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16 Cards in this Set
- Front
- Back
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What 4 things are required for semi-conservative replication? |
1. The 4 types of nucleotide with their complementary bases must be present 2. Both DNA strands must act as a template for attachment of these nucleotides 3. Enzyme DNA polymerase is needed to catalyse the reaction 4. Source of chemical energy needed to drive the process |
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Describe the process of semi-conservative replication |
1. Enzyme DNA helicase break hydrogen bonds linking the base pairs of opposing DNA strands 2. Double helix separates into two strands and unwinds 3. Exposed polynucleotide strands act as templates to complementary nucleotides that are attracted 4. Energy used to activate nucleotides 5. Activated nucleotides joined together by enzyme DNA polymerase to form new polynucleotide strand on each of the original polynucleotide strands of DNA 6. Each new DNA molecule contains half of the original DNA |
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What does mitosis produce? |
Two daughter cells with the same number of chromosomes |
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What holds together two chromatids? |
Centrimere |
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What are the four stages of mitosis? |
Prophase Metaphase Anaphase Telophase |
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What happens in prophase? |
Nuclear envelope disintegrates Nucleolus disappears Chromosomes become visible |
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What happens in metaphase? |
Chromosomes move to the centre of the cell They attach to the spindle fibres that are made of microtubules The spindle fibres are attached to the centrioles which form the poles
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What happens in anaphase? |
Chromatids pulled apart to opposite poles due to the contraction of the spindle fibres |
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What happens in telophase? |
Nuclear envelope and nucleolus reform Spindle fibres disintegrate Chromatids reach the poles and become indistinct Cell division commences |
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What three things is mitosis important for? |
Repair Growth Differentiation |
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What are the three main stages of the cell cycle? |
Interphase Nuclear division Cell division |
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What are the three main stages of interphase? |
First growth- Proteins from which cell organelles are synthesised are produced Synthesis- DNA replicated Second growth- Organelles grow and divide and energy stores are increased |
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What happens during nuclear division? |
When the nucleus either divides into two or four |
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What happens during cell division? |
When the whole cell divides into two or four |
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What is cancer caused by? |
A growth disorder in cells Result of damage to the genes that regulate mitosis and the cell cycle |
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What is cancer? |
The uncontrollable growth of cells |
