Topic 1 cell biology

• Cells


  The building blocks of every organ on the planet
• Organisms


  • Can be Prokaryotes or Eukaryotes
• Prokaryotic cells


  Smaller and simpler, e.g. bacteria
• Eukaryotic cells


  More complex and include plant and animal cells
• Eukaryotes are organisms that are made up of eukaryotic cells
• Bacteria are prokaryotic cells (single-celled organisms)
• Subcellular structures common to most cells

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
• Nucleus


  • Contains genetic material that controls the activities of the cell
• Cytoplasm


  • Gel-like substance where most chemical reactions happen, contains enzymes
• Cell membrane


  • Holds the cell together and controls what goes in and out
• Mitochondria


  • Where most of the reactions for aerobic respiration take place, transfer energy the cell needs
• Ribosomes


  • Where proteins are made in the cell
• Additional structures in plant cells

  • Rigid cell wall
  • Permanent vacuole
  • Chloroplasts
• Rigid cell wall


  • Made of cellulose, supports and strengthens the cell
• Permanent vacuole


  • Contains cell sap, a weak solution of sugar and salts
• Chloroplasts


  • Where photosynthesis occurs, contain chlorophyll to absorb light
• Bacterial cells are much smaller than plant and animal cells
• Bacterial cells


  • Don't have a true nucleus, instead have a single circular strand of DNA floating in the cytoplasm, may also contain plasmids
• Bacterial cells don't have a cell membrane, cell wall, cytoplasm, chloroplasts or mitochondria