Lecture 45 Flashcards
Bacteria typically contain _____ along with their double stranded circular DNA (chromosomes are condensed into ______). These ______ are autonomously replicating circular DNA molecules that confer antibiotic resistance and are the source of toxin production.
Plasmids
Supercoils
Plasmids
Many antibiotics target the peptidoglycan cross-linkage. While Gram ____ bacteria are not very diverse in this linkage, Gram ____ are. This will affect the sensitivity of the bacteria to certain antibiotics. Both _____ and _____ are antibiotics that block the transpeptidation reaction required for cross-linking.
Gram -
Gram +
Penicillin
Vancomycin
Some bacteria can grow in the presence of antibiotics that inhibit cell wall synthesis; they grow without a cell wall. These are called __-forms (“Protoplasts” for Gram ___/”Spheroplasts” for Gram ___), and can be seen sometimes in chronic infections. What would happen to these cells in low vs high osmotic pressure environments?
L-forms
Gram +
Gram -
In low osmotic pressure –> they swell and lyse. In high –> they can survive.
Some species of bacteria, including Clostridium and Bacillus, can alter their life cycles in times of low resources. They form ____, from which almost all the water has been removed, leaving behind some DNA, ribosomes, and heat-resistant Ca-_______ acid.
Spores
Ca-dipicolinic acid
Most bacteria are Heterotrophic, meaning they require a reduced ____ source for energy, sulfate, phosphate, and reduced _____ (a source of NH3 for amino acid synth).
Carbon
Ammonia
Bacteria can be cultured on different media. If the exact contents and their amounts used in the medium are known, it is considered ______. If the contents are not measured, and something like yeast extract is used, this medium is considered _________. Some bacteria MUST be cultured with with cells (i.e. ______ found in armadillos or T. pallidum - causes syphilis - grown in rabbit testicles.)
Defined
Undefined
M. leprae
Bacterial metabolism is diverse, and this can be used diagnostically. For example, N. meningitidis can grow in the presence of ______ alone, while N. gonorrhea requires _____. _____ strips are used to identify differences in bacterial metabolism.
Maltose
Glucose
API strips
The growth cycle of bacteria occurs in four stages: Lag, Log, Stationary, and Death. During which of these stages are bacteria LEAST susceptible to some cell wall antibiotics, and why might that be?
During the Lag and Stationary phase, and probably during the Death phase, because these types of antibiotics require the bacteria to be in a growth phase in order to work.