Download • Microbial Metabolism • What is metabolism? • All chemical

•
•
•
Microbial Metabolism
What is metabolism?
All chemical reactions/activities in cell
–
Catabolism
•
•
Hydrolysis
Use energy to make ATP
–
–
Anabolism
•
•
Dehydration synthesis
Need energy for reaction
–
•
•
•
•
•
•
ADP + Pi + energy  ATP
ATP  ADP + Pi + energy
Enzymes frequently catalyze reactions
Oxidation/reduction
What is the difference between…
Hydrolysis
Condensation (dehydration synthesis)
Exergonic vs. endergonic
•
What are enzymes?
•
Without enzymes, collision theory rules
–
–
•
Need sufficient activation energy
Number of molecules above this activation level = reaction rate
Enzymes are molecules that lower the ______________
–
–
Catalysts
Work on substrate…
•
•
What does the enzyme work on?
Substrate
–
•
Enzyme-substrate complex forms temporarily
–
–
–
•
•
•
Lock and key model
Highly specific fit
End in -ase
Turnover number
–
–
•
Molecules which are changed during reaction
Number of molecules enzyme converts per second
DNA polymerase = 15; lactate dehydrogenase = 1,000
What are the parts of an enzyme?
Some are only a polypeptide chain
Most have two parts
–
–
–
Apoenzyme (polypeptide chain)
Cofactor (inorganic) or coenzyme (organic)
•
•
NAD+ (nicotinamide adenine dinucleotide) us. catabolic
•
•
Coenzyme A (CoA)—pantothenic derivitive (another B vitamin)
NADP+ (nicotinamide adenine dinucleotide phosphate)
anabolic
Others are metals: Cu, Mg, Mn, Zn, Ca, Co
Together these form holoenzyme
•
How does an enzyme work?
•
Enzymes controlled by
–
Enzyme synthesis
•
•
How much is made
Hormones can influence (e.g. TH)
us.
–
Enzyme activity
•
Temperature influences
–
•
•
pH influences
Substrate concentration influences
–
•
•
Saturation point
How does an enzyme work?
Inhibitors influence
–
Competitive
•
–
Fill active site: sulfanilamide vs para-aminobenzoic acid (PABA)
Non-competitive
•
•
•
•
•
•
•
•
•
•
Denaturation
Allosteric inhibition
Factors Influencing Enzyme Activity
Enzymes can be denatured by temperature and pH
Factors Influencing Enzyme Activity
Temperature
pH
Substrate concentration
Factors Influencing Enzyme Activity
Competitive inhibition
Factors influencing enzyme activity
•
•
•
•
•
•
•
•
•
•
•
Feedback inhibition
Cell Energetics
Oxidation-Reduction
Oxidation is the removal of electrons.
Reduction is the gain of electrons.
Redox reaction is an oxidation reaction paired with a reduction reaction.
Oxidation-Reduction
In biological systems, the electrons are often associated with hydrogen atoms. Biological
oxidations are often dehydrogenations.
What happens in carbohydrate catabolism?
Glucose usually is substrate
Glycolysis
–
•
2 ATP
Followed by either
–
Aerobic respiration
• ___ ATP
–
Anaerobic fermentation
• No more ATP
•
What is ATP?
•
•
•
•
•
•
•
Adenosine triphosphate
Made by phosphorylating ______
Equation:
What is glycolysis?
First step to making TP from glucose
Convert glucose to _____________
Some bacteria can breakdown other molecules
–
Pentose phosphate pathway (pentoses)
• E. coli, Bacillus subtilis
•
•
•
•
•
•
•
•
What happens next?
If oxygen present 
Preparatory Stage
Two ATPs are used
Glucose is split to form two Glucose-3-phosphate
Energy-Conserving Stage
Two Glucose-3-phosphate oxidized to two Pyruvic acid
•
•
•
•
•
•
Four ATP produced
Two NADH produced
Intermediate Step
Pyruvic acid (from glycolysis) is oxidized and decarboyxlated.
What is the Krebs Cycle?
AKA citric acid cycle
–
Acetyl CoA (2 carbons) releases energy
–
Produces ATP, CO2, NADH, FADH2
•
NADH and FADH2 to Electron transport chain (ETC)
•
What are some intermediates in the Krebs cycle?
•
•
•
•
•
•
•
•
•
•
Some drugs are metabolized similar to these:
citric acid (6 carbons)
iso-citric acid (6)
alpha-ketoglutaric acid (5)
succinyl CoA (4)
succinic acid (4)
fumaric acid (4)
malic acid (4)
oxaloacetic acid (4)
Krebs cycle animation
•
What is the electron transport chain?
•
Carrier molecules facilitate oxidation and reduction
– Oxidation: loss of electron
– Reduction: gain of electron
•
Transfer electrons from higher to lower energy compounds
– Chemiosmosis w/ oxidative phosphorylation
•
•
•
Prokaryotes: PM
•
•
First ETC animation
Eukaryotes: mitochondrial crista
Disruption of ETC leads to death!
– Cyanide
Second ETC animation
•
What is the sum reaction for aerobic respiration?
Glucose + 6 H2O + 38 ADP + 38 Pi 
6 CO2 + 6 H2O + 38 ATP
•
What happens in anaerobic respiration?
•
Final electron acceptor is not oxygen
–
–
–
–
Various amounts of ATP produced
Slower and less ATP than aerobic respiration
Uses some parts of Krebs cycle
Thus slower growth for anaerobes than aerobes
•
What is fermentation?
•
Pyruvic acid from glycolysis
–
–
–
Converted to end-products
If bacteria only produce lactic acid = homolactic
No additional ATP
•
•
•
What is alcohol fermentation?
Also happens after glycolysis
Produces ethanol and CO2
•
Heterolactic: produces lactic acid + other acids, alcohols
•
What happens in lipid & protein catabolism?
•
•
Some bacteria don’t like carbs!
Lipases break down ______
–
–
•
Useful for oil spill clean up
Extracellular proteases & peptidases break down _______
–
•
•
•
Krebs cycle oxidizes products
Deamination converts amino acids to usable form for Krebs cycle
•
By production is ammonia
Anaerobic Respiration
Energy produced from complete oxidation of one glucose using aerobic respiration.
ATP produced from complete oxidation of one glucose using aerobic respiration.