Energy Metabolism

Question 1

How does the body extract energy from carbs?

Answer 1

Anaerobic and Aerobic pathways

Question 2

How does the body extract energy from fats?

Answer 2

Beta-oxidation

Question 3

How does the body extract energy from proteins?

Answer 3

Deamination

Question 4

Catabolism

Answer 4

Metabolic reactions break down molecules to extract energy

Question 5

Anabolism

Answer 5

Metabolic reactions synthesize building blocks to produce new molecules

Question 6

Carb usual energy from 4 pathways

Answer 6

1. Glycolysis- cytosol
2. Pyruvate to acetyl CoA- Mitochondria
3. Citric Acid Cycle- Mitochondria
4. ETC- Mitochondria

Question 7

Glycosis- Glucose splitting

Answer 7

One six-carbon glucose molecule into two three-carbon pyruvate molecules

Question 8

Where does glycolysis occur?

Answer 8

Cytosol

Question 9

How much ATP does glycolysis use and produce?

Answer 9

Uses 2 ATP and Produces 4 ATP = 2 net ATP

Question 10

Pyruvate to Lactate

Answer 10

When O2 is in short supply, pyruvate forms lactate

Question 11

Lactate

Answer 11

Alternative fuel that muscle cells can use or that the liver cells can convert to glucose through anaerobic pathways

Question 12

Why Lactation?

Answer 12

Speed! Making ATP in the liver is very quick due to glycolysis

Question 13

Pyruvate to Acetyl CoA

Answer 13

Two pyruvate molecules from 1 molecule of glucose, produce two acetyl CoA molecules

Question 14

Why is Pyruvate to Acetyl CoA irreversible?

Answer 14

Acetyl CoA cannot exit via the mitochondrial membrane & enters the citric acid cycle in the mitochondria

Question 15

Citric Acid Cycle

Answer 15

Acetyl CoA combines with oxaloacetate to form citrate and release coenzyme A. The two carbon atoms from acetyl CoA combine with O2 to form CO2

Question 16

What does the Citric Acid Cycle produce?

Answer 16

1. One guanosine triphosphate (GTP)
2. Transfer pairs of high energy electrons to 3 molecules of NAD+ and 1 molecule of FAD
3. Oxaloacetate is regenerated
   One glucose molecule produces two acetyl CoA molecules, the citric acid cycle occurs twice

Question 17

Electron Transport Chain

Answer 17

• NADH AND FADH2 deliver their cargo of high-energy electrons to the ETC
• As electrons travel along the ETC they give up energy to power the production of ATP

Question 18

What is at the end of the ETC?

Answer 18

An oxygen “basket” accepts the energy-depleted electrons and combines them with hydrogen to form water

Question 19

What if there was no oxygen for the ETC to use?

Answer 19

ATP production would stop halting the supply of power for our body’s essential functions

Question 20

How do electrons travel along the ETC?

Answer 20

They move from higher to lower energy levels, releasing energy

Question 21

How is an electrochemical gradient created in the ETC?

Answer 21

Some of the energy that is released is used to pump H+ ions out of the matrix and into intermembrane space, establishing an electrochemical gradient due to charge

Question 22

Where do the H+ ions in the ETC go?

Answer 22

H+ ions flow down the gradient powering ATP synthase

Question 23

Beta-oxidation of fatty acids

Answer 23

Acetyl CoA enters the Citric acid cycle to generate NADH and FADH2 for transferring pairs of high energy electrons to ETC to fuel ATP synthesis in the mitochondria

Question 24

How do fatty acids travel across the mitochondria membrane?

Answer 24

Carnitine transport

Question 25

Extracting Energy from Proteins

Answer 25

During starvation, the body breaks down protein and extracts energy from the amino acids

Question 26

Deamination

Answer 26

Deamination strips down the amino acid to a “carbon skeleton” while producing nitrogen byproduct that becomes urea

Question 27

End Products of Amino Acid Catabolism

Answer 27

The carbon skeleton’s point of entry to the breakdown pathways determines the amount of ATP it produces (the sooner, the better)

Question 28

What does the complete breakdown of amino acids yield?

Answer 28

Urea, carbon dioxide, water, and ATP

Question 29

How is metabolism related to respiration?

Answer 29

The Respiratory Quotient (RQ) is an index of which nutrients are being used by the body to generate ATP

Question 30

What is the respiratory quotient?

Answer 30

The volume of carbon dioxide exhaled divided by the volume of the oxygen used

Question 31

RQ for carbs?

Answer 31

1.0

Question 32

RQ for protein?

Answer 32

0.8

Question 33

RQ for fats?

Answer 33

0.7

Question 34

Why is the RQ for fats and amino acids less than 1?

Answer 34

They require more O2 to produce CO2 and H2O

Question 35

What does anaerobic metabolism use?

Answer 35

Glucose and Glycogen, requiring less O2, increasing RQ value

Question 36

What does aerobic metabolism due?

Answer 36

Breakdown of fats and protein, requiring more O2, decreasing RQ value

Question 37

How is Creatine (Phosphate) made?

Answer 37

Made from amino acids (glycerine)

Question 38

Where is Creatine (Phosphate) synthesized?

Answer 38

Liver

Question 39

Where is Creatine (Phosphate) stored?

Answer 39

Muscle (~94%)

Question 40

How is Creatine (Phosphate) excreted?

Answer 40

The kidneys (creatinine)