Biochemistry and Molecular Biology: Introduction to Metabolism

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Questions and Answers

What is the primary function of ATP in living cells?

To facilitate the controlled release of energy in enzyme-catalysed metabolic pathways
To serve as the 'energy currency' of living cells, providing energy for various cellular activities (correct)
To store energy for long-term use
To act as a precursor molecule for the synthesis of other nucleotides

Which of the following statements is true about anabolic pathways?

They are typically exergonic, releasing energy in the form of ATP
They are only found in prokaryotic cells
They are involved in the synthesis of molecules, often requiring energy input (correct)
They involve the breakdown of molecules to release energy

What is the role of NADH in energy metabolism?

It is a byproduct of glycolysis, with no significant role in energy metabolism
It serves as an energy storage molecule, releasing energy as needed
It acts as an electron acceptor in the electron transport chain
It is a carrier molecule, transferring electrons to other molecules (correct)

What is the primary function of coenzyme A in energy metabolism?

It is a carrier molecule, transferring acetyl groups to other molecules (B) Signup and view all the answers

In eukaryotic cells, where is the β-oxidation pathway typically located?

In the mitochondria (C) Signup and view all the answers

What is the term for the controlled release of energy in enzyme-catalysed metabolic pathways?

Energy coupling (A) Signup and view all the answers

What is the common characteristic of the names of catabolic pathways?

They end in 'lysis' (A) Signup and view all the answers

Where does the generation of ATP and NADH occur?

Mitochondria (C) Signup and view all the answers

What is the purpose of stepwise breakdown in metabolic pathways?

To release energy in small, usable packages (D) Signup and view all the answers

How can metabolic pathways be regulated?

By regulating the activity of specific enzymes (D) Signup and view all the answers

What is the consequence of activating enzyme 1 and enzyme 2 in a pathway?

Speeding up both forward and reverse pathways (D) Signup and view all the answers

Where is energy released at each step in metabolic pathways stored?

In activated carrier molecules (B) Signup and view all the answers

What is the significance of ATP in metabolic pathways?

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

What is the characteristic of ATP that makes it a suitable energy currency?

It is highly stable at pH 6-9 (D) Signup and view all the answers

What is the primary function of ATP in metabolic control?

To regulate enzyme activity (A) Signup and view all the answers

What is the energy available from the hydrolysis of ATP to ADP?

31-50 kJ mole-1 (A) Signup and view all the answers

What is the role of UTP in biosynthetic reactions?

To drive the synthesis of complex sugars (C) Signup and view all the answers

What is the result of transferring two H atoms to NAD+ from a donor?

Two protons are released to solution and two electrons are transferred (B) Signup and view all the answers

What makes the hydrolysis of ATP energetically favourable?

The high energy released from ATP hydrolysis (D) Signup and view all the answers

What is the composition of a hydrogen atom?

1 proton and 1 electron (D) Signup and view all the answers

What is the role of Na+/K+ pumps in the cell?

To maintain the electrochemical gradient (C) Signup and view all the answers

What is the reaction that occurs when glucose is converted to glucose-6-phosphate?

Glucose + ATP → Glucose-6-phosphate + ADP (C) Signup and view all the answers

What is the function of NAD+ in metabolic reactions?

To accept H atoms (B) Signup and view all the answers

What is the result of transferring one H atom to NAD+ from a donor?

One proton is released to solution and one electron is transferred (C) Signup and view all the answers

What is the primary function of ATP in biochemical reactions?

To provide a source of energy for metabolic reactions (C) Signup and view all the answers

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

Thioester bond (B) Signup and view all the answers

What is the primary location of catabolic reactions in a cell?

Mitochondria (C) Signup and view all the answers

What is the term for a metal ion that is required for an enzyme's activity?

Cofactor (A) Signup and view all the answers

What is the correct definition of catabolism?

The breakdown of complex molecules into simpler ones (D) Signup and view all the answers

What is the primary function of enzymes in biochemical reactions?

To stabilize the transition state of a reaction (A) Signup and view all the answers

What is the term for a molecule that is required for an enzyme's activity, but is not a part of the enzyme itself?

Cofactor (B) Signup and view all the answers

What is the primary function of coenzyme A in biochemical reactions?

To facilitate the transfer of acetyl groups (B) Signup and view all the answers

What is the role of the liver in the context of amino acid metabolism?

To remove NH4+ from the body via the urea cycle (C) Signup and view all the answers

What is the result of the transamination reaction between an amino acid and α-ketoglutarate?

The formation of glutamate and ketoacid (D) Signup and view all the answers

What is the role of glutamine in the context of amino acid metabolism?

To transport ammonia from tissues to the liver (B) Signup and view all the answers

What is the byproduct of the deamination reaction of glutamine?

NH4+ (B) Signup and view all the answers

What is the term used to describe the remaining carbon skeleton after the removal of an amino group from an amino acid?

Carbon skeleton (D) Signup and view all the answers

What is the reaction that involves the conversion of glutamine to glutamate and α-ketoglutarate?

Deamination (B) Signup and view all the answers

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Study Notes

Introduction to Metabolism

Metabolism: the sum of all chemical reactions in the body
Anabolism: synthesis of complex molecules from simpler ones, requiring energy
Catabolism: breakdown of complex molecules into simpler ones, releasing energy

Key Features of Metabolic Pathways

Catabolic pathways release energy, anabolic pathways require energy
Pathways can be regulated by controlling specific enzymes
Stepwise breakdown of molecules releases energy in usable packages
Different 'forward' and 'reverse' pathways allow separate regulation

Activated Carrier Molecules

Energy released at each step is stored in activated carrier molecules (e.g. ATP, NADH, FADH2)
Examples of activated carrier molecules: NAD+/NADH, FAD/FADH2, Coenzyme A/acetyl CoA

Importance of ATP

ATP is the energy currency of living cells
ATP is synthesized in catabolic pathways
ATP is structurally stable at pH 6-9, with specific proteins and enzymes recognizing its features

ATP Hydrolysis

ATP breakdown releases energy, which is available for cellular work and chemical synthesis
ATP hydrolysis is energetically favorable due to the high energy of phosphoanhydride bonds

Functions of ATP

Used in metabolic control, regulating enzyme activity
Used in metabolism to add Pi to metabolic intermediates
Other high-energy nucleotide carriers (e.g. UTP, GTP) are used to drive specific biosynthetic reactions

Role of NAD+ and Coenzyme A

NAD+ is an electron acceptor, transferring 2H atoms
Acetyl-CoA is a 'high-energy' thioester bond, storing energy from oxidation of glucose and fatty acids

Metabolic Reactions

Require fuel molecules, enzyme catalysts, and cofactors
Enzyme cofactors can be coenzymes, activating ions, or prosthetic groups

Summary Diagrams

Show summary diagrams of metabolic pathways with links to other main metabolic processes
Cell Biology textbooks show summary diagrams with the cellular location of the main metabolic pathways

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