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You can generate about ____ kcals of energy per mole of ATP
Where does ATP fall on the spectrum of substances that produce a high/low energy yield and substances that are easy/hard to synthesize?
ATP falls in the middle b/w how much energy you get from it and how hard it is to synthesize
What is the immediate primary source of energy?
anaerobic hydrolysis of ATP and rephosphorylation of ADP by creatine phosphate & other enzyme systems
Where does the immediate source of energy generation take place?
Which primary energy source is used to sustain sudden, explosive muscular contraction for a few seconds?
What is the nonoxidative or glycolytic pathway?
catabolism of glucose or glycogen with a net accumulation of lactic acid
(fat & protein can't be used in this pathway)
Where does the glycolytic primary source of energy generation occur?
Which primary energy source is used to sustain rapid, high intensity muscular contractions for 15-30 seconds?
What is the oxidative pathway?
catabolism of carbs, fat and proteins
Where does the oxidative source of energy production occur?
Which energy source is primary for long duration muscular contraction (>1 min)?
What are the 3 enzyme systems involved in the immediate primary energy source?
1. hydrolysis of intramuscular ATP via ATPases
2. phosphocreatine system (ATP-PCr)
3. adenylate kinase/myokinase system (ADP + ADP -> ATP + AMP)
-technically can be aerobic or anaerobic
-10-12 enzyme rxns are required to catabolize glucose & glycogen into ATP
-w/in the glycolytic system, this process is anaerobic
synthesis of glycogen fro glucose for storage in liver & muscle
glycogen is broken into glucose-1 phosphate for use by muscles
synthesis of glucose from pyruvate or lactate, occurs in liver or kidneys
Input & output of glycolysis
1 glucose or glycogen is broken down into 2 pyruvate
byproducts: 2 NADH and 2 or 3 ATP
What is the rate limiting enzyme of glycolysis?
Net energy yield of glucose vs glycogen in glycolysis
Glucose: 2 ATP
Glycogen: 3 ATP
(both processes yield 4 ATP, but 2 are consumed w/ glucose and 1 is consumed w/ glycogen)
What happens to pyruvate and NADH produced by glycolysis?
: transported to mitochondria, NADH shuttles H+ and an electron to the ETC, pyruvate is converted to acetyl-CoA & enters TCA cycle
: NADH is converted to NAD+ by reducing pyruvate to lactate
Is oxygen needed for glycolysis?
no, but its presence determines the fate of pyruvate generated in glycolysis
Accumulation of ___________ inhibits ATP re-synthesis
Benefits of lactate
-links aerobic & anaerobic metabolism
-shuttles NADH & electrons to mitochondria
-helps regulate glucose levels
-stimulates mitochondrial biogenesis
T/F: lactate causes fatigue & soreness
T/F: lactate inhibits ATP formation
What is the fuel source of choice for heart and red skeletal muscle?
Both pyruvate & lactate can be shuttled to other cells/organs and into the mitochondria for:
use as an energy source
(lactate is actively oxidized to pyruvate in working muscle)
Both pyruvate & lactate can circulate to the liver for:
(Cori & glucose-alanine cycles)
What is the purpose of the Cori and glucose-alanine cycles?
help regulate blood glucose levels when circulating blood glucose is low
Is the glycolytic or oxidative system faster?
Which generates more ATP?
glycolytic is faster
oxidative generates much more energy
Is the glycolytic or oxidative pathway the primary means of energy production for low intensity, long duration activities?
In the oxidative pathway, pyruvate is converted to ___________ via which enzyme?
pyruvate dehydrogenase (PDH)
Which enzyme regulates lactate production, generates NADH and CO2 and is often deficient in neurodegenerative diseases?
pyruvate dehydrogenase (PDH)
What is the difference b/w NADH and FADH?
where they enter the ETC and how that affects their ATP yield
-NADH generates 3 ATP
-FADH generates 2 ATP
Where is the electron transport chain located?
inner membrane of mitochondria
In the ETC, H+ are pumped from the mitochondrial matrix to:
the intermembrane space
(a higher concentration of H+ in this space represents potential energy that is harnessed to generate ATP via ATP synthase)
The ETC uses hydrogen-electron pairs harvested from:
NADH & FADH
End byproducts of ETC
CO2 & O2
Net energy yield from the oxidative system
Glycolysis: 8 ATP
(2 ATP, 2 NADH)
Acetyl-CoA: 6 ATP
TCA Cycle: 24 ATP
(2 ATP, 6 NADH, 2 FADH)
Total: 38 ATP if glucose or 39 ATP if glycogen
Which fuel source is abundantly available and highly efficient?
Which fuel source is slow to activate?
fat, also proceeds more slowly than carb metabolism
T/F: carb & lipid metabolism can occur both aerobically and anaerobically
fat metabolism only occurs via aerobic processes
6 Key Events of Lipid Metabolism
1. mobilization- get it out of adipose tissue
2. circulation- transport from tissue to sarcolemma
3. uptake- transport over sarcolemma
4. activation- activate LCFA
5. translocation- transport into mitochondria
6. beta oxidation (TCA & ETC)
hydrolysis of triglyceride into glycerol & FFA
Triglycerides circulate within:
FFA circulate bound to:
ATP is used to esterify FFAs to ____________ which is then translocated across the inner mitochondrial membrane for oxidation
(esterification takes place in cytosol)
What happens in beta oxidation?
-pairs of carbon atoms are cleaved from fatty acyl CoA yielding acetyl CoA
-each acetyl CoA molecule fuels the TCA cycle and ETC
What is another name for beta oxidation?
fatty acid spiral
_____________ oxidation requires more oxygen, but generates more energy than _____________ oxidation
options: carbs, fat
Net energy yield from lipid metabolism
(using palmitate as an example)
8 acetyl-CoA: 96 ATP
7 NADH: 21 ATP
7 FADH: 14 ATP
Activation: -2 ATP
Total: 129 ATP
-lipid oxidation predominates at rest
-utilization transitions to CHO as activity begins & intensity increases
-this can be manipulated w/ training- use fat longer
Respiratory Exchange Ratio (RER)
the ratio of CO2 production to O2 consumption indicates the source of metabolic fuel (CHO vs fat)
RER of 0.7, 0.85 and 1
0.85: transition fat -> CHO
When & where are ketone bodies produced?
produced in the liver under conditions of low CHO intake, prolonged exercise or uncontrolled DM
What is a byproduct of gluconeogenesis?
(FFA -> glucose)
Ketone bodies can be re-converted to ____________ and used as an alternative energy source
Which tissues can use ketone bodies as an alternative energy source?
any tissue w/ mitochondria, esp. NS, kidneys & muscles
when ketone synthesis by liver exceeds utilization by other tissues
-results in ketonemia & ketonuria
-can lead to ketoacidosis
-low insulin levels + high glucagon induces inappropriately high glucose production in liver
-results in inc ketone bodies & lower blood pH which triggers renal excretion of acidic urine
-accompanying diuresis of glucose can result in
potentially fatal dehydration
proteins are catabolized into amino acids
Proteins & amino acids are not "stored", but exist in a state of:
constant synthesis & degradation
Amino Acid Pool
total amino acids available from dietary sources or degradation of existing protein
(total amt of AA in your body at any given time)
Catabolism of amino acids results in energy and:
ammonia, which is converted to urea & excreted
In protein metabolism, the nitrogen containing amine group (NH2) is toxic and must be:
cleaved from the carbon backbone
(transamination or oxidative deamination)
-most common way to cleave the amine group from the carbon backbone of protein during protein metabolism
-amine is transferred to keto analog by transaminases
-often involves the AA glutamate
-another way to cleave the amine group from the carbon backbone of protein during protein metabolism
-occurs in mitochondiral matrix of liver
-NAD+ is reduced to NADH
After protein has been deaminated, amino acids appear as:
pyruvate or other Krebs cycle intermediates
Carbon skeletons of protein (deaminated protein) are degraded via:
-conversion to glucose (glucogenic)
-conversion to ketone acetoacetate or acetyl CoA (ketogenic)
T/F: amino acids can supply carbon needed for gluconeogenesis
In gluconeogenesis w/ protein, AAs are converted to ____________ which is converted to glucose, although this requires significant energy input
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