CHAPTER 1: CELL STRUCTURE
MICROSCOPE IN CELL STUDIES
Magnification calculations:
- Magnification is how many times bigger the image is observed than the
actual.
magnification = image / actual
Eyepiece Graticules & Stage micrometres:
- Eyepiece graticule and stage micrometre used to measure size of the object.
- Stage micrometres are in micrometres and it is usually 1omicrometres
divisions.
- Eyepiece graticule has 100 divisions with no scale.
Magnification:
- How many times bigger the image of a specimen observed is in comparison
to the actual size of the specimen.
- To calculate you multiply the eyepiece lens magnification and the objective
lens magnification
Resolution:
- Ability to distinguish between two separate points. Limited by the wavelength
of light.
- Longer the wavelength of light, the more the light is diffracted.
- Electron microscopes have higher resolution and magnification as electrons
have smaller wavelengths than visible light.
Light microscopes:
- Used for specimens above 200 nm
- Specimens can be living or dead, used to look at whole cells, organisms,
tissues.
, Electron microscopes:
- Used for specimens above 0.5 nm
- Fire a beam of electrons, the electrons are picked by electromagnetic lensa
which shows the image.
- Due to higher frequency of electron waves the magnification and resolution
are better.
- Transmission electron: specimen covered in resin, thin slices made stained
with heavy metals.
- Scanning electron: specimens coated with a thin layer of metal, electrons
reflected making a 3D image.
Eukaryotic Cell structures:
Cell surface membrane:
- All cells are surrounded by a cell surface membrane which controls the
exchange of materials between the internal cell environment and the external
environment.
- Membrane is described as partially permeable
- Cell membrane is formed from a phospholipid bilayer of phospholipids
spanning a diameter of around 10 nm
MICROSCOPE IN CELL STUDIES
Magnification calculations:
- Magnification is how many times bigger the image is observed than the
actual.
magnification = image / actual
Eyepiece Graticules & Stage micrometres:
- Eyepiece graticule and stage micrometre used to measure size of the object.
- Stage micrometres are in micrometres and it is usually 1omicrometres
divisions.
- Eyepiece graticule has 100 divisions with no scale.
Magnification:
- How many times bigger the image of a specimen observed is in comparison
to the actual size of the specimen.
- To calculate you multiply the eyepiece lens magnification and the objective
lens magnification
Resolution:
- Ability to distinguish between two separate points. Limited by the wavelength
of light.
- Longer the wavelength of light, the more the light is diffracted.
- Electron microscopes have higher resolution and magnification as electrons
have smaller wavelengths than visible light.
Light microscopes:
- Used for specimens above 200 nm
- Specimens can be living or dead, used to look at whole cells, organisms,
tissues.
, Electron microscopes:
- Used for specimens above 0.5 nm
- Fire a beam of electrons, the electrons are picked by electromagnetic lensa
which shows the image.
- Due to higher frequency of electron waves the magnification and resolution
are better.
- Transmission electron: specimen covered in resin, thin slices made stained
with heavy metals.
- Scanning electron: specimens coated with a thin layer of metal, electrons
reflected making a 3D image.
Eukaryotic Cell structures:
Cell surface membrane:
- All cells are surrounded by a cell surface membrane which controls the
exchange of materials between the internal cell environment and the external
environment.
- Membrane is described as partially permeable
- Cell membrane is formed from a phospholipid bilayer of phospholipids
spanning a diameter of around 10 nm
