0
What is the major take-home message of Krebs cycle for cell energetics a- it re-generates oxaloacetate b-it generates Acetyl-CoA c- it generate Co2 d- it generates ATP by substrate level phosphoryla?
Tahanisoso3
The major message of the Krebs cycle for cell energetics is that it generates ATP with substrate level phosphorylation.
Wiki User
∙ 10y ago
Add your answer:
Earn +20 pts
What is the Calvin cycle responsible for?
It is responsible for the breakdown of pyruvate/acetylCoA into 1ATP, 4NADH, and 1FADH per cycle. It is a part of cellular respiration.
Is fermentation as effective as glycolysis?
because from glycolisis comes pyruvate, and then it is turned into acetylCoA. Without acetylCoA, nothgn will be able to enter the Krebs Cycle, otherwise known as the Citric acid cycle. Once the AcetylCoA comes in, after the prep cycle, it can then bind to RuBp, turnign into a six carbon sugar.
Why does ketogenesis occur?
Ketogenesis is a metabolic process to form ketone bodies in mitochondrial matrix of hepatocytes in emergency condition from accumulated Acetyl-CoAobtained from increased incomplete fatty acid oxidation due to cellular glucose deprivation.CoA is a complex structure which is impermeable to mitochondrial membranes, Acetate linked to CoA as AcetylCoA is also impermeable.The steps of Ketogenesis occur to remove the CoA from the molecules of AcetylCoA and form a permeable ketone body Acetoacetate( Primary Ketone body).Acetoacetate then spontaneously decarboxylated to stable Acetone and reduced to Beta Hydroxy Butyrate (Secondary ketone bodies).Thus Ketogenesis occur to remove the accumulated impermeable Acetyl-CoA from mitochondrial matrix by forming permeable ketonebodies.Ketogenesis removes the acetate carbon out of matrix and maintain the CoA pool of matrix.
Does glycolosis or Krebs cycle come first?
Glycolysis evolved first. Cells of all types of organisms are able to carry out glycolysis. The Krebs cycle arose after photosynthetic organisms began adding oxygen to the atmosphere because Krebs cycle requires oxygen and glycolysis does not.
Discuss creb's cycle?
KREB'S CYCLE # Kreb's cycle - introduction ## The Kreb's cycle converts pyruvate to CO2 and reducing energy (NADH and FADH2) and phosphorylated energy (GTP). 2 pyruvate + 2 GDP + 2 H3PO4 + 4 H2O + 2 FAD + 8 NAD+ ----> 6 CO2 + 2 GTP + 2 FADH2 + 8 NADH ## The reduced energy can be used to generate ATP using the electron transport chain in the presence of oxygen. ## It is a cyclic process in that oxaloacetate reacts with acetyl CoA to form citrate which starts a series of several other reactions. The final reaction in the series involves the regeneration of oxaloacetate! ## NAD and FAD; both are rather small nucleotide molecules that are electron carriers. FAD can transfer its reducing power to FP. The reduced and oxidized forms of NAD are not clear; thus oxidized NAD can be called => NADox; NAD+; or NAD; Reduced NAD can be called => NADred; NADH; and NADH2. # Kreb's cycle steps: ## The three carbon pyruvate reacts whereby a carbon is lost as CO2. The reaction releases energy such that NAD+ is reduced to NADH. The remaining two carbon compound is not allowed to be free but rather binds a special molecule (coenzyme A) to form acetyl CoA. ### This is essentially an irreversible reaction due to the loss of CO2. ### This reaction is probably more than one step, considering all of the reactants. However, even to this day the intricacies of this reaction are not well understood. ### It is not clear in eukaryotic cells exactly what carbon form passes from the cytoplasm to the mitochondrial matrix (pyruvate? acetyl CoA? an intermediate?) The process looks very complex. ### The binding of CoA-SH to the two carbon molecule is probably a type of handle making it easier for enzymes to act upon it. ## The two carbon chain is released from acetylCoA and binds to the four carbon oxaloacetate to make the six carbon citrate ( a tricarboxylic acid) ### The six carbon molecule is much more manageable by enzymes. (analogy : like eating an ice cream off an ice cream stick). The two carbon molecule will eventually be totally decomposed to again regenerate oxaloacetate, the later of which can be reused again. ## The next reaction removes water from citrate which is followed by a reaction which adds back water!!! The purpose is to rearrange the molecule to make it more convenient to extract the energy. ## The next reaction releases energy to form reduced NADH. ## The reaction of oxalosuccinate (6 carbon molecule) to alpha-ketogluterate (5 carbon molecule) leads to the release of gaseous carbon dioxide. ## The next reaction again utilizes CoA-SH as a handle for one reaction. Energy is also released again as NADH. At this point we also lose the last carbon in the form of CO2. ## The reaction of succinyl-CoA to succinate leads to a phosphorylation of GDP to GTP. A GTPmolecule can be easily converted to an ATP by one more reaction. ## Succinic acid to fumaric acid yields a reduced flavoprotein. This FADH2 can be passed to FPH2 and used in the electron transport chain (in the presence of oxygen) to presumably yield two ATP molecules. ## The final step of malate to oxaloacetate wrings out the last bit of energy (as NADH) of our original glucose. The regenerated oxaloacetate is now ready to react with another acetyl CoA and the whole vicious cycle can be repeated. # Overall energy balance per glucose molecule: # A. Aerobic Anaerobic 2 ATP used in glycolysis ==================> -2 ATP -2 AT P 4 ATP formed in glycolysis ================> +4 ATP +4 ATP 2 NADH2 formed in glycolysis ====via e.t.==> +6 ATP 8 NADH2 formed in Kreb's cycle ===via e.t.==> +24 ATP 2 GTP in Kreb's cycle =====================> +2 ATP 2 FADH2 in Kreb's cycle ===via e.t.=========> +4 ATP Total: 38 ATP 2 ATP ## Frequently 36 ATP are quoted because it is known that in eukaryotic cells that the reduced NAD formed by glycolysis in the cytoplasm must be actively transported across the mitochondrial membrane to be made available to the electron transport chain. The cost of such active transport is one ATP for each NADH transported. Thus, the net gain for each cytoplasmic NADH is only two ATP rather than three. However if one plays this game, then one should also consider the active transport of other molecules as well (pyruvate? phosphate? Mg++? etc.). The actual net gain of ATP is unknown but must be regarded as less than 36. # In eukaryotic cells the Kreb's cycle occurs in the liquid part of the mitochondria (matrix)while the electron transport chain occurs in the inner membrane (cristae). The outer membrane is very porous and has almost no proteins; it seems to have no function and can almost be ignored. In the endosymbiotic theory the inner membrane would correspond to the cell membrane of bacterial prokaryotes and the matrix would correspond to the cytoplasm of bacterial prokaryotes.
What are the building blocks in the body's synthesis and elongation of fatty acids?
acetylCoA
What does Decarboxylation of pyruvate produces?
decarboxylation means removal of co2 from the reaction
What is the Calvin cycle responsible for?
It is responsible for the breakdown of pyruvate/acetylCoA into 1ATP, 4NADH, and 1FADH per cycle. It is a part of cellular respiration.
Is fermentation as effective as glycolysis?
because from glycolisis comes pyruvate, and then it is turned into acetylCoA. Without acetylCoA, nothgn will be able to enter the Krebs Cycle, otherwise known as the Citric acid cycle. Once the AcetylCoA comes in, after the prep cycle, it can then bind to RuBp, turnign into a six carbon sugar.
What major events that occur during Krebs cycle?
Most summaries of the Krebs Cycle will usually indicate that the cycle is an aerobic process (one that requires oxygen) that produces ATP by breaking down glucose.Kreb Cycle shows no oxygen or glucose is used in the cycle and that it does not make much ATP (only one molecule for each acetyl CoA that enters the cycle).
Why does ketogenesis occur?
Ketogenesis is a metabolic process to form ketone bodies in mitochondrial matrix of hepatocytes in emergency condition from accumulated Acetyl-CoAobtained from increased incomplete fatty acid oxidation due to cellular glucose deprivation.CoA is a complex structure which is impermeable to mitochondrial membranes, Acetate linked to CoA as AcetylCoA is also impermeable.The steps of Ketogenesis occur to remove the CoA from the molecules of AcetylCoA and form a permeable ketone body Acetoacetate( Primary Ketone body).Acetoacetate then spontaneously decarboxylated to stable Acetone and reduced to Beta Hydroxy Butyrate (Secondary ketone bodies).Thus Ketogenesis occur to remove the accumulated impermeable Acetyl-CoA from mitochondrial matrix by forming permeable ketonebodies.Ketogenesis removes the acetate carbon out of matrix and maintain the CoA pool of matrix.
Does glycolosis or Krebs cycle come first?
Glycolysis evolved first. Cells of all types of organisms are able to carry out glycolysis. The Krebs cycle arose after photosynthetic organisms began adding oxygen to the atmosphere because Krebs cycle requires oxygen and glycolysis does not.
Where is carbon dioxide formed during glucose metabolism?
When cellular respiration takes place the energy stored in the chemical bonds of glucose (C6H12O6) is released that energy is used to produce ATP(adinosinetri phosphate): In respiration glucose is oxidized and oxygen is reduced to form water(H2O). The carbon atoms of the sugar molecule are released as carbon dioxide (CO2).
Discuss creb's cycle?
KREB'S CYCLE # Kreb's cycle - introduction ## The Kreb's cycle converts pyruvate to CO2 and reducing energy (NADH and FADH2) and phosphorylated energy (GTP). 2 pyruvate + 2 GDP + 2 H3PO4 + 4 H2O + 2 FAD + 8 NAD+ ----> 6 CO2 + 2 GTP + 2 FADH2 + 8 NADH ## The reduced energy can be used to generate ATP using the electron transport chain in the presence of oxygen. ## It is a cyclic process in that oxaloacetate reacts with acetyl CoA to form citrate which starts a series of several other reactions. The final reaction in the series involves the regeneration of oxaloacetate! ## NAD and FAD; both are rather small nucleotide molecules that are electron carriers. FAD can transfer its reducing power to FP. The reduced and oxidized forms of NAD are not clear; thus oxidized NAD can be called => NADox; NAD+; or NAD; Reduced NAD can be called => NADred; NADH; and NADH2. # Kreb's cycle steps: ## The three carbon pyruvate reacts whereby a carbon is lost as CO2. The reaction releases energy such that NAD+ is reduced to NADH. The remaining two carbon compound is not allowed to be free but rather binds a special molecule (coenzyme A) to form acetyl CoA. ### This is essentially an irreversible reaction due to the loss of CO2. ### This reaction is probably more than one step, considering all of the reactants. However, even to this day the intricacies of this reaction are not well understood. ### It is not clear in eukaryotic cells exactly what carbon form passes from the cytoplasm to the mitochondrial matrix (pyruvate? acetyl CoA? an intermediate?) The process looks very complex. ### The binding of CoA-SH to the two carbon molecule is probably a type of handle making it easier for enzymes to act upon it. ## The two carbon chain is released from acetylCoA and binds to the four carbon oxaloacetate to make the six carbon citrate ( a tricarboxylic acid) ### The six carbon molecule is much more manageable by enzymes. (analogy : like eating an ice cream off an ice cream stick). The two carbon molecule will eventually be totally decomposed to again regenerate oxaloacetate, the later of which can be reused again. ## The next reaction removes water from citrate which is followed by a reaction which adds back water!!! The purpose is to rearrange the molecule to make it more convenient to extract the energy. ## The next reaction releases energy to form reduced NADH. ## The reaction of oxalosuccinate (6 carbon molecule) to alpha-ketogluterate (5 carbon molecule) leads to the release of gaseous carbon dioxide. ## The next reaction again utilizes CoA-SH as a handle for one reaction. Energy is also released again as NADH. At this point we also lose the last carbon in the form of CO2. ## The reaction of succinyl-CoA to succinate leads to a phosphorylation of GDP to GTP. A GTPmolecule can be easily converted to an ATP by one more reaction. ## Succinic acid to fumaric acid yields a reduced flavoprotein. This FADH2 can be passed to FPH2 and used in the electron transport chain (in the presence of oxygen) to presumably yield two ATP molecules. ## The final step of malate to oxaloacetate wrings out the last bit of energy (as NADH) of our original glucose. The regenerated oxaloacetate is now ready to react with another acetyl CoA and the whole vicious cycle can be repeated. # Overall energy balance per glucose molecule: # A. Aerobic Anaerobic 2 ATP used in glycolysis ==================> -2 ATP -2 AT P 4 ATP formed in glycolysis ================> +4 ATP +4 ATP 2 NADH2 formed in glycolysis ====via e.t.==> +6 ATP 8 NADH2 formed in Kreb's cycle ===via e.t.==> +24 ATP 2 GTP in Kreb's cycle =====================> +2 ATP 2 FADH2 in Kreb's cycle ===via e.t.=========> +4 ATP Total: 38 ATP 2 ATP ## Frequently 36 ATP are quoted because it is known that in eukaryotic cells that the reduced NAD formed by glycolysis in the cytoplasm must be actively transported across the mitochondrial membrane to be made available to the electron transport chain. The cost of such active transport is one ATP for each NADH transported. Thus, the net gain for each cytoplasmic NADH is only two ATP rather than three. However if one plays this game, then one should also consider the active transport of other molecules as well (pyruvate? phosphate? Mg++? etc.). The actual net gain of ATP is unknown but must be regarded as less than 36. # In eukaryotic cells the Kreb's cycle occurs in the liquid part of the mitochondria (matrix)while the electron transport chain occurs in the inner membrane (cristae). The outer membrane is very porous and has almost no proteins; it seems to have no function and can almost be ignored. In the endosymbiotic theory the inner membrane would correspond to the cell membrane of bacterial prokaryotes and the matrix would correspond to the cytoplasm of bacterial prokaryotes.
Why must cells carry out cellular respiration?
coz ya gay
How do animals produce carbon dioxide?
The process is called respiration, plants respire too but only at night. The word equation for this is: Glucose + Oxygen = Carbon Dioxide + Water + Energy
Why do sperm cells contain large amounts of mitochondria and glucose?
The motile sperm or spermatozoon uses a flagellum to move towards the egg during reproduction. The beating of the flagellum causes the sperm to "swim" towards the egg; however this beating must have an energy source for it to occur. Just as you or I need food as an energy source to swim, the sperm needs an energy source to swim.Since the journey between the testes and the egg is a long journey for a single cell measuring 25 µm (0.0025mm) in length, a lot of energy is required for it to complete the journey. The high abundance of glucose can be explained because glucose can be used by the sperm cell to provide energy in the form of adenosine triphosphate, or ATP.The reason why there are so many mitochondria in a sperm cell is a bit of a mystery because sperm cells produce energy mainly by a process called glycolysis, which does not require mitochondria.Mitochondria produce energy via the process below:Adenosine Triphosphate + ATPase ---> Adenosine Diphosphate + Pi**Where Pi stands for Inorganic Phosphate (orthophosphate)OR SHORTENED REATION EQUATIONATP + ATPase ---> ADP + PiHydrolysing ATP to Adenosine Diphosphate (ADP) releases an inorganic phosphate group in an exothermic process thus "releasing" energy; therefore explaining why ATP is the "univesal energy currency" i.e. because it is possible to derive energy from ATP.The hydrolysis of ATP releases approximately -30.5 kJ mol-1 energy (actually 30.5 kJ mol-1 energy however the negative sign denotes an exothermic reaction).The glucose is made into energy in the following simplified process:i) Glucose enters glycolysis in which 1 molecule of glucose is turned into 2molecules of pyruvate. (Net increase 2 ATP + 4NADH) The process:Glucose -> Glucose-6-phosphate -> Fructose-6-phosphate -> Fructose-1,3-bisphosphate -> { Glyceraldehyde-3-phosphate -> 1,3-bisphosphate glycerate -> 3-phospho glycerate -> 2-phospho glycerate -> Phosphoenolpyruvate -> Pyruvate } x 2ii) Pyruvate is changed into Acetyl CoA by pyruvate dehydrogenase enzyme so that it can be utilised in the Citric Acid Cycle:Pyruvate ----------> Acetly CoAiii) 2x Pyruvate enters the Krebs cycle in which Acetyl Coenzyme A (AcetylCoA) binds with oxaloacetate to form citric acid. (Net increase 2 x 1 GTP)Pyruvate -> Citrate -> Isocitrate -> Alpha - ketoglutarate -> Succinyl CoA -> Succinate -> Fumurate -> Malate -> Oxaloacetate (Cyclic)iv) Electron transport chain (ETC) utilising 3x NADH + H+,1x FADH2 and 1 x ATPfrom the Krebs cycle. (Net increase 24 ATP)Protons obtained from splitting NADH + H and FADH2 e.g.NADH + H+ ---> NAD + H2 H2 ---> 2H+ + 2e-Using proton carriers (known as complexes):Complex I - NADH-Q reductaseComplex II - Succinyl CoA reductaseComplex III - Cytochrome c reductaseComplex IV - Cytochrome c oxidaseProcess:Complex I + II pass electrons to Complex III which passes electrons to Complex IVThe high energy electrons that are passed between the complexes power the proton pumps in order to pump protons from the matrix of the mitochondria into the inner membrane. This creates a proton motor force (PMF) which therefore creates a chemiosmotic (or pH) gradient between the matrix and inner membrane; since protons cause acidity.The high energy electrons then reach ATP synthase (Also known as ATPase) which utilises the energy from the protons and electrons to synthesis ATP from ADP and inorganic phosphate in the reaction previously illustrated:ADP + Pi ---> ATPFollowing this the protons are reassociated with electrons and oxygen to produce water. This explains why oxygen is essential for the ETC (Electron Transport Chain) or Oxidative Phosphorylation, to occur:O2 + 4H+ + 4e+ ---> 4H2OAs such this clearly illustrates why oxygen is necessary for aerobic respiration to occur and therefore why carbon dioxide and water are by-products of aerobic respiration:C6H12O6 + 6O2 ---> 6CO2 + 6H2O + ATPTherefore one molecule of glucose produces a net. increase of 32 molecules of ATP thus allowing approximately 976kJ of energy to be produced from one molecule of glucose depending on condition variables.
