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Flashcards in Bacterial Growth and Metabolism Deck (38)
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1

bacteria replicate by ___

binary fission

2

what is binary fission?

one cell divides to yield 2 daughter cells

3

the growth rate of a particular organism depends on:

availability of nutrients, environmental pH, salinity, and temperature

4

what are prototrophs?

bacteria that can synthesize all essential metabolites

5

what are autotrophs?

bacteria with acquired mutations that require them to obtain certain essential metabolites from the environment

6

most bacteria are inhibited by ___ pH and ___ salt

low (acid); high

7

why are human pathogens classified as mesophiles?

grow optimally bw 30-37C

8

other bacteria can grow in extreme cold of heat. what are these called?

psychrophiles and thermophiles

9

what nutrient stands out as one that greatly impacts the rate of cell division?

iron, important to growth and virulence

10

why is sequestration of free iron in blood and other body fluids by transferrin and lactoferrin (iron-binding proteins) significant?

defense against infection

11

Bacterial growth in a liquid (“broth”) culture can be measured by ___

growing aliquots of the culture on agar medium as the aliquots are taken at various times after broth inoculation

12

bacterial growth can also be followed by measuring the ___ of a liquid culture over time

turbidity; as the bacteria multiply, they cloud the broth which can be visibly seen and measured using a spectrophotometer

13

the bacterial growth curve includes what phases?

lag, exponential, stationary, decline/death phase

14

what is happening in the lag phase?

essentially no growth occurs; bacteria are adapting to new nutrient environment, reprogramming gene expression to meet new needs

15

what is happening in the exponential phase?

establish constant, optimal doubling times; bacteria experience maximal DNA and protein synthesis and are most acutely sensitive to antibiotic therapy; also best time to Gram stain organisms
- exponential growth leads to depletion of nutrients and accumulation of wastes. Metabolism is therefore greatly reduced and rate of cell division becomes equal to rate of cell death

16

what is happening in the stationary phase?

no net increase in number of viable cells (bacteria become somewhat refractive to antibiotic therapy and Gram positive spore
formers initiate sporulation)

17

what is happening in the decline phase?

nutrients deplete and waste increases, the rate of cell death exceeds the rate of cell division

18

what is a biofilm?

bacteria in a biofilm are encased in a protective carbohydrate matrix that is adhesive and only formed after a series of events requiring motility and adhesion of planktonic bacteria

19

why are biofilms significant?

bc of their prevalence, but also bc they are a source of recurrent infections and treatment failures; impairs antibiotic access to the residing bacteria, is anti-phagocytic, and bc of its adherent nature, often requires the removal of an infected implanted valve

20

what is the purpose of metabolism?

provide the energy and building blocks a cell needs to survive and replicate

21

describe oxidative respiration of aerobes and facultative anaerobes?

In the presence of oxygen, aerobes and facultative anaerobes funnel pyruvate through the citric acid cycle and oxygen serves as the final electron acceptor; produces 34 ATP

22

oxid. respiration occurs where?

internal face of cytoplasmic membrane

23

describe anaerobic respiration

In the absence of oxygen, an organic or inorganic compound other than oxygen serves as the final electron acceptor

24

is fermentation an efficient way of generating energy?

no

25

what is the major drawback of oxidative respiration?

produces hydrogen peroxide and superoxide anions (toxic to cell)

26

what enzymes do strict aerobes produce to diffuse the damage caused by production of ROS?

superoxide dismutase, catalase, and peroxidase

27

what enzymes do facultative anaerobes produce to diffuse the damage caused by production of ROS?

superoxide dismutase and peroxidase; will not always have catalase

28

what enzymes do strict anaerobes produce to diffuse the damage caused by production of ROS?

catalase and peroxidase, lack superoxide dismutase so die in presence of O2 due to accumulation of superoxide anions

29

why must bacteria synthesize folic acid?

source of nucleotides and methionine

30

obligate intracellular pathogens are dependent on the host cell for ____

nucleotide cofactors and ATP