Chapter 1- Cells and Cell Processes

A summary of the 1st chapter- Cells and Cell Processes of the AQA GCSE Human Health and Physiology textbook

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1.1 Cell structure, organisation and cellular resp

  • Cell surface membrane- Controls movement of materials in and out of cell
  • Nucleus- Contains genetic material and controls cell activity
  • Cytoplasm- Where most chemical reactions take place
  • Ribosomes- Produce proteins (eg. enzymes, insulin and haemoglobin)
  • Mitochondria- Release energy in aerobic respiration
  • Cytologists study the structure and function of cells, and a cytotechnologist prepares slides of cells to be examined under a microscope
  • A tissue is a group of cells with similar structure and function (eg muscle tissue). Organs contain several tissues (eg the heart is made up of muscle tissue). Systems are groups of organs
  • Respiration is the release of energy from food molecules. The glucose used in respiration is converted usually stored in the cells as fats and glycogen.
  • All living cells respire, as the body needs energy for building molecule, for growth, movement and warmth
  • Aerobic respiration is the release of energy from glucose with oxygen present (glucose+oxygen-> carbon dioxide+ water+energy)
  • During exercise, your body may not be able to provide enough oxygen to muscle cells. Anaerobic respiration (glucose-> lactic acid+ energy)is used to release minimal energy and lactic acid (causes cramp and pain)
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1.2 Cell processes

  • Cell membranes are partially permeable so some materials (like glucose, oxygen and carbon dioxide) can pass through them
  • Molecules and ions move between cells by diffusion. If there is a high concentration of oxygen outside the cell, it will diffuse into the cell (low concentration) in order to evenly disperse
  • Water diffuses across the membrane by osmosis; water moves from an area of high concentration to an area of low concentration
  • Substances which dissolve in water are solutes, and the solute-water balance is regulation of water and dissolves substances in blood plasma
  • Enzymes are large protein molecules. Cells need enzymes to control chemical reactions, but they can cause health conditions if they are missing
  • Enzymes are catalysts, they speed up reactions in building up and building down processes.
  • Human enzymes work best at 37c (body temperature) and at a specific pH, Slight variations will change enzyme activity, but extreme conditions can cause the enzymes to be denatured (the shape changes s0 cannot work)

 

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