Exam 2: Ch 7: Microbial Metabolism Flashcards
Metabolism
pertains to all chemical reactions and physical workings of the cell
Anabolism
synthesis of molecules - building stuff up
requires input of energy
need to take smaller molecules & ATP to make larger molecules
Catabolism
breaks the bonds of larger molecules - breaking stuff down
releases energy
take larger molecules & get smaller molecules and energy
Electron transfer
allows energy to be captured in high-energy bonds in ATP and similar molecules
All catabolic reactions involve it & Cellular respiration is built on it
Directly related to oxidation & reduction electron being passed from one protein to another
By transferring the e-, energy is transferred from A → B
Oxidation
loss of electrons
Reduction
gaining of electron
the charge is reduced but it now has more energy than it did before
Oxidoreductase
enzymes that remove electrons from one substrate and add them to another
their coenzyme carriers are NAD+ and FAD
H+ is often going along in this process
Activation energy
the minimal amt of energy required to be available for bonds to be formed or broken
can be in the form of temp, pressure, etc to increase the number of particle collisions (we don’t have time to wait, so we speed up the reaction with heat/pressure/etc)
Why do humans need enzymes?
The temp and pressure that humans and bacteria would require for their chemical reactions would kill them – so we need ENZYMES
Enzymes reduce the amt of activation energy needed for chemical reactions and speed them up so that life can continue
Enzymes
reduce the amt of activation energy needed for chemical reactions
have specific active sites that bind to specific substrates
Bonds formed btwn the substrate and enzyme are weak and easily reversible
Enzymes are fast!
The # of substrate molecules converted per enzyme per second
Catalase – reacts several million times/sec
Lactase dehydrogenase – reacts a thousand times/sec
Specific active sites
arise due to the folding of a protein (folding is what allows for active sites and the activity of enzymes)
One little change could change the enzyme and make it useless
Substrates
specifically bind to active sites on the enzyme
lock & key
What happens at the end of enzyme-substrate reactions?
once the reaction is complete, the product is released and the enzyme reused
Cofactors
participate in precise functions btwn the enzyme and substrate
help bring the active site and substrate close together
participate directly in chemical reactions with the enzyme substrate complex
The need for trace elements for microorganisms arises from their roles as cofactors for enzymes
Coenzymes (vitamins)
organic compounds that work in conjunction with an enzyme
remove a chemical group from one substrate molecule and add it to another substrate molecule
Carry and transfer hydrogen atoms, electrons, carbon dioxide, and amino groups
Apoenzyme
globular protein that is the main enzyme portion
“the protein part”
How do we regulate enzymes?
Adjust for the level you need at that particular time and in that particular situation
use constitutive & regulated enzymes
negative feedback loop
helps reduce waste from making enzymes that arent needed
Constitutive enzymes
always present in relatively constant amounts regardless of the amount of substrate
keep substrate up → turn the enzyme down
ex. catalase
Regulated enzymes
production is turned on (induced) or turned off (repressed) in responses to changes in concentration of the substrate
regulated thru gene expression
How is enzyme function regulated?
Activity of enzymes influenced by the cell’s environment (natural temp, pH, osmotic pressure)
Denaturation - the weak bonds that maintain native shape of enzyme are broken
Competitive inhibition
inhibits enzyme activity by supplying a molecule that resembles the enzymes normal substrate
“mimic” occupies the active site, preventing the actual substrate from binding
Actually binds to active site
Noncompetitive inhibition
bind to an “allosteric” or “other” site on the enzyme, not the active site
Changes the configuration of the active site so the normal substrate cant bind
Metabolic pathways
Often occur in a multistep series/ pathway
each step catalyzed by an enzyme
Metabolic pathways do not stand alone - they are interconnected and merge at many sites
Linear pathway
production of one reaction is the reactant (substrate) for the next
linear chain reaction
if an enzyme gets cut out, you dont get the next step
