Chapter 1: Cells

• Cells


  The basic building blocks of life
• What cells do


  1. Take in raw materials

  2. Convert materials to new molecules

  3. Use molecules to fulfil different functions
• Cell membrane


  Surrounds the cytoplasm, made of lipids and proteins, partially permeable
• Cell wall


  Surrounds the cell membrane in plant cells, made of cellulose, fully permeable, protects the cell and gives it a fixed shape
• Cytoplasm


  Found inside the cell, enclosed by the cell membrane, site of cellular activities, contains organelles
• Nucleus


  Controls cell activities, essential for cell division, contains chromosomes made of DNA
• Chromosomes


  Long thread-like structures found within the nucleus, made of DNA that carries hereditary information
• Nuclear membrane


  Separates the contents of the nucleus from the rest of the cytoplasm
• Vacuole


  Fluid filled space enclosed by a partially permeable membrane, store substances within the cell
• Mitochondria


  Oval or sausage-shaped organelles, site of aerobic respiration, break down food (glucose) in the presence of oxygen to release energy
• Ribosomes


  Small round structures, either attached to organelles or lie freely in cytoplasm, responsible for protein synthesis
• Chloroplasts


  Oval structures found in plant cells, contain chlorophyll required for photosynthesis
• Cells can be studied using light and electron microscopes
• Cells without a nucleus, like red blood cells, are unable to divide
• Mitochondria


  • Oval or sausage-shaped organelles
  • Site of aerobic respiration
  • Break down food (glucose) in the presence of oxygen to release energy for cellular activities
• Ribosomes


  • Small round structures
  • Either attached to organelles or lie freely in cytoplasm
  • Responsible for protein synthesis
• Chloroplasts


  • Oval structures found in plant cells
  • Contains a green pigment called chlorophyll, which is required for photosynthesis (the process by which plants make food)
• Differences between plant and animal cell


  • Plant cell: Cell wall present
  • Plant cell: Chloroplasts present
  • Plant cell: A large central vacuole
  • Animal cell: Cell wall absent
  • Animal cell: Chloroplasts absent
  • Animal cell: Numerous small vacuoles
• Red blood cells are adapted to transport oxygen around the body
• Root hair cells are adapted to absorb water and mineral salts from the surrounding soil
• Differentiation


  The process by which a cell becomes specialised for a specific function
• Red blood cell


  • Contains haemoglobin
  • Circular biconcave shape
  • Absence of nucleus
  • Flexible
• Muscle cell


  • Contain many mitochondria
  • Has contractile protein fibres
  • Has many nuclei
• Root hair cell


  • Long and narrow extension
  • Maintains a lower water potential in vacuole