Introduction to MID (1/3)

Question 1

What is a gram stain?

Answer 1

Visualize differences in petidoglycan of gram + (purple, thick peptidoglycan layer) and gram - (red/white, thin layer) bacteria

Question 2

What are the different shapes of bacteria?

Answer 2

Question 3

What can you use to stain mycobacteria?

Answer 3

Not gram + or - because they have a waxy coat. Use acid fast stain instead. Note that TB is a mycobacteria

Question 4

Define facultatively anaerobic, aerobic, anaerobic, microaerphilic

Answer 4

facultatively anaerobic: can go both ways

aerobic: needs O2
anaerobic: doesn’t need O2, can possibly die if exposed
microaerphilic: needs a little bit of O2

Question 5

Tree of Gram positive bacteria

Answer 5

Note that it has one membrane but a thick layer of peptidoglycan

Question 6

Tree of Gram Negative Bacteria

Answer 6

Note that it has 2 membranes, but less peptidoglycan. Also has an envelope that contains lipopolysaccharides (LPS), which hold structure and are an endotoxin- binds CD14 on macrophage & TLR & causes inflammatory response.

Question 7

Tree of misc/poorly staining bacteria

Answer 7

Question 8

What is the difference btw endogenous and exogenous bacteria?

Answer 8

Endogenous comes from normal flora i.e. skin, colon, oropharynx. When it penetrates an area that’s normally sterile i.e. blood, bladder, CNS, lower resp tract, sinuses

Exogenous comes from water, air, food, ticks

Question 9

What is 16s rRNA used for?

Answer 9

DNA classification technique. use PCR+ this to characterize noncultivatable pathogens.

It’s a piece of rRNA that’s highly conserved among species

Question 10

What is molecular subtyping and what is it used for?

Answer 10

An enzyme digests DNA, then visualized on a gel

It’s used to designate strains i.e. during an outbreak to show that the source is the same

Question 11

What are typic components of a bacterium?

Answer 11

Capsule, cell membrane, common pili, ribosomes, plasmid, nucleoid, cytoplasm, mesosome, sex pilus

No nuclei!! If nucleus, think yeast

Biofilm = goop that protects it from immune system & antibiotics

Peptidoglycan makes up the cell wall & consists of chains of alternating groups that are cross linked (site of penicillin action)

Cytoplasmic membrane fulfills many functions of eukaryotic organelles i.e. ATP production, protein transport, etc.