cells

• two types of endoplasmic reticulum: rough and smooth endoplasmic reticulum
• rough ER: transports proteins made by the ribosomes to the Golgi apparatus for secretion out of the cell
• smooth ER: synthesises fats and steroids. converts harmful substances into harmless materials — detoxification
• Golgi apparatus: chemically modifies, stores and packages substances made by the ER into vesicles for secretion out of the cell
• Nucleus: contains DNA in the form of chromatin, controls cellular activities
• mitochondria: site of aerobic respiration, where food substances (e.g. glucose) are broken down to release energy
• chloroplast: contains chlorophyll, site of photosynthesis
• cell membrane: controls movement of substances in and out of the cell
• cell wall: gives cell its shape
• ribosomes: synthesises protein
• differences between animal and plant cells:

  1. plant cells have chloroplasts but animal cells do not
  2. plant cells have a cell wall but animal cells do not
  3. plant cells have a large central vacuole but animal cells have many small vacuoles
• How a red blood cell is adapted to its function:

  1. Contains haemoglobin, which binds to oxygen
  2. biconcave: increases SA:V ratio, so oxygen can diffuse in/out of the cell at a higher rate
  3. lacks a nucleus: more space for more haemoglobin, to transport more oxygen
  4. flexible, can squeeze through capillaries
• How root hair cell is adapted to its function:

  1. Long narrow root hair: increases SA:V ratio, to absorb water and minerals at a higher rate
  2. many mitochondria: generate more energy via aerobic respiration, to pump in mineral salts via active transport