Intro to BiologyIntro to Biology

Feb, 2009Feb, 2009

What is Biology?What is Biology?

Biology is the branch of Science that deals Biology is the branch of Science that deals with living organisms. with living organisms.

What do Biologists study? What do Biologists study? ““Umbrella Term” -ologistsUmbrella Term” -ologists Examples??Examples?? Hydrologist, Cytologist, Pathologist, etc.Hydrologist, Cytologist, Pathologist, etc. Heavy vocabulary…but some clues to help!Heavy vocabulary…but some clues to help! What is the most important tool used by What is the most important tool used by

Biologists?Biologists?

MicroscopesMicroscopes

Anton van Leeuwenhoek (1632-1723) was Anton van Leeuwenhoek (1632-1723) was responsible for the first “microscope” as responsible for the first “microscope” as we know them todaywe know them today

Due to his knowledge of lenses he was Due to his knowledge of lenses he was able to construct a piece of equipment able to construct a piece of equipment that made things appear closer and larger.that made things appear closer and larger.

Today’s microscopes use 2 lenses to Today’s microscopes use 2 lenses to magnify specimens. (ocular/objective)magnify specimens. (ocular/objective)

Types of MICROSCOPESTypes of MICROSCOPES

Light vs. ElectronLight vs. Electron Smallest size seen with the Naked Smallest size seen with the Naked

Eye is….Eye is…. 0.2mm = one ridge on your finger 0.2mm = one ridge on your finger

print (resolution OR resolving power)print (resolution OR resolving power) Light Microscopes can view 0.0002 Light Microscopes can view 0.0002

mm mm Electron Microscopes can view Electron Microscopes can view

0.000000002 mm (0.2 nm)0.000000002 mm (0.2 nm)

Compound Light MicroscopeCompound Light Microscope

Crudest of today’s microscopesCrudest of today’s microscopes Uses light passing through a medium Uses light passing through a medium

of liquid to view a specimenof liquid to view a specimen Uses generally a 10X ocular lens in Uses generally a 10X ocular lens in

addition to a 4x, 10x, 40x objective addition to a 4x, 10x, 40x objective lens lens

Magnification = ocular x objectiveMagnification = ocular x objective Limited in it’s magnificationLimited in it’s magnification

Parts of the Compound Microscope Parts of the Compound Microscope – Fill in your sheet as we go!!– Fill in your sheet as we go!!

http://www.biologycorner.com/microhttp://www.biologycorner.com/microquiz/#quiz/#

Focusing a MicroscopeFocusing a Microscope Always start with the low power Always start with the low power

objective (4X)objective (4X). Odds are, you will be able . Odds are, you will be able to see something on this setting. to see something on this setting. Use the Use the Coarse Knob toCoarse Knob to focusfocus..

Once you've focused on low power, Once you've focused on low power, switch to Med Power (10X)switch to Med Power (10X). Use the . Use the Coarse Knob to refocus. Again, if you Coarse Knob to refocus. Again, if you haven't focused on this level, you will not haven't focused on this level, you will not be able to move to the next level.be able to move to the next level.

Now switch to High Power. (40X)Now switch to High Power. (40X) If the specimen is too light or too dark, try If the specimen is too light or too dark, try

adjusting the diaphragm.adjusting the diaphragm.

Making a Wet MountMaking a Wet Mount1.1. Gather a Gather a thin slice/piecethin slice/piece of whatever your of whatever your specimenspecimen is. is.

your specimen is too thick, then the coverslip will wobble your specimen is too thick, then the coverslip will wobble on top of the sample like a see-saw, and you will not be on top of the sample like a see-saw, and you will not be able to view it under High Power.able to view it under High Power.

2.2. Place Place ONE drop of water/dyeONE drop of water/dye directly over the specimen. directly over the specimen. If you put too much water, then the coverslip will float on If you put too much water, then the coverslip will float on top of the water, making it hard to draw the specimen, top of the water, making it hard to draw the specimen, because they might actually float away. (Plus too much because they might actually float away. (Plus too much water is messy)water is messy)

3.3. Place the Place the coverslip at a 45 degree anglecoverslip at a 45 degree angle (approximately) with one edge touching the water drop and (approximately) with one edge touching the water drop and then gently let go. Performed correctly the coverslip will then gently let go. Performed correctly the coverslip will perfectly fall over the specimenperfectly fall over the specimen

Finished with your Microscope?Finished with your Microscope?

1. Store microscopes with the 1. Store microscopes with the scanning objective (4X) in place.scanning objective (4X) in place.2. Wrap cords and cover 2. Wrap cords and cover microscopes.microscopes.3. Wash slides/slips in the sinks and 3. Wash slides/slips in the sinks and dry them, placing them back in the dry them, placing them back in the slide boxes to be used later. slide boxes to be used later. 4. Carry with 2 hands (arm/base)4. Carry with 2 hands (arm/base)5. Put back in the correct location 5. Put back in the correct location

Transmission Electron MicroscopeTransmission Electron Microscope

•Uses electrons instead of light

•Capable of over 2000000X magnification

•Specimens that contain many layers of cells, such as blood vessels, cannot be examined

•A thick specimen would absorb all the electrons and produce a blackened image

•Only view thin sections encased in plastic

TEM cont..TEM cont..

Scanning Electron Microscope Scanning Electron Microscope (SEM)(SEM)

Produces a 3-D imageProduces a 3-D image Provides even greater magnification Provides even greater magnification

than the TEMthan the TEM Takes “pictures” of surfacesTakes “pictures” of surfaces Specimens are usually preserved, Specimens are usually preserved,

coated in a metal, dehydrated…so coated in a metal, dehydrated…so specimen being viewed is non-living.specimen being viewed is non-living.

Scanning Electron MicroscopeScanning Electron Microscope

SEM cont…SEM cont…

Salt

Guess?Guess?

Toilet Paper

Guess??Guess??

Staple going through paper

Guess??Guess??

Mascara Brush

Guess??Guess??

Mosquito Head

Rules for Biological DiagramsRules for Biological Diagrams Unlined paper and a sharp pencilUnlined paper and a sharp pencil Leave an empty margin of about 1 cm all around your pageLeave an empty margin of about 1 cm all around your page When drawing cells, choose only one cell (unless otherwise When drawing cells, choose only one cell (unless otherwise

required) and show the edge of neighbouring cells to show required) and show the edge of neighbouring cells to show the connectionthe connection

Draw outline of your subject with clear and unbroken lines. Draw outline of your subject with clear and unbroken lines. Your drawing should be about ½ of the pageYour drawing should be about ½ of the page Use Figure # and name as your headingUse Figure # and name as your heading Always indicate the magnification below your drawingAlways indicate the magnification below your drawing Use stipples for darkened areasUse stipples for darkened areas Always label to the right with a rulerAlways label to the right with a ruler

Biological Diagrams - Lab #2Biological Diagrams - Lab #2 Following all steps for biological Following all steps for biological

diagrams complete the following:diagrams complete the following: (Do two drawings on one page of plain (Do two drawings on one page of plain

paper)paper)1.1. Obtain a sample from the front and draw Obtain a sample from the front and draw

the specimen in the container (do not the specimen in the container (do not draw the bottle)draw the bottle)