chapter 7-metabolism Flashcards
what is metabolism
the sum of all chemical rxns that occur in the body
what is carbolic rxns and anabolic runs
- Catabolic rxn: breaks down chemicals and release energy
- Anabolic rxn: synthesize chemicals and require energy
what is cellular respiration
describes the biochemical conversion of chemical energy stored in molecular bonds into usable energy (ATP)
-A catabolic process
what are the 2 major pathways of cellular respiration
anaerobic and aerobic respiration
what is internal and external respiration
- internal respiration: exchange of gas between individual cells and the extracellular fluid
- External respiration: inhaling and exhaling of air into and out of the lungs as well as the exchange of gas between alveoli and the blood
which mc are the favoured fuel mc and why
carbohydrates and fats bc of the high # of energy rich C-H bonds
end products of metabolisms are?
H2O and CO2 –> low energy bonds
during cellular respiration the oxidation of what releases energy
C to Co2
what does glycolysis literally mean and what does it lead to
- sugar breaking
- leads to the oxidative breakdown of glucose into 2 mc of pyruvate, the production of ATP and the reduction of NAD+ to NADH
what gets reduced and what get oxidized during glycolysis
glucose is reduced and NAD+ is oxidized
where does glycolysis occur
cytoplasms
can prokaryotic and eukaryotic cells undergo glycolysis
yes
glycolysis is divided into 3 stages what are they
1) energy investment stage
2) cleavage stage
3) energy payout stage
what is the energy investment stage during glycolysis
-2 ATPs are used to add 2 phosphate groups to glucose producing fructose 1, 6 biphosphate ( 6 C) and these actions are completed by kinases
oGlucose glucose 6 phosphate fructose 1,6 biphosphate
what is the cleavage stage of glycolysis
-splits fructose 1,6 biphosphate into glyceraldehyde 3 phosphate and dihydroxyacetone phosphate
oglyceraldehyde 3 phosphate (PGAL) and dihydroxyacetone phosphate (DHAP) are 3 C cpd with a phosphate added
oDHAP is then isomerized to form a second PGAL
what is the energy payout stage
results in the production of ATP
o PGAL–> 1,3 diphosphoglycerate–> 3-phosphoglycerate –>2-phosphoglycerate phosphoenolpyruvate–>pyruvate
oWhen pyruvate gets formed the reduction of NAD+ to NADH occurs which is catalyzed by dehydrogenase) and the production of 2 ATP catalyzed by kinases
o this stage occurs 2 times per mc of glucose
what catalyzes the reduction of NAD+ to NADH during glycolysis
dehydrogenase
what catalyzes the production of ATP during the energy payout stage of glycolysis
kinase
1 mc of ATP produce
1 ) __ mc of pyruvate
2) __ ATP
2 and 2
what is substrate level phosphorylation and an ex
ATP synthesis is directly coupled with the oxidation of glucose without participation of an intermediate mc such as NADH or FADH2
- ex is the product of ATP from glycolysis
what is substrate level phosphorylation
does require an intermediate e carrier such as NADH or FADH2
what is the net rxn of glycolysis
glucose + 2ADP + 2Pi + 2NAD+–> 2 pyruvate + 2ATP + 2 NADH + 2H+ + 2H2O
what are 2 things that can happen to pyruvate after glycolysis
- pyruvate can be reduced during fermentation
- pyruvate is further oxidized during cellular respiration in the mitochondria
what occurs to pyruvate during anaerobic respiration
-NAD+ must be regenerated for glycolysis to continue in the absence of O2 which is done by reducing pyruvate into ethanol or lactic acid via fermentation
what are the 2 types of fermentation that occurs to pyruvate
alcohol fermentation and lactic acid fermentation
what is alcohol fermentation
it occurs in yeast and some bacteria
-The pyruvate produced in glycolysis is converted to ethanol in this way NAD+ is regenerated and glycolysis can continue
what is lactic acid fermentation
occurs in certain fungi and bacteria and in human muscles during strenuous activity
- When O2 supply to muscle cells lag behind the rate of glucose catabolism, the pyruvate generated is reduced to lactic acid
- The NAD+ is regenerated when pyruvate gets reduced
how many ATP are produced during aerobic respiration and anaerobic respiration
36-38 and 2
aerobic respiration an be divided into 3 stages what are they
pyruvate decarboxylation, the citric acid cycle, ETC
where does pyruvate decarboxylation, the citric acid cycle, ETC occur in EUK and PROk
mitochondria, cytoplasm
what electron carriers
NadH and FADH2
what occurs during citric acid cycle
Acetyl-coA then undergoes the citric acid cycle producing electron carriers NadH and FADH2 and regenerating oxaloacetate then repeat of cycle
where is the ETC located
inter membrane space
where in prokaryotes ETC is located
on the bacterial membrane itself
what occurs during pyruvate decarboxylation
1) Pyruvate during glycolysis is transported from cytoplasm to mitochondrial matrix where it is decarboxylation: pyruvate is decarboxylated ( loses a CO2)
2) the acetyl group that remains is transferred to coenzyme A to form acetyl-coA
3) in the processes NAD+ is reduced to NADH
how many ATP are produced during each round of the CAC
1
what type of phosphorylation results in ATP production in the CAC
substrate level phosphorylation
how many ATP are produced from 1 mc of glucose during the CAC
2
How does the CAC start off
acetyl group from acetyl-CoA combine with oxaloacetate to form citrate
what 2 electron carriers get regenerated
NADH and FADH2
what is the net rxn for the CAC per glucose
2 acetly-CoA + 6NAD+ + 2FAD +2GDP + 2Pi + 4H2O–>4CO2 + 6NADH +2FADH2 +2GTP + 4H+ 2CO2
what happens during oxidative phosphorylation
ATP is produced when high-energy potential e are transferred from NADH and FADH2 to oxygen by a series of carrier mc located in the inner mitochondrial membrane
-as e are transferred from carrier to carrier free energy is released which is then used to form ATP
what type of mc are most of the mc in the ETC
cytochrome
what are cytochrome mc
electron carriers that resemble hemoglobin in the structure of their active site
what is unique about the central iron atom of the functional unit
it is capable of undergoing a reversible redox rxn ( can be reduced and oxidized alternatively)
what is the final electron acceptor of the ETC
oxygen
how is water formed during the ETC and what is the rxn
O2 picks up a pair of H ions from the surrounding medium forming water
2H+ +2e +1/2O2–>H2O
what is the coupling agent of oxidation of NADH and FADH2 to the phosphorylation of ADP
a proton gradient across the inner mitochondrial membrane maintained by the ETC
how is the proton gradient produced
1) s NADH and FADH2 pass their electrons to the ETC, hydrogen ions (H+) ions are pumped out of the matrix across the inner mitochondrial membrane and into the intermembrane space at each of the ETC protein complexes
2) the continuous translocation of H+ creates a positively charged acidic environement in the intermembrane space
3) the electrochemical gradient generates a proton-motive force which drives H back across the inner membrane and into the matrix
How does H+ pass through the inner membrane into the matrix when the membrane is impermeable to ions
through specialized channels provide by enzyme complexes called ATP synthase
as H pass through the ATP synthases enough energy is released to allow for what to occur to ADP
phosphorylation of ADP to ATP
what is oxidative phosphorylation
the coupling of the oxidation of NADH and FADH2 with the phosphorylation of ATP
how many ATP are formed during substrate level phosphorylation
4 ATP are produced
-1 glucose mc = 2 ATP from glycolysis and 1 ATP for each turn of the citric acid cycle = 4ATP
how many ATP are formed during oxidative phosphorylation
32 ATP are produced
- each NADH from the CAC generates 3 ATP and there is 6 so 18 ATP
- the 2 NADH that were reduced during glycolysis =4ATP
- the 3NADH during pyruvate decarboxylation generate 3 ATP/NADH=6ATP
- FADH2 generates 2 ATP and there is 2 so 4 ATP
what are the alternate energy sources if glucose is low and their preferential order
carbohydrates, fats, proteins
-They are first converted into either glucose or glucose intermediate which can then be degraded into the glycolic pathway and the CAC
how is carbohydrates used as an alternative energy source
- Disaccharides are hydrolyzed into monosaccharides & most can be converted into glucose or glycolytic intermediates
where is glycogen found and is it a alternative energy source
- stored into liver can be converted when needed into a glycolytic intermediate
where are fat mc stored and in what form
adipose tissue in the form of triglycerides
what hydrolyzes fats when needed for energy
lipases to fatty acids and glycerol
what glycolytic intermediate is glycerol converted into
PGAL
how does a fatty acid enter the citric acid cycle
1) first gets activated in the cytoplasm which requires 2 ATP
2) once activated the fatty acid is transported into the mitochondrion
3) and taken through a series of beta-oxidation cycles that convert it into 2 C fragments
4) the 2 C fragments are converted into acetyl-CoA which then enters the citric acid cycle
how many NADH and FADH2 are produced after one round of beta oxidation of a saturated fat
1 of each
___ meets the long term energy need for a month
fats
there is enough ___ stored in humans to meet the short term energy needed for a day
glycogen
what type of mc yields the greatest number of ATP per gram
fats
when will your body degrade proteins
only when enough carbohydrate or fat is available
what is a transamination reaction
when a.a lose an amino group to form a alpha-keto acid
how does a protein enter the CAC and produce ATP
the C atom of most a.a are converted into acetyl-coA, pyruvate or one of the intermediates in the CAC which enter their respected metabolic pathways allowing cells to produce fatty acids, glucose, or energy in the form of ATP
what is oxidative deamination
removes an ammonia mc directly from the amino acid
where does photosynthesis take place
chloroplasts
the reduction of what occurs in photosynthesis
CO2 to carbohydrates
net rxn of photosynthesis
6CO2 +12H2O +light energy–>C6H12O6 +6O2 + 6H2O
what occurs when water is split during photosynthesis
released their electrons are donated to form ATP and NADPH
what happens to the H atom after water splits during photosynthesis
the H atom combines with C an dO atom from CO2 to form carbohyydrates and more water
is O2 a waste product during photosynthesis
yes
what occurs in light (photolysis rxn) vs dark rxn (reduction synthesis)
the light rxn=split water and produce ATP and NADPH
the dark rxn=form sugar from CO2 and the energy produced in the light rxn
describe cyclic e flow for light rxn
1) absorption of a photon of light by a chlorophyll mc when light strikes P700 ( a special mc in PSI)
2) electrons are excited to a higher energy level and can either flow to cyclic or noncyclic
cyclic:
1) the excited e move along a chain of e carries
2) a series of redox rxn return the e to P700
3) the reactions are harnessed using an ETC, a proton gradient, and ATP synthase to produce ATP from ADP and Pi which is called cyclic photophosphorylation
describe noncyclic e flow for light rxn
1) absorption of a photon of light by a chlorophyll mc when light strikes P700 ( a special mc in PSI)
2) electrons are excited to a higher energy level and can either flow to cyclic or noncyclic
non cyclic:
1) the excited e move to the e acceptor NADP+ which is similar to NAD+ ( that functions in cellular respiration) and forms NADPH
2) light stikes PSII P680 and electrons are excited and move down the same electro carrier chain used in cyclic e flow until they reach PSI and fill in the electron holes
3) ATP is produced by noncyclic photophosphorylation
4) now PSII has holes and is strong enough oxidatzing agent to oxidize wawter and fill the holes
5) water splits into 2 H and 1 O atom and e produced reduce PSII
6) oxygen atoms combine to form O2
what is the net result of noncyclic e flow
NADPH, ATP, and photolysis of water
what does noncyclic e flow produce that cyclic does not
O2 or NADPH
when does the dark rxn occur and why
- during the day when the light rxn are replenishing the supply of ATP and NADPH
what is the source of carbon carbohydrate production in the Calvin cycle
CO2
what is the product of the Calvin cycle
3 C sugar phosphoglyceraldehyde (PGAL)
how many times does the calvin cycle take place
3 times
steps of the calvin cycle
1) CO2 is fixed to RBP ( ribulose bisphosphate) a 5C sugar resulting in a 6 C unstable mc
2) that mc splits to form 2 mc of PGA ( phosphoglyceric acid)
3) PGA is phosphorylated and reduced by ATP, NADPH to form PGAL
4) most of PGAL is recycled to RBP by a complex series of rxn
5) 6 turns of the cycle 12 PGAL ar formed from 6CO2 and 6 RBP
5) the 12 PGAL and 6RBP combine to form glycose the net product
what can PGL be used for
as an intermediate food nutrient, combined and rearranged to form monosaccharide sugars that can be transported to other cells or packaged for storage in insoluble pholysaccharide such as starch
how many cycles of calvin cycle needs to occur to make 1 glucose mc
6
