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Microscope History Robert Hooke First described cells in 1665. He viewed thin slices of cork and compared the boxy partitions he observed to the cells (small rooms) in a monastery. (1635 1702) 2
Microscope History Anton van Leeuwenhoek In 1676 the Dutch scientist observed single-cell organisms ("little animalcules ). He was likely the first person to observe a red blood cell and a sperm cell. (1632 1723) 3
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Microscope History Robert Brown In 1831, Scottish scientist Robert Brown gave the nucleus of a cell its name. (1773 1858) 5
Methods of Cell Study Advances in instruments has led to a better understanding of the structure and function of cells. Compound Light Microscope A. Two lenses (ocular and objective) B. Specimen must be transparent 6
The Compound Light Microscope 7
Function of the Compound Light Microscope 1. Ocular (eye piece) look through, magnifies the image 2. Body Tube - holds lenses 3. Nosepiece - rotates the objectives (lenses) 8
Function of the Compound Light Microscope 4. Stage platform for slide 5. Stage Clips - holds slide in place 5. Diaphragm - controls the amount of light passing through the specimen 9
Function of the Compound Light Microscope 7. Mirror or Light Source (illuminator) - lights the specimen so it is easier to observe 8. Arm used to carry the microscope 9. Base - supports the microscope 10
Function of the Compound Light Microscope 10. Coarse Adjustment Knob - used for preliminary focusing, NEVER used on high power. 11
Function of the Compound Light Microscope 11. Fine Adjustment Knob used to focus on high power, and to fine tune low power. 12
Function of the Compound Light Microscope 12. High Power Objective: This objective has a magnification of 100x (maximum magnification) 13
Function of the Compound Light Microscope 13. Low Power Objective: This objective has a magnification of 10x (minimum magnification) Scanning objective has a magnification of 4x 14
Magnification & Resolution C. Magnification power is equal to the product of the ocular lens times the objective lens. Ocular Resolution - ability to distinguish between (separate) two objects very close together. If you can t read this, it is because you can t distinguish between the letters Objective Total Magnification 10x 10x 100x 10x 40x 400x 15x 40x 600x The properties of light limit the resolving power of the light microscope. 15
Resolution 16
Electron Microscope Uses a beam of electrons instead of light to get greater resolution and magnification (up to 250,000X). 17
Electron Microscope 18
Dissecting Microscope Used for viewing opaque (not seethrough) specimens. Provides a 3-D view. Does not reverse or invert the image 19
Phase Contrast Microscope Provides contrast without stains (stain kills specimens) 20
Phase Contrast Microscope 21
Ultracentrifuge Separates cell parts (organelles) by spinning them in a test tube at high speed (denser parts sink to the bottom of the test tube). 22
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8.Measurements with the microscope Millimeter = mm Micrometer = µm 1000 µm = l mm 1 µm = 1/l000 mm 24
Measuring with a Microscope Measuring the Field of View (FOV) Place a ruler on the stage, and line up one measurement line at the edge of the FOV Measure/estimate the size of FOV 25
Measuring with a Microscope Estimate the size of the object: Size of object = FOV # object that fit across the FOV How big is this cell? 26
Cells 27
Structure of Living Organisms The cell is the basic unit of life. 28
I. The Cell Theory 1. All organisms are made up of one or more cells. 2. These cells working individually, or together in tissues or organs, perform all life functions. 3. All cells come from pre-existing cells. 29
II. Exceptions to the Cell Theory 1. The first cell could not have come from a pre-existing cell. 2. Viruses - which are not cells have hereditary material and can reproduce. 3. Organelles such as mitochondria and chloroplasts have genetic material (DNA) and can reproduce. 30
Two types of Cells Prokaryotic Eukaryotic 31
Prokaryote Do not have structures surrounded by membranes Few internal structures One-celled organisms (ex: bacteria) 32
Eukaryote Contain organelles surrounded by membranes Most living organisms 33
Examples of Cells Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell
Cell Organelles Organelles are small specialized structures that carry out life functions within cells. 35
Animal Cell 36
Plant Cell 37
1. Plasma (Cell) Membrane Regulates the movement of materials into or out of cells. Semi-permeable Selectively-permeable Composed of a lipid bilayer with embedded proteins. It is fluid meaning it is flexible and the parts can move around within the membrane. 38
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2. Cytoplasm Jelly like environment of the cell (mostly H 2 O) Cyclosis: Movement of the cytoplasm (transports materials within the cell) 40
Nucleus and Nucleolus 3. Nucleus controls cell activities surrounded by nuclear membrane. - Contains genetic material (DNA and RNA) - Involved in Reproduction 4. Nucleolus dense region in the nucleus. involved in the synthesis of ribosomes. 41
5. Mitochondrion Site of cellular respiration Produces ATP (energy) for metabolism 42
6. Golgi Complex Synthesizes, packages and secretes (releases) cellular products. 43
7. Ribosomes Site of protein synthesis (ex: enzymes are proteins) 44
8. Endoplasmic Reticulum (ER) Forms passages throughout the cell for intracellular (within the cell) transport. Connects the nuclear membrane to the plasma membrane 45
8. Endoplasmic Reticulum (ER) Two Types of Endoplasmic Reticulum Rough Endoplasmic Reticulum- covered in ribosomes Smooth Endoplasmic Reticulum (no ribosomes) 46
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9. Lysosome Contains digestive enzymes (breaks down damaged organelles or pathogens) 48
10. Vacuole Space in a cell surrounded by a membrane. Food vacuole - stores food to be digested. Contractile vacuole helps to maintain water balance within a cell 49
Organelles in Animal Cells Only Centrioles Play a role in cell division 50
Organelles in Plant Cells Only Chloroplast Perform photosynthesis (produce nutrients) 51
Organelles in Plant Cells Only Cell Wall non-living structure that surrounds, supports and protects the cell. Made of cellulose (a polysaccharide) 52
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