Cell division is part of the cell cycle and is made up of two phases; interphase and the mitosis phase.
The purpose of cell division is so that new cells can be made so that organisms can grow bigger
or repair old/damaged cells. Cell division requires energy (therefore respiration).
Cell division is essential for life!
The purpose of cell division is so that new cells can be made so that organisms can grow bigger
or repair old/damaged cells. Cell division requires energy (therefore respiration).
Cell division is essential for life!
The time from when a cell is formed until it undergoes cell division is called the
cell cycle
The outer circle
The outer circle outlines the basic ratio between the mitosis phase (M) and
interphase (I). The mitosis phase is when mitosis and cytokinesis occur - where chromosomes divide and the cell splits into two identical daughter cells. |
The inner circle
The inner circle outlines what happens during interphase. After mitosis (M) it is the G1 phase. This is where the cell grows and performs its metabolic processes. It also makes proteins needed for DNA replication. The S phase is when the synthesis of new DNA strands occurs - DNA undergoes replication. The G2 phase is where the newly synthesized chromosomes are checked for errors and additional proteins are made before cell division. The G0 phase will occur in cells that don't undergo cell division regularly, such as muscle cells or nerve cells.
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Let's start with
Interphase
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G1 phase
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S phase
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G2 phase
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The first growth phase
The G1 phase occurs immediately after the parent cell divides into two identical daughter cells. During this time, these newly made cells become larger in size and begin carrying out their own metabolic processes. The cell will start to make proteins that it needs for DNA replication (the next step) and some organelles are also copied so that the new cell gets some organelles too! |
The synthesis phase - the making of new chromosomes
During this phase, DNA replication occurs. This is when helicase unzips the double-stranded DNA molecule, primase comes along and adds RNA primers so that DNA Polymerase can attach and start adding nucleotides to the 3' end of the newly made strand. The steps of DNA replication are outlined below. |
The second growth phase
This phase is similar to the G1 phase - as nothing much really happens compared to the other phases.
- The chromosomes made during the S phase are checked over and any mistakes are corrected
- More proteins are made for the cell
- More organelles are made
once interphase is over, the cell is ready to undergo
Mitosis
Factors affecting the rate of mitosis
The rate of mitosis is high in organisms that are in a growth stage of their life. For example
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If the energy and materials (nutrients) required to build new cells are lacking, the rate of mitosis will be slow or even prevented!
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Specific areas of plants and animals have higher rates of mitosis naturally - for example
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As DNA replication (Interphase) and mitosis are highly dependent on enzymes, anything that affects the rate at which enzymes work will also affect the rate of mitosis.
For example
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