ch. 5 biology

The movement of particles from an area of high concentration to an area of low concentration.

A type of passive transport where substances move across a membrane without requiring cellular energy.

The diffusion of water across a selectively permeable membrane from a region of high water concentration to a region of low water concentration.

A solution that has a higher solute concentration than another solution.

A solution that has a lower solute concentration than another solution.

A solution that has the same solute concentration as another solution.

The ability of a solution to cause a cell to gain or lose water. It depends on the relative concentrations of solutes inside and outside the cell.

Specialized organelles found in some single-celled organisms, like Paramecium, that help regulate water balance by expelling excess water.

The capacity to cause change or do work.

Energy associated with motion.

Energy stored due to position or structure.

Energy stored in the chemical bonds of molecules.

The study of energy transformations.

Energy can be transformed but not created or destroyed.

Energy transformations increase disorder in the universe.

A chemical reaction that releases energy.

The movement of substances across a cell membrane with the assistance of transport proteins.

This type of transport protein helps water move across cell membranes quickly.

The ability of a cell membrane to control which substances can enter and leave the cell.

The molecule that provides energy for most active transport processes in cells.

The process by which a cell expends energy (ATP) to move a solute from an area of low concentration to an area of high concentration.

The differences in concentration of a solute between two regions.

Nonprotein helpers that bind to the active site of an enzyme and play a crucial role in catalysis.

Organic cofactors essential for enzyme activity, often derived from vitamins.

A type of enzyme inhibitor that competes with the substrate for binding to the active site of the enzyme.

A type of enzyme inhibitor that binds to a site other than the active site, altering the enzyme's shape and preventing substrate binding.

A type of regulation where the end product of a metabolic pathway inhibits an enzyme earlier in the pathway.

Drugs, pesticides, and poisons that act as enzyme inhibitors, interfering with crucial cellular processes.

Inhibitors that block the active site of an enzyme, preventing the substrate from binding.

Inhibitors that bind to a different site on the enzyme, altering its shape and affecting its activity.

Proteins embedded in cell membranes that help move substances across the membrane.

The release of substances from a cell by fusing a vesicle with the cell membrane.

The process of taking substances into a cell by forming a pouch in the cell membrane.

A type of endocytosis where the cell engulfs large particles, like bacteria or debris.

A type of endocytosis where the cell takes in specific substances by binding to receptors on the cell membrane.

ATP transfers energy from exergonic reactions (releasing energy) to endergonic reactions (requiring energy).

• ATP hydrolysis: The bond between phosphate groups in ATP is broken, releasing energy. This is an exergonic reaction.
• Phosphorylation: The released phosphate group is transferred to another molecule, providing energy for an endergonic reaction.

Exergonic reactions release energy, often by breaking down molecules. Endergonic reactions require energy input, often for building molecules. Energy coupling is the linking of an exergonic reaction to an endergonic reaction.

The ATP cycle is the continuous process of ATP being broken down (hydrolysis) and then re-formed (phosphorylation). The bonds linking phosphate groups in ATP hold the potential energy and breaking these bonds releases energy.

The activation energy is the initial amount of energy needed to start a chemical reaction. Enzymes lower this energy barrier, allowing reactions to occur more easily.

The active site of an enzyme is a specific region where the substrate (the molecule the enzyme acts upon) binds. The shape of the active site is complementary to the shape of the substrate.

The catalytic cycle of an enzyme involves the following steps:

1. Substrate binds to the active site.
2. Enzyme-substrate complex forms.
3. The reaction happens, the substrate is converted to product.
4. Product is released.
5. Enzyme is ready for another substrate.

In the graph, the lower curve represents the enzyme-catalyzed reaction because it has a lower activation energy, meaning the reaction occurs more quickly. Line a represents the activation energy without an enzyme. Line b represents the activation energy with an enzyme. Line c represents the overall energy change of the reaction, which is the same with or without an enzyme.