Summer 2025 Bio 111 Study Guide Chapter 4

Flashcards for Bio 111 Chapter 4 - Energy and Membranes

Energy

The ability to do work.

Kinetic energy

Energy of motion.

Thermal (heat) energy

Energy associated with the movement of atoms and molecules; the colder an object feels, the slower the movement.

Light (solar) energy

Electromagnetic radiation visible to the human eye; contains photons (packets of energy).

Potential energy

Stored energy available to do work (e.g., compressed spring).

Chemical energy

Potential energy released when bonds break.

1st Law of Thermodynamics

Law of energy conservation: energy cannot be created or destroyed, only converted from one form to another.

2nd Law of Thermodynamics

Energy transformations increase entropy (disorder); every reaction loses some energy as heat.

Metabolism

All chemical reactions in a cell.

Anabolism (Anabolic)

Process in metabolism where simple molecules combine to generate complex molecules; requires energy (endergonic).

Catabolism (Catabolic)

Breaks down complex molecules into simpler ones to produce energy; exergonic.

Endergonic

A chemical reaction that requires a net input of energy; products contain more energy than reactants; builds complex molecules from simpler components.

Exergonic

An energy-releasing chemical reaction; the products contain less energy than the reactants; breaks complex molecules into smaller, simpler components.

Oxidation

The loss of one or more electrons by participating in a chemical reaction.

Reduction

The gain of one or more electrons by participating in a chemical reaction.

Photosynthesis

Plants convert light energy into chemical energy, which is then stored in the form of sugars.

Cellular Respiration

Converting chemical energy stored in glucose into a usable form of energy for cells (primarily ATP).

Dehydration Synthesis

Removal of water during a chemical reaction.

Hydrolysis

Break chemical bonds, releases energy. Reactants transform into new substance called products.

ATP Components

A carbon ring called adenine, a ribose sugar, and three phosphate groups; the energy currency of the cell.

Phosphorylating ADP to ATP

Adding a phosphate group to ADP to form ATP to store energy which is then released through hydrolysis.

Enzyme

An organic molecule that catalyzes a chemical reaction without being consumed.

Catalyst

Speeds up chemical reactions by lowering activation energy.

Activation energy

Energy needed to initiate a reaction.

Active Site

Specific binding location for reactants (substrates) on an enzyme where a reaction takes place.

Substrate

Reactants that bind to the active site of an enzyme.

Cofactors and Coenzymes

Inorganic or organic substance required for enzyme activity.

Inhibitors (Competitive and Noncompetitive)

Improve or change enzyme shape by binding change activity of enzyme. Compete's with substrate for active site.

Denature

A protein losses its natural shape and function, often due to environmental factors.

Metabolic pathway

Cells regulate reactions series , each enzyme facilitated , to convert a specific substrateto final product .

Negative feedback

The reactions slow down due to accumulation of an initial product. Maintain homeostasis by counteracting stimulus.

Transport proteins

Act as doors to the cell helping certain molecules across membrane. Passive: Includes diffusion. Active= additional energy (aTp) to move molecules.

Passive Transport

no aip needed-moves molecules from high to low concentration -down accross a membrane gradient).

Facilitated Diffusion

requires a transport protein to help move molecules across membrane without extra energy.

Down or with (concentration gradients)

Movement from an area of high concentration to low concentration

Up or against (concentration gradients)

Movement from low concentration to high concentration requires energy

Diffusion

Particles more randomlyIn all directions ,the net movement is towards areas of lower concentration.

Osmosis

The diffusion of water molecules.

Hypertonic

Higher solute outside cell, water moves out, cell shrinks

Isotonic

Equal solute, equal water, no net movement, normal shape

Hypotonic

Higher water outside, water moves in, cell swells

Central vacuole in plant cells

Stores water which causes the cell to swell and push against the cell wall, creating pressure needed to provide the shape of the plant cell

Pump

A protein that uses energy fromaip to transport NAt out of cells and into K+ cells

Proton pump

A specialized protein that actively transportsAtions across membrane creating a proton gradient.

Endocytosis

a vesicle forms as the cell membrane pinches inward, bringing substances into the cell

Exocytosis

a vesicle carries materials to be transported out of the cell .the membrane surrounding the vesicle merges with the cell membrane,releasing the substance outside the cell.