Energy Flow - Energetics and ATP Hard Questions

What 3 basic things does every cell require?

A membrane, a way to encode/transmit information, and energy.

What is intracellular homeostasis?

Maintaining stable internal conditions despite changes in the extracellular environment.

What 3 conditions must cells regulate for homeostasis?

Glucose levels, ion concentrations, and pH (usually 7.0–7.4).

What is metabolism?

The totality of an organism's chemical reactions, including anabolic and catabolic processes.

How do anabolism and catabolism differ?

Anabolism builds complex molecules and requires energy; catabolism breaks down molecules and releases energy.

What is the difference between kinetic and potential energy?

Kinetic energy is energy of motion; potential energy is stored energy due to position or organization.

What are the first and second laws of thermodynamics?

First: Energy cannot be created or destroyed, only transformed. Second: Natural processes increase the total entropy of a system and its surroundings.

What is entropy, and why does diffusion increase it?

Entropy measures energy dispersal or randomness. Diffusion spreads particles from high to low concentration, increasing their dispersal.

What is ATP, and why is it called the cell's energy currency?

ATP (adenosine triphosphate) is a nucleotide that transfers usable chemical energy to power cellular processes.

How does ATP hydrolysis help power cellular work?

ATP is hydrolyzed into ADP and inorganic phosphate. Phosphate transfer can change another molecule's properties and help drive cellular work.

What is phosphorylation?

The addition or transfer of a phosphate group to a molecule, potentially changing its charge, shape, reactivity, or activity.

What are kinases and phosphatases?

Kinases add phosphate groups; phosphatases remove phosphate groups.

What are the 3 types of cellular work powered by ATP?

Chemical work, transport work, and mechanical work.

How do primary and secondary active transport differ?

Primary active transport directly uses ATP; secondary active transport uses energy stored in an ion concentration gradient.

Why must cells continually regenerate ATP?

ATP is used rapidly for cellular work, so cells must continually replenish it from ADP.

APPLICATION: A cell uses energy to assemble amino acids into a protein. Is this anabolism or catabolism, and why?

Anabolism, because smaller molecules are assembled into a larger, more complex molecule. This process requires energy.

APPLICATION: A cell's pH changes significantly. How could this affect homeostasis and enzyme activity?

Homeostasis is disrupted. Changes in pH can alter enzyme shape or charge, affecting enzyme activity and metabolic reactions.

APPLICATION: Dye spreads evenly through a container of water without stirring. Which law explains this, and what happens to entropy?

The second law of thermodynamics. Entropy increases as the dye becomes more dispersed.

APPLICATION: ATP transfers a phosphate to a transport protein, changing its shape so it moves an ion. Identify the process and explain its purpose.

Phosphorylation. The phosphate changes the protein's properties, enabling it to perform cellular transport work.

APPLICATION: A drug blocks phosphatases. What happens to phosphate removal, and how might protein activity change?

Phosphate removal decreases. Proteins may remain phosphorylated longer, potentially staying activated or inactivated and disrupting cell regulation.

APPLICATION: ATP production stops, but ion gradients remain temporarily. Why does primary active transport fail while secondary active transport may continue briefly?

Primary active transport requires ATP directly. Secondary active transport can temporarily use existing ion gradients, but it declines as those gradients dissipate.

APPLICATION: Why can't a cell use the heat released by ATP hydrolysis as its main method of powering cellular work?

Heat is not efficiently converted into useful cellular work. Cells primarily couple ATP hydrolysis to work through chemical reactions such as phosphorylation.

APPLICATION: If catabolism breaks down nutrients, how can the resulting energy support anabolism?

Catabolism releases energy that can be captured in ATP. ATP then supplies energy to drive anabolic reactions that build complex molecules.

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