Basic Components of Living Systems Key Terms and Processes Flashcards
Describe how to prepare a slide
- place a drop of the sample in the middle of a clean slide and lower a cover slip gently over the drop at an angle, with one edge touching the slide first
- allow the liquid to spread out between the two pieces of glass without applying pressure
Differential staining
differential staining can be used to distinguish between two types of organisms that would otherwise be hard to identify; it can also be used to differentiate between different organelles of a single organism within a tissue sample
Gram Stain Technique
- used to separate bacteria into two groups; gram +ve and gram -ve
- crystal violet is first applied to bacterial specimen on a slide, then iodine, which fixes the dye
- slide is then washed with alcohol, gram +ve bacteria retain the violet dye and appear blue under the microscope
- the gram -ve lose the dye
- they are then stained with a safranin dye; a counter stain
- ## these bacteria will then appear red
Magnification =
actual size
Transmission Electron Microscope
a beam of electrons is transmitted through a specimen and focused to produce an image
resolution : 0.5nm
Scanning Electron Microscope
a beam of electrons is sent across the surface of a specimen and the reflected electrons are collected
Laser Scanning Confocal Microscope
- an LSC moves a single spot of focussed light across a specimen, which causes the fluorescence from the components labelled with a dye.
- the emitted light from the specimen is filtered through a pinhole aperture, only light radiated very close to the focal plane is detected
- as very thin sections of specimen are examin ed and light from elsewhere is removed, very high resolution images can be obtained
Parts of the cell only available to see via an electron microscope
- secretary vesicles
- microfilaments
- mitochondria
- ribosomes on RER
- microvillus
- pinocytotic vescicle
- SER
- lysosome
- nuclear pore
Cell Fractionation
a technique used to separate the different parts of cells
Order of organelles that separate out when spun with a centrifuge
1 ) nuclei 2 ) mitochondria 3 ) lysosomes 4 ) rough endoplasmic reticulum 5 ) plasma membranes 6 ) smooth endoplasmic reticulum 7 ) free ribosomes
Iodine solution stains…
carbohydrates in plant/animal specimens blue/black
it also stains glycogen red
Methylene blue stains…
acidic cell parts (like the nucleus) blue
Gram stain…
stains gram-positive bacteria blue, and gram-negative bacteria red
Toluidine blue stains…
acidic cell parts dark blue
Crystal violet stains…
bacteria purple
