Cell Cycle And Cell Division Flashcards
What are the three reason for a cell to divide?
- Reproduction.
- Growth of organism - chemicals needed by the cell to grow enter and function by diffusion. When cells are too big, diffusion takes too long to get to area, hence why organisms increase the number of cells, not size.
- Repair injuries by replacing old cells in the organism.
What are the three stages of cell division?
Interphase, mitosis, and cytokinesis.
What is interphase?
- Performs all life functions of cell ie. nerve cell, muscle cell, skin cell, epithelial cell.
- Cell grows in size and organelles are doubled ie. cytoplasm, mitochondria, etc.
- DNA is copied.
What is mitosis?
The division/separation of DNA and organelles to opposite sides of the cell.
What is cytokinesis?
In cytokinesis, the organelles are physically separated to form to identical cells by either:
- the cell membrane pinching to form 2 new cells (animal cell)
- a cell plate forming in the middle and developing into a cell wall (plant cell)
What are the four stages of mitosis?
Prophase, Metaphase, Anaphase, Telophase.
What happens during prophase?
The DNA condenses becoming shorter, thicker, and firing chromosomes. Each chromosome is made up of two identical chromatids. Try nuclear membrane starts to dissolve, releasing the chromosome into the cytoplasm.
What happens during metaphase?
The chromosomes line up along the middle of the cell. The nuclear membrane completely dissolves.
What happens during the end of interphase?
The cell has grown. New organelles have formed. DNA has been replicated in the nucleus.
What happens during anaphase?
After the chromosomes have lined up along the middle of the cell, each chromosome separates into two identical single stained parts, now the daughter chromosomes. The spindle fibres pull the daughter chromosomes towards each end of the cell.
What happens during telophase?
In the last stage of mitosis, the chromosomes reach opposite ends of the cell and start to lengthen. A new unclear membrane begins to form around the chromosomes at each end of the cell.
What happens during cytokinesis?
The cell cytoplasm divides. In a animal cell, the cytoplasm is pinched off in the centre, forming two new daughter cells. In a plant cell, a cell plate forms that becomes a cell wall, sealing off the contents of the new cell from each other.
When will a cell not divide and remain in interphase?
- surrounding cell signals indicate to not divide
- not enough nutrients for growth
- DNA has not been replicated
- DNA is damaged
What happens if DNA is damaged?
The cell full try to repair DNA or destroy itself.
