cell biolody

• cell membrane 


  controls the movement of substances going in and out of the cell
• cell wall


  helps strengthen the cell; made of cellulose
• chloroplasts


  absorbs light energy needed for photosynthesis; contains chlorophyll
• mitochondria


  where energy is released for respiration
• ribsomes


  site of protein synthesis
• nucleus


  control the activity of the cell and contains DNA
• plasmids


  small ring of DNA found only in a bacteria cell
• vacuole


  contains cell sap to keep the cell turgid
• cytoplasm


  where most chemical reactions take place
• prokaryotic

  • single-celled
  • no nucleus
  • have small rings of DNA called plasmids
  • smaller than eukaryotic cell
• eukaryotic


  animal and plant cells are eukaryotic. They have DNA that forms chromosomes and is contained in a nucleus.
• light microscope

  • uses light to form images
  • living samples can be viewed
  • relatively cheap
  • low magnification
  • low resolution
• electron microscope

  • uses a beam of electrons to view an image
  • samples cannot be living
  • expensive
  • high magnification
  • high resolution
• Magnification equation?

  magnification=image size/ actual size
• sperm cell

  • fertilises the egg
  • tail to swim to the egg
  • lots of mitochondria to release energy from respiration to swim to the egg
• Red blood cell

  • transports oxygen around the body
  • no nucleus to make room for more oxygen
  • contains a red pigment called haemoglobin that binds to oxygen molecules
  • flat bi-concave disc shape to increase surface area to volume ratio
• muscle cell

  • contracts and releases to allow movements
  • contains protein fibres which contract to make cells smaller
  • contains a lot of mitochondria to release energy form respiration
• nerve cell

  • carries electrical impulses around the body
  • branched endings, called dendrites to make connections with other neurones or effectors
  • myelin sheath insulates the axon to increase transmission speed
• root hair cell

  • absorbs mineral ions and water from the soil
  • long projection speeds up absorption of water by increasing the surface area
  • lots of mitochondria to release energy from respiration
• palisade mesophyll

  • enables photosynthesis in the leaf
  • lots of chloroplast containing chlorophyll to absorb light energy
  • located at the top as there is more light exposure