Cell Division Flashcards
1
Q
What are the 3 phases within interphase?
A
- first growth - the cell grows and proteins from which cell organelles are produced are synthesised
- synthesis - when DNA replicates (not the same as DNA replication - period when this happens)
- second growth - when organelles e.g. mitochondria grow and divide and energy stores are increased, the cell increases further in size
2
Q
What is interphase?
A
- the cell is engaged in metabolic activity in preparation for cell division
- chromosomes are not visible under a light microscope
3
Q
What are the stages of the cell cycle?
A
- interphase
- nuclear division
- cytokenesis
4
Q
What is nuclear division?
A
- division of the nucleus, either by mitosis or meiosis
5
Q
What is cytokenisis?
A
- the process by which the whole cell divides, resulting in an even distribution of organelles and cytoplasm into each daughter cell
6
Q
How long is the cell cycle?
A
- varies between organisms
- typically a mammalian cell takes 24 hours to complete a cell cycle
- of which 90% is interphase
7
Q
What is the definition of mitosis?
A
- the division of the nucleus of a cell that results in each of the 2 daughter cells having an exact copy of the DNA of the parent cell
8
Q
Are daughter cells genetically identical in mitosis?
A
- the daughter cells are genetically identical to the parent cells and each other
- may not be identical due to mutations
9
Q
Describe interphase
A
- DNA widely dispersed in the nucleus
- each molecule replicated to produce a genetically identical molecule
- metabolic activity to prepare for mitosis (second growth)
10
Q
Describe prophase
A
- DNA condenses to form visible chromosomes
- centrioles migrate to opposite poles of the cell and spindle fibres are formed
- the nuclear envelope disintegrates
- chromosomes are randomly arranged
11
Q
Describe metaphase
A
- spindle fibres develop fully to form spindle apparatus
- spindle apparatus stretches from pole to pole
- chromosomes line up along the EQUATOR of the cell, attaching to spindle fibres by their CENTROMERES
12
Q
Describe anaphase
A
- centromeres divide into 2
- the spindle fibres contract, pulling the chromatids to opposite poles
- mitochondria gather near the spindle to supply the energy needed
- (can now be referred to as chromosomes)
13
Q
Describe telophase
A
- chromosomes reach opposite ends of the cell and disperse
- the chromosomes are no longer visible
- nuclear envelope reforms and the spindle disintegrates
- new membranes form around daughter nuclei
14
Q
Describe cytokenesis
A
- cell divides into 2, producing 2 genetically identical daughter cells
15
Q
What is the key difference between telophase and cytokenesis?
A
- telophase - 2 daughter nuclei
- cytokenesis - 2 daughter cells