Microbiology Review Flashcards
What makes something Gram+ or Gram-
Gram positive indicates a thick cell wall, the crystal violet and iodine mixture is not able to escape from the thick peptidoglycan layer. The opposite is true for Gram-
What is the composition of the cytoplasmic membrane?
It is made up of a bilayer of phospholipids. It is amphipathic- there is a different chemical feature on both sides. There is also a lipid bilayer with hydrophilic heads and hydrophobic tails
What is true about both a peripheral protein and a integral protein?
The both function as receptors for cell signaling. Both may interact with cell wall. Both are transporters of nutrients
Functions of the cytoplasmic membrane
Selective BarrierSite of Transport SystemsSite of Crucial metabolic processes Site for special receptors to decent environmental conditions
What compounds are passive transport limited to?
H2O, O2, CO2, and small nonpolar molecules
Describe Facilitated Diffusion
Controlled by shape, depends on a concentration gradient, less important in prokaryotes
Describe the two types of active transport
Primary- utilizes ATP and are uniporters
Secondary- utilized gradients and are symporters and antiporters
What are the 3 types of electrochemical gradients?
Uniport- 1 thing, 1 direction
Symport- 2 things 1 direction
Antiport- 2 things, opposite directions
Describe Gram - cell wall
Has DAPHas direct D-ala binds to Dap Starts link with D-alaVery thin cell wall, about 2-3 layersPeriplasm is more definedHas 2 periplasms
Describe Gram + cell wall
Has L-lysineDoes not have a direct link. 5 glycine residues in a row connect D-ala to L-lysine. This is the peptide interbridge called penta glycine Starts link with D-ala Thick cell wall, 30 or more layersPeriplasm is harder to seeDoes not have an outer membraneOnly 1 periplasm More resistant to osmotic pressuresHas teichoic and lipteichoic acids
What is an endotoxin?
When the macrophages in the bodies immune system target the LPS, it can tear apart the lipid A from the sugar tail, and if the body doesn’t handle it it is very toxic, like anaphylactic shock
What is endotoxin’s benefit to bacteria?
It works as a protective layerIt functions as virulence (survival in humans)- rise in temperature can be a better environment, breakdown of cells is food. It confers negative charge in the bacteria
What is a channel protein?
diffusion of small hydrophilic molecule, can be different sizes based on selective entry of differently sized molecules
What are beta-lactam antibiotics?
An example of these antibiotics is penicillin. These type of antibiotics do NOT break down the cell wall, but they prevent the cell wall from growing. This antibiotic prevents cross linking. The weakened cell wall then ruptures and falls apart.