Module 2.3: Cellular Metabolism

Question 1

In general how does ATP become ADP

Answer 1

When the terminal phosphate of an ATP molecule is split off, it leaves ADP and an inorganic phosphate and energy

Question 2

In order for glycolysis to begin what process needs to occur in order to supply the ATP

Answer 2

Substrate level phosphorylation. Creatine phosphate in cytosol is hydrolyzed, the energy it releases as well as the phosphate are used to create ATP.

Question 3

During substrate level phosphorylation what enzyme catalyzes the process of creating ATP

Answer 3

Creatine Kinase

Question 4

Describe glycolysis in general

Answer 4

It can occur anaerobically, has 10 steps that produce two pyruvic acid and 2NADH and two H+ and a net gain of two ATP

Question 5

What must happen to the pyruvic acid molecules that come from glycolysis before they can enter the citric acid cycle also known as the Krebs cycle

Answer 5

They need to be decarboxylated, have carbon removed

Question 6

What does decarboxylating the pyruvic acid do, and where does this take place

Answer 6

It forms CO2 and NADH, and converts the pyruvic acid into acetyl coenzyme a (acetyl CoA). It takes place in the mitochondrial inner membrane by pyruvate dehydrogenase complex

Question 7

In general describe the citric acid cycle

Answer 7

Takes place in the matrix of the mitochondria, and is an eight step process with many enzymes. Produces four CO2s, 6NADH, 8H+, 2FADH2, and 2ATP. There’s GTP and GDP in here somewhere too

Question 8

What is the key purpose of the citric acid cycle

Answer 8

To produce hydrogen ions for the electron transport chain

Question 9

The hydrogen ions produced in the citric acid cycle for the electron transport chain are carried by what molecules

Answer 9

NAD which is the B vitamin niacin, and FAD which is the B vitamin riboflavin

Question 10

Through the electron transport chain, does FADH or NADH produce more ATP, and why

Answer 10

NADH, because it enters the chain earlier than FADH. NADH enters at complex I, and produces 2.5 molecules of ATP, whereas FADH enters at complex II and produces 1.5 molecules of ATP

Question 11

What is the final electron acceptor in the electron transport chain, and what does it produce

Answer 11

Oxygen, and it combines with hydrogen ions to make H2O

Question 12

In the overall equation for respiration, oxygen breaks glucose apart and takes the stored energy, rearranging atoms into lower energy molecules that will be released. How can this be written simply

Answer 12

Glucose plus O2 = CO2 plus H2O. Written longhand it would be C6H1206+602 =6 CO2 +6 H2O

Question 13

Describe phosphorylation of ADP

Answer 13

A phosphate is added to ADP, making ATP. Endothermic

Question 14

Describe hydrolysis of ATP

Answer 14

Phosphate is removed by water, making ADP. Exothermic

Question 15

What charge does phosphate have

Answer 15

Negative

Question 16

What theoretical amount of ATP is produced by glycolysis, the citric acid cycle, and the electron transport chain, and what is the more realistic number

Answer 16

38 is the theoretical amount, and between 30 and 32 is the more realistic amount

Question 17

In general describe anaerobic metabolism

Answer 17

When there’s not enough oxygen present after glycolysis to form acetyl Koay, pyruvate is converted into lactic acid instead. It is not enter the mitochondria. This process consumes the NADH, and low amounts of ATP result.

Question 18

Give an example of when anaerobic metabolism is used in the body

Answer 18

Used by muscle during short bursts of strenuous exercise

Question 19

Once ATP is made, what is it used in the cell for

Answer 19

Synthesis of new chemical compounds such as proteins, membrane transport, and mechanical work such as muscle contraction