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KIN 425K > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

Metabolism

A

– Sum of all chemical reactions that occur in the body

– Anabolic reactions
Synthesis of molecules
– Catabolic reactions
Breakdown of molecules

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2
Q

Bioenergetics

A

Process of converting foodstuffs (fats, proteins,
carbohydrates) into usable energy for cell work

Formation of ATP
– Phosphocreatine (PC) breakdown - ATP-CP system
– Degradation of glucose and glycogen
*Glycolysis
– Oxidative phosphorylation of ATP

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3
Q

Endergonic reactions

A

– Require energy to be added to the reactants

– Endothermic

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4
Q

Exergonic reactions

A

– Release energy

– Exothermic

Ex. Breakdown of glucose

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5
Q

Coupled reactions

A

Liberation of energy in an exergonic reaction drives an endergonic reaction

Oxidation and reduction are always coupled
reactions

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6
Q

OILRIG

A

Oxidation is loss of electrons

Reduction is gain of electrons

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7
Q

Enzymes

A

Catalysts that regulate the speed of reactions
– Lower the energy of activation

Interact with specific substrates
– Lock and key model

Lower the activation energy

Damaged cells release enzymes into the blood
– Enzyme levels in blood serve as “biomarkers” of disease and/or tissue damage

Diagnostic application
– Elevated lactate dehydogenase or creatine kinase in the blood may indicate a myocardial infarction

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8
Q

Factors That Alter Enzyme Activity

A

Temperature
– A small rise in body temperature increases enzyme
activity
– Exercise results in increased body temperature
– Large increase in body temperature (>41oC) can
denature enzymes and decrease activity

pH
– Changes in pH (increase or decrease) can decrease
enzyme activity
– High intensity exercise decreases muscle pH

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9
Q

Carbohydrates

A

Include monosaccharides, disaccharides, and
polysaccharides

Glucose
– Blood sugar

Glycogen
– Storage form of glucose in liver and muscle
– Synthesized by enzyme glycogen synthase
– Glycogenolysis: Breakdown of glycogen to glucose

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10
Q

Fats

A

Fatty acids
– Primary type of fat used by skeletal muscle

Triglycerides
– Storage form of fat in muscle and adipose tissue
– Broken down into glycerol and three fatty acids via lipolysis

Phospholipids
– Not used as an energy source

Steroids
– Derived from cholesterol-not an energy source
– Needed to synthesize sex hormones

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11
Q

Protein

A

Composed of amino acids

Some can be converted to glucose in the
liver
– Gluconeogenesis

Others can be converted to metabolic
intermediates
– Contribute as a fuel in muscle

Overall, protein is not a primary energy source during exercise

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12
Q

High-Energy Phosphates

A

Adenosine triphosphate (ATP)
– Consists of adenine, ribose, and three linked
phosphates

ATP is NOT energy, it is an immediate energy source

Synthesis: adding a phosphate to ADP
Breakdown: removing phosphate from ATP by using ATPase

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13
Q

ATP-PC system

A

Anaerobic

Immediate source of ATP

ATP already in muscle

Creatine kinase used to make more ATP from PC and ADP (PC + ADP -> ATP + C)

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14
Q

Glycolysis

A

Anaerobic

Breakdown of glucose

– Energy investment phase
*Requires 2 ATP
– Energy generation phase
*Produces 4 ATP, 2 NADH, and 2 pyruvate or 2
lactate

End product (Glucose -> 2 pyruvic acid or 2 lactic acid)

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15
Q

Interaction Between Blood Glucose and Muscle Glycogen in Glycolysis

A

Glycolysis with blood glucose requires investment of ATP to breakdown (32 ATP)

Glycogen does not require investment of ATP, so net yield is greater than blood glucose (33 ATP)

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16
Q

NAD+ in Glycolysis

A

For glycolysis to continue, you need NAD+

NADH must become NAD+ by giving up an H+ (and e-)

NADH produced in glycolysis must be converted back to NAD+
– By converting pyruvic acid to lactic acid
*NADH gives two H+ to pyruvic acid, to for NAD
and lactate. Catalyzed by lactate dehydrogenase
(LDH)
– By “shuttling” H+ into the mitochondria

17
Q

Krebs cycle (citric acid cycle)

A

– Pyruvic acid (3 C) is converted to acetyl-CoA (2 C)
*CO2is given off

– Acetyl-CoA combines with oxaloacetate (4 C) to form citrate (6 C)

– Citrate is metabolized to oxaloacetate
*Two CO2molecules given off

– Produces three molecules of NADH and one FADH2

– Also forms one molecule of GTP
*Produces one ATP

18
Q

Beta Oxidation

A

Beta Oxidation is the Process of Converting Fatty Acids to Acetyl-CoA

Breakdown of triglycerides releases fatty acids

Fatty acids must be converted to acetyl-CoA to be
used as a fuel

Acetyl-CoA enters the citric acid cycle and is used
for energy

19
Q

Electron transport chain

A

After Krebs cycle

– Oxidative phosphorylation occurs in the mitochondria

– Electrons removed from NADH and FADH are
passed along a series of carriers (cytochromes) to
produce ATP
*Each NADH produces 2.5 ATP
*Each FADH produces 1.5 ATP

– Called the chemiosmotic hypothesis

– H+ from NADH and FADH are accepted by O2 to
form water

20
Q

The Chemiosmotic Hypothesis of ATP Formation

A

Electron transport chain results in pumping of H+ ions across inner mitochondrial membrane
– Results in electrochemical (i.e., H+) gradient across
membrane

Energy released to form ATP as H+ ions
diffuse back across the membrane
– ATP synthase uses H+ concentration gradient to phosphorylate ATP.
– H+ travels down concentration gradient and the energy from that phosphorylates ADP to create ATP
ADP + P -> ATP

21
Q

Free Radicals

A

Free Radicals are Formed in the Mitochondria

Free radicals are molecules with an unpaired electron in outer orbital

Free radicals can be produced by the leakage of electrons along the electron transport chain

Free radicals react with other molecules in the cell
– Damages the molecule combining with the radical

Aerobic exercise promotes the production of free radicals in the working muscles
– Exercise-induced free radical production is not due to oxidative phosphorylation in the mitochondria

22
Q

ATP balance sheet

A

Recent research indicates that 1 glucose produces 32 ATP
– Energy provided by NADH and FADH2 also
used to transport ATP out of mitochondria

– 3 H+ must pass through H+ channels to produce
1 ATP

– Another H+ needed to move the ATP across the
mitochondrial membrane

23
Q

Aerobic ATP production from one glucose molecule

A

Glycolysis: 2 ATP is anaerobic; 7 ATP if aerobic
- 2 ATP
- 2 NADH, which form 5 ATP from oxidative phosphorylation

Pyruvate to acetyl-CoA: 12 ATP total to this point
- 2 NADH produced from this conversion, which forms 5 ATP from oxidative phosphorylation

Citric Acid Cycle: 32 total ATP
- 2 GTP produced and used to phosphorylate 2 ADP into 2 ATP
- 6 NADH produced which forms 15 ATP
- 2 FADH2 produced which forms 3 ATP

24
Q

ATP production with one glycogen molecule

A

33 total ATP instead of 32 ATP like blood glucose

An ATP molecule is required (investment phase) to convert blood glucose into glucose 6-phosphate during glycolysis

Glycogen does not require this investment of ATP to be converted into glucose 6-phosphate, so net yield is 1 ATP higher when using glucose during glycolysis

25
Q

Efficiency of Oxidative Phosphorylation

A

One mole of ATP has energy yield of 7.3 kcal

32 moles of ATP are formed from one mole of glucose

Potential energy released from one mole of glucose is 686 kcal/mole

[(32 moles ATP/mole glucose * 7.3 kcal/mole ATP)/686 kcal/mole glucose] * 100 = 34%

Overall efficiency of aerobic metabolism is 34%
– 66% of energy released as heat

26
Q

Control of Bioenergetics

A

Rate-limiting enzymes
– An enzyme that regulates the rate of a metabolic
pathway

Modulators of rate-limiting enzymes
– Levels of ATP and ADP+Pi
*High levels of ATP inhibit ATP production
*Low levels of ATP and high levels of ADP+Pi
stimulate ATP production
– Calcium stimulates aerobic ATP production

27
Q

ATP-PC system rate-limiting enzyme

A

Creatine kinase

Stimulators: ADP

Inhibitors: ATP

28
Q

Glycolysis rate-limiting enzyme

A

Phosphofructokinase

Stimulators: AMP, ADP, Pi, high pH

Inhibitors: ATP, CP, citrate, low pH

29
Q

Citric acid cycle rate-limiting enzyme

A

Isocitrate dehydrogenase

Stimulators: ADP, Ca2+, NAD+

Inhibitors: ATP, CP, citrate, low pH

30
Q

Electron transport chain rate-limiting enzyme

A

Cytochrome oxidase

Stimulators: ADP, Pi

Inhibitors: ATP

31
Q

Interaction Between Aerobic and Anaerobic ATP Production

A

Energy to perform exercise comes from an interaction between aerobic and anaerobic pathways

Depends on duration and intensity of exercise
– Short-term, high-intensity activities have a greater contribution of anaerobic energy systems
– Long-term, low to moderate-intensity exercise have a majority of ATP produced from aerobic sources

KIN 425K (9 decks)

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