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Explain how and why the gluconeogenesis pathway differs from just the reverse of the glycolytic pathway. (5)1. The gluconeogenesis pathway uses 4 enzymes to bypass 3 reactions of glycolysis. Would it have been easier and thus made more sense just to do the reverse of glycolysis to regenerate glucose

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Bunny GreenfelderLv2

15 Jan 2019

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(BIOCHEMISTRY QUESTION)

A. Gluconeogenesis is not just the reverse of glycolysis. Briefly describe one of the steps catalyzed by different enzymes in glycolysis and gluconeogenesis.

B. Explain how a biochemist might dicover that a certain enzyme is allosterically regulated.

C. What are the regulatory implications for the cell with regard to ATP & AMP, given the relative concentrations of ATP & AMP in a cell?

D. Describe the function of fructose 2,6-bisphosphate in overriding the control of gycolysis and gluconeogenesis in liver cells in response to lowered blood glucose levels.

E. The human disease beriberi is caused by a deficiency of thiamine in the diet. People with severe beriberi have higher than normal levels of pyruvate in their blood & urine. Explain this observation in terms of specific enzymatic reaction(s).

My Responses: Could you tell me if these are correct? If not, could you provide the correct answer and explanation?

A. Its a cellular process in which glucose is produced from pyruvate, amino acids, lactate, and other biogenic precursors.

B. They might learn that an enzyme is allosterically regulated if that protein or enzyme undergoes a conformational change modulated by the binding of one or more modulators/effectors to alternate sites on the protein, resulting in a change in its activity. And they usually have more than one polypeptide chain.

C. The regulatory implications for the cell would be that all activity would increase and concentrations would go up unless bound to PFK-1 and then the overall activity would drop.

D. Low blood glucose is when glucagon signals the liver to produce and release more glucose (gluconeogenesis) and stop consumption. Fructose 2, 6-bisphosphate mediates rapid hormonal regulation of glycolysis and gluconeogenesis.

E. Pyruvate is the product of both carbohydrate and amino acid catabolism that enters cellular respiration in the mitochondria when converted to acetyl-CoA catalyzed by the PDH complex. The first step in the PDH complex reaction is a decarboxylation reaction that cannot be catalyzed without the enzyme thiamine pyrophosphate (TPP). This coenzyme is a derivative of thiamine or vitamin B1.

sapphireswan33

1. Integrated metabolism

A. A molecule of glucose that you eat can eventually be transformed into part of a fatty acid that you store. Circle the pathways/cycles below that are part of this overall flow of carbon atoms. Cross out any that are not.

Gluconeogenesis, beta-oxidation, citric acid cycle, glycolysis, urea cycle, fatty acid synthesis

B. Trace the metabolic path of this glucose molecule through the enzymes it encounters along the way to being made into fat. Write all the enzymes in the list below into the proper places in the figure below. If the enzyme is not used, write its name in a ânot used" column. If it is used, write the enzyme in the order that the carbon atoms from glucose encounter the enzymes.

Pyruvate dehydrogenase, fumarase, aldolase, lactate dehydrogenase, pyruvate kinase, acetyl CoA carboxylase, fatty acid synthase, hexokinase, carnitine acyltransferase, ATP synthase

B. What is the minimum number of glucose molecules that would be necessary to be the carbon source for synthesis of a 16-carbon fatty acid through this pathway?

C. How many net glucose can be made from one molecule of a 16-carbon fatty acid?

2. Describe each cycle/transport system (compounds, compartments, tissues) and explain its purpose:

A. citrate transport system

B. Cori cycle

C. glucose/alanine cycle

Explain the logic of these pathway regulations:

A. Phosphofructokinase, not hexokinase, is the main regulation site of glycolysis.

B. SuccinylCoA inhibits the entry of acetyl CoA into the citric acid cycle.

C. NADH inhibits pyruvate dehydrogenase.

D. Citrate inhibits the citric acid cycle and activates acetyl-CoA carboxylase.

E. Insulin leads to activation of glycogen synthase.

ochrereindeer904

For each question,choose the ONE BEST And Give Best Explanation [No Explanation nopoints :( ]

1. Metabolismis

A. the means by whichDNA is stored.

B. the sum of all theanabolic and catabolic reactions in a cell.

C. the reactions thatbreak fuel molecules down to gain energy.

D. the reactions thatsynthesise molecules in the cell.

E. the sum of all thereactions taking place in the mitochondrial matrix.

2. The Krebscycle

A. breaks downpyruvate.

B. oxidizes two-carbonunits to produce carbon dioxide and reduced coenzymes.

C. oxidizesglycerol.

D. drives H+ out of themitochondrial matrix.

E. uses GTP rather thanATP to supply phosphate groups.

3. Which of thefollowing statements about the glycolysis pathway in the cytosol isincorrect?

A. It makes ATP.

B. It makesacetyl-CoA.

C. It interacts with thepentose phosphate pathway.

D. All but three stepsare reversible and therefore also operate in gluconeogenesis.

E. It is oxidative underaerobic conditions.

4. %u03B2oxidation

A. breaks the%u03B2-glycosidic bonds in cellulose.

B. uses acetyl-CoA,NADH, and FADH2 to produce long-chain fatty acids.

C. generates pentosesugars.

D. oxidizes fatty acidsto give acetyl-CoA, NADH, and FADH2.

E. Is part oftriacylglycerol biosynthesis.

5.Gluconeogenesis is not capable of making glucose from

A. alanine.

B. lactate.

C. glycerol.

D. palmitate.

E. 2-oxoglutarate.

6. Which of thefollowing statements is incorrect concerning photosynthesis ingreen

plants?

A. It generates ATP,NADPH, and oxygen.

B. It adds carbondioxide to a five-carbon sugar that is then cleaved to form twomolecules of

phosphoglycerate.

C. Its enzymes are foundin the mitochondria.

D. It uses light energyto drive the splitting of water.

E. Its enzymes are foundin the chloroplasts.

7. Positivefeedback is operating

A. when adenosinemonophosphate activates phosphofructokinase.

B. when cAMP activatestranscription of the lac operon.

C. when tryptophaninhibits transcription of the trp operon.

D. whenN-acyl-HSL promotes transcription of the luxoperon.

E. in all the examplesabove.

8. ATP

A. is converted to ADPas H+ enters the mitochondrial matrix.

B. is a coenzyme.

C. passes through theouter mitochondrial membrane by simple diffusion.

D. cannot be made in theabsence of oxygen.

E. concentrations fall to a low levelin resting cells.

lilacwoodchuck496

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Explain how and why the gluconeogenesis pathway differs from just the reverse of the glycolytic pathway. (5)1. The gluconeogenesis pathway uses 4 enzymes to bypass 3 reactions of glycolysis. Would it have been easier and thus made more sense just to do the reverse of glycolysis to regenerate glucose

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