Microbio Chapter 5- Microbial Metabolism Flashcards
What are enzymes?
Biological catalysts
-Speed up reactions without increase of temperature
Specific (Lock and key model or enzyme-substrate complex)
How do enzymes speed up reactions?
Reduce activation energy needed
What are most enzymes composed of?
Proteins + cofactor
What is the protein portion of an enzyme called?
Apoenzyme
What is a cofactor?
Non-protein portion of an enzyme
What is it called if the cofactor is an organic molecule?
Coenzyme
What factors influence enzyme activity?
- Temperature
- pH
- Substrate
- Inhibitors
What is the optimal temperature for most disease-producing bacteria in the human body? (Optimum)
35C - 40C
-Reaction rate increases as temp increases until too heated
What happens to enzymatic reactions if the temperature is elevated beyond the optimum?
Rate of reaction is reduced and the enzyme is denatured
How does pH affect enzymes?
If pH is too low or too high the reaction rate declines
What happens to enzymatic reactions when the pH is above/below the optimum value?
Reaction rate is reduced and enzyme is denatured
How does substrate concentration affect enzymes?
Increased substrate concentration = increased rate of reaction
What happens when all active sites on the enzyme are filled?
Maximum rate of reaction is reached
-Reaction rate can’t be any faster
What are the two types of inhibitors?
Competitive and Non-competitive
How do competitive inhibitors prevent the enzyme from functioning?
Inhibitor occupies the active site
-Compete with normal substrate for the active site spot
Why are competitive inhibitors able to occupy the active site?
Its shape/chemical structure is similar to normal substrate
-It mimics
What is an example of a competitive inhibitor?
Sulfanilamide
What is Sufanilamide?
Antibacterial drug
What does Sulphanilamide mimic?
PABA (para-aminobenzoic acid)
What is PABA’s function?
Produces folic acid
What happens when Sulphanilamide inhibits?
Folic acid cannot be synthesized
–> DNA/RNA is not synthesised resulting in cell death
How do non-competitive inhibitors prevent the enzyme from functioning?
They interact with another part of the enzyme causing the active site to change its shape making it nonfunctional
What do non-competitive inhibitors play a role in?
Feedback inhibition
What is feedback inhibition?
Stops a cell from wasting chemical resources by preventing it from making a substance
What are the two types of enzymes?
Simple
Conjugated
What are simple enzymes?
Only consist of proteins
What are conjugated enzymes?
Protein+ non-protein
- Apoenzyme + Cofactor
What is the name of an enzyme with an apoenzyme and a cofactor?
Holoenzyme
What are two types of cofactors?
Inorganic and organic
What are examples of inorganic cofactors?
Magnesium
Iron
Calcium
What are organic cofactors called?
Coenzymes
What are many coenzymes derived from?
Vitamins
What are two important coenzymes in cell metabolism?
NAD and NADP
aka Nicotinamide adenine and nicotinamide adenine dinucleotide
What are NAD and NADP derived from?
Vitamin B
(Nicotinic acid)
What is oxidation?
Removal of electrons
What is reduction?
Gain of electrons
What is an oxidation-reduction/ redox reaction?
A pairing of oxidation and reduction reactions
Each time one substance is oxidised another is reduced at the same time
What is another name for oxidation reactions?
Dehydrogenation reactions
What is another name for reduction reactions?
Hydrogenation reactions
Why do cells use oxidation-reduction reactions?
To extract energy from nutrient molecules
What molecule is a valuable nutrient for organisms?
Glucose
How is ATP formed?
Adenosine diphosphate (ADP) + energy + Inorganic phosphate group
What is phosphorylation?
Adding a phosphate to a chemical compound
What is substrate-level phosphorylation?
ATP is formed when a phosphate is transferred from a substrate to ADP
What is oxidative phosphorylation?
Redox: Electrons are transferred from organic compounds to a group of electron carriers (NAD)
electrons are then passed through a sequence of electron carriers aka the electron transport chain
What are the types of respiration?
Aerobic
Anaerobic
Fermentation
What is aerobic respiration?
Uses oxygen
present in most bacteria
O2 absorbs electrons
What is anaerobic respiration?
No oxygen present
Only glycolysis
NO3, SO4 and CO3 absorbs electrons
What is an species of bacteria that uses anaerobic respiration?
Clostridium
What is fermentation?
O2 can be present or absent
Glycolysis only
What is a species of bacteria that undergoes fermentation?
Lactobacillus –> lactic acid
Lactic acid absorbs electrons
What is Catabolism?
releases energy to be used for anabolism by oxidation
What is Anabolism?
Energy stored by ATP is used to form large molecules
