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Description
Flashcards by Talya Hambling, updated more than 1 year ago
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Created by Talya Hambling
over 9 years ago
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| Question | Answer |
| what is mitosis | when a parent cell divides, producing two genetically identical daughter cells (DNA) |
| why does mitosis occur | to repair damaged tissues, and to grow new organisms |
| what is the cell cycle | consists of period of 'interphase' and then mistosis |
| what is interphase | G1 - cell grows, new organelles are made S1 - cell replicates, ready to divide G2 - cell grows more, proteins are made (proteins needed for division) |
| what is stage 1 of mitosis | PROPHASE chromosomes condense, get shorter/fatter. centrioles (protein dots) move to opposite ends of cell, forming spindle fibres between them. nuclear envelope breaks so chromosomes are free |
| what is stage 2 of mitosis | METAPHASE chromosomes, (made up of 2 chromatids joined by centromere), line up along equator and attach to spindle |
| what is stage 3 of mitosis | ANAPHASE centromere splits, separating chromatids. spindles pull each chromatid to opposite poles. |
| what is stage 4 of mitosis | TELOPHASE chromatids become long/thin again, and are chromosomes now. envelope forms around each so 2 nuclei now. cytoplasm splits (cytokinesis) and there are now 2 identical daughter cells |
| how does cancer happen | mutation of a gene that causes uncontrolled mitosis. cells keep dividing until tumour forms and invade surrounding tissues |
| what do cancer treatments target | G1 - chemotherapy prevents enzyme synthesis, so cant move on to S1 stage S1 - radiation damages the formed DNA so cant move onto G2 and mitosis |
| how to calculate mitotic index | number of cells with chromosomes ------------------------------------------------------------- total number of cells observed |
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