1.6 Cell division Flashcards
What do all cells go through before undergoing mitosis?
The cell cycle
What are the phases in the cell cycle?
Interphase then Mitosis
Interphase: G1, S, G2
What percentage of the cell cycle does cell division make up?
5-10% of the cell cycle
What processes occurs in interphase? What is the mnemonic?
DOCTER
DNA replication - Dna is copied during the S phase of interphase
Organelles duplicate - Organelles must be duplicated for twin daughter cells
Cell grows - Cytoplasmic volume must increase prior to division
Transcription + Translation - Key proteins and enzymes must be synthesised
Obtained nutrients - vital cellular materials must be present before division
Respiration - ATP production is needed to drive the division process
What is interphase in simple words?
Phase of the cell cycle where the cell is not dividing but is undergoing G1, S, and G2 phase
What is mitosis and cytokinesis in simple words?
Mitosis: The nuclear division that produces genetically identical daughter cells
Cytokinesis: cytoplasmic division following mitosis
What happens in G0 Phase?
What type of cells remain in G0 phase or a very long time, or even indefinitely?
What type of cell does not undergo G0 phase?
- differentiation
- apoptosis (programmed cell death)
- Senescence (no longer divide)
Specialised cells because once damaged, they are done for, and are not made more of.
Stem cells do not undergo G0 phase
What do checkpoints do in the cell cycle? What is the purpose?
Checkpoints control the mechanism of the cell cycle. They verified that the processes that should occur each stage has been completed correctly before the cell is allowed to move onto the next stage.
- prevent uncontrolled division
- detect any DNA damage
- ensure DNA has replicated
- ensure cell cycle is not reversed
What are the two main types of tumor? What is metastasis?
Benign - tumours that have not spread around the body
Malignant - tumours that can spread around the body
Metastasis - a primary tumor spreading around the body to form a secondary tumor
What is the Hayflick limit?
Hayflick limit is that cells should normally only undergo a certain number of cycles (~50 divisions). If cell division becomes uncontrolled, then a tumor can form which may be malignant (cancerous)
What is the Proto-oncogenes and oncogenes gene?
Which is good which is bad? How can proto-oncogenes gene turn into oncogenes gene? How is the p53 tumour suppressor gene involved?
Proto-oncogenes help regulate cell division by coding for proteins that help regulate cell growth and division.
If proto-oncogenes mutated, they may become oncogenes which can cause cells to fail to undergo apoptosis and instead keep dividing, leaving to a tumour.
The p53 gene is a very important tumour suppressor gene - it triggers the G1 checkpoint and the G2 checkpoint preventing uncontrolled division of cells. p53 will become inactivated with oncogene.
What is a mutation? What are carcinogens?
Mutation is a random change in the structure of DNA (sequence)
Carcinogens are chemicals and agent that can cause cancer.
When you have a longer lifespan you have more exposure to carcinogens and increases the chance of tumor
What are cyclins and CDKs (cyclin-dependent kinases)?
They are cell cycle regulatory proteins. CDK, cyclin-dependent kinases are enzymes that phosphorylate proteins.
CDKs are enzymes that control the cell cycle checkpoints. They are activated by cyclins which bind to the CDK forming a CDK complex.
CDK complexes phosphorylate and activate proteins at checkpoints, allowing to cell to progress through the cell cycle.
1) cycling binds and activate CDK
2) CDK activates target protein to regulate cell cycle
3) Cyclins destroyed when they’re not needed by enzymes breaking them down
What are the 4 main types of cyclin in human cells? What are each responsible for?
Cyclin D - triggers cells to move from G0 to G1 and from G1 to S phase
Cyclin E - prepares the cell for DNA replication in S phase
Cyclin A - activates DNA replication inside the nucleus in S phase
Cyclin B - promotes the assembly of the mitotic spindle (spindle fibres) and other tasks in the cytoplasm to prepare for mitosis.
Which type of reproduction is mitosis an example of? What does it produce?
Asexual reproduction (produces genetically identical cells)