BT Castella Cell Energy and Transport

or this reaction: ATP ADP + Pi (inorganic phosphate), ∆G =

-7.3kcal/mol; exergonic bc negative

What is ADP made up of?

2 phosphate groups, a ribose, and adenine .ADP + phosphate = ATP

What is a catalyst?

A chemical agent that speeds up a reaction with out being consumed by the reaction

Coenzyme

A coenzyme is an organic molecule serving as a cofactor. Most vitamins function as coenzymes in metabolic reactions.

Cofactor

A cofactor is an inorganic nonprotein molecule. Cofactors can be permanently bound to the active site or may bind loosely and reversibly, along with the substrate, during catalysis.

Explain the name ATP by listing all the molecules that make it up.

ATP has a sugar ribose, with the nitrogenous base adenine and a chain of three phosphate groups bonded to it, forming adenosine triphosphate.

Allosteric Regulation

Allosteric regulation is the binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site.

What effect does an enzyme have on EA?

An enzyme catalyzes a reaction by lowering EA barrier.

Which reactions require enzymes to catalyze reactions?

Anabolic

Enzymes use a variety of mechanisms to lower activation energy. Describe another one of these mechanisms.

As the active site of an enzyme clutches the bound substrate, the enzyme may stretch the substrate molecules toward their transition-state form, stressing and bending critical chemical bonds that must be broken during the reaction.

Which type of energy does mole of glucose have?

Chemical

List a kind of work that a cell does. Give an example of each.

Chemical work: he pushing of endergonic reactions that would not occur spontaneously, such as the synthesis of polymers from monomers

Competitive Inhibitor

Competitive inhibitors are substances that reduce the activity of an enzyme by entering the active site in place of the substrate, whose structure it mimics. inside of an active site

Enzymes use a variety of mechanisms to lower activation energy. Describe one of these mechanisms.

Direct participation of the active site in the chemical reaction is another mechanism of catalysis

Explain how protein structure is involved in enzyme specificity.

Enzymes are proteins, and proteins are macromolecules with unique three-dimensioal configuration. The specificity of an enzyme results from its shape, which is a consequence of its amino acid sequence. The specificity of an enzyme is attributed to a compatible fit between the shape of its active site and the shape of the substrate.

Is cellular respiration an endergonic or an exergonic reaction?

Exergonic

How will the bond in ATP break?

Hydrolysis

What is energy coupling?

In cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction.

Enzymes use a variety of mechanisms to lower activation energy. Describe four of these mechanisms.

In reactions involving two or more reactants, the active site provides a template on which the substrates can come together in the proper orientation for a reaction to occur between them.

How is ∆G affected by the enzyme?

It cannot make an endergonic reaction exergonic.

List one kind of work that a cell does. Give an example of each.

Mechanical work: beating of cilia, the contraction of muscle cells, and the movement of chromosomes during cellular reproduction

For an exergonic reaction, is ∆G negative or positive?

Negative

To summarize, if energy is released, ∆G must be what?

Negative because exergonic

Noncompetitive Inhibitor

Noncompetitive inhibitors are substances that reduce the activity of an enzyme by binding to a location remote from the active site, changing the enzyme's shape so that the active site no longer effectively catalyzes the conversion of substrate to product. goes into allosteric site

Name a human enzyme that functions well in pH 2. Where is it found?

Pepsin, found in the human stomach

Which type of energy does water behind a dam have?

Potential

Enzymes use a variety of mechanisms to lower activation energy. Describe a mechanism.

The active site may also provide a microenvironment that is more conducive to a particular type of reaction than the solution itself would be without the enzyme.

Allosteric Acvtivator

The binding of an activator to a regulatory site stabilizes the shape that has functional active sites

Recall that enzymes are globular proteins. Why can extremes of pH or very high temperatures affect enzyme activity?

Three-dimensional structures of proteins are sensitive to their environment. As a consequence, each enzyme works better under some conditions than other conditions, because these optimal conditions favor the most active shape for their enzyme molecule.

List one of the main kinds of work that a cell does. Give an example of each.

Transport work: the pumping of substances across membranes against the direction of spontaneous movement; possible examples include the sodium-potassium pump and proton pump

What effect does temperature of substrate have on the rate of an enzyme reaction?

Up to a point, the rate of an enzymatic reaction increases with increasing temperature, partly because substrates collide with active sites more frequently when molecules move rapidly. Above that temperature, however, the speed of the enzymatic reaction drops sharply.

What effect does pH have on the rate of an enzyme reaction?

With some exceptions, the optimal pH values for most enzymes fall in the range of pH 6-8.

What is activation energy (EA)?

amount of energy that reactants must absorb before a chemical reaction will start.

Photosynthesis

an anabolic reaction. plants absorb sunlight and convert it for energy; endergonic

Kinetic Energy

associated with relative motion of objects

What is free energy?

change of reaction that tells us if the reaction occurs spontaneously; this energy can do work when temperature and pressure are uniform (∆G)

Anabolic Reaction

consumes energy to build larger, complex molecules from simpler ones (needs energy), uphill reaction; endergonic

The change in free energy (∆G)

is related to the change in enthalpy, or change in total energy (∆H), and change in entropy (T∆S): ∆G = ∆H - T∆S

Metabolism

is the totality of an organism's chemical reactions; transforms matter and energy (laws of thermodynamics)

Potential Energy

non-kinetic energy due to location or structure

In many cellular reactions, a phosphate group is transferred from ATP to some other molecule in order to make the second molecule less stable. The second molecule is said to be

phosphorylated

When the terminal phosphate bond is broken, a molecule of inorganic phosphate P i is formed, and energy is

released

Catabolic Reaction

releases energy by breaking down complex molecules into simpler compounds (releases energy); exergonic

Processes with a negative ∆G are

spontaneous

Allosteric Inhibitor

the binding of an inhibitor stabilizes the inactive form of the enzyme.

What effect does initial concentration of substrate have on the rate of an enzyme reaction?

the higher the concentration the hight the enzyme will react

Cellular Respiration

this reaction releases energy so that the cell can use it for activities; exergonic

What is meant by induced fit?

when the enzyme changes shape to fit into the substrate