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Microscopes. THE DISCOVERY OF THE CELL. It was not until the mid-1600’s that scientists began to use microscopes to observe cells. In 1665, Englishman Robert Hooke used an early compound microscope to look at a slice of cork, plant material. CORK CELLS.

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the discovery of the cell
THE DISCOVERY OF THE CELL

It was not until the mid-1600’s that scientists began to use microscopes to observe cells.

In 1665, Englishman Robert Hooke used an early compound microscope to look at a slice of cork, plant material.

slide5
Hooke saw thousands of empty chambers which he called cells. They reminded him of a monastery’s tiny rooms, which were called cells.

In Holland around the same time, Antonvan Leeuwenhoek used a single-lens microscope to observe pond water and other things.

He discovered that living things seemed to be everywhere, even in the water he was drinking.

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DUST MITE

EUGLENA

FLAGELLA

paramecium
Paramecium

Spirogyra

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Transmission electron microscope

electrons pass through thin slices of cell parts

Cells must be dead and in a vacuum

2D picture (flat)

TEM is used to study the internal structure of cells.

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CONFOCAL LIGHT

TEM

CHLOROPLAST

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Scanning electron microscope

Do not have to cut cells into slices

Cells must be dead and in a vacuum

produces three-dimensional images of cells

SEM is used to study details of the surface of the specimen.

TEM is more powerful than SEM

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MARINE DIATOM

SEM

SCANNIING ELECTRON MICROSCOPE

pea weevil egg

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White pine sheath mite on eastern white pine

Scanning electron microscope image of white pine sheath mite

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Red Blood Cells

  • most common type of blood cell in the human body
  • These biconcave-shaped cells have the tall task of carrying oxygen to our entire body; in women there are about 4 to 5 million RBCs per micro liter (cubic millimeter) of blood and about 5 to 6 million in men.
  • People who live at higher altitudes have even more RBCs because of the low oxygen levels in their environment. 
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Purkinje Neurons

Of the 100 billion neurons in your brain. Purkinje (pronounced purr-kin-jee) neurons are some of the largest. Among other things, these cells are the masters of motor coordination in the cerebellar cortex. Toxic exposure such as alcohol and lithium, autoimmune diseases, genetic mutations including autism and neurodegenerative diseases, can negatively affect human Purkinje cells. 

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Hair Cell in the EarHere's what it looks like to see a close-up of human hair cell stereo cilia inside the ear. These detect mechanical movement in response to sound vibrations. 

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Blood Vessels Emerging from the Optic NerveIn this image, stained retinal blood vessels are shown to emerge from the black-colored optic disc. The optic disc is a blind spot because no light receptor cells are present in this area of the retina where the optic nerve and retinal blood vessels leave the back of the eye. 

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Tongue with Taste BudThis color-enhanced image depicts a taste bud on the tongue. The human tongue has about 10,000 taste buds that are involved with detecting salty, sour, bitter, sweet and savory taste perceptions.  Thai people have very few -- most killed by eating spicy food. 

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Tooth PlaqueBrush your teeth often because this is what the surface of a tooth with a form of plaque looks like. 

slide23

Blood ClotRemember that picture of the nice, uniform shapes of red blood cells you just looked at? Well, here's what it looks like when those same cells get caught up in the sticky web of a blood clot. The cell in the middle is a white blood cell. 

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Alveoli in the LungThis is what a color-enhanced image of the inner surface of your lung looks like. The hollow cavities are alveoli; this is where gas exchange occurs with the blood. 

slide25

Villi of Small IntestineVilli in the small intestine increase the surface area of the gut, which helps in the absorption of food. Look closely and you will see some food stuck in one of the crevices. 

types of light microscopes
Types of light microscopes:
  • Compound light microscope: clear resolution to about 1,000 times the size of the actual specimen.
  • Allows visible light to pass through the specimen and use two lenses to form an image.
  • The two lenses of a compound light microscope:
    • ocular lens (eyepiece): located at the top portion of the microscope; usually has a magnification of 10X.
    • objective lens: located on the revolving nose piece, varies in magnification.
      • The shortest objective lens is a low power magnifier (usually 10X), the longer ones are high power (usually up to 40X or 43X) The magnification is marked on each objective lens.
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Total magnification of an image =

magnifying power of ocular lens X magnifying power of the objective lens.

  • For example, with a 10X ocular lens and a 40X objective lens:
    • total magnification of the image is 10 X 40 = 400X
    • You must always identify the magnification used when observing a specimen.
  • The advantage of the light microscope is that they make it possible to study small living organisms. Chemical dyes help to show specific structures in a cell.
the parts of the microscope and their function
The Parts of the Microscope and Their Function

Maintains

proper distance

between lenses

Magnification

Hold objectives-

rotates to change

magnification

Support body tube

Magnification

Supports slide

Holds slide

In place

Focuses image

Regulates

amount of light

Sharpens the image

Reflects light

towards eyepiece

Supports microscope

proper procedures
Proper Procedures
  • Carry the microscope with one hand under the base while grasping the arm with the other hand
  • Place microscope ~5 inches from the edge of the table

Be careful of the cord when moving around the lab tables!!

proper procedures1
Proper Procedures

3. Rotate the nosepiece to obtain the proper objective lens

Make sure the lens clicks into place!!

4. Look through the eyepiece and switch on the lamp

This is your field of view!

proper procedures2
Proper Procedures

5. Place slide on stage, center specimen over stage

6. Locate specimen on low power using coarse adjustment

7. Carefully switch to medium or high power

8. Focus image with fine adjustment

Avoid damaging slide!

Do not use coarse adjustment with high power!

storing the microscope
Storing the Microscope

Four steps prepare the microscope for storage:

  • the 10X objective is in place
  • the stage is all the way down
  • the power is off
  • the cord is wrapped around the base
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Let’s Review!

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10.

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4.

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5.

6.

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14.

Eyepiece

Body tube

Nosepiece

Arm

Low power

Medium power

Stage

High power

12.

Stage clips

Coarse adjustment

Diaphragm

13.

Fine adjustment

Light source

Base