1-4 Bacterial Function and Growth

Question 1

What are some bacterial structures that are important to pathogenesis?’

Answer 1

1. flagella - long polymers of flagellin. corkscrew propulsion. rotate. powered by transmem e- gradients
2. Ribosomes (70s not 80s) - chemical differences between eu and pro ribosomes make them great drug target.
3. Spores(endospores) allow survival in extreme conditions. Triggered by nutrient depletion. Standard for autoclaving.
4. spores

Question 2

How does the whip-like motion of flagella differ from the movement of eukaryotic cilia?

Answer 2

bacteria flagella do not whip.

Question 3

Describe the signficance of exponential growth to pathogenesis and lab diagnosis

Answer 3

Pathogenesis - immune system has small window to fight before infection gets out of control

Lab diagnosis - able to quickly culture large amounts of bacteria for identification

Question 4

Bacterial generation time is limited primarily by

Answer 4

availability of nutrients

Question 5

Predictable pattern of bacteria in culture

Answer 5

1. lag - sense new environment, up-regulate metabolism and growth
2. log - rapid cell division, exponential growth curve
3. stationary - nutrient depletion/waste accumulation slows growth rate to death rate
4. death - waste accumulation/nutrient depletion kills remaining bacteria

Question 6

Describe fermentation and its significance in vitro culture

Answer 6

fermentation - bacteria lacking enzymes to detoxify oxygen radicals and regerate oxidized coenzymes will metabolism sugar into organic acid (inefficient), only 2 ATP.

Lab significance - acids can be detected by pH indicators in media, revealing ability of bacteria to ferment the sugar and narrowing the differential.

Question 7

Describe oxygen based ATP generation and describe its significance in vitro culture

Answer 7

Rely on oxygen as the final electron acceptor in the efficient electron transport chain

lab significance - able to grow in wide variety of settings. Able to easily reveal if bacteria require oxygen, narrowing differential.

Question 8

What is “quorum sensing”?

Answer 8

the ability of some bacteria to sense population density and alter genetic expression accordingly. conserve energy, and coordinate attack

Question 9

What are some molecule types that are common to many quorum sensing systems?

Answer 9

Inducers, Receptors, transcription activators, density dependent gene products.

at low pop density - inducers are produced, and either floats off or is eventually accepted by receptor but there is not enough to trigger the transcription activator

at high enough density, high levels of inducer bind to receptor and trigger the transcription activator. A “density dependent gene product” is produced.

Question 10

____ mediate the interaction of bacteria with mucosal epithelium

Answer 10

pili

Question 11

______ retard phagocytosis

Answer 11

polysaccharide capsules

Question 12

both gram (-) have ______ in their cell wall

Answer 12

LPS endotoxin

Question 13

the survival ability of spores is based on their enhanced metabolism (t/f)

Answer 13

false

Question 14

spores are formed under_____

Answer 14

adverse environmental conditions

Question 15

spores are are metabolically _____ and contain dipicolinic acid which is a/an ____

Answer 15

inactive, calcium chelator

Question 16

spores are formed primarily by organisms of the genus neisseria (t/f)

Answer 16

false