CH1 Cells

• Cells


  Basic unit of life
• Cells


  • Highly organised biological system consisting many organelles
  • Each organelle performs specific functions
  • Organelles are co-ordinated to carry out cellular processes needed to sustain life
• Cell components


  • Nucleus
  • Cytoplasm
  • Cell surface membrane
  • Smooth endoplasmic reticulum
  • Rough endoplasmic reticulum
  • Ribosome
  • Golgi body
  • Mitochondrion
  • Chloroplast
  • Vacuole
  • Cell wall
• Nucleus


  • Spherical, double membrane-bound organelle that contains genetic material (DNA)
  • Controls the biochemical reactions in the cell
• Cytoplasm


  • Gel-like substance enclosed within cell membrane
  • Site of biochemical reactions
• Cell surface membrane


  • Partially permeable membrane made of lipids
  • Controls the movement of substances in and out of the cell
• Smooth endoplasmic reticulum


  • Network of tubular membrane-enclosed structures continuous with nuclear envelope
  • Without ribosomes
  • Synthesis of lipids, cholesterol and steroids
  • Converts harmful substances into harmless materials (detoxification)
• Rough endoplasmic reticulum


  • Network of flattened membrane-enclosed structures continuous with nuclear envelope
  • With ribosomes attached to the surface
  • Modification of proteins synthesised by the attached ribosomes
  • Transport of proteins to Golgi body
• Ribosome


  • Small organelle made of RNA and proteins
  • Attached to RER: synthesise proteins for secretion
  • In cytoplasm: synthesise proteins to be used within the cell
• Golgi body


  • Curved stacks of flattened membrane-bound structures
  • Chemically modifies, sorts, and packs proteins into vesicles for secretion out of the cell
• Mitochondrion


  • Ovoid, double membrane-bound organelle that has a highly folded inner membrane
  • Site of aerobic respiration where glucose is oxidised to release energy for biochemical reactions in the cell
• Chloroplast


  • Ovoid, double membrane-bound organelle that contains an inner third layer of membrane containing chlorophyll
  • Chlorophyll converts light energy to chemical energy for the formation of glucose during photosynthesis
• Vacuole


  • Fluid-filled space enclosed by a membrane
  • Large and centralised in plant cells, contains cell sap enclosed by tonoplast
  • Small and numerous in animal cells
  • Stores water and dissolved substances like mineral salts and amino acids
• Cell wall


  • Inelastic, strong layer made of cellulose
  • Protects the cell from mechanical damage
• Specialised cells


  • Differentiated from stem cells
  • Develop specific structures to carry out specific functions more efficiently
• Specialised cells


  • Red blood cell

  Root hair cell

  Xylem vessel

  Muscle cell
• Red blood cell


  Contains haemoglobin that binds oxygen reversibly and allows red blood cell to transport oxygen from lungs to the rest of the body

  Biconcave disc shape to increase surface area to volume ratio to increase the rate of diffusion of oxygen in and out of the cell

  No nucleus to have more space to contain more haemoglobin so that more oxygen can be carried
• Root hair cell


  Has a long and narrow protrusion to increase surface area to volume ratio for the faster absorption of water by osmosis and mineral salts by diffusion and active transport

  Has numerous mitochondria to carry out aerobic respiration to release energy for the active transport of mineral salts into the cell
• Xylem vessel


  Hollow lumen without cross walls and protoplasm to reduce resistance to the flow of materials for faster transport of water and mineral salts up the xylem vessel

  Lignified cell walls so walls are stronger to provide mechanical support for the plant and prevents the xylem vessels from collapsing under negative pressure generated by transpiration pull
• Muscle cell


  Has numerous mitochondria to carry out aerobic respiration to release energy for muscular contractions
• Production and secretion of amylase by a salivary gland cell


  Ribosomes synthesise the polypeptides that make up amylase

  The polypeptides enters the rough endoplasmic reticulum and is transported to the Golgi body

  The Golgi body chemically modifies, sorts, and packs the amylase into secretory vesicles

  Secretory vesicles migrate to the cell surface membrane, fuses with the membrane, and releases amylase out of the cell