24 Questions
Why should all metabolic pathways be regulated?
To maintain cellular homeostasis
Why is the hexokinase step not the committed step in glycolysis?
It is reversible
Why is fructose 1,6-bisphosphate converted to glyceraldehyde-phosphate and dihydroxyacetone phosphate?
To yield intermediates for further glycolytic reactions
Why is glucose frequently administered intravenously to patients?
To maintain stable blood sugar levels
What is the role of Gibbs free energy in biochemical reactions?
Determining the direction of spontaneous reactions
How does entropy impact biological systems?
It influences the spontaneity of chemical reactions
What is the role of the pyridoxal-5-phosphate cofactor in the deamination process of amino acids?
Facilitating the removal of the amino group
What is the enzyme, coenzyme, and vitamin required for transamination?
Transaminase, NADPH, Vitamin B6
Why are people with Glucose-6-phosphate dehydrogenase (G6PD) deficiency at risk of haemolytic anemia?
Reduced antioxidant capacity
What does the pentose phosphate pathway tailor to meet the body's specific need of NADPH?
Generation of ribose-5-phosphate
In the citric acid cycle, which enzyme catalyzes the first reaction?
Citrate synthase
How is the citric acid cycle regulated?
Inhibition by high levels of NADH and ATP
What is the final product generated directly by the conversion of Succinyl CoA in the Krebs Cycle?
Succinate
Which molecule is oxidized to produce FADH2 in the Krebs Cycle?
Succinate
How many molecules of NADH are produced from the Krebs Cycle after one turn?
Three
Who was awarded the Nobel Prize in Physiology or Medicine for his work on proposing the Krebs Cycle?
Sir Hans Adolf Krebs
What is the key compound identified by Fritz Lipmann and Nathan Kaplan essential for the operation of the Krebs Cycle?
Coenzyme A
Where does the Krebs Cycle take place in most living organisms?
Mitochondria
What is the initial step that initiates the Krebs Cycle?
Formation of citrate
Which compound is formed by the oxidation of isocitrate in the Krebs Cycle?
Alpha-ketoglutarate
What is the final product after the conversion of alpha-ketoglutarate in the Krebs Cycle?
Succinyl CoA
Which of the following best describes the Krebs Cycle's pathway?
Closed loop where the last part regenerates the compound used first
What is the role of oxaloacetate in the Krebs Cycle?
Regeneration of the compound used in the first step
Which part of a cell does the Krebs Cycle mainly take place in?
"Mitochondria"
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.
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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