Microbial Energetics Flashcards
Microbial diversity equals
metabolic diversity
What are photolithoautotrophs?
Get energy from light
What are chemoheteroorganotrophs?
Get energy from oxidation and organic compounds
What are chemolithoautotrophs?
Oxidize inorganic chemicals for energy
What is the definition of metabolism?
The sum total of all rxns which occur in a cell. Consists of two types of processes, catabolism and anabolism
What is the definition of catabolism?
The use of chemical reactions to generate energy and reducing power (electrons) that drive cellular functions. These reactions can involve the breakdown of complex molecules into smaller ones, but these are many exceptions where this doesn’t occur
What is the definition of anabolism?
Synthesis of needed cellular structures from simpler compounds, this requires energy often from reducing power.
What is the requirement for growth?
Energy
Energy is able to do _____.
work
In the gibbs free energy equation what do the following mean…
a. H
b. S
c. G
a. total energy of a rxn
b. amount of energy that is lost to disordering (entropy) the system and is not available for work
c. the amount of free energy available to do work
An increase in S results in….
randomization of the system giving a negative delta G (favorable)
A decrease in S results in…
Ordering of a system and a positive delta G
Breaking things down often ______ energy?
Releases
Building things up ________ energy?
Costs
If there is a high substrate concentration what will happen to the rate of rxn?
Increase and we see a forward rxn
If there is a low concentration of products what will happen to the rate of the rxn?
Increase the rate of the forward reaction
All reactions require _____ to occur?
activation energy
What is the reaction intermediate?
Two substrates that are destabilized and brought together
What is the purpose of enzymes?
- Bring substates together (increase local concentration)
- Bend substrates to resemble the reaction intermediate
What is chemical energy?
Potential energy of electrons
What is an electron donor?
something that loses electrons and gets oxidized
What is an electron acceptor?
something that gains electrons and gets reduced
How is energy released?
Energy is released as electrons move to place of lower potential energy
How is electron transfer linked to ATP synthesis?
Electron transfer is associated with the release of potential energy, captured by ATP, an energy carrier
Chemicals ____ in their tendency to donate or accept electrons?
VARY….Can be measured or expressed in half rxns
Oxidized form of rxns are always on _____ while reduced forms always on _____.
Left
Right
A lower MeV corresponds to…..
good electron donors
A higher MeV corresponds to….
good electron acceptors
What kind of reduction potential does a donor have?
Negative reduction potential
What kind of reduction potential does an acceptor have?
Positive reduction potential
When calculating potential drop a positive drop in potential corresponds
favorable rxn
Electron transfer is not often ____.
direct
What protein electron carriers shuttle electrons?
- Cytochromes
- Flavoproteins
What protein small molecule electron carriers shuttle electrons?
- NADH
- FADH
- Quinones
What do energy storage systems do?
capture energy released from chemical reactions
Released free energy can be conserved by the cell as what?
Chemical bond or ion motive force
What is an example of chemical energy storage?
ATP binding - conformational change - ATP hydrolyzed to go back to original form
ATP…..
Stores chemical energy
What are other ways to store chemical energy (molecules)?
- PEP
- CoA
- Acetyl-P
Chemical energy can be stored as what?
Phosphate bonds
Free energy can be _______.
Manipulated
Enzymes ______ reactions.
bind
What is fermentation?
Reactions that occur in the absence of oxygen. both donor and acceptor are both organic chemicals
What is Substrate level phosphorylation and what is it used for?
Energy generation! Synthesis of ATP from ADP is coupled with the breakdown of high energy organic substances
What are systems used for generating energy?
- substrate level phosphorylation
- membrane system phosphorylation
What are membrane systems of phosphorylation?
- oxidative or electron transport level phosphorylation
- anaerobic respiration
- photophosphorylation
What is a glycolytic pathway?
Breaks down glucose down to smaller molecules
The Embden-Meyerhoff Pathway is present in?
Many bacteria and Archaea
What organisms use Entner Douderoff Pathway?
Mostly strictly aerobic bacteria
What is hexose splitting?
- Molecule activated then split
- The reaction pulled toward GAP
- Phosphates added and then removed as energy
What does the Entner-Duodoroff Pathway yield?
2 reducing equivalents NAD NADH
What are the end products of glycolysis?
Pyruvate
NADH
What is pyruvate used for?
Carbon source
What is NADH used for?
Biosynthesis reactions
What is the rest of NADH used for after biosynthesis reactions?
Fermentation you have to get rid of excess NADH
What is the definition of fermentation?
Energy yielding process wherby organic molecules serve as both electron donors and acceptors
In fermentation what is pyruvate used for?
Important intermediate
How is energy derived for fermentation?
Substrate-level phosphorylation
What is the energy yield for fermentation?
Generally really low
Is oxygen involved for fermentation?
NO
What are typical substrates for fermentation?
- Sugar
- Amino Acids
What are typical products that depend on substrates?
- organic acids - lactic and acetic acid
- alcohols - ethanol, methanol, butanol
- Gases - hydrogen gas and carbon dioxide
What are the three important fermentations we discussed in class?
- Alcoholic fermentation by Saccharmoyces yeast
- Homofermentation - lactic acid only product
- Propionic fermentation of Propionibacterium
Alcoholic fermentation is a ____ step reaction?
2
What are the two steps of alcoholic fermentation?
- Decarboxylation to form acetylaldehyde
- Reduction to ethanol using NADH
How many breweries are in the US?
> 8000 breweries
What are brewing ingredients for beer?
- Malted Barley
- Water
- Hops
- Yeast
What are the steps of the brewing process?
- Malting germinate barely
- mashing
- extract starch
- convert sugars - Boil wort, add hops
- Fermentation glycolytic pathway
What is the process of ethanol formation?
Take pyruvate and aetyladehyde and it is combined and reduced to ethanol.
Acetylaldehyde is a ______ taste?
Green apple tast
In ethanol formation if there is a back up of acetylaldehyde what happens?
Green apple taste
what are the steps of beer production?
- Malting
- Mashing
- boiling
- Fermentation
- bottling and distribution
For homofermentation how many ATP are added per glycolysis?
2
For homofermentation how many ATP are generated per glucose?
4 ATP
2 NET ATP
What are different lactic acid bacteria?
- Streptococcus
- Lactococcus
- Some lactobacillus
What is heterofermentation?
Different fermentation of glucose
How many ATP are yielded from heterofermentation?
1 ATP
What are the products of heterofermentation?
- Lactate
- CO2
- Ethanol
What are different heterofermentation bacteria?
- Leucocnostoc
- Other lactobacillus
What are the steps in cheese making?
- Collect and pasturize raw milk
- Add starter culture
- Add renet and form milk curds
- Curd concentration
- Press curds into molds and salt
- Added second starter culture if needed
- Age for weeks
- Remove the cheese from molds and package for sale
What is kimchi?
Vegetable fermentation (Natural fermentation)
How is kimchi fermented?
Fermented by cabbage by lactic acid bacteria and coliforms
What gives kimchi its natural flavor and texture?
lactic acid bacteria
What is the fermentation progression of kimchi?
(KNOW CHART ON LEC SLIDES)
1st Coliforms
- non pathogenic klebsiella and enterobacter
- ferments sugar to acidic products and lowers pH to 5
2nd Lauconostoc
- Lactic acid bacteria
- Heterofermentative - gas produced
- stops fermentating at about pH 4.5
3rd Lactobacillus
- Homofermentative
- produces more lactic acid
- lowers pH to near 4.0
chocolate undergoes what kind of fermentation?
Natural fermentation
What are the psycho active products in chocolate?
- Anandamide (A) - blissful feeling
- Theobromine - Stimulant (B)
Explain chocolates fermentation process?
- Cacao pods have seeds (beans) covered in mucilage (carbohydrate)
- Pods are broken open and natural microbes ferment mucilage
- Complex succession of microbes make products
