Cell Division - Mitosis Flashcards
What are the two types of cell division?
- Mitosis
- Meiosis
In mitosis what does the parent cell divide to produce?
Two genetically identical daughter cells
What does the cell cycle consist of?
A period of cell growth and DNA replication called interphase. Mitosis happens after that. Interphase is divided into three separate growth stages. These are called G1, S and G2
Explain G1
Cell grows and new organelles and proteins are made
Explain S
Cell replicates its DNA, ready to divide by mitosis
Explain G2
Cell keeps growing and proteins needed for cell division are made
What are the four stages of mitosis?
- Prophase
- Metaphase
- Anaphase
- Telophase
Explain interphase
Cell carries out normal functions but prepares to divide. DNA is unravelled and replicated, to double its genetic content. The organelle are replicated and the ATP content is increased
Explain prophase
The chromosomes condense, getting shorter and fatter. Tiny bundles of protein called centrioles start moving to opposite ends of the cell, forming a network of protein fibres called the spindle. The nuclear envelope breaks down and chromosomes lie free in the cytoplasm
Explain metaphase
The chromosomes (each with two chromatids) line up along the middle of the cell and become attached to the spindle by their centromere
Explain anaphase
The centromeres divide, separating each pair of sister chromatids. The spindles contract, pulling chromatids to opposite poles of the spindle, centromere first, making the chromosomes appear v-shaped
Explain telophase
The chromatids reach opposite poles of the spindle, they uncoil and become long and thin again. A nuclear envelope forms around each group of chromosomes, so there are now two nuclei. The cytoplasm decides (cytokinesis). There are now two daughter cells that are genetically identical to each other and the daughter cell
Cancer is the result of uncontrolled cell division, explain
Mitosis and the cell cycle are controlled by genes. If there’s a mutation in the gene that controls cell division, the cell grows out of control. The cells keep dividing to form a tumour. Cancer is a tumour that invades surrounding tissue
What are some treatments for caner designed to do?
To control the rate of cell division in tumour cells by disrupting the cell cycle. This kills the tumour cells
Do cancer treatments distinguish between normal cells and tumour cells?
No, they also kill normal body cells that are dividing. However, tumour cells divide much more frequently than normal cells, so the treatments are more likely to kill tumour cells