Bio ATP and Enzyme Notes

feedback inhibition

the end product of a metabolic pathway, shuts down the pathway to prevent waste of energy and chemical resources

noncompetitive/allosteric inhabition

noncompetitve inhibitors bind to allosteric sites, this bonding changes the shape + prevents enzyme function bc the active sit is now full; reaction rate decreases if noncompetitive inhibitors bind to allosteric sites

competitive inhabition

molecules that bind reversinly or irreversibly to the active site of the enzyme; they compete with normal enzyme for enzymes active site; if inhib. conc. is greater than > substrate conc., the reaction is slow; if inhib. conc. is less than < substrate conc., reactions are normal; irreverisble binding=enzyme fucntion is prevented, reversible=enzyme can regain function once the inhibitor detaches

cofactors/co enzymes

enzyme helpers, such as vitamins (opposite of inhibitors)

denature

enzyme loses its physical or chemical properties and is no longer able to bind with a substrate; usually permanent and catalytic ability is lost/heavily decreased

optimal temp and pH

best temp and ph for enzymes to react quickest, around 37 degrees celcius and 7 pH; pH determined by H+ ions in solution

how can enymes 3D shape help lower activation energy?

3D structure/tertiary = active site + induced fit

substrate specificity

the ability of an enzyme to selectively bind to a specific substrate (or group of closely related substrates) and catalyze its conversion into a product

activation energy

he minimum amount of energy required for a chemical reaction to proceed; represents the energy barrier that reactants must overcome to transform into products.

catalyst/enzyme

protein that speeds up reactions, without it, reaction would take forever

regeneration of ATP

ATP is renewable and regenerated by the addition of a phosphate group to ADP

enery coupling

use of exergonic reactions to drive endergonic processes

endergonic reaction

absoprtion of energy, non-spontaneous, deltaG>0

exergonic reaction

release of energy, spontaneous, deltaG<0

free energy

Free energy (G) is the energy available to do work;Spontaneous reactions have a negative ΔG and release energy;non-spontaneous reactions have a positive ΔG and require energy input.

2nd law of thermodynamics

use of energy creates more disorder (entropy) / disorder always increases over time

1st law of thermodynamics

energy is conserved, cant be created or destroyed

anabolic pathways

build complex molecules from simple ones;absorb /consume energy

catabolic pathways

break down reactions into simpler ones; release erngy

metabolic pathways

Each step in a metabolic pathway is catalyzed by a specific enzyme, and the products of one reaction become the substrates for the next (catabolic vs. anabolic)

Consider a situation in which the enzyme is operating at optimum temperature and pHpH, and has been saturated with substrate. What is your best option for increasing the rate of the reaction?

Increase the enzyme concentration.

You have added an irreversible inhibitor to a sample of enzyme and substrate. At this point, the reaction has stopped completely.

What can you do to regain the activity of the enzyme?

The enzyme is inactive at this point. New enzyme must be added to regain enzyme activity.

You have an enzymatic reaction proceeding at the optimum pH and optimum temperature. You add a competitive inhibitor to the reaction and notice that the reaction slows down.

What can you do to speed the reaction up again?

Add more substrate; it will outcompete the inhibitor and increase the reaction rate.

In general, enzymes are what kinds of molecules?

proteins

Enzymes work by _____.

reducing activation energy

What name is given to the reactants in an enzymatically catalyzed reaction?

substrate

As a result of its involvement in a reaction, an enzyme ____

is unchanged

When substrate molecules bind to the active site of the enzyme, the enzyme undergoes a slight change in shape?

True

If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?

Nothing; the reaction will stay at equilibrium.

The active site of an enzyme is the region that

binds substrates for the enzyme.

Describe the induced fit model of enzyme activity

the binding of substrate changes the conformation of the active site to bind substrate more tightly

A noncompetitive inhibitor decreases the rate of an enzymatic reaction by

changing the shape of the enzyme active site.

A mutation results in an amino acid substitution at a site distant from the active site of an enzyme. How might this amino acid change alter the active site and substrate specificity of the enzyme?

by changing the conformation of the enzyme

Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions?

γ-phosphate (the terminal phosphate)

What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?  

hydrolysis        

What is the free energy change (ΔGΔG) of the hydrolysis of ATP to ADP?

The free-energy change (ΔGΔG) of the hydrolysis of ATP to ADP and P_i may vary considerably with variations in pH, temperature, atmospheric pressure, and concentrations of reactants and products.

The energy from the hydrolysis of ATP may be directly coupled to endergonic processes by the transfer of the phosphate group to another molecule?

True

The cycling between ATP and ADP + P_i provides an energy coupling between catabolic and anabolic pathways?

True

ATP serves as an energy shuttle in the cell, coupling exergonic and endergonic reactions?

True

ATP hydrolysis in a test tube releases only about half as much energy as ATP hydrolysis in the cell…

reactant and product concentrations in the cell are different from the standard conditions used in a test tube.

example of an exergonic reaction

hydrolysis of glycogen to release glucose monomers

example of a catabolic pathway

providing energy that can be used to drive cellular work

example of an anabolic pathway

a set of reactions that combine monomers into larger, more energy-rich polymers

Hydrolysis of ATP releases energy, which ultimately results in the production of ADP and inorganic phosphate. What generally happens to the inorganic phosphate produced in the cytosol?

it is combined with ADP to regenerate ATP.

The rate of the reaction is greater than when the same reaction occurs in the absence of an enzyme?

True

enzymes

macromolecules, protein, reuseable, catalysts that speed up reactions, tertiary shape must be maintained for functionality, have a region called an active site; can facilitate synthesis or digestion reactions, lower activation energy requirements

substrate

molecule that can interact with enzyme

active site

has a unique shape and size, may have a charge, physical and chemical properties of substrae must be compatible

energy etc

some reactions result in a net release of energy an d some result in a net absorption of energy; release of E requires less EA than absorption of E

saturation

initital substrate will increase reaction rate, but too much will fully saturate it and plateau the rate; more conc. of products decrease amount of substrate

all living things need…

input of energy (energy is lost naturally as heat)

living cells are not at…

equilibrium

organisms capture and store …

energy

electron transport chain

as e- pass through the e- transport chain, protons are actively transported across a membrane, creating a gradient

ATP synthase

proteins diffuse through this, which powers ATP synthesis

ATP has more potential energy than ADP?

True.

energy from catabolic/exergonic reactions makes…

ATP

consuming energy (food) forms…

ATP

ATP hydrolysis is a reaction

exergonic

metabolism

totality of an organisms chemical reactions

ATP is made up of

adenosine, ribose, triphosphate

induced fit

enzymes change shape

nonpolar side chains

hydrophobic

polar side chains

hydrophillic

acids charge

neg

bases charge

pos

open vs. isolated system

open exchanges energy with environment/surroundings while isolated does not

side chains interact with..

each other through hydrogen bonds, hydrophobic intercations, and ionic bonds to form a proteins 3D shape ; pH can alter the charge which can alter the shape

inhibitors must…

out compete the natural receptors

the rate of enzyme reaction does not increase indefinately as temp keeps rising?

true

low temp does not decrease enzyme catalyzed reaction rates by denaturing the enzyme ?

true

3 types of enrgy

chemical, heat, kinetic

less reacntant, more product

endergonic

ADP has less potential energy than ATP?

true

free energy

the amount of energy available for a thermodynamic system to perform thermodynamic work