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Bellas Microbiology Exam II With 100% Verified Solutions | Updated & Verified | 2024
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Bellas Microbiology Exam II With 100% Verified Solutions | Updated & Verified | 2024
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Bellas Microbiology Exam II With 100% VerifiedSolutions | Updated & Verified | 2024
Prokaryote Cell Walls - ✔✔- Provides structure and shape and protects cell from osmotic forces -->
most bacteria live in hypotonic (low salt) solutions; keep H20 fr moving into bacteria & burst it
- not in animals; can target cell wall of bacteria with antibiotics
Bacteria Cell Walls - ✔✔- Most have cell wall composed of peptidoglycan; a few lack a cell wall entirely
- Peptidoglycan composed of sugars, NAG and NAM (mostly sugar w/ peptide change)
- Chains of NAG and NAM attached to other chains by tetrapeptide crossbridges (scaffolding type
structure) -Amino acids tie bridges together
- Two basic types of bacterial cell walls - Gram-Positive & Gram-Negative
Gram-Positive - ✔✔- Relatively thick layer of peptidoglycan
- Contains unique polysaccharides called teichoic acids
- Some covalently linked to lipids, forming lipoteichoic acids that anchor peptidoglycan to cell membrane
(phospholipid bilayer)
- Retains crystal violet dye in Gram staining procedure; appear purple
- Acid-fast bacteria contain up to 60% mycolic acid; helps cells survive desiccation
Gram-Negative - ✔✔- Have only a thin layer of peptidoglycan (can't adhere to crystal violet
therefore appears pink following Gram stain)
,- Have a outer membrane composed of phospholipids, channel proteins (porins), and lipopolysaccharide
(LPS) --> this part is extremely toxic
Lipopolysaccharide (LPS) - ✔✔- Union of lipid with sugar
- Also known as endotoxin (lipopolysaccharide)
- Lipid portion known as lipid A (extremely poisonous)
- Released from dead cells when cell wall disintegrates
- May trigger fever, vasodilation, inflammation, shock, and blood clotting
- Can be released when antimicrobial drugs kill bacteria
Archael Cell Walls - ✔✔- Do not have peptidoglycan
- Cell walls contain variety of specialized polysaccharides and proteins
Prokaryotic Cytoplasmic Membrane - ✔✔Phospholipid Bilayer --> lipids and associated proteins
Prokaryotic Membrane Function - ✔✔- Controls passage of substances into and out of the
cell; selectively permeable
- Functions in energy production - bacteria need ATP, but bacteria has no mitochondria, therefore,
ATP produced by cytoplasmic membrane
- Harvests light energy in photosynthetic prokaryotes --> no chloroplasts, therefore occurs w/in plasma
membrane
Control across membrane - ✔✔- Naturally impermeable to most substances - middle is pure lipid, so
no polar materials can pass thru
, - Proteins allow substances to cross membrane
- Occurs by passive or active processes
Passive Processes - ✔✔- Diffusion - nonpolar molecules
- Facilitated Diffusion- proteins assist as nonspecific channel protein for polar molecules (shielded from
lipid environment)
- Osmosis (water movement)
-->Isotonic (same salt) Solution - no change
-->Hypertonic (high salt) Solution - shrivels as water moves out of
cell -->Hypotonic Solution - swell and burs as water moves in.
Active Processes - ✔✔- Active Transport - utilizes carrier proteins and expends
ATP -->Uniport - one substance moves one way (one in) -->Antiport - one moves
in while another moves out
--> Symporti - two move the same way (often coupled; both in)
- Group Translocation - substance chemically modified during transport; doesn't utilize ATP
-->Maintains a concentration gradient and electrical gradient; collectively known as electrochemical
gradient - Chemicals concentrated on one side of the membrane or the other; Voltage exists across
the membrane
Prokaryotic Cytoplasm - ✔✔- Cytosol - liquid portion of cytoplasm
- Inclusions - may include reserve deposits of chemicals
- Ribosomes - sites of protein synthesis
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