LESSON 5 - bioenergetics of muscle metabolism in the mitochondria Flashcards
what are the four sources of ATP resynthesis during “all-out” exercise ?
- ATP
- glycolysis
- PCr
- Oxidative
between ATP, glycolysis and PCr, which is “stored in very limited quantities”?
ATP
between ATP, glycolysis and PCr, which is “found within your muscles”?
PCr
which are two substrate level phosphate/anerobic metabolic pathways that can help us re-synthesize ATP so that we can continue to exercise ?
PCr and Glycolysis
what does the Krebs cycle need to function ?
oxygen
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_________ contributes to ATP resynthesis requirements but has a low ATP yield
glycolysis
which source of ATP during “all-out” exercise leads to NO exhaustion ?
Oxidative
what source provides a lot of ATP for an indefinite amount of time ?
oxidative phosphorylation
what are the two non oxidative energy sources ?
- phosphocreatine
- glycolysis / glycogenolysis
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___________ can sustain ATP resynthesis requirements indefinitely
oxidative phosphorylation
what is glycolysis ?
the breakdown of glucose
what is glycogenolysis ?
the breakdown of glycogen
where do non oxidative energy sources exclusively occur ?
within the muscle fiber cytosol (sarcoplasm)
where do oxidative energy sources exclusively occur ?
in the mitochondria
what are the two oxidative energy sources ?
- citric acid cycle / electron transport
- fatty acids from beta oxidation
ADP + P + energy = ATP via _____________
phosphorylation
what is an example of moderate-intensity exercise ?
walking
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________________ efficiently sustains all the ATP resynthesis once steady state is achieved
Oxidative Phosphorylation
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______________ contribute very little at the beginning and not at all during steady state
PCr and glycolysis/glycogenolysis
describe the order once you begin with glucose or glycogen …
becomes G6P eventually becomes pyruvate
what does it mean if were in the aerobic state ?
lacking oxygen
what does it mean for pyruvate if were in the aerobic state ?
not able to put pyruvate in Krebs cycle and turns into lactate which eventually becomes pyruvate again
what does it mean if you have lactate acid buildup ?
the muscles get tired and may not be able to contract as effectively (muscle cramp)
what happens if you have a stockpile of pyruvate ?
slows down glycolysis
what are the four key components of the mitochondria ?
- outer membrane
- inner membrame
- intermembrane space
- matrix
define the outer membrane of the mitochondria :
contains proteins and lipids and special pores that allow entry to most ions and small molecules
define the inner membrane of the mitochondria :
loaded with proteins and enzymes for transferring electrons to O2 and impermeable to most ions and polar molecules unless they have specific transporters
define the intermembrane space of the mitochondria :
contains key proteins including creatine kinase and cytochrome c
define the matrix of the mitochondria :
viscous medium containing all enzymes for the citric acid cycle
which component of the mitochondria is quite permeable to things ?
outer membrane
which component of the mitochondria increases SA ?
inner membrane
which component of the mitochondria transfers electrons to oxygen ?
inner membrane
which component of the mitochondria is where the citric acid cycle occurs ?
intermembrane space
which component of the mitochondria is where many enzymes are present ?
matrix `
in skeletal muscle where is the mitochondria found ?
beneath the sarcolemma and between myofibrils
why is mitochondria found where it in within skeletal muscles ?
mitochondria us used to resynthesize ATP therefore found between myofibrils since that’s where ATP is located for muscle contractions
what is the term for contracting fibers ?
myofibrils
what type of reaction is the conversion of pyruvate to acetyl-CoA ?
irreversible reaction
the conversion of pyruvate to acetyl-CoA is catalyzed by which enzyme ?
pyruvate dehydrogenase
what does it mean if a reaction is irreversible ?
only goes in one direction
where is pyruvate located ?
cytosol
where is coenzyme A located ?
mitochondria
what is the general reaction for pyruvate to acetyl CoA ?
2 pyruvate +2CoA+2NAD = 2 acetyl-CoA +2CO2 +2NADH+2H
how does pyruvate travel from the cytosol into the mitochondria ?
transport protein
why is CO2 important within a pyruvate to acetyl-CoA reaction ?
gas exchange; one of the ways we make CO2 in our skeletal muscles
why is NADH important ?
for oxidative phosphorylation (because those are carrying electrons to the electron transport chain)
what is TCA ?
tricarboxylic acid (aka Krebs cycle)
what is the second stage of carbohydrate breakdown ?
Krebs cycle (TCA)
what oxydizes acetyl-CoA ?
TCA (the Krebs cycle)
what is the Krebs cycle ?
sequence of metabolic events that remove 4 electrons pairs from acetyl groups and attach 3 pairs to coenzymes NAD and 1 pair to FAD
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“much of the free energy of oxidation of acetyl-coA is concerned in the reduced coenzymes ________ and ________”
NADH and FADH2
in regards to REDOX reactions what does “OIL” stand for ?
oxidation involved LOSS of electron
in regards to REDOX reactions what does “RIG” stand for ?
reduction involves GAIN of electron
between “OIL” and “RIG” which includes a gain of oxygen or loss of H ?
OIL
between “OIL” and “RIG” which includes a loss of oxygen or gain of H ?
RIL
what is GTP used for ?
used to resynthesize an ATP
what is GDP ?
high energy phosphate similar to ATP or ADP
what is the malate-aspartate shuttle ?
translocates electrons from glycolysis across the inner membrane of mitochondria
why is the malate-aspartate shuttle required ?
because the inner membrane is impermeable to NADH
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___________ is the primary electron donor t the electron transport train
NADH
what do we use since NADH is impermeable to the inner membrane of the mitochondria ?
malate-aspartate shuttle
what is NADH in regards to the Krebs cycle ?
byproduct of the Krebs cycle
what does ETC stand for ?
electron transport chain
what does the electron transport chain do ?
transfer electrons and releases energy from it
what is the ETC ?
a series of proteins and organic molecules packed in the inner membrane that transfer electrons (from NADH & FADH) from one member of the ETC to another in a series of redox reactions
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energy released in these ETC reactions transfer protons ___ from the matrix to intermebrane space creating a proton gradient across that provides an electrochemical potential energy
H
what chain “breaks a bond in order to release energy “ ?
electron transport chain
what happens to the ETC if there is no O2 ?
ETC will stop running
where is O2 present within the electron transport chain ?
O2 is present at the end of the chain where it accepts electrons to form water
the byproducts of the Krebs cycle go where and to do what ?
go to the electron transport cycle to produce ATP
how many steps of the ETC are there ?
4
name the four ETC steps :
- delivery of electron by NADH and FADH2
- electron transfer and proton pumping
- splitting of O2 to form H2O
- ATP resynthesis
what happens in step 1 of the ETC ?
transfer electron pairs to molecules near the start of the ETC, turn back to NAD and FAD
what happens in step 2 of the ETC ?
- as electrons pass through chain, they move from higher to lower energy level, releasing energy
- energy is used to pump H out of the matrix to establish an electrochemical gradient
what happens in step 3 of the ETC ?
at the end of chain, 2 electrons are transferred to O2 which splits in half and takes up 2H to form H2O
what happens in step 4 of the ETC ?
H ions flow down their gradient and back into matric massing through an ATP synthase enzyme which uses the proton flow to synthesize ATP
which step of the ETC is most important ?
step 4
what happens if one o the chains of the ETC is destroyed ?
you can still use the others
what are the three stages of oxidation of carbohydrates ?
stage 1 = glycolysis
stage 2 = Krebs cycle
stage 3 = electron transport chain
within the Krebs cycle how many ATP per molecule of glucose oxidized is created ?
32
the continual ATP process is called __________-
oxidative phosphorylation
what are the three prerequisites of continual ATP resynthesis during coupled oxidative phosphorylation of macronutrients ?
- availability of reducing agents NADH or FADH2
- presence of a terminal oxidizing agent as oxygen
- sufficient quantity of enzymes and metabolic machinery in tissues to make energy transfer reactions “go” at appropriate sequence and rate
why do we break down carbs ?
to yield ATP that owe require for our cells to function
what is the Creatine Kinase and the PCr shuttle ?
connects sites of ATP production with sub cellular sites of ATP utilization
what does CK stand for ?
creatine kinase
where is CK found in ?
both the intermembrane space and the cytosol
what happens with ATP if you increase exercise intensity ?
the need to resynthesize ATP will increase
where in the circulation is O2 distributed ?
red blood cells
