6.4 Enzymes speed up metabolic reactions by lowering energy barriers

What determines the rate of a reaction?

Activation Energy

induced fit

Brings chemical groups of the active site into positions that enhance their ability to catalyze the chemical reaction. change in the shape of an enzyme so it fits more snug with the substrate. {caused by entry of substrate}

How does an enzyme catalyze a reaction?

It lowers the activation energy allowing reactants to absorb less energy than they would need to absorb without the enzyme in order to reach transition state.

What would happen if enzymes didn't regulate chemical traffic through pathways of metabolism?

The cell would become congested because many chemical reactions would take a long time

Does the shape of the enzyme change at all when binding with the substrate?

Yes, as the substrate enters the active site, the enzyme changes shape slightly due to interactions between the substrates chemical groups and the chemical groups on the side chain of the amino acids that form the active site. This provides a more snug fit between the enzyme and the substrate.

catalyst

chemical agent that speeds up reaction without being consumed by the reaction

coenzyme

cofactor in an organic molecule

Activation Energy

energy required to contort the reactant molecules so the bonds can break -amount of energy needed to push reactants uphill so downhill part can occur

enzyme

macromolecule that acts as a catalyst

Formation of new bonds releases (more/less) energy than was invested in the breaking of the old bonds

more

Do enzymes change the change in free energy and switch the type of reaction?

no

cofactor

nonprotein helpers for catalytic activity

active site

pocket/groove on the surface of the enzyme where catalysis occurs. place where the substrate binds to the enzyme

How does temperature affect the conditions of enzyme activity?

rate of reaction increases with temperature up to a point -above this temp, the speed of reaction increases because thermal agitation disrupts bonds that stabilize the active shape -below this temp, the enzyme changes shape

substrate

reactant enzyme acts on

enzyme + substrates has a ______ reaction with the enzyme substrate complex which has a _____ reaction with the product: the enzyme + products

reversible reversible

What does the specificity of the enzyme result from?

shape

Why do molecules absorb thermal energy?

so the reactants accelerate and collide more often as well as more forcefully.

enzyme-substrate complex

temporary complex formed when enzyme binds with its substrate

True or false: only certain substrates can fit in a specific enzyme's active site

true

When changing one molecule into another, it usually involves the contorting of a starting molecule into a highly (stable/unstable) state before reaction can begin.

unstable

when is an enzyme saturated?

when concentration of substrate is high enough that all active sites are engaged. As soon as one leaves another enters

transition state

when molecules have absorbed enough energy for the bonds to break. (unstable condition)

How does pH affect the conditions of enzyme activity?

when the solution is too acidic/too basic it denatures the protein