Cell Structure

Cell Structure

1. Microscopes

   • Light
     • Uses glass lenses to refract light and increase magnification
       • Light is focused on object using condenser lens
         • Passed through specimen and refracted by objective lens
           • Reaches eyepiece lens, where image is flipped right way up
     • Resolution tends to be low
       • Resolution is degree of detail
       • Magnification is increases apparent size
     • Stains tend to be chemicals that react with chemicals found in sample or attach to cellular parts
   • Electron
     • Tranmission Electron Microscope
       • Passes electrons through object
     • Scanning Electron Microscope
       • Bounces electrons off object
     • Stains tend to be heavy metal ions
       • Ions are positive and stop electrons passing, causing a darkening effect in final image

2. Eukaryotic Organelles

   • Animal Specific
     • Centrioles
       • Make microtubules
         • Then orders them to make spindle for mitosis
   • Plant Specific
     • Chloroplasts
       • Membranes called grana form stacks of thylakoids
         • Light is used to split water into hydrogen ions
           • Used to make ATP
     • Cell Walls
       • See Cell Membranes Mind Map
   • Nucleus
     • The Nucleus houses the chromosomes, which contain the DNA of the cell
       • It is surrounded by a nuclear envelope
         • This has nuclear pores to allow mRNA in and out
   • Endoplasmic Recticulum
     • Rough
       • Covered in ribosomes
         • Place of protein synthesis
     • Smooth
       • Various uses
     • Membrane that separates cisternae from cytoplasm
       • Synthesisied proteins stored in cisternae
   • Golgi Apparatus
     • Combines small molecules to make bigger ones
       • Bigger molecules packaged to make vesicles
         • Sent out of cell or stored
     • Makes Lysosomes
   • Lysosomes
     • Bags of digestive enzymes
       • Sperm cells have specialised lysosomes
   • Mitochondria
     • Site of aerobic respiration
     • Has a double membrane
       • Inner makes cristae
         • ATP formed here
           • ATP= Energy currency
       • Background material called matrix
   • Cell Membrane
     • See Cell Membranes Mind Map
   • Cilia and Flagella
     • Cilia= Short structures
     • Flagella= Long structures
     • Can be used to move cell
       • Arranged with two microtubules in the centre and 9 pairs circling
         • Called 9+2
   • Vacuoles
     • Storage for food in liquid form
       • Larger in Plants and used for sap

3. Prokaryotic cells

   • No Nucleus
     • Chromosomes present but not as we know them
       • Circular and not associated with histones
   • No Mitochondria
   • No Chloroplasts
   • Ribosomes about 2/3rds smaller
   • No Cytoskeleton
   • Has Cell walls but not as we know it
   • Flagella only, and different structure