Cell bio & transport

• Eukaryotic cells


  Animal and plant cells have genetic material (DNA) that forms chromosomes and is contained in a nucleus
• Cell membrane


  • Controls the movement of substances in and out of a cell
• Animal cell


  • Nucleus contains DNA
  • Mitochondria where energy is released through respiration
• Plant cell


  • Cell wall made of cellulose, which strengthens the cell
  • Permanent vacuole contains cell sap
  • Chloroplasts contain chlorophyll to absorb light energy for photosynthesis
  • Ribosomes are the site of protein synthesis
• Bacteria


  • Single-celled
  • No nucleus, have a single loop of DNA
  • Have small rings of DNA called plasmids
  • Smaller than eukaryotic cells
• Specialised cells


  • Sperm cell
  • Red blood cell
  • Muscle cell
  • Nerve cell
  • Root hair cell
  • Palisade cell
• Sperm cell


  Fertilise an ovum (egg)
• Sperm cell


  • Tail to swim to the ovum and fertilise it
  • Lots of mitochondria to release energy from respiration, enabling the sperm to swim to the ovum
• Red blood cell


  Transport oxygen around the body
• Red blood cell

  • No nucleus so more room to carry oxygen
  • Contains a red pigment called haemoglobin that binds to oxygen molecules
  • Flat bi-concave disc shape to increase surface area-to-volume ratio
• Muscle cell


  Contract and relax to allow movement
• Muscle cell


  • Contains protein fibres, which can contract to make the cells shorter
  • Contains lots of mitochondria to release energy from respiration, allowing the muscles to contract
• Nerve cell


  Carry electrical impulses around the body
• Nerve cell


  • Branched endings, called dendrites, to make connections with other neurones or effectors
  • Myelin sheath insulates the axon to increase the transmission speed of the electrical impulses
• Root hair cell


  Absorb mineral ions and water from the soil
• Root hair cell


  • Long projection speeds up the absorption of water and mineral ions by increasing the surface area of the cell
  • Lots of mitochondria to release energy for the active transport of mineral ions from the soil
• Palisade cell


  Enable photosynthesis in the leaf
• Palisade cell


  • Lots of chloroplasts containing chlorophyll to absorb light energy
  • Located at the top surface of the leaf where it can absorb the most light energy
• Light microscope


  Uses light to form images, living samples can be viewed, relatively cheap, low magnification, low resolution
• Electron microscope


  Uses a beam of electrons to form images, samples cannot be living, expensive, high magnification, high resolution
• Electron microscopes allow you to see sub-cellular structures, such as ribosomes, that are too small to be seen with a light microscope
• Magnification


  Calculated as: image size / actual size
• Diffusion


  The spreading out of particles, resulting in a net movement from an area of higher concentration to an area of lower concentration. Factors which affect the rate of diffusion: difference in concentration, temperature, and surface area of the membrane.
• Osmosis


  The diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane.
• Active transport


  The movement of particles from a more dilute solution to a more concentrated solution using energy from respiration.
• Key terms


  • cell membrane
  • cell wall
  • chloroplast
  • chromosome
  • concentration
  • cytoplasm
  • dilute
  • DNA
  • eukaryotic
  • gill filaments
  • gradient
  • magnification
  • mitochondria
  • nucleus
  • partially permeable membrane
  • passive process
  • permanent vacuole
  • plasmid
  • prokaryotic
  • resolution
  • ribosome
  • root hair cell
  • stomata