Week 6: Generation Time and Microbial Metabolism

Question 1

generation time

Answer 1

time bw cellular divisions, or the time it takes a population of bacteria to double

Question 2

bc population size doubles with every replication, the growth is

Answer 2

exponential

Question 3

final number of bacteria =

Answer 3

initial number of bacteria x 2^ number of generation

Question 4

The generation time of a
bacteria is 10 minutes. You
inoculate a sample with 10
bacteria. How many bacteria
would you have after 2 hours?

Answer 4

How many generations in two
hours?
• 2 hrs x 60 mins/hour = 120min
• 120min/ 10 min/generation = 12
generations

• Final number = 10 x 212
• Final number = 10 x 4,096
• Final number = 40,960

Question 5

The generation time of a
bacteria is 20 minutes. After two hours there are 640,000 bacteria. How many were in the sample to begin with (at time =0 min)

Answer 5

How many generations in two
hours?
• 2 hrs x 60 mins/hr = 120min
• 120min/ 20min/generation = 6
generations

• 640,000 = initial number x 26
• 640,000 = initial number x 64
• 640,000/64 = initial number
• 10,000 = initial number

Question 6

Metabolism

Answer 6

The biochemical reactions occurring within a cell or organism
How a cell obtains, stores and uses energy

Question 7

Exergonic reactions;

Answer 7

chemical reactions where energy is released

Question 8

Exergonic reactions occur

Answer 8

when biological molecules are digested

Question 9

Endergonic reaction;

Answer 9

chemical reactions where energy is absorbed (energy

is required for the reaction to take place)

Question 10

Endergonic reactions occur

Answer 10

when biological molecules are synthesized

Question 11

Coupled reaction

Answer 11

• When endergonic and exergonic reactions are paired

* The energy released by the exergonic reaction is used in the endergonic reaction

Question 12

When one phosphate is cleaved it releases a
large amount of stored chemical energy and
produces

Answer 12

ADP

Question 13

cellular respiration occurs in 3 stages

Answer 13

• Glycolysis
• Kreb’s Cycle
• Electron Transport

Question 14

Glycolysis

Answer 14

• Glucose is oxidized and broken down into
two 3-carbon molecules
• Some ATP is generated; some energy is
captured in NADH

Question 15

Kreb’s Cycle

Answer 15

• The 3-carbon molecules are further
oxidized
• Some ATP is generated; some energy is
captured in NADH and FADH2

Question 16

Electron Transport

Answer 16

• NADH and FADH2 are reduced, providing
the energy required to generate most of
the ATP from cellular respiration

Question 17

In prokaryotes the components of the electron transport chain (ETC) are
embedded in the

Answer 17

plasma membrane

Question 18

in eukaryotes the components are located in

the

Answer 18

inner mitochondrial membrane

Question 19

Components of the ETC include:

Answer 19

• Membrane-bound proteins associated with molecules derived from B vitamins or metallic
ions (ex. Iron)
• Other, non-protein, hydrophobic molecules
• Final electron acceptor molecules

Question 20

electron transport

Answer 20

the NADH and FADH2 transport their electrons to the ETC, where they
are oxidized. The electrons released are passed between electron carriers
embedded in the membrane to a final electron acceptor.
As the electrons are passed between carriers, protons (H+) are actively pumped
across the membrane creating a proton gradient
• A build up of protons on one side of the membrane holds energy which is
harnessed to generate ATP

Question 21

Aerobic respiration is the term used for organisms

Answer 21

that use O2 as a final

electron acceptor

Question 22

(anaerobic) ETC final electron acceptors can be one of several molecules:

Answer 22

sulfate, nitrate, carbon dioxide

Question 23

proton gradient

Answer 23

As H+ ions are pumped outside of
the cell (prokaryotes) an unequal
distribution of H+ ions accumulates
outside of the cell

Question 24

ATP Synthase is an enzyme consisting of two functional components:

Answer 24

• Transmembrane channel
Allows the passage of H+ ions back into the cell
• Head portion (on the intracellular side) Binds to ADP and phosphate

Question 25

In aerobic respiration,

Answer 25

a single glucose molecule digested through all three
stages of cellular respiration will result in the generation of approximately
35 ATP molecules

Question 26

In anaerobic respiration,

Answer 26

the ETC is less efficient at pumping protons, and
therefore less ATP is generally formed. This is the main reason why
anaerobic microbes tend to grow slower than aerobic microbes.

Question 27

in fermentation to regenerate NAD+ so that glycolysis can continue,

Answer 27

NADH is oxidized and

pyruvate is reduced