Post on 24-Dec-2015
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.
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
Nucleoidregion
Prokaryotic cell
Nucleus
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lor i
z ed
TE
M 1
5, 0
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Eukaryotic cellOrganelles
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.
•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.
Viruses are not cells! But they invade cells!
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