Photosynthesis, Cellular Respiration, Enzymes

Question 1

Metabolism

Answer 1

Sum of an organism’s chemical reactions. Manages the material and energy resources of a cell.

Question 2

Catabolic pathway

Answer 2

Release of energy by breakdown of complex molecules. An example is digestive enzymes breaking down food.

Question 3

Anabolic pathway

Answer 3

Consume energy to build complex molecules from simple ones. An example is when your body links amino acids to form muscle in response to exercise.

Question 4

Energy

Answer 4

Capacity to do work

Question 5

Chemical energy

Answer 5

A form of potential energy that is stored in molecules. The amount of energy a molecule has depends on its bonds.

Question 6

First law of thermodynamics

Answer 6

States that the energy of the universe is constant. Energy can be transferred and transformed but not created or destroyed.

Question 7

Second law of thermodynamics

Answer 7

Every energy transfer or transformation increases the amount of entropy (disorder) in the universe.

Question 8

Free energy (delta G)

Answer 8

The part of a system’s energy that is able to perform work when the temperature is uniform

Question 9

Exergonic reaction

Answer 9

Energy is released spontaneously (may not be quick), G is negative.

Question 10

Endergonic reaction

Answer 10

Requires energy to proceed and absorbs free energy from the system. G is positive.

Question 11

Energy coupling

Answer 11

The use of an exergonic process to drive an endergonic one. A key way for cells to manage energy resources.

Question 12

ATP

Answer 12

A molecule made of 3 phosphate groups. When one is hydrolyzed energy is released in an exergonic reaction. This is used to do the endergonic work of the cell.

Question 13

ADP

Answer 13

When ATP transfers one phosphate group through hydrolysis.

Question 14

Substrate

Answer 14

Reactant that an enzyme acts on. Converted into products that are released from the enzyme.

Question 15

Catalysts

Answer 15

Substances that change the rate of a reaction without being altered in the process. They work by lowering the activation energy but without changing the free energy change.

Question 16

Active site

Answer 16

Part of the enzyme that binds to the substrate. They bind to form an enzyme substrate complex held together by weak interactions (hydrogen or ionic bonds).

Question 17

Cofactors

Answer 17

Nonprotein helpers. Called a coenzyme if organic (vitamins).

Question 18

What affects the activity of an enzyme?

Answer 18

1. Protein enzymes have a 3D shape that will be altered by changes in pH or temperature, causing it not to function effectively.
2. Many enzymes require cofactors to function properly (zinc, iron).
3. Competitive inhibitors reduce the efficiency of the enzyme.
4. Noncompetitive inhibitors inhibit enzyme activity by changing its shape.

Question 19

Competitive inhibitors

Answer 19

Compete with the substrate for the active site on the enzyme. Compete for the active site, and are chemically similar to the substrate.

Question 20

Noncompetitive inhibitors

Answer 20

Bind to another part of the enzyme, changing its shape.

Question 21

Allosteric site

Answer 21

Specific binding site, not the active site.

Question 22

How do enzyme regulators work?

Answer 22

Bind to an allosteric site, which changes the shape of the enzyme. This can either inhibit or stimulate enzyme activity.

Question 23

Feedback inhibition

Answer 23

The end product on an enzyme’s pathway can switch it off by binding to an allosteric site of an enzyme in the pathway.

Question 24

Oxidation-reduction reactions

Answer 24

Electrons are transferred from one reactant to another. Reactions of cellular respiration occur this way

Question 25

Oxidation

Answer 25

Loss of electrons from reactant, as well as energy.

Question 26

When does glucose lose electrons?

Answer 26

Throughout respiration. Each electron travels with a proton, which forms a hydrogen atom. Hydrogen atoms are passed to an electron carrier (coenzyme NAD).

Question 27

Glycolysis

Answer 27

1. Occurs in the cytosol. Glucose in broken into 2 pyruvate molecules (3 Carbon sugars).
2. There is an ATP consuming phase, where 2 ATP molecules are consumed to make glucose less stable and more reactive.
3. 4 ATP are produced (2 net ATP) as well as 2 molecules of NADH.

Question 28

What happens after glycolysis?

Answer 28

1. Pyruvate is oxidized. It becomes acetyl coA
2. A transport protein moves pyruvate into the mitochondria.
3. There, a CO2 molecule is removed, pyruvate loses electrons to convert NAD to NADH, and coenzyme A joins to form acetyl coA.

Question 29

Citric acid cycle

Answer 29

1. Occurs in the mitochondria
2. Glucose has been broken down completely and CO2 is released as a waste product.
3. Each cycle requires one acetyl CoA. 2 cycles are needed to oxidize glucose.
4. Total products: 4 CO2, 6 NADH, 2 FADH, 2 ATP
5. Energy is held in the electrons of the electron carriers, NADH and FADH.