Topic 1: Cell biology

• Diffusion- The net movement of particles from an area of high concentration to a lower concentration, can occur in both liquids and gas and can go across cell membranes
• Animal and plant cells are eukaryotic (has a nucleus) whereas bacteria is prokaryotic (doesn’t have a nucleus)
• Cell membrane controls which substances can pass in and out of the cell
• Nucleus controls the cell and holds DNA
• Cytoplasm is where chemical reactions take place
• Ribosomes do protein synthesis
• The cell wall supports and structures the cell
• Vacuole contains cell sap
• Chloroplasts are the site of photosynthesis
• Mitochondria are the site of respiration
• A circular strand of DNA is called a plasmid, contains genes needed to survive and reproduce
• Plasmids contain extra genes
• Flagella propels the bacteria and helps it move
• Resolution- a measure of how detailed the image is (higher resolution = clearer image)
• Magnification= image size/object size
• Light microscopes:

  • Easy to use
  • Relatively cheap
  • Rely on light (large wavelength)
  • Resolution is limited, smaller details will be blurry
  • Cant study subcellular structures
• Electron microscopes:

  • Very expensive
  • Hard to use
  • use electron instead of light (smaller wavelength)
  • Have 2000x better resolution than light microscopes
• Factors that affect diffusion:

  • Concentration gradient
  • Temperature
  • Surface area
• For all 3 factors that affect diffusion, the higher the level of the factor the higher the rate of diffusion
• Osmosis is the net movement of water molecules across a partially permeable membrane, from a region of higher water concentration to an area of lower concentration
• Water concentration- the amount of water as compared to other molecules, like sugars or salts that are dissolved in the water
• There is a higher water concentration outside of the cell. The difference in concentration means that water particles will diffuse from the outside of the cell, down the concentration gradient into the cell
• Active transport is the movement of molecules against their concentration gradient, from an area of lower concentration to an area of higher concentration. Requires energy from the cell and always take place across a membrane
• Root hair cells use active transport to absorb minerals as there is I higher concentration of minerals outside the cell
• Specialised cells have a specific role in the body, to help them fulfil that role they have a specific shape or structure and have specific amounts of different organelles
• Differentiation is the process by which a cell changes to become specialised
• Carbohydrates are found in starchy foods such as bread and pasta. They are needed as an energy source for chemical reactions and movement
• Lipids are fats and oils and are found in fish, dairy, nuts and seeds. Lipids provide energy long-term, keeps us warm due to insulation and protect our organs