theory & bacterial growth

Question 1

bacterial growth curve phases

Answer 1

1- Lag
2- Log
3- Stationary
4- Death

Question 2

Lag phase

Answer 2

First;
normal cellular metabolism;
no change in cell #;
short delay before undergoing growth

Question 3

Log phase

Answer 3

Second;

maximal growth rate; high sensitivity to antibiotics

Question 4

Stationary phase

Answer 4

Third;

cell division = cell death (NO net gain of cells);

Question 5

death phase

Answer 5

Fourth;

toxic environment, accumulation of wastes;

Question 6

environmental factors affecting

bacterial growth

Answer 6

salt
pH
temp
oxygen

Question 7

salt

Answer 7

low salt, hypotonic, osmolysis prevented by cell wall

high salt, hypertonic, cell lyse

Question 8

osmotolerance

Answer 8

ability to tolerate wide range of salt concentrations

Question 9

pH

Answer 9

external

Question 10

temperature

Answer 10

affects internal & external;

temp range is in which the enzymes can function

Question 11

oxygen

Answer 11

deadly, toxic;
strict anaerobes- DIE In presence of O2
strict aerobes- REQUIRE O2 to grow
facultative anaerobes- grow better in PRESENCE of O2
aerotolerant- do NOT use O2, not affected by presence
microaerophiles- [LOW] O2 required

Question 12

O2 free radical

Answer 12

breaks covalent bonds, backbones of DNA, bonds with enzyme

Question 13

superoxide dismutase

Answer 13

enzyme that detoxifies free radicals, strict anaerobes lack it

Question 14

catalase

Answer 14

enzyme used to detoxify free radicals;
strict anaerobes lack;
req’d to metabolize O2

Question 15

endosymbiotic theory

Answer 15

organelles (mitochondria & chloroplasts) of euks arose from proks that had developed a symbiotic relat w/ the euk to be;
both benefit