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UNIT 1: CELLULAR BIOLOGYUNIT 1: CELLULAR BIOLOGY

1.1 Cell Theory & the Microscope1.1 Cell Theory & the Microscope

Cell Theory

1. All living things are composed of one or more cells.

2. Cells are the basic structural and functional units of life.

3. All cells arise from the division of other cells

Note: Robert Hooke discovered cells in 1655

How? …………

Robert Hooke

Hooke viewed a thin cutting of cork and discovered empty spaces contained by walls which he termed them cells

Compound Light Microscope

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Compound Light Microscope1. ocular

2. body tube

3. arm

4. stage clip adjustment knob

5. coarse adjustment knob

6. fine adjustment knob

7. revolving nosepiece

8. objective

9. aperture

10. stage clip

11. stage

12. condenser

13. diaphragm

14. light

15. base

Compound Light Microscope

Microscope Part

Function

1. ocular eyepiece lens, magnifies 10X

2. body tube directs light into ocular, supports

3. arm support

4. stage clip adjustment knob

moves slide around

5. coarse adjustment knob

moves stage up and down to focus image

Compound Light Microscope

Microscope Part

Function

6. fine adjustment knob

fine focus for most clear image

7. revolving nosepiece

holds objective lenses & facilitates changing

magnification

8. objective lens further magnifies the image

9. aperture opening to allow light to hit the specimen

10. stage clip holds slide in place

Compound Light Microscope

Microscope Part

Function

11. stage place specimen on it

12. condenser focuses light into a beam

13. diaphragm controls the amount of light hitting the specimen

14. light sends out light rays so specimen is visible

15. base supports microscope

Compound Light Microscope• has two lenses

1. ocular lens (10X)2. objective lens (4X, 10X, 40X)

- Low 4X- Medium 10X- High 40X

magnification:

the ability of lenses to enlarge the image of a specimen

magnification = ocular lens X objective lens400X = 10X times 40X

Other kinds of Microscopes

• Do you know any other kinds?

• ..\Videos\Different-Kinds-of-Microscopes[www.savevid.com].3gp

The Transmission Electron Microscope (TEM):

• How it works:Uses invisible beam of electrons that

pass through the specimen.

Best to observe:

Very thin pieces of the specimen.

Magnify up to:5 000 000X

Human Lung Tissue – Alveolar area

The Scanning Electron Microscope (SEM):

http://legacy.mos.org/sln/sem/seminfo.html

How it works: Reflects electrons from the surface of the

specimen.

Magnifies to:

300 000X

Best to observe:

Thicker specimens, surface features

Radiolarian (SEM)

• single-celled organism.• live in large quantities as part of the

ocean's plankton.

Magnification: X 750

Bladderwort

• Plant that live in fresh water• Lives where nutrients are scarce• Supplements its diet with insects or

other small organisms

Magnification: X 100

• http://www.telegraph.co.uk/science/picture-galleries/7924099/Creepy-crawlies-Amazing-Scanning-Electron-Microscope-pictures-of-insects-and-spiders.html

TEM & SEM

Scanning electron microscope image of a snowflake.

Transmission electron microscope image of the influenza virus.

Cholera TEM OR SEM??

Microscope ActivityWorking in pairs, identify all of the parts of the microscope. (Quiz each other)

Materials: compound light microscopeslide & cover slip coloured picture from a magazine

1. Cut out a small letter “e” and picture from the magazine.

Answer the following questions with your partner:

a) What happens when you move the slide to the right?

b) What happens when you move the slide down?

c) Describe the magnified image when looked at under high power? How does this differ when viewed with the unaided eye?