Notes from Lecture 9

Notes from Lecture in class today 9/2

b. Archaea
i. Root work archae – meaning really old – thought to have not changed much for a very long period of time
ii. No nucleus, like bacteria, but otherwise more similar to eukaryotic cells than bacteria cells
1. An enzyme they make, RNA polymerase (transcription of RNA), is virtually identical to the ones that eukaryotes make.
2. Archeal cell membrane chemistry is like eukaryotes – Phospholipid bilayer
iii. Live in extreme environments:
1. Geysers
2. Ocean vents
3. Other water with very high temperatures (>100 degrees C)
4. Dead Sea, etc.
iv. PROBABLY, archaea cannot make us sick
c. Bacteria
i. Prokaryotes
ii. Distinct cell walls and cell membrane structures not found in Archaea or Eukaryotes
iii. Distinct RNA polymerase
iv. Gram-positive
1. Minority of bacteria on earth, but important clinically
2. Plasma membrane – innermost border of gram-positive bacteria, hydrophilic parts on the outside and hydrophobic on the inside.
3. Peptidoglycan cell wall cross-linked with lipoteichoic acid (LTA) - ~30+ layers –
a. Peptidoglycan – carbohydrate/sugar component & protein component
b. Lipoteichoic Acid (LTA) – fatty acid
v. Gram-negative
1. Plasma membrane
2. Cell wall, NO LTA – peptidoglycan is not as cross-linked and is not quite as tough
3. Cell wall is MUCH thinner than gram-positive only having 4-5 layers
a. Treat with crystal violet and then iodine… those two form together and clump inside the cell staining it purple
b. Drip ethanol to decolorize the bacteria which starts to remove the clumps
i. Gram-negative – all clumps are dissolved making the bacteria bleached
c. Pink safranin dies it all pink

Hope these are useful for someone :)
Wendy

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