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Comparison of Sizes: Molecules, Organelles, and Cells

Explore the relative sizes of molecules, organelles, and cells using SI units. Learn about the three-dimensional nature of cells and the use of microscopes to study them. Understand the differences between prokaryotic and eukaryotic cells and their associated diseases.

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Comparison of Sizes: Molecules, Organelles, and Cells

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  1. 1.1.6 Define organelle.An organelle is a discrete structure within a cell, and has a specificfunction.1.1.7 Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles and cells, using appropriate SI units.molecules (1 nm),thickness of membranes (10 nm), viruses (100 nm), bacteria (1 μm),organelles (up to 10 μm), most cells (up to 100 μm). Thethree-dimensional nature/shape of cells should be emphasized.

  2. Microscope facts • Magnification is the increase in the apparent size of an object; for example, 1,000X • Resolution is a measure of the clarity of an image • A light microscope can resolve objects as small as 2 m • The electron microscope (EM) allows greater magnification than Light microscope (LM) and reveals cellular details • Uses a beam of electrons rather than light • Has much greater resolution than LM (2 nm) • Can magnify up to 100,000 times • Cannot be used with living specimens

  3. Electron Microscope • Transmission electron microscope (TEM) studies the details of internal cell structure • Scanning electron microscope (SEM) studies detailed architecture of cell surfaces

  4. Modifications to LM use different techniques to enhance contrast and selectively highlight cellular components

  5. Prokaryotes • ‘Pro’ means ‘before’ • ‘Kary’ means kernal • Prokaryotes are cells without a nucleus! • They are SMALL • Example: Bacteria

  6. FYI on measurements:

  7. You can fit 100 prokaryotes into one eukaryote! Prokaryotes have a cell wall, DNA, membrane, and ribosomes… and some have a capsule

  8. Prokaryotic cell Nucleoid region LE 4-3a Colorized TEM 15,000 Nucleus Organelles Eukaryotic cell

  9. Where is the nucleoid region?

  10. Anthrax! Bacterial disease.

  11. Impetigo, common bacterial disease

  12. Leprosy, bacterial disease

  13. Tetanus, bacterial disease

  14. Necrotizing fasciitis also known as ‘flesh eating bacteria’

  15. …Maggot Debridement Continued…

  16. The Story of Vitus Smieja

  17. Other famous prokaryotic diseases: • Gonorrhea • Acne • Syphilis • Typhoid fever • Staph infection • Gangrene

  18. Bacteria or single cell organisms invade cells or tissues. Some produce a toxin. This post is probably full of bacteria! • This may cause a staph infection – caused by the bacteria staphylococcus aureus which invades cuts and breaks in the skin

  19. staphylococcus aureus • About 20% of the population are always colonized with S. aureus, 60% are intermittent carriers, and 20% never carry the organism. • ‘Superbug’ • Staph infections, including MRSA, generally start as small red bumps that resemble pimples, boils or spider bites. These can quickly turn into deep, painful abscesses that require surgical draining. Sometimes the bacteria remain confined to the skin. But they can also burrow deep into the body, causing potentially life-threatening infections in bones, joints, surgical wounds, the bloodstream, heart valves and lungs.

  20. Viruses are not cells! But they invade cells! • This is a virus. It injects its DNA or RNA into a healthy cell. • The virus’ DNA then takes over the cell, and makes many more Virus. • The cell eventually dies.

  21. AIDS virus on a cell

  22. Herpes simplex 1 (viral disease)

  23. Herpes Gladiatorum –shut wrestling down for 8 days last year

  24. Virus if it were big…

  25. Eukaryotes Cells of plants and animals These cells have a nucleus

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