Apoptosis - programmed cell death 0.0 / 5 ? BiologyCellular processesA2/A-levelOCR Created by: Steff06Created on: 24-04-16 15:03 What is apoptosis? Programmed cell death. 1 of 17 How does it compare to cell necrosis? Cell necrosis is untidy and damaging cell death that occurs after trauma and releases hydrolytic enzymes. 2 of 17 What speed is the process? Very quick process. 3 of 17 What is the first thing that happens in apoptosis? Enzymes break down the cell cytoplasm. 4 of 17 What then happens to the cytoplasm? Cytoplasm becomes dense, with organelles tightly packed. 5 of 17 What happens next? The cell surface membrane changes and small bits called blebs form. 6 of 17 What happens to the chromatin? Chromatin condenses and nuclear envelope breaks. DNA breaks into fragments. 7 of 17 What happens after DNA breaks into fragments? Cell breaks into vesicles that are taken up by phagocytosis. Cellular debris is disposed of and does not damage other tissues or cells. 8 of 17 What is apoptosis controlled by? Cell signals including cytokines, hormones, growth factors and nitric oxide. 9 of 17 What can nitric oxide do? Induce apoptosis by making inner mitochondrial membrane more permeable to hydrogen ions, dissipating the proton gradient. 10 of 17 What is apoptosis part of? Plant and animal development. 11 of 17 What happens to excess cells? They shrink, fragment and are phagocytosed so components are reused and no harmful hydrolytic enzymes are released. 12 of 17 Where are proteins released to and what happens? Proteins released into cytosol. Bind to apoptosis inhibitor proteins and allow process to take place. 13 of 17 Does each tissue use the same signals for inducing apoptosis? No, different tissues use different signals to induce it. 14 of 17 What do apoptosis allow in limb development? Allows digits to separate from each other. 15 of 17 What should the rate of dying balance? The rate of cells produced my mitosis. 16 of 17 What 2 things happen if these rates don't balance? Too little apoptosis leads to formation of tumours. Too much leads to cell loss and degeneration. 17 of 17
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