Biochemistry Basics: Enzymes and Energy

Questions and Answers

What are enzymes?

They are lipids.

They are proteins that behave as catalysts. (correct)

They are nucleic acids.

They are carbohydrates.

Enzymes work by _____.

reducing the energy of activation.

Most enzymes are _____.

proteins.

What specific types of energy are present in a candy bar?

Heat, chemical energy stored in bonds, and potential energy. Signup and view all the answers

Why is the statement 'When energy changes forms, some energy is always lost' incorrect?

It implies that some energy is destroyed. Signup and view all the answers

Entropy is a tendency toward _____.

a decrease in order. Signup and view all the answers

Which of the following represents an increase in entropy?

A broken glass. Signup and view all the answers

Where does the energy that life uses to combat entropy come from?

The majority of living things get their energy from the sun. Signup and view all the answers

Which of the following is true about the reaction of ADP and phosphate to form ATP?

The reaction is endergonic. Signup and view all the answers

Which of the following reactions could be coupled with the synthesis of ATP from ADP and phosphate?

The breakdown of sugar into water and carbon dioxide. Signup and view all the answers

What name is given to the reactants in an enzymatically catalyzed reaction?

Substrate. Signup and view all the answers

As a result of its involvement in a reaction, an enzyme _____.

unchanged. Signup and view all the answers

Why can't amylase digest cellulose?

The bonds of cellulose do not fit properly in the active site. Signup and view all the answers

How is an intermediate best defined?

A product of one reaction that will serve as a reactant in another reaction. Signup and view all the answers

How do competitive inhibitors stop a chemical reaction?

They bind in the active site of an enzyme. Signup and view all the answers

Why does feedback inhibition occur at the beginning of a metabolic pathway instead of in the middle?

Because all of the initial substrates would still be used up. Signup and view all the answers

Why do most enzymes not work if the temperature is raised too much?

Enzymes denature at higher temperatures. Signup and view all the answers

What is more efficient for E. coli bacteria: using lactose or glucose as an energy source?

Glucose. Signup and view all the answers

Study Notes

Enzymes

Enzymes are proteins that act as catalysts, speeding up biochemical reactions.
They lower the energy of activation, making reactions occur more easily.
Most enzymes are proteins, serving crucial roles in various biochemical processes.

Energy Types

Candy bars contain heat energy, chemical energy from bonds (Calories), and potential energy from their position (e.g., on a table).

Thermodynamics

The second law of thermodynamics indicates energy transforms; however, energy is not destroyed, merely lost as heat.
The first law of thermodynamics asserts that energy cannot be created or destroyed.

Entropy

Entropy refers to the tendency for orderly systems to become disordered.
An increase in entropy can be seen in actions like breaking a glass, which results in more pieces and greater disorder.

Energy Sources for Life

Most organisms derive energy from the sun, either through photosynthesis or consuming other organisms that have utilized sunlight.

ATP Formation

The reaction forming ATP from ADP and phosphate is endergonic, requiring energy input.
The breakdown of ATP into ADP and phosphate is exergonic, releasing energy.
Coupling ATP synthesis with an exergonic reaction, like sugar breakdown, allows for efficient energy transfer.

Substrates and Enzyme Actions

Reactants in enzymatically catalyzed reactions are called substrates.
Enzymes remain unchanged post-reaction, allowing them to be reused.

Enzyme Specificity

Amylase can digest starch but not cellulose due to differences in the bond structure preventing proper alignment in the enzyme's active site.
An intermediate is defined as a product from one reaction that will serve as a reactant in another reaction.

Inhibition and Regulation

Competitive inhibitors block enzymatic reactions by occupying the active site, preventing the substrate from binding.
Feedback inhibition occurs at the beginning of metabolic pathways to conserve initial substrates and regulate processes.

Enzyme Stability

Enzymes denature at elevated temperatures or unsuitable pH/salt concentrations, altering their shape and functionality.
E. coli optimally uses glucose for energy but can use lactose with the enzyme lactase, albeit less efficiently.

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Test your understanding of fundamental concepts in biochemistry including enzymes, thermodynamics, and energy types. Explore how these concepts apply to life and the processes that govern energy changes. Ideal for students diving into the intricate details of biological energy systems.