BIOL331 Midterm: BIOL 331 Midterm 1 Review
5 Aug 2016
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Biology 331: advanced cellular biology midterm 1 review. Optical microscopy cannot resolve details that are less than the wavelength of visible light (0. 4-0. 7 m) Bacteria and mitochondria are the smallest entities visible by light microscopy (0. 5 m wide) The objective lens collects a light ray cone to create an image and the condenser lens focuses this cone of light onto each point of the specimen. Cells are colourless and translucent: enhance contrast by staining so light passing through will undergo phase shift. Phase contrast microscopy: increases the phase shift of light. Differential interference contrast microscopy: uses interference to increase contrast. Dark-field microscopy: light comes in from the side, only scattered light enters the objective. Electronic imaging systems are used to overcome difficulties in detecting very dim light very useful in fluorescence microscopy. Stains: dyes absorb light of certain wavelengths, and also introduce contrast by reducing the amplitude of light pass through which reduces brightness.
