10/8/23, 7:44 PM
chapter 3 book notes
about:blank
1/4
Ch 3 – bioenergetics
metabolism – chemical reactions throughout the body; includes synthesis and breakdown
anabolic (synthesis) and catabolic (catabolic)
bioenergetics – converting foodstuffs into a biologically usable form of energy
Cell Structure
-CHON
-organic contain carbon and inorganic don’t
-cell membrane, nucleus, cytoplasm
ocell membrane – protective barrier between the interior of the cell and the extra
cellular fluid
ogenes located within the nucleus contain genetic material that is used to
synthesize the proteins that determine the structure and function of the cell
ocytoplasm – fluid, contains organelles and cellular proteins
-mitochondrion – powerhouse of the cell and is involved in the oxidative conversion of
foodstuffs into usable cellular energy, aerobic, provide muscles with energy
Biological energy transformation
-endogenic require energy and exogenic give off energy
-coupled reactions – reactions that are linked, the liberation of free energy in one
reaction is used to drive a second reaction
oxidation reduction reactions
-oxidation – removing an electron from an atom or molecule
oO2 tends to accept electrons (ETC)
-reduction – adding an electron to an atom or molecule
-oxidation-reduction reactions are always coupled because a molecule cannot be oxidized
unless it donates an electron to another atom
-reducing agent donates the electron
-oxidizing agent accepts the electron
-typically involves transfer of hydrogen atoms H+ ions
-nicotinamide adenin dinucleotide (NAD) and flavin adenine dinucleotide (FAD) are often
reduced/oxidized (NAD+ to NADH; FAD to FADH2)
enzymes
-catalysts that regulate the speed of cellular chemical reactions
-does not cause or change the nature; simply changes the rate
-activation energy – energy required to initiate chemical reaction
-enzymes can lower the activation energy
-enzyme-substrate interaction
-enzymes are classified based on the type of reaction they perform
-factors that alter enzyme activity – the optimal temperature and PH
Fuels for Exercise
-during exercise the primary nutrients used for energy are fats and carbohydrates
10/8/23, 7:44 PM
chapter 3 book notes
about:blank
2/4
carbohydrates
-4 kcal/g
-glucose is stored in animal cells as glycogen
-monosaccharide
osimple sugar
oglucose and fructose
-disaccharides
osucrose
-polysaccharides
oglycogen (glycogen glucose is glycogenolysis)
fats
-9 kcal/g
-fatty acids – primary form of fat used as energy source
-triglycerides
-phospholipids
-steroids - cholesterol
proteins
-4 kcal/g
-amino acid glucose glycogen
-amino acid metabolic intermediates fuel
-requires proteins to be broken down into amino acids to be used as fuel
High energy Phosphates
-ATP
oadenine
oribose
othree linked phosphates
oADP + Pi
oATPase breaks the bond and releases energy
Bioenergetics
-muscle cells produce ATP using a combo of 3 metabolic pathways
-1. Formation of ATP by phosphocreatine breakdown
-2. Formation of ATP via the degradation of glucose or glycogen
-3. oxidative formation of ATP
anaerobic ATP production
-ATP-PC system, short-term, high-intensity exercise, 5-15 seconds
oATP ADP + Pi + Energy
-glycolysis, breakdown of glucose or glycogen to form 2 molecules of pyruvate or lactate,
transfer energy from glucose to synthesize ATP, produces net gain of 2 or 3ATP and 2
pyruvate/lactate
oenergy investment phase and energy generation phase
oglucose + 2ATP 2 pyruvate/lactate + 4ATP
10/8/23, 7:44 PM
chapter 3 book notes
about:blank
3/4
oglycogen + 1ATP 2 pyruvate/lactate + 4ATP
oNAD+ NADH which is then shuttled into the mitochondria to return back to
NAD+ and the electron joins the ETC
aerobic ATP production
-citric acid cycle
-electron transport chain
-the process of aerobic production of ATP is oxidative phosphorylation
CAC
-pyruvate 2acetyl Co-A + CO2
-net: 3 NADH and 1 FADH
-each molecule of glucose results in 2 turns of the CAC
-primary function of CAC is to remove electrons from NADH and FADH
-an electron from FADH 1.5 ATP
-an electron from NADH 2.5 ATP
-FATS
obeta oxidation: oxidize fatty acid to form acetyl-CoA
ofats fatty acid + glycerol acetyl-CoA
-PROTEINS
o amino acids CAC or pyruvate or acetyl-CoA
-OXIDATION OF CARBS, FATS, OR PROTEINS
-PRODUCES CO2 AND SUPPLIES ELECTRONS TO BE PASSED THROUGH THE ETC
Electron Transport Chain
-produce ATP in the mitochondria
-electrons from NADH and FADH are used to rephosphorylate ADP into ATP
-small amount of electrons leak out of ETC and form free radicals which are highly
reactive molecules – muscular exercise does not increase the production of free radicals
omost actually happen at rest!
-at the end of ETC, O2 accepts electrons to form H2O
-chemiosmotic hypothesis – aerobic formation of ATP
-1 NADH 2.5ATP
-1 FAD 1.5 ATP
Aerobic ATP Tally
Metabolic process High energy
products
ATP from oxidative
phosphorylation
ATP subtotal
Glycolysis 2 ATP
2 NADH
-
5
2 (anaerobic), 7
(aerobic)
Pyruvate to A-CoA 2 NADH 5 12
CAC 2 GTP
6 NADH
2 FADH
-
15
3
14
29
32
GRAND TOTAL: 32 ATP for glucose (33 for glycogen)
10/8/23, 7:44 PM
chapter 3 book notes
about:blank
4/4
Efficiency of Oxidative Phosphorylation
-aerobic metabolism of one molecule of glucose results in the production of 32 ATP
molecules, whereas the aerobic ATP yield for glycogen is 33 ATP
-overall efficiency of aerobic respiration is approximately 34%, with the remaining 66% of
the energy being released as heat
Control of Bioenergetics
- metabolism is regulated by the control of enzymatic activity
- rate limiting enzyme determines the speed of the metabolic pathway involved
- how do rate limiting enzymes control the speed?
ofound early in the pathway
oactivity is regulated by modulators which increase or decrease enzyme activity
control of ATP-PC system
- increase in ADP concentration stimulates creatine kinase to trigger breakdown of PC
- increase in ATP concentration inhibits kinase activity (negative feedback)
Control of glycolysis
- rate limiting enzyme is phosphofuctokinase (PFK) – near beginning of glycolysis
ohigh levels of ADP + Pi enhances PFK activity, ATP inhibits PFK activity
- phosphorylase – rise in sarcoplasmic Ca++ activates phosphorylase which beings to
break down glycogen to glucose, also indirectly stimulated by epinephrine
control of CAC and ETC
- isocitrate dehydrogenase – rate limiting enzyme in CAC
oinhibited by ATP and stimulated by ADP + Pi
- cytochrome c oxidase – rate limiting enzyme in ETC
oinhibited by ATP and stimulated by ADP + Pi
Interaction Between Aerobic/Anaerobic ATP production
- energy to perform exercise comes from an interaction of anaerobic and aerobic
pathways
- shorter activity – greater anaerobic contribution; long term activity – greater aerobic
contribution
