Mitosis & Cell Cycle Flashcards
What are the two types of cell division in eukaryotes?
- Mitosis
* Meiosis
What is mitosis?
Mitosis is a division of a cell that results in each of the daughter cells having an exact copy of the DNA of the parent cell.
What is a key feature of the cells that result from itosis?
Both cells have the exact same genetic makeup as the parent cell.
What are the stages of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
What is Interphase?
- The cell carries out normal functions and prepares to divide.
- The Cell’s DNA is unraveled and replicated to double its genetic content.
- Organelles are also replicated so it has spare ones for the new cells.
- ATP content is increased.
What happens during prophase?
- The chromosomes first become visible, and shorten and thicken.
- Centrioles comes to the opposite ends of the cell.
- From each of the centrioles, spindle fibres develop, which span the cell from pole to pole, these are known as the spindle apparatus.
- Nucleolus disappears and the nuclear envelope breaks down, leaving the chromosomes free in the cytoplasm of the cell.
- The chromosomes are drawn towards towards the equator of the cell by the spindle fibres attached to the centromere.
What happens during Metaphase?
- The chromosomes are visible as chromatids.
- Each chromatid is an identical copy of DNA from the parent cell.
- Chromatids are joined by the centromere.
- to the centromere, microtubules from the poles are attached.
- Chromosomes are pulled along the spindle apparatus and arrange themselves along the equator of the cell.
What happens during Anaphase?
- The centromeres divide into two.
- Spindle fibres pull the individual chromatids making up the chromosome apart.
- Chromatids move rapidly to the opposite poles of the cell.
What provides the energy for anaphase?
Mito chondria, which gather around the spindle fibres.
What happens during telophase?
- Chromatids reach the opposite poles on the spindle, they uncoil and become long and thin again, and are now chromosomes again.
- Nuclear envelope forms around each group of chromosomes, so now their are two nuclei.
What happens during cytokinesis?
- Cytoplasm divides.
* Now two daughter cells that are genetically identical to the original cell and to each other.
What are the three stages of the cell cycle?
- Interphase ( Makes up most of the cell cycle, no cell division takes place )
- Nuclear Division
- Division of the cytoplasm ( Cytokineses ).
What is the cell cycle?
Regular cycle of division separated by periods of cell growth.
What are the four stages of the cell cycle?
- Gap Phase 1
- Synthesis
- Mitosis
- Gap Phase 2
What stages are interphase?
- Gap Phase 1 & 2
* Synthesis
What is the cell cycle controlled by ( and therefore mitosis too ) ?
Genes
How is a cancer formed?
- When cells have divided enough times, they stop dividing.
- A mutation can occur in a gene that controls cell division, resulting in cells growing out of control.
- Cells will keep on dividing to make more and more cells, creating a mass of cells, a tumour.
- A cancer is a tumour that invades surrounding tissue
What is a cancer?
A tumour that invades surrounding tissue
What are the two types of tumours?
- Malignant
* Benign
Why are more cancer cells affected than normal cells with cancer treatments?
Tumour cells divide much more frequently than normal cells, therefore the treatments that affect the cell cycle are more likely to kill tumour cells.
How do drugs used to treat cancer disrupt the cell cycle?
- Preventing DNA from replicating.
* Inhibiting the metaphase stage of mitosis by interfering with spindle formation.
What are some downsides to using cancer treatments that affect cell cycles?
They also affect normal dividing cells, and some cells divide very frequently, like hair cells, which can lead to non cancerous cells also being frequently targeted.
How do cancer treatments affect the G1 Phase?
Chemotherapy:
• Chemical drugs prevent the synthesis of enzymes needed for DNA replication.
• If these are not produced, the cell then is unable to enter the synthesis phase, disrupting the cell cycle.
• If the cell cycle is disrupted, the cell is forced to kill itself.
How do cancer treatments affec tthe S phase?
- Radiation and some drugs can damage DNA.
- At several points int he cell cycle, the DNA in the cell is checked for damage.
- If severe damage is detected, the cell will kill itself, preventing further tumour growth.
