Chapter 25: Metabolism & Nutrition

Question 1

ATP

Answer 1

Provides and stores energy of cells (which consistently need energy for function).

It is the primary energy-carrying molecule of a cell!

Question 2

Metabolism

Answer 2

The sum of all the chemical reactions occurring within the cells of an organism.

Catabolism - take care of the food-to-energy breakdown.
Anabolism - use energy to synthesize larger molecules.

Question 3

Nutrients

Answer 3

Contained in everything we eat, and must break down in order to get into our cells as energy.

Question 4

Nutrient processing

Answer 4

Stage 1: nutrients from the GIT are absorbed and enter the blood stream to reach tissue cells

Stage 2: in the cytoplasm of tissue cells, the nutrients either break down further to harvest energy to form pyruvic acid and acetyl CoA (glycosides), OR, are used to build complex molecules (lipids, proteins, glycogen.)

Stage 3: in the mitochondria, oxygen completes the breakdown of food into CO2 and H2O, which creates ATP

Question 5

Carbohydrate metabolism

Answer 5

Carbohydrates are broken down into monosaccharides (glucose❗️, fructose, and galactose) (catabolism). Then energy from glucose is transferred to the ATP (anabolism)

Question 6

Cellular respiration

Answer 6

The process that releases energy from glucose and makes it available for cellular use.

Involves 4 sets of reactions:
1) Glycolysis
2) Formation of acetyl CoA
3) Krebs cycle
4) Electron transport chain (ETC)

Question 7

Glycolysis

Answer 7

Occurs in cell cytoplasm.

• Starts with 4 ATP, but used 2 to begin
• 1 glucose molecule (6C), breaks down into 2 pyruvic acids (3C each)
• during the process, glucose has lost 4 hydrogen atoms that now bind with 2 molecules of NAD+, which creates 2 NADH and 2H+ (which goes straight to the Electron Transport Chain).
• this process ends with a net gain of 2 ATP = 4 ATP total

Question 8

Aerobic / anaerobic processes

Answer 8

Aerobic = oxygen is required for reaction.

Anaerobic = oxygen in not required for reaction.

Question 9

Formation of Acetyl CoA

Answer 9

Occurs in mitochondrial matrix.

• pyruvic acids are converted into 2 acetyl CoA, and are brought into Krebs cycle.
• when entering the mitochondria, each pyruvic acid loses a CO2 molecule and a pair of H atoms. The H’s bind to NAD+ to make 2 NADH and 2H+ (these go straight to the Electron Transport Chain.

Question 10

Krebs cycle

Answer 10

Occurs in the mitochondrial matrix.

• is a cycle that must repeat twice per glucose since it is processing 2 acetyl CoA’s.
• 1 acetyl CoA produces: 2 CO2, 3 NADH, 1 FADH, and 1 ATP
• all products get taken to the Electron Transport Chain

Question 11

Electron transport chain (ETC)

Answer 11

Occurs in the cristae.

• NADH’s and FADH will donate their H ions and electrons.
• the electrons move through proton pumps and propel H ions out of the pump and into the inner membrane space.
  -these H ions will make a [ ] gradient and diffuse back into the matrix via the enzyme ATP synthase. This makes the ATP synthase spin and turn ADP into ATP.
• and the end of the ETC, the loose electrons will bind to a oxygen molecule and H ions to form water.

Total ATP per glucose = 30-32