Tools and Techniques of the Biologist

The Microscope

The Parts of the Microscope Ocular (A) Body Tube (B) Course Adjustment (I) Nose Piece (C) High Power Objective Fine Adjustment (D) 40x (J) Low Power Objective (E) 10x Arm Stage (K) (F) Clips Diaphragm (L) (G) Light Source (H) Base (M)

The Parts of the Microscope Compound Light microscope two ___________________________ - uses _______________ lenses. One lens enlarges the specimen and the second magnifies it even more. Specimens must be ______________________. Parts of the compound Light Microscope. ____________________ - is used to “look through” and is closest to the eye. Usually magnifies _______________. _______________ - lens closest to the _______________. Usually magnifies at _______________. _______________ - rotating piece that holds the _______________. _______________ - holds eyepiece lens at top and objective lenses at the bottom. _______________ - platform that holds the specimen to be examined. Thin and transparent Ocular or eye piece 10x Objective lens specimen 10x to 50x nosepiece objectives Body tube stage

The Parts of the Microscope clips _______________ - holds glass slide in place. _______________ - regulates the amount of _______________ that reaches the specimen. _______________ - reflects and focuses _______________ on the specimen. _______________ - holds the _______________ and _______________. _______________ - supports the microscope. _______________ - large knob used for _______________ of the specimen with the _______________ objective. _______________ - small knob used for _______________ with low power objectives and for all focusing with the high power objective. diaphragm light mirror light arm tube stage base Course adjustment Rough focusing Low power Fine adjustment Fine focusing

The Parts of the Microscope _______________ - to determine the total magnification of the microscope, multiply the magnification of the _______________ by the magnification of the objective lens. Example: Ocular = 10x Objective = 40x Total Magnification: _____ X _____ = _____ _______________ - the ability of the microscope to show two points that are close together, as separate images. This is another name for _______________. magnification ocular 10 40 400 resolution Sharpness of image

Viewing Objects under the Microscope Low power Position the specimen under the _______________. Make sure the _______________ is at its _______________ (allows the most light through). Focus under low power using the __________________ first, and then the _______________ to sharpen the image if needed. Scan the field of view under low power. Switch to high power checking to make sure the high power lens does not hit the slide. Focus under high power using the _______________ only. As magnification increases, the size of the image _______________. _______________ - what you see when you look through the ocular. As magnification increases, the field of view _______________. diaphragm Maximum opening Course adjustment Fine adjustment Fine adjustment increases Field of view decreases

Viewing Objects under the Microscope Upside downs and backwards The image is always viewed __________________________. As power of the objective increases, the brightness _______________. Moving the slide to the right causes the image to move to the _______________. Moving the slide to the left causes the image to move to the _______________. Moving the slide up causes the image to move _______________. Moving the slide down causes the image to move _______________. decreases left right down up

Measuring under the Microscope

Dissecting microscope Other Microscopes Electron microscope _______________ - uses beams of _______________. It can magnify objects greater than 200,000 times. It is used in studying _______________ structures of cells. The specimen must be _______________. Living specimens would be killed by processes that are used to prepare the sample. _______________ or _______________ - magnifies _______________. Has an ocular and objective for each eye. Gives a _______________ view of the image. Used during _______________ and to study external structures of small plants and animals. electrons detailed Dead stereomicroscope Dissecting microscope 5x – 20x 3D dissections

Technique centrifuge ultracentrifuge _______________ and _______________ . An instrument which separates suspensions according to the _______________ of the suspended materials. An Ultracentrifuge is used to separate cell parts such as the nucleus and mitochondria out of cells. Microdissection instruments: Small instruments used With the help of _______________ for laparoscopic surgery and for removal of _______________. density The microscope Cell parts

Staining Materials Needed Clean glass slide Distilled water Sample for staining Plant: such as onion skin Animal: human cheek cells Cover slip Staining agent Iodine: used for plant cell staining Methylene Blue: used for animal cell staining Note: staining will kill the plant or animal cell sample being used Two eye droppers One for water One for staining agent Paper towel

Start with a clean glass slide Step One – the Slide Start with a clean glass slide

Place a few drops of water in the center of the slide Step Two – the Water Place a few drops of water in the center of the slide

Place sample to be stained in center of the slide over the water Step Three – the Sample Place sample to be stained in center of the slide over the water

Step Four – the Cover Slip Place cover slip over sample to be stained at 45o angle to the slide

Add a few drops of stain (like iodine) to the edge of the cover slip Step Five – the Stain Add a few drops of stain (like iodine) to the edge of the cover slip

Step Six – the Draw Put a piece of paper towel on the other edge of the cover slip to draw the stain across

Step Seven – the Staining As the stain moves under the cover, it stains the sample

Stained sample is complete Step Eight – Done Stained sample is complete

Tissue Culture and Sterilization ______________________________ is a technique used to maintain living tissue or _______________ in a laboratory setting for further study. _______________ culture taken at the doctor’s office. _____________________________ fertilization. Embryos are kept alive and grown in a laboratory setting. ______________________________ can be a tissue culture for mosquitos. _______________ the process of _______________ all the microorganisms. Use of an _______________ sterilizes dental and surgical tools at very high temperatures. microorganisms throat In vitro Stagnant water sterilization killing autoclave

Indicators _______________ . Scientists use indicators which are chemicals that ______________________________ in the presence of certain other substances. _______________ turns blue-black in the presence of starch. ______________________________ which changes from blue to brick red in the presence of glucose when heated. _______________ paper which changes color in the presence of an acid or a base. Bromothymol Blue which changes from blue to yellow in the presence of _______________. Indicators Change color iodine Benedict’s Solution pH Carbon dioxide

Chromatography _______________ a technique used for analyzing the chemical make-up of a mixture. This technique separates substances based on their chemical or physical properties. Various _______________will form. Each band of color indicates a separate substance in the test material. chromatography Bands of color

Electrophoresis _______________ is a technique to separate substances according to size, shape, and electric charge. This technique is called _______________. Gel Electrophoresis DNA Fingerprinting

Steps in Gel Electrophoresis DNA Extract the __________ (genetic material) from various kinds of tissue such as blood, skin, hair, semen, or saliva The DNA is cut into different size pieces by using a special type of protein called a ____________________ The solution containing the DNA fragments is then placed in __________ on a flat plate of gel, and an ______________________ is passed through the gel plate Since DNA has a ___________ charge, it is ___________ to the ___________ electrode The smaller the fragment of DNA, the ___________ and ___________ it moves. This forms a ___________ that will be matched against a known sample of DNA. Restrictive enzyme wells Electric current negative attracted positive faster farther fingerprint

Steps in Gel Electrophoresis