Mitosis Flashcards
1
Q
What are the stages interphase is subdivided into?
A
Gap phase 1, synthesis and gap phase 2
2
Q
Gap phase 1
A
- Cell grows
- Organelles replicate
- Proteins made
3
Q
Synthesis
A
- DNA replicates
4
Q
Gap phase 2
A
- Cell grows
- Proteins needed for cell division made
5
Q
Interphase
A
- DNA unravels and replicates (doubling genetic content)
- Organelles replicate
- ATP content is increased
6
Q
What is mitosis needed for?
A
Growth of multicellular organisms and repair of damaged tissues
7
Q
Structure of chromosomes in mitosis
A
- During prophase, chromosomes condense and appear as two chromatids joined in the middle by a centromere
- During metaphase, chromosomes line up on equator and attach to spindle fibres by the centromere
- During anaphase, centromere divides and chromosomes are pulled to opposite poles
- During telophase, chromosomes uncoil
8
Q
Prophase
A
- Chromosomes condense
- Centrioles move to poles, forming the spindle
- Nuclear envelope breaks down and chromosomes lie free in cytoplasm
9
Q
Metaphase
A
- Spindle fibres form
- Spindle attaches to centromere of chromosomes
- Chromosomes (each with two chromatids) line up along equator
10
Q
Anaphase
A
- Centromeres divide, separating each pair of sister chromatids
- Spindles contract, pulling chromatids to opposite poles, centromere first (chromatids appear v-shaped)
11
Q
Telophase
A
- Chromatids reach the opposite poles on the spindle and uncoil, now chromosomes again
- Spindle fibres disintegrate
- Nuclear envelope reforms
- Cytokines finishes (now two genetically identical daughter cells)
12
Q
How does a tumour form?
A
A mutation (changes in the base sequence of an organism’s DNA) in a gene that controls cell division, resulting in uncontrolled growth and division of cells
13
Q
How does chemotherapy treat cancer?
A
- Preventing DNA from replicating
- Inhibiting metaphase by interfering with spindle formation
14
Q
Mitotic index calculation
A
Mitotic index = number of cells with visible chromosomes / total number of cells observed
15
Q
How do you prepare a root tip cell squash to investigate mitosis?
A
- Add a 10ml hydrochloric acid to a beaker
- Place 2cm of root tip in the acid and leave for 15 minutes
- Set up the microscope
- Rinse root tip in distilled water in a watch glass
- Use a scalpel to cut 1mm from the tip of the root and place on the slide
- Cover with touladine blue stain and macerate to separate cells
- Add cover slip with gentle pressure to spread the material
