Biochemistry: Deamination, Urea Cycle, and Transamination Quiz
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Questions and Answers

Why should all metabolic pathways be regulated?

  • To ensure energy is efficiently utilized
  • To increase the rate of metabolic reactions
  • To maintain cellular homeostasis (correct)
  • To prevent the buildup of toxic intermediates

Why is the hexokinase step not the committed step in glycolysis?

  • It is reversible (correct)
  • It occurs after the phosphofructokinase step
  • It does not require ATP
  • It is not an early step in the glycolysis pathway

Why is fructose 1,6-bisphosphate converted to glyceraldehyde-phosphate and dihydroxyacetone phosphate?

  • To form ATP molecules
  • To generate NADH for energy production
  • To increase the pH of the cytoplasm
  • To yield intermediates for further glycolytic reactions (correct)

Why is glucose frequently administered intravenously to patients?

<p>To maintain stable blood sugar levels (B)</p> Signup and view all the answers

What is the role of Gibbs free energy in biochemical reactions?

<p>Determining the direction of spontaneous reactions (D)</p> Signup and view all the answers

How does entropy impact biological systems?

<p>It influences the spontaneity of chemical reactions (C)</p> Signup and view all the answers

What is the role of the pyridoxal-5-phosphate cofactor in the deamination process of amino acids?

<p>Facilitating the removal of the amino group (C)</p> Signup and view all the answers

What is the enzyme, coenzyme, and vitamin required for transamination?

<p>Transaminase, NADPH, Vitamin B6 (A)</p> Signup and view all the answers

Why are people with Glucose-6-phosphate dehydrogenase (G6PD) deficiency at risk of haemolytic anemia?

<p>Reduced antioxidant capacity (A)</p> Signup and view all the answers

What does the pentose phosphate pathway tailor to meet the body's specific need of NADPH?

<p>Generation of ribose-5-phosphate (C)</p> Signup and view all the answers

In the citric acid cycle, which enzyme catalyzes the first reaction?

<p>Citrate synthase (D)</p> Signup and view all the answers

How is the citric acid cycle regulated?

<p>Inhibition by high levels of NADH and ATP (C)</p> Signup and view all the answers

What is the final product generated directly by the conversion of Succinyl CoA in the Krebs Cycle?

<p>Succinate (B)</p> Signup and view all the answers

Which molecule is oxidized to produce FADH2 in the Krebs Cycle?

<p>Succinate (A)</p> Signup and view all the answers

How many molecules of NADH are produced from the Krebs Cycle after one turn?

<p>Three (A)</p> Signup and view all the answers

Who was awarded the Nobel Prize in Physiology or Medicine for his work on proposing the Krebs Cycle?

<p>Sir Hans Adolf Krebs (C)</p> Signup and view all the answers

What is the key compound identified by Fritz Lipmann and Nathan Kaplan essential for the operation of the Krebs Cycle?

<p>Coenzyme A (C)</p> Signup and view all the answers

Where does the Krebs Cycle take place in most living organisms?

<p>Mitochondria (C)</p> Signup and view all the answers

What is the initial step that initiates the Krebs Cycle?

<p>Formation of citrate (C)</p> Signup and view all the answers

Which compound is formed by the oxidation of isocitrate in the Krebs Cycle?

<p>Alpha-ketoglutarate (D)</p> Signup and view all the answers

What is the final product after the conversion of alpha-ketoglutarate in the Krebs Cycle?

<p>Succinyl CoA (A)</p> Signup and view all the answers

Which of the following best describes the Krebs Cycle's pathway?

<p>Closed loop where the last part regenerates the compound used first (D)</p> Signup and view all the answers

What is the role of oxaloacetate in the Krebs Cycle?

<p>Regeneration of the compound used in the first step (D)</p> Signup and view all the answers

Which part of a cell does the Krebs Cycle mainly take place in?

<p>&quot;Mitochondria&quot; (A)</p> Signup and view all the answers

Flashcards

Fructose 1,6-bisphosphate to Glyceraldehyde 3-P conversion

A biochemical reaction that converts fructose 1,6-bisphosphate into two simpler molecules, glyceraldehyde 3-phosphate and dihydroxyacetone phosphate.

Gibbs Free Energy

The energy available to do useful work in a chemical reaction at a constant temperature and pressure.

Entropy

A measure of the disorder or randomness in a system.

Catabolic Pathways

Metabolic pathways that break down complex molecules into simpler ones, releasing energy.

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Anabolic Pathways

Metabolic pathways that synthesize complex molecules from simpler ones, requiring energy.

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Metabolic Pathways

Series of reactions that change a starting molecule into a final product.

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Committed Step

A step in a metabolic pathway that is essentially irreversible, driving the pathway forward.

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Deamination

The removal of an amino group from an amino acid.

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Pyridoxal-5-phosphate

A cofactor involved in deamination reactions, crucial in the process.

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Urea Cycle

A cycle of biochemical reactions that convert ammonia into urea, a less toxic form.

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Citric Acid Cycle

A series of biochemical reactions that oxidizes acetyl-CoA, producing energy.

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Pentose Phosphate Pathway

A metabolic pathway that generates NADPH and ribose-5-phosphate.

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NADPH

A reduced form of NADP+, acting as a reducing agent.

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Glucose-6-phosphate dehydrogenase

An enzyme crucial for regeneration of NADPH by converting glucose-6-phosphate to 6-phosphogluconate.

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Hemolytic Anemia

A condition resulting from an inability to produce or use NADPH, leading to disrupted red blood cell function.

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Cellular Respiration

Process of converting glucose and other nutrients into ATP.

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Acetyl CoA

A molecule carrying acetyl groups for reactions.

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Oxaloacetate

A four-carbon molecule that combines with Acetyl CoA in Citric acid cycle.

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Citrate

Six-carbon molecule formed when Acetyl Co-A reacts with Oxaloacetate, beginning the Citric Acid cycle.

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Redox Reaction

Reaction where electrons transfer from one molecule to another.

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Krebs Cycle

Alternative name for Citric Acid Cycle.

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ATP

A molecule storing cellular energy.

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FADH2

A molecule storing energy to be used in ATP production from redox reaction during Citric acid cycle.

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Study Notes

Biochemistry Exam Questions

  • The exam consists of 4 questions, with a total of 2 hours to complete.
  • Question 1 is about biochemistry, with 5 parts (a, b, c, d, and e).
  • Part a asks to draw a reaction mechanism for converting fructose 1,6-bisphosphate to glyceraldehyde 3-phosphate and dihydroxyacetone phosphate.
  • Part b explains the terms Gibbs free energy, entropy, and their significance in metabolism.
  • Part c discusses why catabolic and anabolic pathways differ, and why metabolic pathways should have a committed step.

Deamination and Urea Cycle

  • Deamination is the process of removing an amino group from an amino acid.
  • The pyridoxal-5-phosphate cofactor plays a crucial role in the deamination process.
  • The enzyme, coenzyme, and vitamin required for transamination are not specified.
  • The urea cycle is regulated and linked to the citric acid cycle.
  • The urea cycle is called a "cycle" because it involves a series of reactions that regenerate the initial reactant.

Pentose Phosphate Pathway

  • The pentose phosphate pathway is tailored to meet the body's specific need for NADPH but not ribose-5-phosphate.
  • The pathway is essential for generating NADPH, which is necessary for reducing oxidized glutathione.
  • People with glucose-6-phosphate dehydrogenase (G6PD) deficiency are at risk of hemolytic anemia due to their inability to regenerate NADPH.
  • The pentose phosphate pathway has five importance: generating NADPH, producing ribose-5-phosphate, and maintaining the balance of reactive oxygen species.

Citric Acid Cycle

  • The citric acid cycle, also known as the Krebs cycle, is a crucial process in cellular respiration.
  • The cycle is a series of reactions that takes place in the mitochondria of most living organisms.
  • The cycle is initiated when acetyl CoA reacts with oxaloacetate to form citrate and release coenzyme A (CoA-SH).
  • The cycle consists of 7 steps, each catalyzed by a specific enzyme.
  • The cycle produces energy through the formation of ATP, NADH, and FADH2.
  • The energy is generated through a series of redox reactions, where electrons are transferred from one substance to another.

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Test your knowledge on biochemistry topics such as deamination of amino acids, role of pyridoxal-5-phosphate, regulation of urea cycle, links to citric acid cycle, and enzymes/coenzymes involved in transamination. Explore key concepts in metabolic pathways.

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