Flashcards in MIP: Intro to Bacteriology Deck (42):
Why doesn't prokaryotic mRNA need processing?
It doesn't contain introns and can be translated immediately as it is synthesized
Where do many eukaryotic organelle functions take place in prokaryotic cells?
Within the cell membrane
What allows antibiotics to target bacterial protein synthesis without affect human protein synthesis?
Prokaryotes have 70S ribosomes, and eukaryotes have 80S ribosomes
What is the general process of performing a Gram Stain?
1) Smear on Glass Slide
3)Crystal Violet stain
4) Gram's iodine
6) Safranin red
Following the process of Gram staining, how will a Gram + bacteria appear compared to a Gram - bacteria?
Gram + bacteria will be purple and Gram - will be red
What does an acid fast positive stain look like? An acid- fast negative?
Acid fast positive will stain cytoplasm red, negative will stain cytoplasm blue
What are some factors that could complicate a Gram stain?
Prior antibiotic exposure, age of bacterial cells, starvation of bacterial cells, ineptness at staining
What is a bacterial capsule?
A high molecular weight polysaccharide or peptide that surrounds the bacterial cell wall
Which branch(es) of the immune system is/are important to defeating encapsulated bacteria and how?
Both innate (complement opsonization) and acquired (antibody opsonization)
A deficiency in what part of the immune system will make a patient more susceptible to encapsulated bacteria?
What are the structural components of Gram + and - bacterial cell walls?
Gram + cell walls contain a thick layer of peptidoglycan, with teichoic and lipoteichoic acids intertwined within the cell wall. Gram - have an outer membrane comprised of lipopolysaccharide
What is peptidoglycan?
N-acetylmuramic acid and N-acetylglucosamine crosslinked with peptide chains and pentaglycine interbridges
What bacteria have a periplasmic space? What is it? What's in it?
Gram negative between the outer and inner cell walls- contains a thin layer of peptidoglycan and multiple enzymes like beta-lactamases
What are the two cellular appendages that extend off of bacteria?
Pili and Flagella
What are the two types of pili and what are they used for?
Common (type Iv) pili that extend, grab onto something, and retract, moving the cell; Sex pili- for sexual reproduction
What are flagella?
Long helical filaments extending from cell membrane to exterior of the cell
What are bacterial inclusion bodies?
Storage Reserve granules
What are spores?
A survival structure- nucleic acid, encapsulated in endospores
What are the three major pathways nutrients are fed into?
Glycolytic or anaerobic pathways, TCA cycle, Pentose phosphate pathway
True or False: Bacteria do not use oxidative phosphorylation.
False- some anaerobes may
What aerobic bacterial enzymes are esp. useful in detoxifying molecular oxygen?
Catalase and superoxide dismutase
What is a facultative aerobe?
They can use O2 if present, but can survive on aerobic metabolism.
Which antibiotics are only useful for treating infections caused by aerobic bacteria?
Which antibiotic is widely used for treating infections caused by strict anaerobes?
What was the first antibiotic? To what category of antibiotics does it belong?
How do sulfonamides work?
Sulfa drugs block the synthesis of folic acid
What is the mechanism of trimethoprim's action?
Inhibition of bacterial dihydrofolate reductase
How does rifampicin work as an antibiotic?
Inhibiting RNA polymerase
What is the structure of bacterial chromosomes?
Circular and supercoiled
What enzymes involved in unwinding unwind the bacterial chromosome and allow replication of the chromosome? What antibiotic interferes with this process?
Topoisomerase and DNA gyrase; Fluoroquinolones
How are bacterial chromosomes contained within the cell?
Packaged with polyamines into structure called the nucleoid
What are plasmids? What are the three major types?
Genetic elements that replicate independently from chromosomes; F (fertility) plasmids, R (resistance) plasmids, and Virulence plasmids
What is a bacteriophage?
A virus that infects bacteria
True or False: Some pathogenic bacteria actually need to be infected with a phage in order to be virulent.
What is transduction?
The use of phage to transfer bacterial DNA from one organism to another
What is transformation?
When bacteria die, their DNA is released into the environment and can be taken up by other bacteria
What are the phases of the bacterial growth cycle? In which phase are many antibiotics most effective?
Lag phase, log phase, stationary phase, and death phase; Log phase
What are the factors that keep bacterial growth in check in reality?
Limitation of nutrients; competition for food and space, immune systems
What is metabolic parsimony?
Organisms expend energy only if they have to
What is sterilization and what are the methods to achieve it?
Sterilization is the killing of all microbial forms, including spores- can be done by autoclaving, dry heat, irradiation, or gas vapors.
What is disinfection? What agents are commonly used for this?
Most microbial forms are destroyed, but spores and other resistant forms endure; Chloride (bleach) and phenolic (lysol) compounds are commonly used.