cells

• All organisms are made of cells
• Large organisms contain millions of cells (Multicellular)
• Some organisms are made of just a single cell (Unicellular)
• To see cells clearly, you need to use a microscope
• Light microscope shines light through the piece of animal or plant you are looking at
• Light microscope uses glass lenses to magnify and focus the image
• A very good light microscope can magnify about 1500 times
• Cell membrane


  A very thin layer of protein and fat that controls what goes in and out of the cell. It is partially permeable.
• Cell wall


  Surrounds all plant cells, made mainly of cellulose. Helps to protect and support the cell.
• Cytoplasm


  A clear jelly that is nearly all water, containing many dissolved substances. It is where metabolic reactions take place.
• Vacuole


  A fluid-filled space inside a cell, surrounded by its own membrane. Plant cells have large permanent vacuoles, animal cells have smaller vacuoles called vesicles.
• Nucleus


  Where the genetic information is stored on chromosomes made of DNA.
• Chloroplasts


  Found in plant cells, contain chlorophyll which absorbs energy from sunlight for photosynthesis.
• Mitochondria


  Found in almost all plant and animal cells, where aerobic respiration happens to release energy from glucose.
• Ribosomes


  Tiny structures found in almost all animal and plant cells, where the cell makes proteins.
• Bacterial cells


  • Known as prokaryotic cells, unicellular, have a cell wall not made of cellulose, have cytoplasm and ribosomes.
• Specialised cells have a particular function to perform, and their structure is modified to help them carry out that function effectively.
• Examples of specialised cells

  • Ciliated cell
  • Neurone
  • Red blood cell
  • Sperm cell
  • Egg cell
  • Root hair cell
  • Palisade mesophyll cell
• Magnification


  The ratio of the size of the image to the actual size of the object
• Converting between units


  1. Divide by 1000 to convert mm to m

  2. Multiply by 1000 to convert m to mm

  3. Divide by 1000000 to convert cm to m

  4. Multiply by 1000000 to convert m to cm