Lecture 44

Question 1

Gram + bacteria stain _____ (color) while Gram - stain ____. Mycobacteria require ____-____ stain, Mycoplasma lack a cell wall, so they do not stain. Treponema and spirochetes are Gram ___, but stain very poorly.

Answer 1

Blue

Pink

Acid-Fast

Gram -

Question 2

Gram + and Gram - bacterial cell structure differs in that Gram ____ have a thick cross-linked Peptidoglycan cell wall, while Gram ____ have a thin cell wall with an outer membrane comprised of ______ (LPS). Keep in mind the difference in the Cell wall thickness is responsible for the difference in Gram staining.

Answer 2

Gram +

Gram -

Lipopolysaccharide

Question 3

With the exception of mycoplasma, bacterial cell membranes do not contain _____. Remember this is a key component of mammalian cell membranes that increases rigidity. This means bacterial cell membranes are more _____-sensitive. This is why they require a Cell Wall.

Answer 3

Sterols

Osmo-sensitive

Question 4

Gram + bactial have ______ and _________ acid on their cell walls that function as virulence factors. They can release inflammatory cytokines, but they are about 20X less potent than _____. With that in mind, which would be more likely to cause sepsis, Gram + or Gram -?

Answer 4

Techoic acid

Lipotechoic acid

LPS

Gram - more likely to cause sepsis.

Question 5

Gram - bacteria outer membranes (encompassing the cell wall) is composed of LPS with the following component structures: \_\_\_\_ antigens (antigenic)
Core polysaccharide
Lipid \_\_ (not antigenic, but acts as an ENDOTOXIN.)

Answer 5

O antigens

Lipid A

Question 6

During normal growth, Gram - bacteria shed their LPS, which binds to an LPS Binding Protein in the blood, and then binds CD14/TLR4 on ______ (which cell type?) –> this induces a cascade of cytokines that causes a systemic inflammatory response (aka Sepsis).

Answer 6

Macrophages

Question 7

Some bacteria produce an LPS-rich ____, which helps them escape phagocytosis. They are can be opsonized, but phagocytes can not bind the opsonizing proteins bc the _____ acts as a buffer. The same is true of biofilm.

Answer 7

Capsule

Capsule

Question 8

Some bacteria produce _____, which allows them to be motile. It is antigenic and known as “H” antigen.

Answer 8

Flagella

Question 9

Bacteria also contain ____. The “Common” one facilitates bacteria-human cell _____, while the “Sex” one facilitates bacteria-bacteria cell _____ for genetic transfer via ______ (term for this type of genetic transfer).

Answer 9

Pili

Adhesion

Adhesion

Conjugation