lecture 8-10

Question 1

Chemoautotrophs / Chemolithotrophs

Answer 1

energy from inorganic compounds
(litho = rocks)

Question 2

Chemoheterotrophs / Chemoorganotrophs

Answer 2

energy from organic compounds

Question 3

microbes are classified based on their…

Answer 3

carbon and energy acquisition

Question 4

Autotrophs

Answer 4

– Photoautotrophs
– Chemoautotrophs (chemolithotrophs)

Question 5

Heterotrophs

Answer 5

– Photoheterotrophs
– Chemoheterotrophs (or chemoorganotrophs)

Question 6

Nitrogen fixers (called ______) have
______________; converts inorganic N2 to
ammonium ions (NH4+)

Answer 6

diazotrophs, nitrogenase enzyme

Question 7

Most bacteria divide by

Answer 7

binary fission

Question 8

Liquid media or broth:

Answer 8

cells are in suspension

Question 9

Solid media:

Answer 9

usually gelled/solidified with agar

Question 10

Cell grows as Colony Forming Units (CFU); a colony =

Answer 10

a visible group of microbial cells that developed from
the same mother cell

Question 11

Complex/rich media:

Answer 11

nutrient rich; exact composition is poorly defined

Question 12

Minimal defined media:

Answer 12

contain only those nutrients that are essential for growth of a given microbe

Question 13

Enriched media:

Answer 13

complex media to which specific factors are added; the microbe is not capable of making them but needs them to grow

Question 14

Selective media:

Answer 14

favour the growth of one organism over another.

Question 15

Differential media:

Answer 15

exploit biochemical/physiological differences between two species that grow equally well (in the medium)

Question 16

pure cultures isolated by two techniques:

Answer 16

Dilution streaking and Spread plating

Question 17

Lag phase

Answer 17

• Bacteria adapt themselves to growth conditions
• Bacteria are maturing and not yet
  able to divide
• Synthesis of RNA, enzymes and
  other molecules occurs

Question 18

four phases of growth:

Answer 18

◦ lag, exponential/logarithmic (log), stationary, death

Question 19

Exponential/Logarithmic (log) phase

Answer 19

• Characterized by cell doubling
• Log growth cannot continue
  indefinitely as medium is depleted of
  nutrients and enriched with wastes in
  batch cultures

Question 20

Exponential/Logarithmic (log) phase can be split into two phases:

Answer 20

early and late

Question 21

Early exponential phase:

Answer 21

cells growing at the maximum rate (physiologically) possible based on conditions available

Question 22

Late exponential phase:

Answer 22

slowing of growth rate due to cell density, competition for nutrients, accumulating
waste products, etc. (decrease in slope)

Question 23

Stationary phase:

Answer 23

• overall population growth plateaus
• Due to a growth-limiting factor such as the depletion of essential nutrient(s), and/or formation of an inhibitory product
• horizontal linear part of the curve

Question 24

Death phase:

Answer 24

Without any new nutrients (and/or production of toxic byproducts by dying cells), all cells will eventually die off
4. Death phase

Question 25

The chemostat ensures...

Answer 25

continuous logarithmic growth by constantly adding and removing equal amounts of culture medium