Open Stax Biology Ch 6

Why is ATP considered the energy currency of the cell?

It can transport energy to locations within the cell. (The hydrolysis of ATP releases free energy which is used to perform cellular work, such as pumping a solute across a cell membrane in active transport.)

Cell metabolism is a complex process that uses many types of chemicals in a variety of processes. Which of the following statements is true?

A loss of enzymes would result in cell death.

Explain in your own words the difference between a spontaneous reaction and one that occurs instantaneously.

A spontaneous reaction is one which releases free energy and moves to a more stable state. Instantaneous reactions occur rapidly with sudden release of energy.

What molecule most easily transports energy around the cell to power cellular processes?

ATP

How does ATP supply energy to chemical reactions?

ATP dissociates and the energy released by breaking of a phosphate bond within ATP is used for phosphorylation of another molecule. ATP hydrolysis also provides energy to power coupling reactions. (When ATP is utilised in a reaction, it transfers its third phosphate with energy to the chemical reaction. It phosphorylates another molecule and makes the energy available. Also, ATP hydrolysis is performs work in cells by energy coupling.)

What is the underlying principle that supports the idea that all living organisms share the same core processes and features?

All organisms must harvest energy from their environment and convert it to ATP to carry out cellular functions.

Why are anabolic and catabolic chemical reactions dependent on each other in a metabolic pathway?

Anabolic reaction utilizes the energy released by the catabolic reactions to form complex compounds.

Enzymes facilitate chemical reactions that result in changes to a substrate. How does the induced fit model of enzymes and substrates explain their function?

Both enzyme and substrate undergo dynamic changes, inducing the transitions state of the substrate.

How does energy get to a cell, whether it is a single-celled or multicellular organism?

Catabolism of glucose and other molecules results in the release of energy. That energy is then utilized by cells of single-celled as well as multicellular organisms for cellular activities.

Why is the activation energy, 𝐸A, always positive regardless of whether the reaction is an exergonic or endergonic reaction?

It is because the transition state exists at a higher energy state than the reactants.

What is true about the energy released by the hydrolysis of ATP?

It provides energy to coupled reactions. (Cells couple the exergonic reaction of ATP hydrolysis with endergonic reactions, allowing them to proceed. Thus, it provides energy to coupled reactions.)

Explain why transitional states are unstable.

Molecules have strained molecular structure with high energy. (The molecules are strained and possess high energy to cross the activation energy barrier.)

Name two different cellular functions that require energy.

Phagocytosis helps amoebae take up nutrients and pseudopodia help the amoebae move.

Plants must have adequate resources to complete their functions. If they do not have what they need, there are changes in the organism's metabolism. What happens to the metabolism of a plant that does not have adequate sunlight?

Photosynthesis slows and less glucose is produced for energy use.

What happens when potential energy is turned into kinetic energy?

Potential energy will be expressed in the form of heat, movement or work.

It has been accepted that life on the Earth started out as single celled, simple organisms, which then evolved into complex organisms. How did evolution proceed to produce such a wide variety of living organisms from a simple ancestor?

Prokaryotes produced the protists, which branched into the fungi, plants, and animals.

Imagine an elaborate ant farm with tunnels and passageways through the sand where ants live in a large community. Now imagine that an earthquake shook the ground and demolished the ant farm. In which of these two scenarios, before or after the earthquake, was the ant farm system in a state of higher or lower entropy? Why?

The ant farm is in the state of high entropy after the earthquake and energy must be spent to bring the system to low entropy.

Describe the evolution of metabolic pathways as they developed on Earth.

The earliest pathways that developed on earth were anaerobic because the primitive atmosphere didn't have oxygen. These pathways were used by primitive prokaryotic microorganisms. Over time, photosynthesis developed, which led to increase of oxygen in atmosphere. This allowed aerobic cellular respiration.

What is the difference between the first and second laws of thermodynamics?

The first law involves conserving energy while the second law involves the inability to recapture energy.

Which of the following is the best example of the first law of thermodynamics?

a power plant burning coal and producing electricity

What type of reaction allows chemicals to be available for an organism's growth and maintenance in a timely manner?

enzymatically facilitated reactions

Which chemical reaction is more likely to occur?

exergonic

When the air temperature drops and rain turns to snow, which law of thermodynamics is exhibited?

first law of thermodynamics

Consider a pendulum swinging. Which type(s) of energy is/are associated with the pendulum in the following instances: the moment at which it completes one cycle, just before it begins to fall back towards the other end the moment that it is in the middle between the two ends just before it reaches the end of one cycle (before step 1)

potential kinetic potential and kinetic

Which of the following molecules is likely to have the most potential energy?

sucrose

What part of ATP is broken to release energy for use in chemical reactions?

the bond between the second and third phosphates

What does Δ⁢H denote in the Gibbs equation?

the enthalpy lost in a chemical reaction

What is the most common reaction coupled with other reactions to power them within the cell?

the hydrolysis of ATP (Cells couple the exergonic reactions of ATP hydrolysis with endergonic reactions, thus allowing them to proceed. An example of this is a transmembrane ion pump, which is important for cellular function.)