1 Review Facts About Living Things

2 What Are the Main Characteristics of organisms? 1. Made of CELLS 2. Require ENERGY (food) 3. REPRODUCE (species) 4. Maintain HOMEOSTASIS 5. ORGANIZED 6. RESPOND to environment 7. GROW and DEVELOP 8. EXCHANGE materials with surroundings (water, wastes, gases)

3 LEVELS OF ORGANIZATION Living Levels: 1. CELL (makes up ALL organisms) 2. TISSUE (cells working together 3. ORGAN (heart, brain, stomach …) 4. ORGAN SYSTEMS (respiratory, circulatory …) 5. ORGANISM

4 THE CELL All living things are made of cells. All living things are made of cells. Cells are the basic unit of life. Cells are the basic unit of life. Cells come from the reproduction of existing cells (cell division). Cells come from the reproduction of existing cells (cell division).

The Microscope

Learning Objectives By the end of this topic, you will be able to: 1.Name the parts of the microscope and their functions. 2.Use the microscope to observe biological specimens 3.Know the difference between the light microscope and the electron microscope

7 First to View Cells In 1665, Robert Hooke used a microscope to examine a thin slice of cork (dead plant cell walls) In 1665, Robert Hooke used a microscope to examine a thin slice of cork (dead plant cell walls) What he saw looked like small boxes What he saw looked like small boxes

8 First to View Cells Hooke is responsible for naming cells Hooke is responsible for naming cells Hooke called them “CELLS” because they looked like the small rooms that monks lived in called Cells Hooke called them “CELLS” because they looked like the small rooms that monks lived in called Cells

9 Anton van Leeuwenhoek In 1673, Leeuwenhoek (a Dutch microscope maker), was first to view organism (living things) In 1673, Leeuwenhoek (a Dutch microscope maker), was first to view organism (living things) Leeuwenhoek used a simple, handheld microscope to view pond water & scrapings from his teeth Leeuwenhoek used a simple, handheld microscope to view pond water & scrapings from his teeth

Compound Microscopes a.The Eyepiece Lens is the lens that you look through. b.The objective lens is the lens that is immediately above the specimen. The microscopes used in our lab are called compound microscopes because they have two magnifying lens

The Objective Lenses There are three objective lenses: - the scanning lens with the 4X label - the low power lens with the 10X label - the high power lens with the 40X label

Parts of the Microscope

The Microscope Eyepiece Nosepiece Objective Lens Stage Clips Light Diaphragm Course Focus Fine Focus

Parts of the Microscope PartFunction LensesMagnification Stage To place the slide on Clips Hold the slide in place Diaphragm To control the amount of light Coarse Focus Knob To focus the image Fine Focus Knob To precisely focus the image Light To supply light to the object

Learning Check Label the parts of the Microscope

Magnification Magnification = the magnifying power of the eyepiece lens x the magnifying power of the objective lens. Example: Eyepiece lens = 10X Objective lens = 4X Total magnification = 10 x 4= 40X

Focussing The Image course focus The course focus knob allows for dramatic or large movement of the objective lens. fine focus The fine focus knob allows for very slight movement of the objective lens.

The Stage and the Diaphragm stage The stage has two metal clips to hold the microscope slide in place. diaphragm The diaphragm allows light to be focused onto the specimen through a hole in the stage.

Light Microscope Elodea - Aquatic Plant 40X400X

ELECTRON MICROSCOPE

Electron Microscope Uses Electrons instead of light Uses Electrons instead of light Electrons have much lower wavelength than light Electrons have much lower wavelength than light Resolution is much better Resolution is much better Magnification is much greater Magnification is much greater

Images from Electron Microscope Bacteria Cytplasm Platelet

Now lets get familiar with the light microscope by using it!

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How to correctly use microscope

Draw labelled diagrams of your observations under low power and under high power.

Learning Check What is the function of each of these parts of the Microscope? Eyepiece Lens Objective Lens StageClips DiaphragmCoarse Focus Knob Fine focus KnobLight

What have you learned? Can you? 1.Name the parts of the microscope and their functions. 2.Use the microscope to observe biological specimens 3.Outline the differences between the light microscope and the electron microscope

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