Concept explainers
Interpretation: To determine the amount of energy, in terms of ATP consumption expended in the formation of a molecule of urea from ammonium ion and oxaloacetate.
Concept introduction: Urea cycle is a cyclic biochemical pathway that involves the production of urea using ammonium ions and aspartate molecules as nitrogen sources. It converts toxic ammonium ion to urea which is then excreted from the body in urine.
Urea cycle constitutes 4 steps. In step 1 carbamoyl phosphate transfers its carbamoyl group to ornithine to produce citrulline. Citrulline then condenses with aspartate in the second step to form argininosuccinate which then cleaves in the third step to form arginine and fumarate. In the final step, arginine reacts with water to produce urea.
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- How many ATP molecules (or equivalents) are consumedduring: b. removal of an ammonium ion by urea cycle?arrow_forwardidentify the major reactants and products of the urea cycle.arrow_forwardIdentify urea in the Urea cycle below and show/explain where the two Nitrogen atoms of urea originate from. 3 2 ATP + HCO3 + NH3 4 CPS-1 2 ADP, P₁ NH3 CH₂ CH₂ CH₂ HC-NH3 Coo 1 7 H₂N NH₂ H₂N O=UN ARG1 H₂O OPO3²- feeli. NH₂ CH₂ CH₂ OTC CH₂ P₁ HỘ—NH3* ·8-3-4-8 • ASL CH 5 ΝΗ CH₂ CH₂ CH₂ HỘNH3 COO NH₂ 3 3 ASS NH COO ΝΗ CH₂ CH₂ COO- CH₂ CH₂ HỘ NH3* COO 4 ATP PP₁ L-Asp AMParrow_forward
- What are the energy consuming steps of the urea cycle and what is the energetic cost of the urea cycle in terms of ATP equivalents? How is this cost partially offset and what is the total net cost of the urea cycle?arrow_forward(a) How many ATP equivalents are consumed by the reactions of the urea cycle? (b) Operation of the urea cycle actually generates more ATP than it consumes. Explain.arrow_forwardThe urea cycle can be summarized through the following reaction: O || H₂N-C-OPO3= COO- | H3N-CHCH₂COO- O || H₂N-C-NH2 + -OOCCH = CHCOO- 1. Write the reactions, using structural formulas that lead to the formation of carbamoyl phosphate and its subsequent incorporation into the urea cycle. Name the enzymes and how they are activated.arrow_forward
- How many moles of ATP are produced by the complete oxidation of 1 mol of myristic acid?arrow_forwardHow is the urea cycle linked to the citric acid cycle? Write the net equation of the urea cycle and indicate whether energy is produced or consumed by the cycle. What type of damage occurs if there is a defect in the urea cycle?arrow_forwardThe urea cycle can be summarized through the following reaction: O || H2N-C-OPO3 + COO- | H3N-CHCH₂COO b. O || H2N-C-NH2 1a Write the reactions, using structural formulas that lead to the formation of carbamoyl phosphate and its subsequent incorporation into the urea cycle. Name the enzymes and how they are activated. 1 + OOCCH=CHCOO- Write the rest of the reactions that constitute the urea cycle using structural formulas. Name the enzymes that catalyze each reaction. Indicate which reactions occur in the mitochondrion and which occur in the cytoplasm.arrow_forward
- Why is glycolysis more rapid after the infusion of fructose?arrow_forwardWhich of the following statements about the transamination and deamination steps of amino acid degradation is true? (A) a-ketoglutarate is always formed during a transamination between an amino acid and glutamate. (B) Transamination reactions produce glutamate that is deaminated after entering the urea cycle. (C) Free ammonia is removed from glutamate using glutamate dehydrogenase and NAD+ as an oxidizing agent. (D) The free NH4+ that is removed from glutamate during the deamination reaction is used to form glucose.(E) The carbon backbone that results from transamination enters the mitochondria to be used in the urea cycle.arrow_forwardWhat is the role of the urea cycle in amino acid breakdown?arrow_forward
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