B1 Cell biology

• Eukaryotic cells


  Animal and plant cells that have genetic material (DNA) that forms chromosomes and is contained in a nucleus
• Characteristics of animal cells


  • Cell membrane
  • Cytoplasm
  • Nucleus
  • Mitochondria
  • Ribosomes
  • Cytoplasm
• Characteristics of plant cells


  • Cell membrane
  • Cytoplasm
  • Nucleus
  • Chloroplasts
  • Permanent vacuole
  • Cell wall
• Characteristics of prokaryotic cells (bacteria)


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


  Uses light to form images
• Electron microscope


  Uses a beam of electrons to form images
• Magnification


  Image size / actual size
• Electron microscopes allow you to see sub-cellular structures, such as ribosomes, that are too small to be seen with a light microscope
• Specialised cells


  Cells in animals and plants that differentiate to form different types of cells
• Examples of specialised cells


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


  • 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
• 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


  • 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


  • 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