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What were the first organisms to inhabit Earth?
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Prokaryotes
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What are teh three most common shapes of Prokaryotes?
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Spherical (Cocci)
Rod-shaped (Bacilli) Spiral |
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What does the cell wall do in Prokaryotes?
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Maintains cell shape
Provides physical protection Prevents bursting in hypotonic environment Prevents shrinking in hypertonic environment |
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If the Prokaryote loses water, what will happen internally?
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Severe water loss inhibits cell reproduction
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Eukaryotic cell walls are made of cellulose or chitin, while Prokaryotic cell walls are made from...(name and define)
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Peptidoglycan - a network of modified-sugar polymers cross-linked by short polypeptides
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Does the Prokaryote have any of these: nuclear envelope, memebrane-bound organelles, introns, circular chromosomes?
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No to all except circular chromosomes
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Do Archaea have peptidoglycan?
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No, but they have a lot of other polysaccharides and proteins, NO PEPTIDOGLYCAN
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How do we distinguish between different types of (Eu)bacteria? (just the name)
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We use the Gram Stain method, divides bacteria into two groups based on cell-wall composition
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What is Gram-Positive and Gram-Negative Bacteria?
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G-P: simpler walls, large amounts of peptidoglycan on top with cell membrane on bottom and proteins mixed in
G-N: more complex, less peptido-glycan, but they have not only a plasma membrane on bottom but a new outer membrane on top that is technically considered part of the cell wall with the peptidoglycan that's in the middle. Their outermembrane contains a lot of lipopolysaccharides (carbs bonded to lipids) |
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How does the Gram-Stain Method Work?
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Samples are stained with a crystal violet dye, iodine, alcohol, and then another red dye. GP bacteria will trap the crystal violet which will mask the red dye. The GN bacteria will not capture crystal violet dye easily, and will absorb the red dye.
GP purple GN red |
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How is Gram-Staining important (like in medicine)
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The lipid portions of the lipopolysaccharides of GN bacteria are really toxic, causes fever or shock, and the GN outer membrane will protect from body defenses, its more resistant. When you detect it, you will know how to treat it better.
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What is the outer most layer of a prokaryote? Cell Wall? (name and define)
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The capsule - a sticky later of polysaccharide or protein, enables prokaryote to adhere to their substrate or other individuals or colony, protect against dehydration, protect prok from attacks
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How exactly do Prokaryotes stick to their substrate or to whatever? (name and define)
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Fimbriae - hair-like protein appendages
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What are sex pili?
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Appendages that pull two cells together priod to DNA transfer from one cell to another
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How fast can prokaryotes move?
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50 um/sec, 50 times their body length
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