eukaryotic cell division?
G1 - Normal cell metobolism and growth
S - DNA replication occurs
G2 - Preparation for cell division
What are the 5 stages of mitosis, in order?
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
What happens in prophase?
DNA condenses to form chromatin in to sister chromatids, the centresome divides and microtubules begine to form the mitotic spindle.
What happens in prometaphase?
Microtubules bind to the kinetechores (protein structures on chromosomes) anchoring them to the mitotic spindle.
What happens in Metaphase?
The mitotic spindle organises the chromosomes into the middle of the cell.
What happenes in Anaphase?
Microtubules pull the sister chromatids apart, this happens as the microtubules contract and expand to pull the chromatids to opposite ends of the cell.
What happens in Telophase?
The two sets of chromosomes separated during anaphase are used to create new nuclei, the cell then splits in two via cytokenesis.
What is Cytokenesis?
A pinching action separates the cytoplasm into 2 separate cells. In animals a cleavage furrow forms, in plants a cell plate forms.
Why do liver cells divide?
In response to injury.
Why do muscle cells divide?
Muscle cells do not divide, they repair themselves.
What does the protein complex that regulates cell cycle consist of?
2 subunits:
- a regulatory subunit - termed cyclin
- A catalytic subunit (Cdk - cyclin dependant kinase) which only phosphoylates other proteins when bound to cyclin.
What is MPF (Maturation-promoting factor)?
When cyclin binds to Cdk it forms a protein complex called MPF.
If a Cdk-cyclin complex becomes more abundant in G2 phase and dissapears before G1 phase, what does this suggest?
The complex helps the cell move past the G2 phase.
What are oncogenes?
Cells that actively promote cell division.
What is the p53 gene?
A tumor supressor gene that prevents cells with damaged DNA from replicating.
What are the three types of mutation that can lead to cancer?
- Translocation
- Transcription
- Gene deletion
- Point mutations
