Unit 3: Cellular Energetics

Question 1

What is the active site? (when it pertains to biology)

Answer 1

The binding site of an enzyme, where the substrate binds.

Question 2

What is a substrate?

Answer 2

The chemical that an enzyme binds to and changes.

Question 3

What is an allosteric inhibitor?

Answer 3

A chemical that binds to an enzyme (can be on or off the active site), and inhibits enzyme function.

Question 4

What is an allosteric enhancer?

Answer 4

A chemical that binds to an enzyme, and increases enzyme function.

Question 5

True or False; Not all metabolic reactions that occur within a cell involve energy.

Answer 5

False; All metabolic reactions involve a transfer of energy.

Question 6

What is cellular respiration?

Answer 6

The process of converting glucose into carbon dioxide and water, while releasing energy in the process.

Question 7

What are the stages of cellular respiration?

Answer 7

Glycolysis, the Krebs Cycle, and the Electron Transport Chain.

Question 8

What is glycolysis?

Answer 8

Essentially, it is the conversion of glucose into pyruvic acid (or pyruvate), releasing a small amount of ATP in the process.

Question 9

True or False: Glycolysis is anearobic.

Answer 9

True!

Question 10

What is produced from glycolysis?

Answer 10

Two pyruvate, a net gain of two ATP (four were used), and NADH molecules.

Question 11

What happens if there is no oxygen available to a cell?

Answer 11

The cell goes from glycolysis, to anaerobic fermentation, converting pyruvate into either lactic acid (animals), ethanol, acetone, or some other chemical. This allows the cell to continue running glycolysis, albeit temporarily, by recycling NADH.

Question 12

What is the chemical formula for cellular respiration?

Answer 12

Csub6Hsub12Osub6 + Osub2 —> COsub2 + Hsub2O (+ ATP)

Question 13

What is the Krebs Cycle?

Answer 13

Pyruvic acid is converted to Acetyl CoA, which is converted to citric acid, and back to Acetyl CoA, in a cyclical fashion, producing much ATP. The cycle continues for as long as Acetyl CoA is added to the cycle.

Question 14

What is produced by the Krebs Cycle?

Answer 14

ATP, NADH, FADHsub2, and COsub2

Question 15

What happens with the Electron Transport Chain?

Answer 15

NADH and FADHsub2 are changed into NAD+ and FAD, as they donate electrons to the cytochromes (the electron receiving proteins embedded in the membrane of the mitochondria), moving protons against the concentration gradient into the intermembrane space. The protons move back into the cell through the enzyme ATP synthase; This movement powers the enzyme, allowing it to take ADP and P and turn it into ATP synthase.

Question 16

What happens if there is no oxygen available to the mitochondria?

Answer 16

The electron at the end of the Electron Transport Chain won’t be removed, because there is nothing to receive it. This will back up production, and stop up the Krebs Cycle.

Question 17

What is the chemical formula for photosynthesis?

Answer 17

6Hsub2O + 6COsub2 = Csub6Hsub12Osub6 + 6Osub2

Question 18

What are the two stages of photosynthesis?

Answer 18

The light dependent reactions, and the light independent reactions.

Question 19

What occurs in the light dependent stage?

Answer 19

Photons of light strike the photosystems, exciting the electrons and creating/releasing enough energy to free one electron, which jumps down a chain of proteins, like with the Electron Transport Chain, pumping in protons. The protons leave through the ATP synthase embedded in the walls of the thylakoid, which powers the enzyme and creates ATP. Water is split, creating protons, and adding electrons to the chlorophyll. Some of the components of the split water are also used to create NADPH.

Question 20

What are the products of the light-dependent stages?

Answer 20

ATP, oxygen, protons, NADPH.

Question 21

What occurs in the light independent stage? (also known as the Calvin Cycle)