2 - Basic components of living systems Flashcards
Development of Cell Theory
1665 - Cell first observed.
1674 - First living cell observed.
1832 - Evidence for the origin of new pant cells.
1833 - Nucleus first observed.
1837 - The birth of a universal cell theory.
1845 - Evidence for he origin of new animal cells.
1860 - Spontaneous generation disproved.
Light Microscope
2 lenses : objective lens, eyepiece lens.
Cheap
Easy to use
Portable and light
Able to be used to study whole living specimens
Allow x1500
Electromagnetic spectrum wave = 400-700 nm. So the closer structures are together they will appear as on object
Scanning Electron Microscope
3D image with a magnification from x15 up to x200000.
Image is black and white
Specimen still has to placed in a vacuum and is often coated with a fine film of metal.
Transmission Electron Microscope
Specimen has to be chemically fixed by dehydrated and stained.
Beam passes through the specimen, which is stained with metal salts.
2D black and white image this image is called an electron micrograph
Laser Scanning Microscope
They use laser light to scan an object point by point and assemble.
Images are high resolution and show high contrast.
They can be used to observe whole specimens as well as cells.
Magnification
The number of times larger an image appear, compared with the size of the object.
Resolution
The clarity of an image; the highest the resolution, the clearer the image.
Dry Mount
Solid specimens are viewed whole or cut into very thin slices with a sharp blade.
Place the specimen on the plate and cover with a cover slip over the sample.
Wet Mount
Specimen are suspended in a liquid such as water immersion in oil. A cover slip placed on from an angle.
Squash Slides
A wet mount is first prepared, then a lens tissue used to gently press down the cover slip. Depending on the sample squashing it could damage the sample. Squash sample need soft sample.
Smear Slides
The edge of a slide, creating a thin even coating on another slide.
Gram stain technique
Crystal violet is first applied to a bacterial on a slide, then iodine which fixes the dye. Then the slide is washed alcohol.
Acid-fast technique
A lipid solvent is used to carry carbolfuchsin dye into the cells being studied.
Calculating magnification
image size/actual size = magnification
Eyepiece graticule
A measuring device. It is placed in the eyepiece of a microscope and acts a ruler when you an object under the microscope