Chapter 6

Question 1

Metabolism

Answer 1

The totality of an organisms chemical reactions (emergent properties)

Question 2

Metabolic pathway

Answer 2

A series of chemical reactions that either builds a complex (anabolic) or breaks down a complex (catabolic).

Question 3

What are the types of energy

Answer 3

Kinetic- energy associated with the relative motion of objects
Thermal energy- kinetic energy due to the random motion of atoms and molecules.
Potential energy- energy matter possesses as a result of its location.
Chemical energy- energy available in molecules for release in a chemical reaction (potential)

Question 4

Thermodynamics

Answer 4

Study of the energy transformations that occur in a collection of matter.

Question 5

Laws of thermodynamics

Answer 5

1. Energy can be transferred and transformed but never created or destroyed.
2. Energy transfer or transformation increases the entropy of the universe.

Question 6

Entropy

Answer 6

A measure of disorder or randomness (heat released)

Question 7

Spontaneous process

Answer 7

A process that occurs without an overall input of energy. It is energetically favourable.

Ex: gravity pushes ball down hill

Question 8

Free energy

Answer 8

The portion of a systems energy that can perform work when temperature and pressure are uniform throughout the system

Question 9

/\G=

Answer 9

G(final state) -G(initial state)

Question 10

If you have a -/\G what can be implied

Answer 10

• no input of energy needed
• spontaneous
• exergonic
• loses free energy
• final state more stable

Question 11

Where is the /\G value at equilibrium

Answer 11

The lowest G can be for the system

Question 12

A process is spontaneous and can perform work only when it’s moving ____

Answer 12

Towards equilibrium

Question 13

Exergonic reaction

Answer 13

Proceeds with a new release of free energy (negative G). Occurs spontaneously.

Question 14

Endergonic reactions

Answer 14

A non-spontaneous chemical reaction, in which free energy is absorbed from the surroundings

Question 15

Reactions in isolated system eventually reach____

Answer 15

Equilibrium

Question 16

What powers cellular work?

Energy coupling?

Answer 16

ATP- coupling exergonic reactions to endergonic reactions.

The use of an exergonic process to drive an endergonic one.

Question 17

Describe the hydrolysis process of ATP

Answer 17

Bonds between the phosphate groups are broken by hydrolysis or the addition of a water molecule. The Terminal phosphate is broken by this molecule. Exergonic reaction releases energy. All phosphate groups in ATP are negatively charged so the like charge repels. This makes it very unstable.

Question 18

If the /\G of a reaction is less than the amount of energy released from ATL hydrolysis what can happen?

Answer 18

Two reactions can be coupled to the overall they are exergonic. (Involves phosphorylation)

Question 19

Phosphorylated intermediates

Answer 19

A molecule (often reactant) with a phosphate group covalently bound to it, making it more reactive (less stable) than the unphosphorylated molecule.

Question 20

Hydrolysis leads to a change in _____ in proteins that enables its ability to _____

Answer 20

Shape, bind to another molecule

Question 21

Regeneration of ATP

Answer 21

Free energy required to phosphorylate ADP comes from exergonic breakdown reactants in the cell.

Question 22

Enzyme

Answer 22

A macromolecule that acts as a catalyst, a chemical agent that speeds up a reaction without being consumed by the reaction.

Question 23

Activation Energy

Answer 23

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

Question 24

How does heat help with reaching the activation energy barrier?

What is at the top of activation energy?

Answer 24

Thermal energy results in more collisions and the breaking of bonds.

Transition state

Question 25

Catalysis

Answer 25

A process by which a catalyst selectively speeds up a reaction without itself being consumed.

Question 26

How does an enzyme catalyze a reaction

Answer 26

Lowering the EA barrier

Question 27

Substrate

Answer 27

The reactant an enzyme acts on

Question 28

Enzyme substrate complex

Answer 28

A temporary complex formed when an enzyme binds to its substrate molecule.

Question 29

Active site

Answer 29

Pocket or groove on the surface of the enzyme where catalysis occurs. Typically formed by a few of the enzymes amino acids.

Question 30

Induced fit

Answer 30

Cause by the entry of the substrate, the change in shape of the active site of an enzyme so that it binds more snugly to the substrate.

Question 31

How many substrates can be turned to products per second per enzyme?

Answer 31

~1000

Question 32

What holds the substrate to the active site?

Answer 32

Weak interactions p, such as hydrogen bonds and ionic bonds

Question 33

How do enzymes lower activation energy

Answer 33

1. Orients substrates so that reaction can occur 2. Stretches/ bends substrate to break critical bonds 3. Provides microenvironment suitable for reaction 4. Brief covalent bonding between substrate and amino acid side chain helps with reaction.

Question 34

When talking about Enzymes what does saturation mean? How does a cell deal with saturation

Answer 34

As soon as the product exits an active site, another substrate enters. Cell makes more enzymes

Question 35

As temperature increases, enzyme reaction rates ______ Why?

Answer 35

Increase- causes more substrates to enter active sites. To a point!! Then the enzyme is desaturated at higher temps

Question 36

Cofactors

Answer 36

Any non protein molecule or ion that is required for the proper functioning of an enzyme. Can be permanently bound to the active site or may bind loosely and reversibly, along with the substrate during catalysis.

Question 37

Types of cofactors

Answer 37

Inorganic -zinc, iron Organic-vitamins Many are trace elements

Question 38

Enzyme inhibitors

Answer 38

Certain chemicals that selectively inhibit the action of specific enzymes. If Inhibitor attaches by covalent bond it is irreversible. Most are weak though. Can be toxins, poisons or antibiotics or naturally produced by cell to regulate metabolic activity.

Question 39

Competitive inhibitor

Answer 39

A substance that reduced the activity of an enzyme by entering the active site in place of the substrate, whose structure it mimics.

Question 40

Non competitive inhibitor

Answer 40

A substance that reduces the activity of an enzyme by binding to a location remote from the active site, changing the enzymes shape so that the active site no longer effectively catalyzes the conversion of substrate to product.

Question 41

Allosteric regulation

Answer 41

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

Question 42

How do molecules naturally regulate enzymes

Answer 42

By non competitive binding. They change enzyme shape and function at active site.

Question 43

Cooperativity

Answer 43

Kind of allosteric regulation whereby a shape change in one subunit of a protein causes by substrate binding is transmitted to all other subunits, facilitating binding of additional substrate molecules to those subunits.

Question 44

Feedback inhibitor

Answer 44

A metabolic pathway is halted by the inhibitory binding of its end product to an enzyme that acts early in the pathway.

Question 45

Is catalysis reversible?

Answer 45

Yes, but they mainly move in one direction because net direction always goes towards equilibrium.

Question 46

Changing confirmation of one active site of a multi subunit..

Answer 46

Changes confirmation of all subunits