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Unit 2: Cells & Microscope

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  1. Unit 2: Cells& Microscope

  2. Cell Objectives: 1. Know the Organization of life. 2. Know who firstsaw cells. 3. Know The Cell Theory. 4. Know the differences between Prokaryotic and Eukaryotic cells. 5. Know the 12 organelles in Eukaryotic cells. 6. Know the differences between plant and animal cells.

  3. Cells All living things are composed of cells. A cell is a membrane-covered structure that contains all of the materials necessary for life. An organism is anything that can live on its own.

  4. Organisms can be unicellular or multicellular. Unicellular: Made up of only one cell. They usually need to be seen using a microscope. Multi-cellular: Made up of more than one cell. They have groups of cells that work together.

  5. Discovery of Cells Cells were discovered in 1665 by Robert Hooke. He was looking at cork from the bark of a tree using a microscope. Anton van Leeuwenhoek saw the first living cells in 1673. He observed pond scum, blood and was the first person to see bacteria.

  6. The Cell Theory Scientists later discovered a lot more about cells using more powerful microscopes. They developed The Cell Theory. The Cell Theory States: • Cells are the smallest living thing • Every living thing is made of cells • Cells divide to form new cells Theodor Schwann developed the theory in 1839.

  7. Make up Make up Make up Make up Organization of Life For Multi-cellular organisms: cells tissues organs organ systems organisms

  8. Types of Cells Prokaryotic: • Cells that do NOT have a nucleus • Do NOT have membrane bound organelles • Circular DNA • Bacteria • Cells that DO have a nucleus • Do have membrane bound organelles • Linear DNA • All other organisms Eukaryotic:

  9. Cell Parts (Organelles) Eukaryotic Cells: • cytoplasm • cell membrane • cell wall • nucleus • nucleolus • ribosomes • endoplasmic reticulum • mitochondria • chloroplast • Golgi complex • vacuole • lysosomes

  10. Types of Eukaryotic Cells Animal: Plant:

  11. Types of Eukaryotic Cells Animal: Plant:

  12. Function of cell parts 1. Cytoplasm • Jelly-like fluid inside cell • Organelles are found floating here

  13. Function of cell parts 2. Cell Membrane • Protects the cell • Keeps cytoplasm inside • Allows materials in and out of the cell

  14. Cell wall Cell membrane Function of cell parts 3. Cell Wall • Provides strength and support to cell membrane • Found only in plant cells • Gives plant cells their square shape

  15. Function of cell parts 4. Nucleus • Control center of the cell = “brain” • Where DNA is found 5. Nucleolus • Stores materials to make ribosomes • Found inside nucleus

  16. Function of cell parts 6. Ribosomes • Site of protein synthesis • Amino acids are joined together to make proteins. • Are found in cytoplasm or attached to endoplasmic reticulum • Smallest but most abundant organelle

  17. Function of cell parts 7. Endoplasmic Reticulum (ER) • Internal delivery system • Makes lipids and other materials for inside and outside the cell. • Breaks down drugs and other harmful chemicals. • May be covered with ribosomes (Rough Endoplasmic Reticulum) • Found near nucleus

  18. Function of cell parts 8. Mitochondria • Powerhouse of the cell • Energy for the cell is made here from nutrients • Surrounded by two membranes

  19. Function of cell parts 9. Chloroplast • Absorbs sunlight to help plants make nutrients for energy • Contains chlorophyll (green pigment) • Found only in plant cells

  20. Function of cell parts 10. Golgi Complex • Materials are packaged in vesicles for shipment outside of the cell. • Located near the cell membrane

  21. Function of cell parts 11. Vacuole • Stores water and other liquids • Large vacuoles found in plants Contractile Vacuole: • Squeezes excess water out of the cell

  22. Function of cell parts 12. Lysosomes • Digest (breakdown) materials found in vesicles with enzymes (chemicals). • Get rid of wastes • Protect the cell against invaders • Found in Animal cells

  23. cell wall cell membrane chloroplast lysosome cytoplasm nucleolus nucleus DNA ER mitochondria Golgi Complex ribosome vacuole Animal Cell Plant Cell

  24. Comparing Plant & Animal Cells Plant Both Animal vacuole nucleus mitochondria cytoplasm Cell wall lysosomes ribosomes Golgi complex nucleolus Cell membrane Chloroplast DNA ER

  25. Microscope Objectives: 1. Know the parts of the microscope. 2. Know the functions of microscope parts. 3. Know how to determine orientation of an object under the microscope. 4. Know how to determine magnification, field of view and size of an object. 5. Know proper technique to use microscope.

  26. Microscope parts Use this diagram to label your microscope picture

  27. Microscope Functions Eyepiece: The part you look through. Where you place your eye. Arm: Attaches eyepiece to the base. Body tube: Supports the eyepiece Coarse adjustment knob: This moves the stage up and down to get object into initial focus. NEVER use under high power. Fine adjustment knob: Used to make small adjustments to the focus.

  28. Microscope Functions Nosepiece: Rotating piece that changes objectives (low & high) Objectives: Lens that magnify the object Stage: The place where the specimen is placed. Stage clips: Holds the specimen slide in place. Diaphragm: Allows different amounts of light through the slide. Light source: Reflects light onto the stage to observe specimen Base: Supports the entire microscope

  29. Determining total magnification Multiply the magnification of the eyepiece by the magnification of the objective. Eyepiece = 10x Objective = 4x Total magnification = 10 x 4 = 40x Eyepiece = 10x Objective = 40x Total magnification = 10 x 40 = 400x

  30. cover slip slide Object Orientation e As you look through the eyepiece the image you see is upside down and backwards from the specimen on the slide. If you move the slide to the left the object moves to the right in the eyepiece. If you move the slide to the right the object moves to the left in the eyepiece.

  31. Field of View Each mark = 1 mm or 1000 μm Determine the field of view by counting marks under low power. 100x Field of view = 3mm or 3000 μm Determining object size Using the determined field of view: 1. Count the number of cells in a row. 2. Divide the number of cells into the field of view in μm. 100x • 6 cells • 3000 μm / 6 cells = 500 μm (size of one cell)