Lecture 5: Energy Metabolism and Calorimetry

Question 1

catabolism

Answer 1

metabolic reactions that break down molecules to extract energy

Question 2

anabolism

Answer 2

metabolic reactions that synthesize building blocks to make new molecules

Question 3

chemical energy

Answer 3

energy contained in the bonds between atoms of a molecule

Question 4

4 pathways to extract energy from carbs

Answer 4

• glycolysis
• pyruvate to CoA
• the citric acid cycle
• the electron transport chain

Question 5

glycolysis

Answer 5

one 6-C glucose molecule is split into 2 3-C pyruvate molecules

• occurs in the cytosol, does not require oxygen
• uses 2 atp and produces 4 atp
• transfers high energy electrons to NAD+ shuttle molecules

Question 6

products of glucose breakdown

Answer 6

ATP, water and carbon dioxide

Question 7

NADH and FADH2

Answer 7

electron couriers that transport high energy electrons (taken from breakdown of glucose) to be later used for ATP synthesis

Question 8

What happens to pyruvate in the presence of and without oxygen?

Answer 8

with oxygen: pyruvate to Acetyl CoA (1 pyruvate molecule=1 acetyl Coa molecule)
w/o O2: pyruvate to lactate (can be stored in the liver to make glucose again later)

Question 9

where does acetyl CoA go once it’s produced?

Answer 9

It’s stuck in the mitochondria and so it has to enter the citric acid cycle in the mitochondria.

Question 10

products of the citric acid cycle

Answer 10

• 1 GTP (guanosine triphospate)
• electrons pairs: 3 for NAD+ and 1 for FAD
• CO2
• oxaloacetate combines with acetyl CoA and then is released again to repeat the cycle

Question 11

electron transport chain

Answer 11

NADH and FADH2 collect their energized electrons to transport them to somewhere in the mitochondria whee they can make ATP from ADP and another phosphate. when the electrons have given up their power, they go to an oxygen “basket” and are combined with hydrogen to form water.

Question 12

where does beta-oxidation (breakdown) of fatty acids take place?

Answer 12

in the mitochondria

Question 13

lipase digestion of lipids produces what?

Answer 13

glycerol and free fatty acids

Question 14

how do you extract energy from proteins?

Answer 14

deamination: strips down the amino acid to a carbon skeleton. byproduct is N, which becomes urea and is excreted in urine. type of carbon skeleton determines how much ATP you get.

Question 15

what do free fatty acids break down into?

Answer 15

snipped in two to form acetyl CoA, which enters the Krebs cycle. high energy electrons transported to form ATP.

Question 16

calorie

Answer 16

heat needed to raise 1 kg of water from 0 C to 1C

Question 17

RQ

Answer 17

respiratory quotient. indirect calorimetry. volume of CO2 exhaled divided by volume of O2 breathed in. RQ is different for different macronutrients.

Question 18

doubly labeled water

Answer 18

indirect calorimetry. you basically lace water with radioactive isotopes and see how much H and O you lose in your urine to find CO2.

Question 19

heart rate as indicator of energy expenditure

Answer 19

indirect calorimetry.

Question 20

direct calorimetry

Answer 20

• put someone in a box and measure different in heat of water entering and exiting the chamber
• bomb calorimeter: combust food and see how much heat is produced.

Question 21

wilbur atwater

Answer 21

• first guy to measure calories w RQ and the box
• did it for a bunch of different foods
• “father of nutritional science”
• 1844-1907
• controversy with alcohol

Question 22

amount of energy absorbed from various macronutrients depend on their…

Answer 22

digestibility (intake - fecal excretion / intake)