Enzymes Flashcards
why do we use Enzymes?
to speed up chemical reactions
What are exergonic reactions?
even energy-releasing reactions that require energy input to get started
what is activation energy (Ea)?
the initial energy input in exergonic reactions that are later paid back
how do enzymes speed up reactions?
by lowering energy barriers
whats is a catalyst?
like enzymes, macromolecules that speed up reactions but are not consumed in the process. Breaking down and re forming bonds requires energy
are transition states unstable or stable
unstable
what is activation energy
energy often in the form of heat. Typically this
accelerates reactants and causes bonds to move, more likely bonds will break.
why dont cells heat up if heat can overcome Ea
Heat can denature proteins and kills cells. Non-selective: all reactions would be sped-up
What are enzyme limits
cannot change delta G, they cannot make an endergonic process exergonic
what is a substrate
the reactant that the enzyme acts on, When bound to the active site, forms the enzyme-substrate complex through an induced fit
How do enzymes lower activation energy
1-Substrates enter active sites 2-substrates are held in the active site by weak interactions 3- Substrates are converted to products 4-Products are released 5- Active site is available for new substrates
what is the activation energy reaction type
The reactions thermodynamic barrier
WHat are Components that influence activity
Cofactors(generally ions, found in trace elements) and Coenzymes (organic molecules)
Difference between Competitive inhibition and Noncompetitive inhibition
Competitive inhibition - mimics the substrate, blocks binding site, can be overcome by increasing substrate concentration. Noncompetitive inhibition-alters enzyme shape, an active site much less efficient (ex- toxins, poisons, pesticides, and antibiotics)
Enzyme evolution components
DNA-transcription to RNA-translation to polypeptide
Regulation of enzymes
Cell switched on and off the genes that encode specific enzymes, regulates activity of enzyme
What is Allosteric regulation
regulatory molecule binds to a protein at one site and affects function at another site. Can be Stimulatory or inhibitory. Most enzymes regulated this way consist of multiple subunits
What is cooperativity
binding one substrate to one active site affects catalysis in other active sites
What is Feedback inhibition
end product accumulation shuts down the pathway
