Transcript organelles
1.1.6 Define organelle. An organelle is a discrete structure within a cell, and has a specific function. 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). The three-dimensional nature/shape of cells should be emphasized. 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 Electron Microscope – Scanning electron microscope (SEM) studies detailed architecture of cell surfaces – Transmission electron microscope (TEM) studies the details of internal cell structure Modifications to LM use different techniques to enhance contrast and selectively highlight cellular components Prokaryotes • • • • • ‘Pro’ means ‘before’ ‘Kary’ means kernal Prokaryotes are cells without a nucleus! They are SMALL Example: Bacteria FYI on measurements: You can fit 100 prokaryotes into one eukaryote! Prokaryotes have a cell wall, DNA, membrane, and ribosomes… and some have a capsule LE 4-3a Prokaryotic cell Nucleoid region Nucleus Organelles Eukaryotic cell Where is the nucleoid region? Anthrax! Bacterial disease. Impetigo, common bacterial disease Leprosy, bacterial disease Tetanus, bacterial disease Necrotizing fasciitis also known as ‘flesh eating bacteria’ …Maggot Debridement Continued… The Story of Vitus Smieja Other famous prokaryotic diseases: •Gonorrhea •Acne •Syphilis •Typhoid fever •Staph infection •Gangrene • 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 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. 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. AIDS virus on a cell Herpes simplex 1 (viral disease) Herpes Gladiatorum –shut wrestling down for 8 days last year Virus if it were big… Eukaryotes Cells of plants and animals These cells have a nucleus