Lecture 18: Principles Of metabolism

Question 1

Anabolism does what?

Answer 1

Use the energy harvested from catabolism to drive the synthesis of many molecules that form the cell.

Question 2

Use the energy harvested from catabolism to drive the synthesis of many molecules that form the cell, is what?

Answer 2

Anabolism.

Question 3

What is oxidation?

Answer 3

When the energy from organic molecules is extracted.

Question 4

When the energy from organic molecules is extracted, is what?

Answer 4

Oxidation.

Question 5

What is aerobic respiration?

Answer 5

When cells allow carbon and hydrogen atoms to combine to make H20 and CO2 to obtain energy.

Question 6

When cells allow carbon and hydrogen atoms to combine to make H20 and CO2 to obtain energy.

Answer 6

Aerobic respiration.

Question 7

What is the most energetically stable form of carbon and hydrogen?

Answer 7

CO2 and H20

Question 8

Describe the relationship between oxidation and reduction.

Answer 8

They occur simultaneously. If one molecule gains an electron, another one loses an electron.

Question 9

When a molecule picks up an electron, what does it also do?

Answer 9

It also picks up a proton, since protons are freely available in water.

Question 10

What are the important carrier molecules?

Answer 10

NADH, NADPH, ATP.

Question 11

Catabolic pathways do what?

Answer 11

They break down food molecules into smaller molecules.

Question 12

How is ATP synthesized? Is this favorable or unfavorable?

Answer 12

When a terminal phosphate is added to ADP, this is energetically unfavorable.

Question 13

They break down food molecules into smaller molecules, is what?

Answer 13

Catabolism.

Question 14

What are the two opposing streams of reactions that take place in cells?

Answer 14

Catabolic pathways and anabolic pathways.

Question 14

When the phosphoryl group of ATP is transferred between molecules to release the energy contained in the high energy bonds of ATP, is what?

Answer 14

Phosphoryl-transfer reaction.

Question 15

If C-H bonds increases, this is reduction or oxidation?

Answer 15

Reduction.

Question 16

What do activated carrier molecules do?

Answer 16

They store and transfer energy.

Question 17

For metabolism, what stores and transfers energy?

Answer 17

Activated carrier molecules.

Question 18

True or false: ATP is the only carrier molecule that contains high energy phosphoryl bonds.

Answer 18

False. Other molecules, like phosphoenolpyrivate and creative phosphate also have high energy phosphoryl bonds.

Question 20

What is absolutely needed for cell metabolism, and why?

Answer 20

Enzymes are absolutely needed, because they catalyze the rates of reactions within the cell.

Question 21

Why is ATP an energy rich molecule?

Answer 21

It has two high-energy phosphoanhydride bonds.

Question 22

How is ATP hydrolyzed? Is this energetically favorable or unfavorable?

Answer 22

ATP is hydrolyzed when the terminal phosphoanhydride bond is hydrolyzed to make ADP and P/inorganic phosphate.

Question 23

How are unfavorable metabolic reactions driven?

Answer 23

By coupling them with the hydrolysis of ATP.

Question 23

Is the NAD+ to NADH ratio kept high or low, and why?

Answer 23

The ratio is kept high, so there’s a lot of NAD+ to be an oxidizing agent in catabolic pathways.

Question 24

What keys points about how energy is stored by activated carrier molecules?

Answer 24

• they are stored in one or more energy-rich covalent bonds
• they are stored in an easily exchangeable form, either as a transferable chemical group or electrons at a high energy level.

Question 25

If C-H bonds decreases, this is reduction or oxidation?

Answer 25

Oxidation.

Question 26

NADH, NADPH, ATP, are examples of what?

Answer 26

Carrier molecules.

Question 29

In addition to the hydrolysis of ATP, what other mechanism drives transfer of energy within cells?

Answer 29

Phosphoryl transfer reactions.

Question 30

What is a phosphorylating transfer reaction?

Answer 30

When the phosphoryl group of ATP is transferred between molecules to release the energy contained in the high energy bonds of ATP.

Question 31

How are unfavorable condensation reactions forced to occur?

Answer 31

By phosphoryl transfers.

Question 32

Is the ratio of NADP+ to NADPH kept high or low, and why?

Answer 32

The ratio is kept low, so that there is a lot NADPH to act as a reducing agent in anabolic pathways.

Question 33

How does the extra phosphate differentiate NADH from NADPH?

Answer 33

The extra phosphate group is far from the region involved in electron transfer so there’s no effect on the electron-transfer properties, but it does affect how it is recognized differently by enzymes than NADH.

Question 34

NADH is used for what? NADPH is used for what?

Answer 34

NADH is used as an intermediate in catabolic pathways to generate ATP, NADPH is used to catalyze anabolic reactions.

Question 35

What is phosphoryl transfer potential?

Answer 35

The energy stored in a phosphoryl bond.