Unit 2 - Efficiency and Inhibitors Flashcards
tally;
CO2 / ATP / NADH / FADH2
in
gylocolysis =
PO =
krebs =
glycolysis = 0,2,2,0
Pyruvate Oxidation = 2,0,2,0
Krebs cycle = 4,2,6,2
Total 6,4,10,2
1 NADH makes….
1 FADH2 makes…
substrate level ATP…
3 ATP x 10 = 30
2 ATP x 2 = 4
= 4
TOTAL ATP = 38
Grand total of ATP
- 34 mols of ATP formed in ETC
- 2 in Krebs
- 2 in Glycolysis
- per glucose = 38ATP
- actual yield =30ATP
Why is the actual yield only 30 ATP?
-inner mitochondrial membrane may leak H+
- ATP required to prepare cell for glycolysis
How Efficient is Cellular Respiration
-Hydrolysis of ATP from ADP Pi = 31kj/mol
if the complete oxidation of glucose produces 38 ATP…
then the total energy stored through ATP is 1178kj/mol
but glucose contains 2870kj/mol of energy
1178/2870 x 100 = 41%
41% efficientce
therefore a max of 41% in glucose is made into ATP and the rest of potenital energy is dissipated as thermal energy
what abt the NADH formed in the cytosol
during glycolysis, 2 NADH r formed. these 2 electron carriers cannot access the ETC in the mitochondria. to overcome this problem, cells use one of two shuttle systems that transfer the high energy e- from NADH across the inner mitochondrial membranes and into the matrix
2 types of shuttles
1) malate-aspartate shuttle
2) glycerol-2-phosphate shuttle
Malate-aspartate shuttle
the NADH in the cytosol is oxidized to NAD+ and e- r transferred across the membrane and used to reduce NAD+ to NADH within the matrix
Glycerol-3-phosphate shuttle
-invloves the transfer of e- across the membrane from NADH to FAD in the matrix
- forming FADH2 = less free energy
- CELLS that use this system generate the equivalent of 2 rather than 2 ATP for every NADH
- why malate shuttle is more efficient
- produce 2 fewer ATPs per glucose
Creatine Phosphate
demand for energy in the cell can fluctuate dramatically. Cells may need a burst of energy during periods of high activity (muscle cells) buta low demand for energy at another time
ATP levels high in the cell
the last phosphate of ATP gets transferred to creatine. when phosphorylated, creatine bc a high energy mol called creatine phospahte
high levels of ATP reaction
creatine + ATP = creatine phosphate + ADP
ATP levels r low
it gets transferred back to ADP to make more ATP. The cell is able to recerse the rxn abt to generate more ATP quickly.
Low levels of ATP reaction
creatine phosphate = creatine + ATP
what is the final e- acceptor in ETC
oxygen
what happens if oxygen is unavailable (4)
1) ETC backs up
2) ATP production ceases
3) cells run out of energy
4) and u die
Interrupting Cellular Respiration (3)
Poisons
1) block electron transport chain (ie. CO)
2) inhibit ATP synthase (ie. antibiotic oligomycin)
3) make membrane leaky to H+ ions (ie. dinitrophenol)
Poisons (5)
1) hydrogen cyanide
2) carbon monoxide
3) rotenone
4) dinitrophenol
5)oligomycin
Hydogen Cyanide
- a chemical used in poisonous gas
- inhibits cytochrome oxidase (supply of oxygen to body tissues is still plentiful but cells cannot use the oxygen efficiently)
Carbon Monoxide
- binds to and inhibits cytochrome c oxidase
(binds to hemoglobin at an oxygen binding site) - sources of CO house fires, paint strippers, exhaust etc
Rotenone
- used in pesticides of piscicide
- prevents e- passing from NADH, and dehydrogenase to UB
- poorly absorbed through the skin, but not often deadly but can cause vomiting. but purposeful ingestion can be fatal
Dinitrophenol
- DNP is an uncoupler or has the ability to separate the flow of e- and pumping of H+ ions from ATP synthesis
-energy from e- cannot be used in ATP synthesis - used to be given as a weight loss drug
Oligomycin
- antibiotic that inhibits ATP synthase by blocking its proton channel necessary for oxidative phosphorylation of ADP to ATP
- stop ETC
Brown Fats
-special type of tissue associated w generation of heat and more abundant in hibernating mammals and newborns
white / brown / beige fats
white = found in surrounding organs
brown = important for energy storage, burns fat to help make heat
beige = mix of both
Regulating Cellular Respiration
most metabolic pathways r regulated by supply and demand through the process of feedback inhibition
how do we avoid making to much ATP
FEEDBACK INHIBITION
- we dont wanna waste cell resources
- so FI regulates pathway by one of the products of the pathway
Phosphofructokinase (PFK)
regulated by ATP and ADP derivative called AMP, and CITRATE, as well as some other mols we won’t discuss here
Feedback Inhibition in ATP
-in aerobic respiration, ATP inhibits enzymes throughout the pathway
ATP - regulator of PFK =
if there is already enough ATP in the cell, glycolysis does not need to make more
ATP inhibits PFK
which prevents creation of fructose-1,6-bisphosphate slows or stops glycolysis
AMP
Adenosine monophosphate is a + regulator of PFK. when a cell is v low on ATP, it will star squeezing more ATP out of ADP mols by converting them to ATP and AMP
(ADP + ADP = ATP + AMP)
Feedback Inhibition high levels of AMP
means that the cell is starved for energy, and that glycolysis must run quickly to replenish ATP
Feedback Inhibition Citrate
the first product of Krebs cycle, can also inhibit PFK. if citrate builds up, this is a sign that glycolysis can slow down, bc the Krebs cycle is backed up and doesn’t need more fuel
Alternatives to Glucose
carbs, fats, and proteins can fuel respiration
- when they r converted to mol that enter glycolysis or the Krebs cycle
Other carbohydrates
glycolysis accepts a wide range of carbs fuels
- single or joined sugars
- broken dow into single sugars
- converted to glucose or glycolysis intermediate, enters glycolysis
Polysaccharides =
other 6c sugars =
(Hydrolysis)= glucose
ie. starch / glycogen
(Modified)= glucose
ie. galactose/fructose
Proteins
- the chain of AA
- amino acid have NH3 groups removed and converted to pyruvate, acetyl-CoA, or CA cycle intermediate to enter pyruvate oxidation or Krebs cycle
Proteins =
(Hydrolysis)= aa
three types of extracted fluids
= waste product excreated as ammonia, urea, or uric acid
carbon skeleton
= enters glycolysis or Krebs cycle at different stages
Fats (triglycerides)
Triglyceride = glycerol + 3 fatty acids
- broken down into gycerol and fatty acids
- glycerol converted to G3_ and enters glycolysis
- fatty acids r converted to acetly-CoA and enters Krebs
Beta-Oxidation
a process in which fatty acids r broken down into acetly-CoA through catabolism
Fats =
(Hydrolysis) = glycerol and fatty acids
glycerol (2C) makes=
G3P = glycolysis
fatty acids =
2c acetyl groups = acetyl CoA = Krebs cycle
Carbs vs. Fats
fat generates 2x ATP vs. carbs
- more C in gram of fat
- more O in gram of carbs
energy density in
carbs
fats
proteins
carbs = 17
fats = 37
proteins = 17
Metabolism
coordination of diestion and synthesis - by regulating enzymes
Digestion
-digestion of carbs, fats, and proteins (all catabolized through the same pathways but enter at diff points)
- cell extracts energy from every source
Synthesis
- enough energy? build stuff
- cell uses points in glycolysis and krebs as links to pathways
- run the pathways backwards (eat to much fuel; build fat)
pyruvate =
krebs cycle =
acetyl CoA
= glucose
= aa
= fatty acids
food mols provide raw materials for biosynthesis
cells use some food mols and intermediates from glycolysis and the krebs as raw materials ie process of biosnthesis and consumes ATP
Fuelfor respiration ultimately comes from photosynthesis
all organisms
- can harvest energy from organic mols
plants but not animals
- can also make mols from inorganic sources by the process of photosynthesis
