6.2 - Mitosis Flashcards
1
Q
What are chromatids?
A
When a DNA molecule (chromosome) is converted into two identical DNA molecules
2
Q
What is the centromere?
A
A region where the two chromatids are joined together.
They need to be kept together so they can be precisely moved and segregated equally
3
Q
What are the stages of mitosis?
A
- Prophase
- Metaphase
- Anaphase
- Telophase
4
Q
What does Prophase consist of?
A
- The chromatin condenses to form chromosomes. The nucleolus disappears + the nuclear membrane begins to breakdown
- Protein microtubules link the poles of the cell. The fibres forming the spindle help move the chromosomes in correct positions
- In Animal/Plant cells, two centrioles migrate to opposite poles of the cell. (Centrioles help form spindle fibres)
- The spindle fibres attach to specific areas on the centromeres and start to move the chromosomes to the centre
The nuclear envelope disappears
5
Q
What does Metaphase consist of?
A
- The chromosomes are moved by the spindle fibres to form a plane in the centre of the cell, called the metaphase plate, and held in position
6
Q
What does Anaphase consist of?
A
- The centromeres holding the chromatids divide and the chromatids are separated.
- They are pulled to opposite poles of the cell by the shortening spindle fibres.
7
Q
What does Telophase consist of?
A
- The chromatids have reached the poles and are called chromosomes
- The new sets of chromosomes assemble at each pole and the nuclear envelope reforms around them
- The chromosomes uncoil and the nucleolus forms
8
Q
What does Cytokinesis consist of?
A
Animal cells:
- a cleavage furrow forms in the middle of the cell
- the cell membrane is pulled inwards by the cytoplasm until it can fuse
Plant cells:
- Vesicles from the Golgi apparatus assemble where the metaphase plate was formed
- They fuse with each other and the cell membrane, dividing the cell into two
- New sections of cell wall then form along the new sections
