Lecture 10

Question 1

Kreb’s Cycle
Net (For each (blank))
3 NADH + H+
1 FADH2
2 CO2
1 ATP
X2 for glucose or Glycogen

Answer 1

acetyl CoA

Question 2

32 to 33 molecules ATP for every glucose molecule

-about 35-40% (blank)

Answer 2

efficiency

Question 3

Oxidation of Fat
•(blank): major fat energy source
– Broken down to 1 glycerol + 3 FFAs
– Lipolysis, carried out by lipases
• Rate of FFA entry into muscle depends on (blank)
• Yields ~3 to 4 times (blank) ATP than glucose
• Slower than glucose oxidation

Answer 3

triglycerides

concentration gradient

more

Question 4

Fatty Acid (FA) Metabolism
• Break down of FFA to form reducing equivalents and (blank)
• 2 sources of FFA
– Adipose cell triacylglycerides
– Intramuscular triacylglycerides

Answer 4

acetyl CoA

Question 5

(blank) is the process by which fatty acids, in the form of Acyl-CoA molecules, are
broken down in mitochondria to generate Acetyl Co-A, the entry molecule for the Kreb’s Cycle.
• It occurs in many tissues including liver, sk.ms and heart.
• Fatty acid oxidation doesn’t occur in the (blank), as fatty acid can’t be taken up by that organ.

Answer 5

beta-oxidization

brain

Question 6

The beta oxidation of fatty acids involve three stages:

1. Activation of (blank) in the cytosol
2. Transport of activated fatty acids into mitochondria (carnitine shuttle)
3. Beta oxidation proper in the mitochondrial (blank)

Answer 6

fatty acids

matrix

Question 7

Fatty Acids must be linked to Coenzyme A Before They Are (blank) in the mitochondria

Answer 7

oxidized

Question 8

• Entry of FA into mitochondria regulated by (blank)
• CPT1 is believed to be rate determining for FA
oxidation

Answer 8

CPT1

Question 9

β-Oxidation of Fat
• Process of converting (blank) to acetyl-CoA before entering Krebs cycle (fatty acid activation)
• Requires up-front expenditure of 2 ATP
• Number of steps depends on number of carbons on FFA
– 16-carbon FFA yields 8 acetyl-CoA
– Compare: 1 glucose yields 2 acetyl-CoA
– Fat oxidation requires more O2 now, yields
far more ATP later

Answer 9

FFA’s

Question 10

Oxidation of Fat:
Krebs Cycle, Electron Transport Chain
• Acetyl-CoA enters Krebs cycle
• From there, same path as (blank)
• Different FFAs have different number of (blank)
– Will yield different number of acetyl-CoA molecules
– ATP yield will be different for different FFAs
– Example: for palmitic acid (16 C): 106 ATP
net yield

Answer 10

glucose oxidization

carbons

Question 11

The β oxidation pathway is (blank). The product, 2 C shorter, is the input to another round of the pathway.
If the fatty acid contains an even number of Catoms, the final reaction cycle (for which the substrate is butyryl-CoA) yields 2 copies of acetyl CoA

Answer 11

cyclic

Question 12

(blank) is converted to the Glycolysis intermediate glyceraldehyde 3- Phosphate, by reactions catalyzed by:

Answer 12

glycerol

Question 13

• Once FFA reach the muscle they must be actively transported into the mitochondria
• FFA cannot cross mitochondrial (blank)
• A series of reactions allow FFA to be transported

Answer 13

membrane

Question 14

Beta-oxidization

Each “Turn” 
– (blank) 2C
– 1 Acetyl CoA
– 1 NADH
– 1 FADH2
• This process repeats until FA CoA has been totally 
broken into 2C acetyl CoA molecules

Answer 14

removes

Question 15

Substrate metabolism efficiency
– 40% of substrate energy = (blank)
– 60% of substrate energy = (blank)

Answer 15

ATP

heat

Question 16

(blank) Calorimetry
• Pros
– Accurate over time
– Good for resting metabolic measurements
• Cons
– Expensive, slow
– Exercise equipment adds extra heat
– Sweat creates errors in measurements
– Not practical or accurate for exercise

Answer 16

direct

Question 17

(blank) Calorimetry
• Estimates total body energy expenditure based on O2
used, CO2 produced
– Measures respiratory gas concentrations
– Only accurate for steady-state oxidative metabolism
• Older methods of analysis accurate but slow
• New methods faster but expensive

Answer 17

indirect

Question 18

V•O2: volume of O2 (blank) per minute
– Rate of O2 consumption
– Volume of inspired O2 −volume of expired O2

V•CO2: volume of CO2 (blank) per minute
– Rate of CO2 production
– Volume of expired CO2 −volume of inspired CO2

Answer 18

consumed

produced

Question 19

(blank) Exchange Ratio
• O2 usage during metabolism depends on type of fuel being oxidized
– More carbon atoms in molecule = more O2 needed
– Glucose (C6H12O6) < palmitic acid (C16H32O2)
• Respiratory exchange ratio (RER)
– Ratio between rates of CO2 production, O2 usage
– RER = V
• CO2/V• O2

Answer 19

respiratory

Question 20

Indirect Calorimetry (blank)
• CO2 production may not = CO2 exhalation
• RER inaccurate for protein oxidation
• RER near 1.0 may be inaccurate when lactate buildup is higher than CO2 exhalation
• Gluconeogenesis produces RER <0.70

Answer 20

limitations

Question 21

Isotopic Measurements
• Isotope: element with (blank) atomic weight
– Can be radioactive or nonradioactive
– Can be (blank) throughout body
• 13C, 2H (deuterium) common isotopes for studying energy metabolism
– Easy, accurate, low-risk study of CO2 production
– Ideal for long-term measurements (weeks)

Answer 21

atypical

traced

Question 22

Basal Metabolic Rate
• Basal metabolic rate (BMR): rate of energy expenditure at (blank)
– In supine position
– Thermo(blank) environment
– After 8 h sleep and 12 h fasting
• Minimum energy requirement for living
– Related to fat-free mass (kcal kg FFM-1 min-1)
– Also affected by body surface area, age, stress, hormones, body temperature

Answer 22

rest

neutral

Question 23

Resting metabolic rate (RMR)= Resting Energy Expenditure (REE)
– Similar to BMR (within 5-10% of BMR) but easier
– Doesn’t require stringent standardized (blank)
– 1,200 to 2,400 kcal/day
• Total daily metabolic activity
– Includes normal daily (blank)
– Normal range: 1,800 to 3,000 kcal/day
– Competitive athletes: up to 10,000 kcal/day

Answer 23

conditions

activites

Question 24

RER – gives us an idea of the type of food substrate being oxidized
Based on indirect calorimetry which measures the CO2 released and
the O2 consumed. RER = VCO2/VO2
BMR – basal metabolic rate reflects the minimum amount of energy
required (i.e. energy expenditure) to carry out essential physiological
function. Also measured by indirect calorimetry but
must be measured under strict conditions.
RMR – resting metabolic rate doesn’t require the stringent conditions.
(it is very close – within (blank)% of the BMR- with BMR being slightly
Lower)

Answer 24

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