mcb exam 2

Question 1

What are the different microbial nutritional groups based on their needs for carbon and energy

Answer 1

• Heterotroph
• Autotroph

Question 2

Hetertroph

Answer 2

must obtain carbon in an organic form

Question 3

Autotroph

Answer 3

uses inorganic CO2 as its carbon source

Question 4

Decomposers

Answer 4

metabolizing the organic dead matter of dead organisms

Question 5

Saprobes

Answer 5

free living microorganisms that feed on organic detritus from dead organisms

Question 6

Parasites

Answer 6

derive nutrients from the cells or tissues of a living host

Question 7

Influences a hypotonic, hypertonic and an isotonic solution would have on a typical microbial cell

Answer 7

• Hypotonic: solute concentration of the external environment is lower than the cells internal environment
• Hypertonic: the environment has a higher solute concentration than the cytoplasm
• Isotonic: the environment is equal in solute concentration to the cell’s internal environment

Question 8

Different transport mechanisms for moving substances in and out of a cell

Answer 8

• Simple diffusion:
• Facilitated diffusion:
• Carrier-mediated active transport:
• Group translocation:
• Endocytosis

Question 9

Which transport mechanisms require the expenditure of energy in form of ATP?

Answer 9

• Active transport (endocytosis, group translocation, carried mediated active transport

Question 10

Phases of microbial growth.

Answer 10

• Lag
• Log/Exponential
• Stationary
• Death

Question 11

What does “doubling time” mean?

Answer 11

• The time required for a complete fission cycle (parent cell to two new daughter cells)

Question 12

Different methods and equipment used in enumerating microbial growth

Answer 12

• Turbidometry: relies on the simple observation that a tube of clear nutrient solution becomes cloudy or “turbid” as microbes grow in it.
• Direct total cell count: counting the number of cells in a sample microscopically
• Polymerase chain reaction (PCR): quantify bacteria without culturing them

Question 13

Lag phase

Answer 13

“flat period”, populations appear to not be growing or growing at a less exponential rate

Question 14

Log/Exponential phase

Answer 14

cells reach the maximum rate of cell division. Curve increases dramatically

Question 15

Stationary phase

Answer 15

population enter a survival mode; cells stop growing or grow slowly

Question 16

Death phase

Answer 16

cells die at an exponential rate.

Question 17

Hypotonic

Answer 17

solute concentration of the external environment is lower than the cells internal environment

Question 18

Hypertonic

Answer 18

the environment has a higher solute concentration than the cytoplasm

Question 19

Isotonic

Answer 19

the environment is equal in solute concentration to the cell’s internal environment

Question 20

Simple diffusion

Answer 20

fundamental property of atoms and molecules that exist in a state of random motion

Question 21

Facilitated diffusion

Answer 21

• Molecules bind to specific receptor in membrane and is carried to other side
• Molecule specific. Goes both directions
• Rate of transport is limited by number of binding sites on transport proteins

Question 22

Carrier-mediated active transport

Answer 22

Atoms or molecules are pumped into or out of the cell by specialized receptors

Question 23

Group translocation

Answer 23

Molecule is moved across membrane and simultaneously converted to a metabolically useful substance

Question 24

Endocytosis

Answer 24

-(Bulk transport) Mass transport of large particles, cells and liquids by engulfment and vesicle formation
- Phagocytosis moves solids into cell; pinocytosis moves liquids into cell