Cell Structure

• Aerobic Respiration definition and word equation. 


  .The release of energy using oxygen.

  .Glucose + oxygen -> carbon dioxide + water+ energy.
• Resolution


  The ability of an optical instrument to distinguish between two points.
• Types of Microscopes


  .Optical microscopes.

  .Laser scanning microscope.

  .Electron microscopes- transmission and scanning.
• Optical (light) Microscopes


  .Portable, study whole living specimens.

  .Mag up to X1,500-X2,000.

  .Use visible light- limited resolution.

  .Unable to see small things, like ribosomes.

  .Photomicrograph-photograph of image.
• Laser Scanning Microscopes (confocal)


  .Laser light does not pass through specimen, sca3Dns the surface point by point displaying pixel information on computer.

  .3D image of whole living organisms and cells.

  .Used in research and the medical profession.
• Electron Microscopes

  .Beam of fast travelling electrons.

  .Wavelength of 0.004nm.

  .Greater resolution.

  .Electrons fired from cathode and focused by magnets.
• Transmission Electron Microscope


  .2D black and white image- electron micrograph.

  .Can produce a magnification of X2million.

  .Specimen has to be chemically fixed by being dehydrated.

  .Beam of electrons passes through specimen- stained with metal salts.
• Scanning Electron Microscopes


  .Electrons bounce off the surface and focus on screen.

  .3D image.

  .Mag X15- X200,000.

  .Placed in vacuum and coated with film of metal.
• The Logarithmic Scale


  .A nonlinear scale often used when analyzing a large range of quantities.

  .Enables plotting of very small or very large sizes on a small sheet of graph paper, and compaisons over a large range.
• Slides and Photomicrographs

  Staining Specimens:

  .Many biological specimens are transparent so difficult to distinguish structures.

  .Stains are coloured chemicals that bind to areas of cells/tissues, making it easier to see their structures.
• All Purpose Stains

  .Methylene blue.
• Differentiated Stains


  .Aetic orcein binds to DNA, staininh chromosomes dark red.

  .Eosin stains cytoplasm.

  .Sudan stains lipids red.

  .Iodine in potassium iodide solution stains cellulose (plant walls) yellow, and starch granules black/blue.
• Prepared Specimens have been:

  .Dehydrated

  .Embedded in wax to prevent disortion during slicing.

  .Sliced into thin sections using microtome, which are stained and mounted.
• Section of a Leaf- transverse and longitude. 


  .Transverse- sliced down.

  .Longitude- sliced horizontal.
• Measuring Objects seen in a Light Microscope

  .Eyepiece graticule- a transparent disc with a scale, placed into the piece.

  .Calibration- standardises small differences between microscopes to ensure that measurements are accurate.

  .Stage micrometre- a microscope slide with an accurate scale etched on it.
• Calibration Method

  1> Place the stage micrometre onto the stage and graticule into the eyepiece.

  2> At one magnification focus and line up the two scales so that you can compare one with the other.

  3> Record how many eyepiece units (EPUs) are equivalent to a known measurement on the stage micrometre.

  4> Repeat steps 2-3 for each magnification of your microscope.
• Making and Secreting Protein: 


  .Info in book. . .
• Diagram of a Prokaryotic Cell: 


  .

  
• Similarities between Prokaryotic Eukaryotic Cells: 


  .Plasma membrane.

  .Cytoplasm

  .Ribosomes

  .DNA and RNA.
• Differences between Prokaryotic and Eukaryotic Cells: 


  .Prokaryotic cells:

  .Much smaller.

  .No nucleas.

  .No centrioles.

  .Smaller ribosomes.

  .No membrane bound organelles (mitochondria, ER, chloroplasts, GA).

  .Wall made from peptoglycan- not cellulose.

  .Naked DNA, not associated with histone proteins (chromosomes), they float free in the nucleoid.
• Endosymbiont Theory: 


  .Evidence (molecular, biological, fossil) that eukaryotic cells evolved from prokaryotes, 1.5-2 billion years ago.

  .Prokaryotes ingested (not digested) other prokaryotes with an inward-folding membrane (for making ATP/containing chlorophyll).

  .Double-membraned organelles formed as an invaded membrane fold around these invading prokaryotes.

  -This produces mitochondria and chloroplasts.

  -These share prokaryotic characteristics: small ribosomes, loops of DNA, RNA and binary fission.