Biology Chapter 4: How Cells Obtain Energy

A series of chemical reactions that modify a starting molecule step-by-step, creating a final product.

A metabolic pathway that builds complex molecules from simpler ones, requiring energy.

A metabolic pathway that breaks down complex molecules into simpler ones, releasing energy.

A protein that facilitates or catalyzes chemical reactions in biological systems.

A system that can exchange energy with its surroundings.

A system that cannot exchange energy with its surroundings.

The study of energy and energy transfer involving physical matter.

The sum of all chemical reactions in a living organism, composed of anabolism and catabolism.

A process that requires energy input to proceed.

A process that releases energy.

The small amount of energy needed to start a chemical reaction.

A substance that speeds up a chemical reaction without being consumed in the process.

Chemical reactions occurring within a living organism.

Enzymes lower the activation energy needed for a chemical reaction to occur.

Enzymes do not change whether a reaction is exergonic or endergonic; they only affect the speed.

A specific molecule that a drug interacts with to produce its effect. It's like a lock that the drug key fits into.

A class of drugs that lower cholesterol levels by inhibiting the enzyme HMG-CoA reductase, responsible for cholesterol synthesis.

A multi-stage process involving target identification, drug design, in vitro and clinical trials, and regulatory approval before a drug reaches the market.

Controlling the activity of enzymes by factors like inhibitors or activators, impacting metabolic pathways and drug effectiveness.

Molecules that bind to enzymes and reduce their activity, preventing them from catalyzing reactions.

Experiments conducted on humans to evaluate the safety, efficacy, and proper dosage of a new drug candidate.

The final step in drug development, where regulatory agencies like the U.S. Food and Drug Administration assess the safety and efficacy of a drug before making it commercially available.

A metabolic process where yeast converts sugars into ethanol (alcohol) and carbon dioxide, releasing energy. It is used to produce alcoholic beverages like wine and beer.

During fermentation, the yeast produces both ethanol (alcohol) and carbon dioxide. The carbon dioxide can be released as a gas or remain dissolved, affecting the final drink.

Yeast cannot survive in high ethanol concentrations. Natural alcoholic beverages typically have an alcohol content of 12% or less because higher concentrations become toxic to the yeast.

A type of respiration that occurs in the absence of oxygen. Organisms use alternative electron acceptors to generate energy.

A group of Archaea that reduce carbon dioxide to methane as their primary energy source. They are found in environments like wetlands and animal digestive systems.

These bacteria use sulfate as an electron acceptor in anaerobic respiration, producing hydrogen sulfide. They are found in oxygen-poor environments like marine sediments.

Microorganisms that can survive and thrive in both the presence and absence of oxygen. They can use aerobic respiration when oxygen is available and switch to fermentation in its absence.

Microorganisms that can only survive and grow in the absence of oxygen. Oxygen is toxic to them and can even kill them.

Uneven distribution of charged particles (like H+) across a membrane, creating both concentration and electrical potential differences.

A protein complex embedded in the mitochondrial membrane that generates ATP using the energy from the electrochemical gradient of H+ ions.

The movement of H+ ions across a membrane through ATP synthase, driven by the electrochemical gradient, to generate ATP.

The process of producing ATP using the energy released from electron transport chains, coupled with chemiosmosis.

A series of protein complexes in the mitochondrial membrane that transfer electrons, releasing energy to pump protons and create an electrochemical gradient.

NADH, a carrier of electrons, can be used to generate more ATP than FAD+. The specific transporter (NAD+ or FAD+) used in different tissues impacts ATP yield.

The efficiency of proton pumping (H+ ions) by ETC complexes varies between species and tissues, impacting ATP yield. Also, intermediate molecules are used for other processes, further affecting the net ATP production.

At the end of the ETC, electrons are used to reduce oxygen, attracting hydrogen ions to form water. This process is essential for completing the electron transport chain.

Certain types of fermentation like alcoholic fermentation produce gas as a byproduct. This gas production is useful in identifying specific bacteria in laboratory settings.

Fermentation pathways are essential for regenerating NAD+ needed for the sixth step in glycolysis. Without this regeneration, glycolysis stalls, and ATP production from glucose stops.

Metabolic pathways are interconnected. The breakdown of carbohydrates, proteins, and lipids eventually converges into glycolysis and the citric acid cycle.

Metabolic pathways are open systems, meaning that substances can enter from other pathways, and other substances can leave for other pathways.

Glycogen, a polymer of glucose, serves as short-term energy storage in animals. It is synthesized when excess glucose is available and broken down when blood sugar levels drop.

Glycogen stored in muscle cells can be used as an energy source during exercise, extending the time ATP can be produced.

Sucrose, a disaccharide composed of glucose and fructose, is broken down in the small intestine, making glucose and fructose available for absorption.

After sucrose breakdown, glucose and fructose are absorbed separately from the small intestine into the bloodstream.