A2.2 Flashcards
Cell Structure
Microscopy
What is Cytology?
- Specific branch of biology that is focused on study of the cell and all aspects related to cellular structure and function.
- Relies on microscopes to provide understanding.
Microscopy
What is Magnification?
Magnification:
- The increase in an object’s image size compared to its actual size. (how many times larger is the viewed image that the object itself.
- Can be calculated by dividing size of the image by actual size of the object.
Actual Image: Image size/ mag
Mag: image size/ actual image
Image Size: Actual x Mag
Microscopy
What is meant by resolution
Minimal distance between two points/ objects at which they can still be distinguished as two.
— INDICATOR OR CLARITY (high res, higher clarity)
- Relationship between resolution and mag = inverse, as mag gets higher, resolution gets lower.
Microscopy
What is a micrograph?
A photo taken through a microscope to reveal the view of the microscope.
- Can be done from a light microscope but the ones of organelles are from an electron microscope.
- Often black and white
Microscopy
What does it mean to freeze fracture?
A technique that aids in viewing internal structures with an electron microscope.
1) specimen is rapidly frozen, then broken apart (fractured) creating a plane through the cell that can be observed.
2) Ice can be vaporized off and then a carbon/ patinum vapor is used to etch the surface and examine that etching under microscope.
Microscopy
What is a fluorescent stain?
Dyes that combine only with specific cellular components.
- When samples are irritated with UV/ violet blue light, those parts that it combines with will fluoresce and product visable colours to highlight those cellular components.
- Special microscopes have been nuilty that use high power LEDs to produce bright images.
Microscopy
What is immunofluorescence?
A more recent development in visibility enhancement.
- Makes use of antibodies that have dyes combined with them.
- Antibiodies are matched to identify/ bind to certain target molecules, often protiens.
- Antibiody binds to the target molecule —> creates a coloured glow.
- Used to detect viral proteins inside of cells.
Microscopy
Micrometre vs Centimetre
Micro –> 10^6 metres, would be 10^4 centimetres or 10^3 mm.
1 Micrometre = 0.001 mm.
Microscopy
Benefits of a Light Microscope
- Can pass light through organisms and are able to be used with both living/dead specimens.
- Affordable, safe, provide quality images at lower magnifications + visable colour
Microscopy
Benefits of an Electron Microscope
- Use beams of electrons
- Short wavelength of electrons preserves resolution at higher magnifications
- can magnify up to 1,000,000 times.
- can not be used with living species/ always black and white
Microscopy
Coarse Focus vs Fine Focus
COARSE - makes larger adjustments bring objects into focus. Used first.
FINE - Adds sharpness and clarity.
Microscopy
To calculate actual size
Magnification=image size/actual size.
- Use scale bar to find the first determine the magnification.
Microscopy
Scanning Electron Mciroscpoe vs Transmission
SEM - (scanning electron microscope): uses a beam of electrons to scane the outer surface of the specimen –> provides detailed images of the exteriors.
TEM - (transmission electron microscope): beams electrons through a thin section of the specimen to allow internal structures to be viewed.
Microscopy
Cryogenic Electron Mircosopy
(Cryo-EM), used for researching protein structure.
- protein solution is applied to a grid, this layer is flash frozen (like with liquid ethane)
- frozen protein gird is placed in an electron microscope, the pattern the electrons are transmitted by the protein is recorded, the computer uses the pattern to create a theorised 3D protein structure image.
Microscopy
Benefits of Flurorescent Stains
- stains bind to specific structures, help them to stand out from surrounding structures.
- special fluroescent microscopes are useful at creating imgaes that clearly show the placement of key cellular structures.
