Flashcards in 8.1 Metabolism Deck (20)
What is the site called on an enzyme where non-competitive inhibitors can bind to?
What do metabolic pathways consist of?
chain reactionsand cycles and enzyme-catalysed reactions
How do most chemical changes occur?
Through a metabolic pathway in a sequence of small steps where some form organic compounds (anabolic) and some break down (catabolic)
What is an example of a metabolic chain reaction?
glycolysis: chain of 10 enzyme controlled reactions, converts glucose to pyruvate
Give an example of a metabolic pathway that forms a cycle
Krebs cycle (respiration); Calvin Cycle (photosynthesis)
What is activation energy?
energy needed for a reaction to occur, so that substrates pass a certain transition state to form products;
How does an enzyme catalyse a reaction?
substrate binds to active site;
substrate is altered by breaking or weakening bonds of substrates;
lowering activation energy;
reaches transition state faster;
converts to product and released;
rate of reaction increases;
In most biological reactions, is the energy released greater or smaller?
greater (products are most stable)
When does the conformation of an enzyme change?
As substrate binds to active site, conformation alters/shape of active site becomes complementary to substrate;
when substrate is released enzyme returns to original conformation
What are inhibitors?
chemical substances that bind to enzymes to reduce the activity
What are competitive inhibitors?
substrate and inhibitor are chemically similar;
inhibitor binds to active site of enzyme;
blocks substrate from binding to active site;
enzyme activity is prevented until inhibitor dissociates
What are non-competitive inhibitors?
substrate and inhibitor are not similar;
inhibitor binds to allosteric site (not active);
changes conformation of enzyme;
enzyme may stop catalysing/catalyse slower
How is rate of reaction of an enzyme affected by competitive inhibitor as substrate concentration increases.
as substrate concentration increases, substrates become increasingly more likely to bind to active site because inhibitor only blocks the site temporarily
How is rate of reaction of an enzyme affected by non-competitive inhibitor as substrate concentration increases.
Substrate cannot prevent the binding of inhibitor (even at high concentration); same proportion of enzymes is inhibited at all substrate concentrations
What are allosteric interactions?
enzymes regulated by inhibitors binding to special sites on the enzyme away from the active site
What is end-product inhabitation?
when in a metabolic pathway, product of last reaction of pathway inhibits enzyme that catalysis first reaction;
negative feedback loop
What is the advantage of end product inhabitation?
if there is excess of end product the whole pathway is switched off with no intermediates (to reach equilibrium)
Example of end product inhabitation
amino acid threonine is converted to isoleucine; when isoleucine builds up it acts as inhibitor
What is bioinformatics?
approach whereby multiple research groups can add information to database enabling other groups to query the database