Week 6: Generation Time and Microbial Metabolism Flashcards
generation time
time bw cellular divisions, or the time it takes a population of bacteria to double
bc population size doubles with every replication, the growth is
exponential
final number of bacteria =
initial number of bacteria x 2^ number of generation
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?
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
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)
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
Metabolism
The biochemical reactions occurring within a cell or organism
How a cell obtains, stores and uses energy
Exergonic reactions;
chemical reactions where energy is released
Exergonic reactions occur
when biological molecules are digested
Endergonic reaction;
chemical reactions where energy is absorbed (energy
is required for the reaction to take place)
Endergonic reactions occur
when biological molecules are synthesized
Coupled reaction
- When endergonic and exergonic reactions are paired
* The energy released by the exergonic reaction is used in the endergonic reaction
When one phosphate is cleaved it releases a
large amount of stored chemical energy and
produces
ADP
cellular respiration occurs in 3 stages
- Glycolysis
- Kreb’s Cycle
- Electron Transport
Glycolysis
• Glucose is oxidized and broken down into
two 3-carbon molecules
• Some ATP is generated; some energy is
captured in NADH
Kreb’s Cycle
• The 3-carbon molecules are further
oxidized
• Some ATP is generated; some energy is
captured in NADH and FADH2
Electron Transport
• NADH and FADH2 are reduced, providing
the energy required to generate most of
the ATP from cellular respiration
In prokaryotes the components of the electron transport chain (ETC) are
embedded in the
plasma membrane
in eukaryotes the components are located in
the
inner mitochondrial membrane
Components of the ETC include:
• Membrane-bound proteins associated with molecules derived from B vitamins or metallic
ions (ex. Iron)
• Other, non-protein, hydrophobic molecules
• Final electron acceptor molecules
electron transport
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
Aerobic respiration is the term used for organisms
that use O2 as a final
electron acceptor
(anaerobic) ETC final electron acceptors can be one of several molecules:
sulfate, nitrate, carbon dioxide
proton gradient
As H+ ions are pumped outside of
the cell (prokaryotes) an unequal
distribution of H+ ions accumulates
outside of the cell
ATP Synthase is an enzyme consisting of two functional components:
• Transmembrane channel
Allows the passage of H+ ions back into the cell
• Head portion (on the intracellular side) Binds to ADP and phosphate
In aerobic respiration,
a single glucose molecule digested through all three
stages of cellular respiration will result in the generation of approximately
35 ATP molecules
In anaerobic respiration,
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.
in fermentation to regenerate NAD+ so that glycolysis can continue,
NADH is oxidized and
pyruvate is reduced
