MIP: Intro to Bacteriology

Question 1

Why doesn’t prokaryotic mRNA need processing?

Answer 1

It doesn’t contain introns and can be translated immediately as it is synthesized

Question 2

Where do many eukaryotic organelle functions take place in prokaryotic cells?

Answer 2

Within the cell membrane

Question 3

What allows antibiotics to target bacterial protein synthesis without affect human protein synthesis?

Answer 3

Prokaryotes have 70S ribosomes, and eukaryotes have 80S ribosomes

Question 4

What is the general process of performing a Gram Stain?

Answer 4

1) Smear on Glass Slide
2) Heat fixing
3) Crystal Violet stain
4) Gram’s iodine
5) Decolorizer
6) Safranin red

Question 5

Following the process of Gram staining, how will a Gram + bacteria appear compared to a Gram - bacteria?

Answer 5

Gram + bacteria will be purple and Gram - will be red

Question 6

What does an acid fast positive stain look like? An acid- fast negative?

Answer 6

Acid fast positive will stain cytoplasm red, negative will stain cytoplasm blue

Question 7

What are some factors that could complicate a Gram stain?

Answer 7

Prior antibiotic exposure, age of bacterial cells, starvation of bacterial cells, ineptness at staining

Question 8

What is a bacterial capsule?

Answer 8

A high molecular weight polysaccharide or peptide that surrounds the bacterial cell wall

Question 9

Which branch(es) of the immune system is/are important to defeating encapsulated bacteria and how?

Answer 9

Both innate (complement opsonization) and acquired (antibody opsonization)

Question 10

A deficiency in what part of the immune system will make a patient more susceptible to encapsulated bacteria?

Answer 10

Complement deficiency

Question 11

What are the structural components of Gram + and - bacterial cell walls?

Answer 11

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

Question 12

What is peptidoglycan?

Answer 12

N-acetylmuramic acid and N-acetylglucosamine crosslinked with peptide chains and pentaglycine interbridges

Question 13

What bacteria have a periplasmic space? What is it? What’s in it?

Answer 13

Gram negative between the outer and inner cell walls- contains a thin layer of peptidoglycan and multiple enzymes like beta-lactamases

Question 14

What are the two cellular appendages that extend off of bacteria?

Answer 14

Pili and Flagella

Question 15

What are the two types of pili and what are they used for?

Answer 15

Common (type Iv) pili that extend, grab onto something, and retract, moving the cell; Sex pili- for sexual reproduction

Question 16

What are flagella?

Answer 16

Long helical filaments extending from cell membrane to exterior of the cell

Question 17

What are bacterial inclusion bodies?

Answer 17

Storage Reserve granules

Question 18

What are spores?

Answer 18

A survival structure- nucleic acid, encapsulated in endospores

Question 19

What are the three major pathways nutrients are fed into?

Answer 19

Glycolytic or anaerobic pathways, TCA cycle, Pentose phosphate pathway

Question 20

True or False: Bacteria do not use oxidative phosphorylation.

Answer 20

False- some anaerobes may

Question 21

What aerobic bacterial enzymes are esp. useful in detoxifying molecular oxygen?

Answer 21

Catalase and superoxide dismutase

Question 22

What is a facultative aerobe?

Answer 22

They can use O2 if present, but can survive on aerobic metabolism.

Question 23

Which antibiotics are only useful for treating infections caused by aerobic bacteria?

Answer 23

Aminoglycosides

Question 24

Which antibiotic is widely used for treating infections caused by strict anaerobes?

Answer 24

Metronidazole

Question 25

What was the first antibiotic? To what category of antibiotics does it belong?

Answer 25

Prontosil; Sulfonamides

Question 26

How do sulfonamides work?

Answer 26

Sulfa drugs block the synthesis of folic acid

Question 27

What is the mechanism of trimethoprim’s action?

Answer 27

Inhibition of bacterial dihydrofolate reductase

Question 28

How does rifampicin work as an antibiotic?

Answer 28

Inhibiting RNA polymerase

Question 29

What is the structure of bacterial chromosomes?

Answer 29

Circular and supercoiled

Question 30

What enzymes involved in unwinding unwind the bacterial chromosome and allow replication of the chromosome? What antibiotic interferes with this process?

Answer 30

Topoisomerase and DNA gyrase; Fluoroquinolones

Question 31

How are bacterial chromosomes contained within the cell?

Answer 31

Packaged with polyamines into structure called the nucleoid

Question 32

What are plasmids? What are the three major types?

Answer 32

Genetic elements that replicate independently from chromosomes; F (fertility) plasmids, R (resistance) plasmids, and Virulence plasmids

Question 33

What is a bacteriophage?

Answer 33

A virus that infects bacteria

Question 34

True or False: Some pathogenic bacteria actually need to be infected with a phage in order to be virulent.

Answer 34

True

Question 35

What is transduction?

Answer 35

The use of phage to transfer bacterial DNA from one organism to another

Question 36

What is transformation?

Answer 36

When bacteria die, their DNA is released into the environment and can be taken up by other bacteria

Question 37

What are the phases of the bacterial growth cycle? In which phase are many antibiotics most effective?

Answer 37

Lag phase, log phase, stationary phase, and death phase; Log phase

Question 38

What are the factors that keep bacterial growth in check in reality?

Answer 38

Limitation of nutrients; competition for food and space, immune systems

Question 39

What is metabolic parsimony?

Answer 39

Organisms expend energy only if they have to

Question 40

What is sterilization and what are the methods to achieve it?

Answer 40

Sterilization is the killing of all microbial forms, including spores- can be done by autoclaving, dry heat, irradiation, or gas vapors.

Question 41

What is disinfection? What agents are commonly used for this?

Answer 41

Most microbial forms are destroyed, but spores and other resistant forms endure; Chloride (bleach) and phenolic (lysol) compounds are commonly used.

Question 42

What is antisepsis? What are commonly used agents to achieve this?

Answer 42

Microbes are inhibited or eliminated in or on living tissue. Ethyl or isoproyl alcohol, betadine, etc.