Lecture 3: Cell Structures Flashcards
(31 cards)
Atomic Force Microscopy
Enables visualization of untreated cells by detection of Van der Waals forces
Inclusion in bacterial cell structures
Large deposits of foreign, aggregated proteins
Periplasmic space
Space found only in gram-negative bacteria between inner and outer membranes
Phospholipid Bilayer
Hydrophilic phosphate outward, hydrophobic lipid inward
Hopanoid
Class of lipid acting as a stiffening agent of cell to improve membrane integrity
Role of membrane proteins
-Structural support
-Detection of environmental signals
-Secretion
-Transport
-Respiration
Passive diffusion
-Small uncharged molecules
-No Transporters needed
-Down gradient
Passive transport
-Charged, hydrophilic, large molecules
-No transporter needed
-Down gradient
Active transport
-Charged hydrophilic, or large molecules
-Need transporter proteins
-Against gradient
-Often accompanied with ATP hydrolysis to use energy from the reaction to move things up a gradient (Unfavorable)
Cardiolipin
Double phospholipid joined by a third glycerol to allow for curvature in cells
Movement of acids & bases across membrane
Equilibrium with weak acids and bases is always possible and allows neutral charged to cross the membrane
Effect of cyclization of membrane lipids
Reduces fluidity to allow stiffness in the membrane for cell integrity
Effect of penicillin on peptidoglycan
Blocks the cross-bridge formation with D-Alanine
Effect of vancomycin on peptidoglycan
Binds D-Ala to D-Ala to block cross-bridge formation
Teichoic Acid
Regulates enzymes that kill peptidoglycan & promotes cell integrity by threading through multiple layers (GRAM POSITIVE ONLY)
Amino acids linkages in peptidoglycan (Stereochem)
Ribosome protein synthesis always makes L-amino acids, therefore, the D-amino acids must be added separately
GT Glycosyltransferase subunit
Catalyzes polymerization of lipid to form glycan chain of NAG & NAM via lipid polymerization to form a glycosidic bond.
PBP Transpeptidase subunit
Catalyzes the cross-linkages of peptidoglycan layers using pentaglycine
Affect of Beta-Lactam antibiotics
Blocks cross-linking of peptidoglycan layers by blocking transpeptidase active site to prevent pentaglycine formation
Slime Layer
-Found in both gram-positive & negative bacteria
-Crystalline sheet made of protein or peptidoglycan
-May help bacteria interact with the host, form biofilm, or swim
Lipopolysaccharide
-Found in many Gram-negative bacteria
-Stimulates host responses
-Endotoxin causing immune system to activate when bacterial cell is lysed
-Provides protection to cell from antibodies
Pili
-Smaller structures more abundant than flagella
-Aid in cell secretion
-Aid in adhesion via biofilm
-Allow twitching motility
-Conjugation
Nucleoid
Region where DNA is condensed and packed since bacteria lack nuclei
ParB
-Protein that forms dimers that recognizes and binds to centromere-like sites on DNA known as parS sites
-ParB clusters will form a cage
