Cells

• Organisms are made up of cells
• Most organisms are multicellular and have cells that are specialised to do a particular job
• Microscopes are needed to study cells in detail
• Animal cells


  • Have a basic structure
  • Can be viewed with light microscope and transmission electron microscope
• Mitochondria


  Structures in the cytoplasm of all cells where aerobic respiration takes place
• Ribosomes


  The site of protein synthesis
• Cell structures and their functions

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


  A jelly-like material that contains dissolved nutrients and salts and structures called organelles. It is where many of the chemical reactions happen.
• Nucleus


  Contains genetic material, including DNA, which controls the cell's activities
• Cell membrane


  Its structure is permeable to some substances but not to others. It therefore controls the movement of substances in and out of the cell.
• Mitochondria


  Organelles that contain the enzymes for respiration, and where most energy is released in respiration
• Most cells are specialised and are adapted for their function
• Animals and plants therefore consist of many different types of cell working together
• Organisms are made up of cells
• Most organisms are multicellular and have cells that are specialised to do a particular job
• Microscopes are needed to study cells in detail
• Nucleus


  Contains genetic material, including DNA, which controls the cell's activities.
• Cell membrane


  Its structure is permeable to some substances but not to others. It therefore controls the movement of substances in and out of the cell.
• Ribosomes


  A tiny organelle where protein synthesis occurs.
• Chloroplast


  Organelles that contains the green pigment, chlorophyll, which absorbs light energy for photosynthesis. Contains the enzymes needed for photosynthesis.
• Cell wall


  Made from cellulose fibres and strengthens the cell and supports the plant.
• Permanent vacuole


  Filled with cell sap to help keep the cell turgid.
• Animal cells may also have vacuoles, but these are small and temporary. In animals, they are commonly used to store or transport substances.
• Organisms are made up of cells
• Most organisms are multicellular and have cells that are specialised to do a particular job
• Microscopes are needed to study cells in detail
• Eukaryotic cell


  A type of cell that has a nucleus
• Prokaryotic cell


  A simple cell that does not have a nucleus - the DNA is free in the cytoplasm
• Comparison of eukaryotic and prokaryotic cells

  • Size: Eukaryotic 5 μm - 100 μm, Prokaryotic 0.2 μm - 2.0 μm
• Archaea


  Microorganisms which are similar in size and structure to bacteria but are genetically different
• comparing eukaryotic and prokaryotic cells

  • Outer layers: Eukaryotic - cell membrane, surrounded by cell wall in plants and fungi, Prokaryotic - cell membrane, surrounded by cell wall
• comparing eukaryotic and prokaryotic cells

  • Cell contents: Eukaryotic - cytoplasm, cell organelles including mitochondria, chloroplasts in plants, ribosomes, Prokaryotic - cytoplasm, ribosomes, no mitochondria or chloroplast
• comapring eukaryotic and prokaryotic cells

  • Genetic material: Eukaryotic - DNA in a nucleus, plasmids in some simple eukaryotes, Prokaryotic - DNA is a single molecule free in cytoplasm, additional DNA on plasmids
• comparing prokaryotic and eukaryotic cells

  • Cell division: Eukaryotic - mitosis, Prokaryotic - binary fission
• cell heirachy

  
  

  The levels of organisation in multicellular organisms are:organelles → cells → tissues → organs → organ systems → living organism. A structure that performs specific functions within a cell.
• An example of a Prokaryotic cell is a bacterium
• An example of a Eukaryotic cell is an animal and a plant cell