Metabolism: Catabolism and Anabolism

Questions and Answers

What is the primary function of Coenzyme A in cellular metabolism?

To catalyze enzyme reactions

To store energy from glucose and fatty acid oxidation (correct)

To facilitate the breakdown of ATP

To act as a prosthetic group

What is the energy yield from the breakdown of one mole of ATP?

Approximately 20 kJ

Approximately 31 kJ (correct)

Approximately 50 kJ

Approximately 40 kJ

In which cellular compartment do the three stages of catabolism of sugars, fats, and amino acids occur?

Endoplasmic Reticulum

Nucleus

Mitochondria

Cytosol (correct)

What is the term for the 'high energy' bond that links the acetyl group to Coenzyme A?

Thioester bond Signup and view all the answers

What is the role of cofactors in enzyme catalysis?

To facilitate the binding of substrates to the enzyme Signup and view all the answers

What is the term for the summary diagrams shown in biochemistry and cell biology textbooks?

Summary diagrams Signup and view all the answers

What is the correct definition of catabolism?

The breakdown of energy-rich molecules to release energy Signup and view all the answers

What is the term for the metal ions that are required for an enzyme's activity?

Activating ion Signup and view all the answers

What is the function of Na+/K+ pumps in cellular metabolism?

To maintain the balance of ions across the cell membrane Signup and view all the answers

What is the byproduct of the reaction Glucose + ATP → Glucose-6-phosphate + ADP?

Pi Signup and view all the answers

Which of the following nucleotides drives the synthesis of proteins?

GTP Signup and view all the answers

What is the net result of the glycolysis pathway?

Oxidation of glucose to pyruvate Signup and view all the answers

What is the net result of transferring 2 H atoms to NAD+?

Release of 2 H+ and gain of 2 e- Signup and view all the answers

What prevents glucose 6-phosphate from diffusing back across the lipid membrane?

The negative charges on the phosphate group Signup and view all the answers

What is the product of aerobic metabolism of pyruvate?

Acetyl-CoA Signup and view all the answers

What is the characteristic of catabolic pathway names?

They always end with 'lysis' Signup and view all the answers

What is the role of NAD+ in metabolism?

To accept H atoms and form NADH Signup and view all the answers

What is the co-factor that is oxidised in anaerobic metabolism?

NADH Signup and view all the answers

Why are metabolic pathways stepwise?

To release energy in small, manageable packages Signup and view all the answers

What is the composition of a hydrogen atom?

1 proton and 1 electron Signup and view all the answers

What is the result of transferring 1 H atom?

Transfer of 1 H+ and 1 e- Signup and view all the answers

What is the number of carbon atoms in one molecule of glucose?

6 Signup and view all the answers

What is the role of activated carrier molecules in metabolism?

To store energy released at each step Signup and view all the answers

What is the function of ATP in metabolic control?

To regulate enzyme activity Signup and view all the answers

What is the significance of ATP in metabolic pathways?

It is the energy currency of the cell Signup and view all the answers

How many molecules of pyruvate are produced from one molecule of glucose in glycolysis?

2 Signup and view all the answers

What is the result of hydrolysis of ATP?

ADP + Pi + energy Signup and view all the answers

Why is the hydrolysis of ATP energetically favourable?

Due to the phosphoanhydride bonds in ATP Signup and view all the answers

What is the significance of the specific proteins, enzymes, etc. in ATP?

They recognize the structural features of ATP Signup and view all the answers

What is the characteristic of anabolic pathway names?

They always end with 'genesis' Signup and view all the answers

What is the importance of regulating specific enzymes in metabolic pathways?

To regulate the pathway Signup and view all the answers

Why is ATP chemically stable at pH 6-9?

Due to its structural features Signup and view all the answers

What is the final electron acceptor in the electron transport chain?

O2 Signup and view all the answers

What is the purpose of the protein complexes in the electron transport chain?

To pump protons into the intermembrane space Signup and view all the answers

What is the result of the proton flow back through the membrane via ATP Synthase?

The synthesis of ATP from ADP + Pi Signup and view all the answers

What happens to the carbon skeleton of amino acids that are surplus to requirements?

It is further metabolised Signup and view all the answers

Where are the protein complexes of the electron transport chain embedded?

The inner mitochondrial membrane Signup and view all the answers

What is the result of the electrochemical gradient created by the electron transport chain?

The pumping of protons into the intermembrane space Signup and view all the answers

What is the role of NADH and FADH2 in the electron transport chain?

They are the reduced electron carriers that are oxidised Signup and view all the answers

What is amino acid metabolism also known as?

Nitrogen metabolism Signup and view all the answers

Study Notes

Metabolism

Metabolic pathways can be divided into two categories: catabolism (breakdown of molecules to release energy) and anabolism (synthesis of molecules to store energy)
Catabolic pathway names end in '-lysis', while anabolic pathway names end in '-genesis'

Energy Release and Storage

Energy released from catabolic pathways is stored in activated carrier molecules such as ATP, NADH, and FADH2
ATP is the primary energy currency of the cell, with a hydrolysis energy of -31 to -50 kJ/mole
ATP is chemically stable at pH 6-9 and has specific structural features recognized by proteins and enzymes

Regulation of Metabolic Pathways

Metabolic pathways can be regulated by controlling specific enzymes
Activating certain enzymes can speed up or slow down specific pathways
Different 'forward' and 'reverse' pathways allow for separate regulation

Activated Carrier Molecules

ATP is used in metabolic control, adding Pi to metabolic intermediates, and driving biosynthetic reactions
UTP and GTP are also high-energy nucleotides used to drive specific biosynthetic reactions
NAD+ is a high-energy electron carrier molecule that accepts H atoms and is used in catabolic pathways

Enzyme Cofactors

Enzyme cofactors include ATP, coenzymes, activating ions, and prosthetic groups
ATP acts as a high-energy cofactor for kinase enzymes, releasing energy upon breakdown
Metal ions such as Mg2+ and Zn2+ are required for enzyme activity

Cellular Location of Metabolic Pathways

Catabolism of sugars, fats, and amino acids occurs in three stages
Glycolysis occurs in the cytosol, while the electron transport chain and citric acid cycle occur in the mitochondria

Glucose Metabolism

Glucose is metabolized via the glycolysis pathway, resulting in the formation of pyruvate
In aerobic metabolism, pyruvate is transported into the mitochondria and oxidized to acetyl-CoA
In anaerobic metabolism, pyruvate is reduced to lactate, with simultaneous oxidation of NADH to NAD+

Electron Transport Chain

The electron transport chain is a series of protein complexes embedded in the mitochondrial inner membrane
Electrons are transported along the chain, releasing energy that is used to pump protons into the intermembrane space
The resulting electrochemical gradient is used to drive the synthesis of ATP from ADP + Pi via ATP synthase

Amino Acid Metabolism

Amino acid metabolism involves the removal of the nitrogen from the α-amino group and further metabolization of the carbon skeleton
Amino acid metabolism is complex and varied, with different pathways for different amino acids

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Description

This quiz covers the basics of metabolism, including catabolism and anabolism processes, and their relation to energy production and consumption. It focuses on the differences between glycolysis, gluconeogenesis, lipolysis, and lipogenesis.