Enzyme Function and Metabolic Pathways

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Questions and Answers

What is a ribozyme?

An RNA molecule that can act as an enzyme (correct)

A ribonucleotide sequence that catalyzes reactions

A carbohydrate that functions as a catalyst

A type of protein enzyme

What effect does increased CO2 concentration have on blood acidity?

It neutralizes blood acidity

It causes the blood to become more acidic (correct)

It has no effect on blood acidity

It makes the blood alkaline

What does the Michaelis-Menten constant (Km) indicate?

The concentration of substrate at which reaction velocity is half of Vmax (correct)

The rate of reaction at maximum substrate concentration

The total number of enzyme-substrate complexes formed

The effectiveness of an enzyme inhibitor

Why do some scientists believe early protocells were RNA-based?

RNA can perform multiple roles, including self-replication and catalysis Signup and view all the answers

What was a significant obstacle faced by Maude Menten during her studies?

She faced gender discrimination preventing her from conducting research in Canada Signup and view all the answers

What effect does ethanol have on the NMDA receptor?

It inhibits its function. Signup and view all the answers

Which statement correctly describes the characteristics of non-competitive inhibition?

Vmax is lower and Km is unchanged. Signup and view all the answers

Which of the following is an example of competitive inhibition?

Cocaine competing with dopamine at the re-uptake receptor. Signup and view all the answers

What is a primary function of membranes in relation to enzymes?

Membranes help compartmentalize products from substrates. Signup and view all the answers

How are membrane proteins typically produced?

In the Golgi apparatus after being synthesized. Signup and view all the answers

What was Buchner's contribution to the understanding of fermentation?

He showed that it could occur without living cells using zymase. Signup and view all the answers

What does the term 'induced fit' refer to in enzyme function?

The enzyme's shape is modified to fit the substrate upon binding. Signup and view all the answers

What factors can influence the rate of enzyme-controlled reactions?

Temperature, pH, and concentration of both enzyme and substrate. Signup and view all the answers

Which of the following statements about enzymes is accurate?

Enzymes can be saturated and are unchanged by reactions. Signup and view all the answers

What role do cofactors play in enzyme activity?

They assist enzymes in catalyzing reactions. Signup and view all the answers

Which of the following is true about lysozyme?

It can kill bacteria by hydrolyzing complex sugars. Signup and view all the answers

How does lysozyme interact with its substrate?

By destabilizing the substrate and lowering the activation energy. Signup and view all the answers

What is a coenzyme and provide an example?

An organic cofactor; e.g., NAD+ or B vitamins. Signup and view all the answers

What is indicated by Gibb’s Free Energy in a closed system?

The amount of energy available to do work Signup and view all the answers

What does the First Law of Thermodynamics state?

Energy can only be transformed or transferred Signup and view all the answers

How does the Second Law of Thermodynamics relate to cellular processes?

It implies that energy input is necessary to prevent disorder Signup and view all the answers

What is the relationship between activation energy and enzyme-catalyzed reactions?

Enzymes lower activation energy to facilitate reactions Signup and view all the answers

What role do genes play in metabolism?

Genes regulate which proteins are synthesized, influencing metabolism Signup and view all the answers

What concept did Erwin Schrödinger introduce regarding living cells?

Living systems can reverse entropy through energy flow Signup and view all the answers

What does end product inhibition achieve in metabolic pathways?

It prevents excessive production of metabolites Signup and view all the answers

What primarily composes most enzymes?

Proteins Signup and view all the answers

What phenomenon does diffusion illustrate regarding physical laws?

Order can emerge from chaos. Signup and view all the answers

In an exergonic reaction, what happens to electrons?

They move to a lower energy level. Signup and view all the answers

What process is described by the term 'oxidation' in the context of electrons?

Electron loss. Signup and view all the answers

Which of these correctly defines metabolism?

All the chemical reactions that occur within a cell. Signup and view all the answers

What is the primary role of enzymes in metabolic reactions?

To reduce the energy required for the reactions. Signup and view all the answers

Which statement correctly differentiates between catabolic and anabolic reactions?

Anabolic reactions require energy, while catabolic reactions release energy. Signup and view all the answers

What is the relationship between chaos and the laws of physics as indicated in the content?

Chaos at a small scale can give rise to observable ordered phenomena. Signup and view all the answers

What occurs when the state of a cat is observed in the context of quantum mechanics?

It collapses into a single state of being alive. Signup and view all the answers

What is the role of NAD+ in oxidation-reduction reactions?

It binds to enzymes and facilitates the transfer of hydrogen atoms. Signup and view all the answers

Which statement accurately describes the function of enzymes in metabolic pathways?

Enzymes catalyze specific biochemical reactions without being consumed. Signup and view all the answers

What happens to NAD+ during the reaction described in the content?

It gets oxidized to form NADH. Signup and view all the answers

In the described metabolic pathways, which product is formed as an end result?

End product G Signup and view all the answers

How are metabolic pathways generally evolved based on the content provided?

From end products backwards to initial substrates. Signup and view all the answers

What describes the role of enzymes in the process shown in the diagrams?

They function to facilitate the conversion of substrates into intermediates. Signup and view all the answers

What is the primary function of energy-rich molecules in metabolic pathways?

To provide the energy needed for cellular processes. Signup and view all the answers

Which intermediate substrate is associated with the enzyme pathway described?

Intermediate substrate A Signup and view all the answers

Study Notes

Enzyme Function

Enzymes are organic catalysts, primarily proteins (sometimes RNA)
Enzymes are specific, meaning they catalyze specific reactions
Enzymes can become saturated with substrate
Enzymes are unchanged by participating in reactions
Enzymes function within a narrow range of optimal conditions
Cofactors and coenzymes help enzymes in their reactions
Cofactors are non-protein helpers, e.g., zinc, iron
Coenzymes are organic cofactors, e.g., NAD+, and B vitamins
Enzymes usually work better in the presence of a cofactor or coenzyme
Substrates bind to active sites on enzymes allowing chemical reactions to be sped up. Enzyme-substrate complex (ES).
Proteins, including enzymes, are flexible, allowing substrates to bind. This is called induced fit
Enzymes catalyze reactions by lowering the activation energy
Many enzymes work together in metabolic pathways that are frequently associated with membranes.

Metabolic Pathways

Metabolic pathways are series of enzyme-catalyzed reactions that build up (anabolism) or break down (catabolism) molecules
Metabolic pathways often occur in sequential stages, increasing the speed and efficiency of the process
Membranes help to compartmentalize metabolic products so that the reaction rates stay high. The membranes are usually complex and dynamic structures. Membrane proteins are made in the Golgi body.

Enzyme Inhibition

Enzyme inhibition is the process of altering the natural action of an enzyme -Competitive inhibitors resemble the substrate and bind to the active site preventing the substrate from binding -Noncompetitive inhibitors bind to an allosteric site which changes the shape of the enzyme so it can no longer bind to the substrate.

Enzyme Kinetics

Enzyme kinetics studies how factors affect the rate of enzyme-controlled reactions
Factors determining reaction rate (enzyme-kinetics) include enzyme-substrate collisions, enzyme binding ability, substrate concentration, temperature, pH, ionic concentration, and any chemicals that interfere with enzyme shape. -Michaelis-Menten equation is a quantitative description of enzyme kinetics.
Km is a measure of how well the enzyme binds the substrate, and V_max is the maximum rate of reaction.
Graphs, such as Lineweaver-Burk plots, are used to visualize enzyme kinetics, and can show the effects of competitive versus non-competitive inhibitors
- Competitive inhibitors increase KM
- Non-competitive inhibitors decrease V_max

Redox Reactions

Redox reactions are chemical reactions that involve a transfer of electrons.
In oxidation, electrons move away from a molecule, in reduction electrons move toward a molecule. -Oxidation reactions release energy -Reduction reactions absorb energy -Oxidation-reduction reactions can be coupled. Reactions tend to happen as a pair.

Activation Energy

Activation energy is the minimum amount of energy needed for a reaction to start and proceed.
Enzymes work by lowering the activation energy, and thereby speeding up the reaction
This occurs because enzymes orient and hold reactants together, strain their chemical bonds, and provide a favorable chemical environment near the active site.

ATP

ATP (adenosine triphosphate) is a high-energy molecule that acts as an energy currency in cells
ATP is involved in catabolic anabolic reactions
Catabolism is the breakdown of complex molecules into simpler molecules releasing energy that is stored in ATP
Anabolism is the energy requiring building up of complex molecules from simpler molecules using the energy stored in ATP

End Product Inhibition

End-product inhibition is a regulatory mechanism in which the output of a metabolic pathway inhibits an enzyme earlier in the pathway.
End-product inhibition is also called feedback inhibition
It helps regulate the rate of reaction of enzymes in metabolic pathways
This mechanism ensures that an excess amount of the end product is avoided

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Description

This quiz explores the key aspects of enzyme function and metabolic pathways. It covers concepts such as enzyme specificity, the role of cofactors and coenzymes, and the dynamics of enzyme-substrate interactions. Test your understanding of how enzymes catalyze reactions and their essential role in metabolism.