Detailed notes

• Animal and plant cells are eukaryotic. They have a

  • cell membrane
  • cytoplasm
  • Nucleus containing DNA
• Bacterial cells are prokaryotic and are much smaller. They have a..

  • Cell wall
  • Cell membrane
  • Cytoplasm
  • Single circular strand of DNA and plasmids (small rings of DNA found in the cytoplasm)
• Centi 


  0.01
• Milli


  0.001
• Micro 


  0.000,001
• Nano 


  0.000,000,001
• Nucleus

  • Contains DNA coding for a particular protein needed to build new cells
  • Enclosed in a nuclear membrane
• Cytoplasm

  • Liquid substance in which chemical reactions occur
  • Contains enzymes
• Cell membrane 


  Controls what enters and leaves the cell
• Mitochondria

  • Where aerobic respiration reactions occur, providing energy for the cell
• Ribosomes

  • Where protein synthesis occurs
• Chloroplast

  • where photosynthesis occurs providing food for the plant
  • Contains chlorophyll pigment which harvests the light needed for photosynthesis
• Permanent vacuole

  • Contains cell sap
  • Found within the cytoplasm
  • improves cell’s rigidity
• Cell wall

  • Made from cellulose
  • provides strength and structure to the cell
• Cell wall in bacteria

  • Made of a different compound
• Bacteria cell: Single circular strand of DNA

  • as they have no nucleus, this floats in the cytoplasm
• In bacteria cell: plasmids 


  Small rings of DNA
• Sperm cells

  • Streamlined head and long tail to aid swimming
  • Many mitochondria which supple energy to allow the cell to move
  • The acrosome (top of the head) has digestive enzymes which break down the outer layers of membrane on the egg cell
• Nerve cells

  • Long axon, letting impulses be carried along long distances
  • having lots of extensions from the cell body means brain he’s connections with other nerve cells
  • nerve ending have many mitochondria which supply the energy to make neurotransmitters which allow impulses to be passed from one cell to another
• Muscle cells

  • special proteins slide over each other, causing the muscle to contract
  • Lots of mitochondria provide energy for contraction
  • They store glycogen for respiration
• Root hair cells

  • have a large surface area to allow more water to be absorbed
  • large permanent vacuole affects the speed of movement of water from the soil to the cell
  • Mitochondria provide energy for active transport of mineral ions into the cell
• Phloem cells

  • transports food sugars, amino acids dissolved in water
  • requires energy
  • up and down
• Xylem cell

  • physical process
  • water and minerals
  • upwards
• Light microscope

  • maximum magnification of x2000
  • maximum resolution of 200nm (the lower the better)
• Electron microscope

  • maximum magnification of up to x2,000,000
  • maximum resolution of 10nm
• Magnification = magnification of eyepiece lens x magnification of the objective lens
• image size / magnification = size of object