Tools and Techniques of Biology- Microscope Notes Applied Biology Tools and Techniques of Biology- Microscope Notes

Compound Light Microscope Shines light through a specimen 2 lenses magnify an image Specimens must be thin- single celled organisms or multicellular organisms sliced thin

Eyepiece/Ocular Lens Magnifies image 10X

Objective Lens Enlarges image Three types of objective lens (on ours) Scanning: Magnification X4 Low Power: Magnification X10 High Power: Magnification X40

Nosepiece Rotating structure attaching objective lenses above the specimen

Stage Platform that supports slide Moves up and down with coarse and fine adjustment knobs Often has stage clips

Light Source Light bulb Some microscopes use mirrors to direct light

Magnification Increase of an object’s apparent size Determined by power of the ocular lens X objective lens Example: Ocular lens is 10X and scanning objective is 4X Total magnification is 40X

Resolution Power to show details clearly in an image Light microscopes have limited resolution Electron microscopes have higher resolution

Electron Microscope Uses a beam of electrons to magnify an image (not light) Images are always black and white Not for viewing live organisms Electrons have a wavelength 100,000 times smaller than visible light

Electromagnetic Spectrum

Scanning Electron Microscope SEM Electron beam passes over surface of 3-D object creating 3-D images

Transmission Electron Microscope Transmits electrons through a thinly sliced specimen (use diamond knives to cut thin enough sections) Magnify objects up to 200,000 times

Units of Measurement Need a common measurement system to compare results Système International d’Unités (SI) Based on the metric system

Metric System Decimal system based on powers of 10 Base Units: describe length, mass, time, and other quantities Multiples of base units designated by prefixes Base Quantity Name Abbreviation Length Meter m Mass Kilogram kg Time Second s Electric current Ampere A Thermodynamic temperature Kelvin K Amount of substance Mole mol Luminous (light) intensity Candela cd

Metric Unit Prefixes Text Symbol Factor Tera T 1,000,000,000,000 Giga Mega M 1,000,000 Kilo k 1,000 Hecto h 100 None 1 Deci d 0.1 Centi c 0.01 Mili m 0.001 Micro µ 0.000,001 Nano n 0.000,000,001 Pico p 0.000,000,000,001

Metric Staircase Chart from http://facultyfiles.deanza.edu/gems/heyerbruce/B11L01.pdf

Derived units Base units can’t be applied to area or volume Quantity Name Abbreviation Area Square meter m2 Volume Cubic meter m3 Density Kilogram per cubic meter kg/m3 Specific volume Cubic meter per kilogram m3/kg Celsius temperature Degree Celsius °C Time Minute 1 min = 60 sec Hour 1 h = 60 min Day 1 day = 24 h Liter 1 L = 1,000 cm3 Mass Kilogram metric ton 1,000 g = 1 kg 1 t = 1,0000 kg Base units can’t be applied to area or volume Mathematical relationship between two base units or two derived units

Powers of 10- Just how big or small are things? Powers of 10 video 1977 http://www.powersof10.com/ Scale of the Universe tool