3.5 Physiology of the GI Tract- Cell Metabolism

Question 1

Metabolism

Answer 1

a set of chemical reactions that are essential for the body to sustain life

Question 2

Anabolism

Answer 2

the set of reactions in which smaller molecules are combined to make larger, more complex molecules

Question 3

Catabolism

Answer 3

the set of reactions in which larger molecules are broken down to be used as energy sources for the body

Question 4

Adenosine triphosphate (ATP)

Answer 4

Most widely used form of energy in the cells
- ATP has energy to donate

Question 5

Adenosine diphosphate (ADP)

Answer 5

• one less phosphate group than ATP
• ADP can accept energy (phosphate group) to become ATP

Question 6

Cellular respiration

Answer 6

the process by which cells generate ATP

Question 7

Aerobic respiration

Answer 7

• function that most organisms carry out
• requires oxygen and a fuel (glucose)
• releases carbon dioxide, water, and ATP

Question 8

Carbohydrates

Answer 8

• main source of energy for cells with the body
• digests carbohydrates into glucose

Question 9

Glucose metabolism

Answer 9

• used by the body primarily during high energy demands
• glucose is one of the most abundant biomolecules
• the catabolism of glucose is an important metabolic pathway used by microorganisms for ATP production
• complete catabolism of a single molecule of glucose (C6H12O6) yields up to 38 ATP with three distinct transitions:
• glycolysis
• cellular respiration
• the electron transport chain

Question 10

Glycolysis

Answer 10

• process of breaking down a 6-carbon molecule of glucose into two 3-carbon molecules of pyruvate
• process yields 2 molecules of ATP per molecule of glucose

Question 11

Cellular respiration

Answer 11

• an aerobic process (oxygen must be present)
• used by cells to produce energy

Question 12

Tricarboxylic acid (TCA cycle)

Answer 12

• also known as the Krebs Cycle or the citric acid cycle
• central pathway of respiration
• pyruvic acid (product of glycolysis) is converted to carbon dioxide forming 2 ATP
• (one ATP for each pyruvate processed) and an abundance of electron carriers: NADH and FADH2
• primary function of TCA cycle is the production of NADH & FADH2
• transfer of NADH & FADH2 will fuel the generation of ATP via the electron transport system

Question 13

Mitochondria

Answer 13

Respiration takes places in and around this double sided organelle

Question 14

Fermentation

Answer 14

Takes place in the absence of oxygen

Question 15

Electron transport chain

Answer 15

continuation of cellular respiration

Question 16

Complete catabolism of glucose

Answer 16

yields 2 ATP from glycolysis, 2 ATP from the TCA cycle and 34 ATP from the electron transport system, for a total of 38 ATP from a single glucose molecule

Question 17

Proton motive force

Answer 17

• drives H+ back through the ATP synthase complex
• located in the membrane
• production of up to 34 molecules of ATP

Question 18

Lipid metabolism

Answer 18

• occurs in the liver by a process known as beta-oxidation
• used by the body primarily during low energy activities
• yields twice the amount of ATP than when a carbohydrate or protein is broken down

Question 19

Protein metabolism

Answer 19

• only takes place when carbohydrates and fats are unavailable to the body
• proteins are the building blocks for the cells
• saved as a last resort

Question 20

Ammonia

Answer 20

Product formed when protein is used for ATP as the amino group is removed from the protein
- harmful to the body and must be converted into a different form
- usually combined with CO2 in the liver to create urea

Question 21

Urea

Answer 21

• ammonia + carbon dioxide combined in the liver
• excreted from the body in the urine