CH6 mitosis Flashcards
1
Q
What does mitosis results in
A
Two identical daughter cells
2
Q
When is mitosis necessary
A
- when all daughter cells have to be same as parent cell
- growth, replacement and repair of tissues
- asexual reproduction
3
Q
What happens to the DNA before mitosis
A
- each DNA molecule is converted into two identical DNA molecules called chromatids
- two chromatids are joined together at region called centromere
4
Q
What is the order of mitosis
A
Prophase, metaphase, anaphase, telophase
5
Q
What occurs during prophase
A
- chromatin fibres coil and condense to form chromosomes that will take up stain
- nucleolus disappears and nuclear membrane begins to break down
- protein microtubules form spindle-shaped structures linking poles of cell
- two centrioles migrate to opposite poles of cell
- spindle fibres attach to specific areas on centromeres
- by end, nuclear envelope has disappeared
6
Q
What occurs during metaphase
A
- chromosomes are moved by the spindle fibres to form a plane in the centre of the the cell
7
Q
What occurs during anaphase
A
- centromeres holding pairs of chromatids together divide
- chromatids are seperated and pulled to opposite poles of cell by shortening spindle fibres
8
Q
What occurs during telophase
A
- chromatids have now reached poles and are called chromosomes
- two new sets of chromosomes assemble at each pole and nuclear envelope reforms
- chromosomes start to uncoil and nucleolus is formed
9
Q
What is cytokinesis
A
Actual division of cell into two separate cells
10
Q
How does cytokinesis occur in animal cells
A
- a cleavage furrow forms around the middle of the cell
- cell surface membrane is pulled inwards by cytoskeleton until close enough to fuse around middle forming two new cells
11
Q
How does cytokinesis occur in plant cells
A
- vesicles from gogli apparatus begin to assemble in same place as metaphase plate
- vesicles fuse with each other and cell surface membrane which divides cell into two
- new sections of cell wall then form along new sections of membranee
