Cell cycle 0.0 / 5 ? BiologyCell CycleUniversitySQA Created by: amykaneCreated on: 05-12-17 02:50 What happens during prophase? chromosome condense and become visible, spindle fibers emerge, nuclear envelope breaks down, centrioles move towards opposite poles 1 of 12 Facts about centrioles? Only found in animal cells. Self-replicating. Made of bundle of micro-tubules. They make spindle fibers 2 of 12 What happens during metaphase? Thick, coiled chromosomes lined up in centre of cell on metaphase plate. Spindle fibers are attached to chromosomes 3 of 12 What happens during anaphase? Chromosomes break at centromeres and sister chromatids move to opposite ends of cell 4 of 12 What happens during telophase? chromosomes reach poles of cell, uncoil and lengthen. Spindle fibers disintegrate. Nuclear envelope reforms. Nucleoli disappear. 5 of 12 What happens in cytokinesis? Division of the cytoplasm. In animals, a cleavage furrow forms, microfilaments contract and cut the cell in two. 6 of 12 What is cell cycle controlled by? Proteins called cyclins and a set of enzymes that attach to cyclins, becoming activated cyclin dependant kinases. (CDKs) 7 of 12 How are cyclins turned on? They are specifically turned on by phosphorylation at the stage of the cell cycle they are needed. 8 of 12 What are cyclins controlled by? CDKs 9 of 12 What are cyclin-dependant kinases controlled by? oncogenes P35 and inhibitors (CDIs) such as P21 10 of 12 What are the CDIs then controlled by? oncogenes and tumour suppressor genes such as p53 11 of 12 What is cell cycle arrest controlled by? tumour suppressors p53 and pRB 12 of 12
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