Section 7 Flashcards
What is an antiseptic?
used to treat severe infections in the 1800s
damaging to human tissue
What did Alexander Fleming do?
discovered penicillin
What was the antiseptic dilemma?
most casualties of war resulted from infections and treatments given after the battles
What is Paul Ehrlich’s magic bullet hypothesis?
certain chemicals could selectively bind to specific bacteria
What is the zone of inhibition?
circular area around spot of antibiotic where bacteria colonies don’t grow
What can penicillin inhibit and leave unharmed?
inhibits growth of gram-positive bacteria
leaves eukaryotic cells unharmed
What are characteristics of antibiotics?
1) therapeutic agents
2) selectively toxic towards microbes
3) generally antibacterial
4) small molecules (secondary metabolites)
5) originally referred to compounds produced by microorganisms, but today term is used for synthetic antimicrobials
What are β-lactams?
class of antibiotics
What kind of ring structure do β-lactams have?
4-member ring structure
What do 4-member ring structures do?
enables β-lactams to inhibit bacterial cell wall synthesis
What is an antibiotic?
any small molecule produced by a microbe that kills or inhibits growth of other microbes
What are streptomyces?
most prolific antibiotic producer that contains “silent” pathways
What are “silent” pathways?
genes that aren’t expressed under lab conditions
What are biosynthesis pathways?
chemical reactions catalyzed by enzymes within a cell
What 3 amino acids is penicillin a product of?
cysteine
valine
α-aminoadipate
What is the mode of action?
biochemical interaction that allows antibiotic to have inhibitory effect
What is the cell wall composed of?
polysaccharides peptide-peptidoglycan
What does peptidoglycan do?
protects bacteria from forces in the environment
What is gram-positive?
bacteria have thick peptidoglycan layer exposed to environment
What is gram-negative?
bacteria have thin peptidoglycan layer in between cytoplasmic membrane and other membrane
What are the 3 main ribosomal sites?
1) macrolides (E site)
2) aminoglycosides (A site)
3) P site
What are the 2 mechanisms bacteria do to resist an antibiotic?
1) random mutation in normal gene
2) may acquire preexisting resistance gene from another bacterium
