3B Mitosis Flashcards
1
Q
interphase (5)
A
- new DNA is produced
- chromosomes replicate
- new proteins, cytoplasm and cell organelles are made
- ATP production is stepped up to provide energy needed as the cell divides
- when everything the cell needs is present, and cell is large enough, interphase ends and mitosis begins
2
Q
draw/label interphase
A
see book
3
Q
prophase (5)
A
- nucleolus breaks down
- each chromosome consists of two daughter chromatids that are attached at centromere
- centrioles begin to pull appart to form spindle
- by prophase they are called chromatids
- chromosomes coil up and can take on stains
4
Q
draw/label Prophase
A
see book
5
Q
metaphase (5)
A
- chromatids line up on equator
- nuclear membrane has broken down
- centrioles have moved to opposite poles
- spindle (microtubules) has formed between centrioles
- the centromere of each chromatid is associated with a separate microtubule of the spindle
6
Q
function of spindle? (2)
A
- the spindle is what moves the chromosomes, so it must form before the chromosomes start to move
- energy is supplied by ATP produced during cell respiration
7
Q
draw/ label metaphase
A
see book
8
Q
anaphase (2)
A
- centromeres split so that the two identical linked chromatids become separate
- the chromatids from each pair are pulled, centromere first, to opposite poles
9
Q
draw/label anaphase
A
see book
10
Q
telophase (4)
A
- spindle fibres break down
- nuclear envelope forms around the two sets of chromosomes
- the nucleolus and centrioles re-form
- chromosomes begin to unravel and separate, they become less dense and harder to see
11
Q
draw/label telophase
A
see book
12
Q
cytokinesis
A
- final phase of cell cycle, when cytoplasm divides
13
Q
cytokinesis in animal cells (2)
A
- a ring of contractile fibres tightens around the centre of the cell
- they continue to contract until the two cells have been separated
14
Q
cytokinesis in plant cells (4)
A
- a cellulose wall builds up from the inside of cell outwards
- the basic structure of the cell wall forms within each vesicle
- vesicles fuse to join cell wall together
- small gaps left between the vesicles form plasmodesmata
15
Q
why can asexual reproduction, for which mitosis is used, be a problem? (3)
A
- results in genetically identical individuals
- becomes a problem when living conditions change in some way
- change in temp, new disease can cause total destruction of a group, because they are genetically identical, if one cannot cope, the others also can’t
