Microscopes Flashcards
What is resolution?
The ability to distinguish between two separate points/objects - min distance apart two objects can be in order for them to appear as two separate items - depends upon wavelength and type of radiation used
Greater resolution ….
Greater clarity - clearer and more precise/detailed image
What is magnification?
The number of times larger an image appears than the original specimen
What is a light microscope?
A series of lenses (compound microscope) through which ordinary white light can be focussed - low resolution due to the long wavelength of light
What is an electron microscope?
The process by which electrons are fired at a specimen at a high speed from an electron gun onto a fluorescent screen of photographic plate with the use of an electromagnet and a vacuum - higher resolution (electron beam has a very short wavelength) and magnification than a light microscope
What is a transmission electron microscope?
When a beam of electrons pass through the specimen to produce a high resolution image
What is a scanning electron microscope?
The process by which electrons bounce off the surface of the specimen producing an image with a 3D appearance
What is the calculation for magnification?
I = A/M
I = Image shown A = actual image M = magnification
What is cell fractionation?
A technique used to isolate parts of a cell for further study
Why is the solution cold, isotonic and buffered?
Cold to reduce enzyme activity
Isotonic to prevent organelles bursting or shrinking as a result of the osmotic loss of gain of water
Buffered to maintain a constant pH
What is the order of collection after cell fractionation?
The organelles are collected the in order of density with the most dense being collected first: nucleus Mitochondria Lysosomes ER Ribosomes
What is differential centrifugation?
A procedure separating certain organelles from whole cells for further analysis of certain parts of the cell
What is (ultra)centrifugation?
The process of separating out particles of different sizes and densities by spinning them at a high speed in a centrifuge. Then studying the structure and function of organelles in isolation under an electron microscope
What is the supernatant (liquid)?
The liquid portion of a mixtue left at the top of the tube when suspended particles (solid residue) have been separated out at the bottom during centrifugation
What is the centrifugal force?
It keeps an object rotating in a circle
