9700 · 5.1
Replication and division of nuclei and cells flashcards
Revision flashcards for Cambridge 9700 Replication and division of nuclei and cells (syllabus 5.1). Flip, recall, then mark a real past-paper question.
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What is semi-conservative replication?
The process where a DNA molecule replicates to produce two new DNA molecules, each containing one original (parental) strand and one newly synthesised strand.
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What is the function of the enzyme DNA helicase?
It unwinds the DNA double helix by breaking the hydrogen bonds between complementary base pairs, separating the two strands to act as templates for replication.
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What is the function of the enzyme DNA polymerase?
It catalyses the formation of phosphodiester bonds between adjacent nucleotides during DNA replication. It also has a proofreading function to correct errors.
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Name the four stages of mitosis in order.
Prophase, Metaphase, Anaphase, Telophase (PMAT).
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What is the main event of Metaphase?
Chromosomes, each consisting of two sister chromatids, align along the metaphase plate (equator) of the cell, attached to the mitotic spindle.
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What is the main event of Anaphase?
Sister chromatids separate at the centromere and are pulled to opposite poles of the cell by the shortening of spindle fibres. They are now considered individual chromosomes.
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What is a telomere?
A region of repetitive nucleotide sequences at each end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes during replication.
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How does uncontrolled cell division lead to tumour formation?
Failure of cell cycle checkpoints, often due to mutations in oncogenes or tumour suppressor genes, leads to rapid, unregulated cell proliferation, forming a mass of cells known as a tumour.