cell cycle Flashcards
(14 cards)
What is mitosis needed for?
Growth of organisms and repair of tissues.
What are the two main stages of the cell cycle?
Mitosis and interphase.
What is the order of the two gap phases and the synthesis phase?
g1, s, g2.
What happens in the G1 phase?
The cell grows, new organelles and proteins are made.
What happens in the G2 phase?
The cell continues growing, proteins needed for division are synthesised
What happens in the synthesis phase?
The cell replicates its DNA
What happens in prophase?
- Chromosomes condense
- Spindle fibres form from centrioles.
- The nuclear envelope breaks so chromosomes are free in the cytoplasm.
What happens in metaphase?
- Chromosomes line up at the centre of the cell and become attached to the spindle fibres at the centromere.
What happens in anaphase?
- Spindle fibres contract, pulling chromatids apart at the centromere
- Chromatids are pulled to opposite poles of the cell.
What happens in telophase?
- Chromatids reach opposite poles of the cell and uncoil, becoming long and thin again.
- Nuclear envelopes form around each group of chromosomes
- Cytoplasm divides, cytokinesis finishes.
What happens in interphase?
- The cell carries out normal functions and prepares to divide by unravelling and replicating DNA.
- Organelles are replicated and ATP content is increased.
How are tumours formed?
Tumours are formed when uncontrolled cell division can take place due to mutations in the gene that controls cell division.
How can cancer treatment target the cell cycle?
Some treatments target the G1 (growth and protein synthesis phase), by preventing the synthesis of enzymes needed for DNA replication, stopping the cell entering the S phase and causing cell death.
Other treatments target the S phase, by causing damage to DNA. At several points during the cell cycle, the cell is checked for damage. If severe damage is detected, the cell kills itself, preventing further tumour growth.
What is cancer?
Cancer is a tumour that invades surrounding tissue.
