BIO103 - CH09 VOCAB - how cells harvest energy

energy

The capacity to cause change, especially to do work (to move matter against an opposing force).

work

A measure of energy expended by moving an object, usually considered to be force times distance... definitely more applicable in a physics discussion but still important, big picture-wise, in biology.

potential energy

A phrase that we've used in multiple chapters... the energy that matter possesses as a result of its location/position or spatial arrangement (structure). Relate this to stability... unstable positions and/or arrangements have more of this type of energy.

chemical energy

A phrase that we've used in multiple chapters... the energy available in molecules for release in a chemical reaction; a form of potential energy. Think of chemical energy in relation to adenosine triphosphate (ATP)... how does the arrangement (and lack of stability of that arrangement) of the components in ATP contribute to potential (chemical) energy.

adenosine triphosphate

An adenine-containing nucleoside triphosphate that releases free energy when its phosphate bonds are hydrolyzed. This energy is used to drive endergonic reactions in cells. Abbreviated as ATP.

[Understand the arrangement of the components that make up ATP]

metabolism

The totality of an organism's chemical reactions, consisting of catabolic and anabolic pathways, which manage the material and energy resources of the organism.

metabolic pathway

A series of chemical reactions that either builds a complex molecule (anabolic pathway) or breaks down a complex molecule to simpler molecules (catabolic pathway).

catabolic pathway

A metabolic pathway that releases energy by breaking down complex molecules to simpler molecules.

anabolic pathway

A metabolic pathway that consumes energy to synthesize (build) a complex molecules from simpler molecules.

hydrolysis

A chemical reaction that breaks bonds between two molecules by the addition of water; functions in disassembly of polymers to monomers, the removal of a phosphate group from ATP to make ADP (and the release free energy, -7.3 kcal/mol), and many other reactions in the cell. {catabolic OR anabolic???]

redox reaction

A phrase/idea that many students have problems conceptualizing. A chemical reaction involving the complete (or partial) transfer of one or more electrons from one reactant to another. Remember, it's all about the electrons... make sure to review electronegativity!!!

oxidation

The complete or partial loss of electrons from a substance involved in a redox reaction. In biology (in you!), we strip hydrogens (more importantly, the electron from each hydrogen!!!) from the foods we eat in order to make ATP.... think about all of the hydrogens in fats.

reduction

The complete or partial addition of electrons to a substance involved in a redox reaction (opposite of oxidation!!!). In biology (in you!), we strip electrons (from each of the hydrogens in our foods) and give them to oxygen (O2). NOTE: the transfer of electrons from something LESS ELECTRONEGATIVE (e.g. carbon on a fatty acid chain) to something MORE ELECTRONEGATIVE (e.g. oxygen you breathe in) is an EXERGONIC (negative change in free energy) reaction.... think about the "change" in stability here.

NAD+

The oxidized form (= hydrogens were stripped/taken) of nicotinamide adenine dinucelotide, a coenzyme that can accept electrons, becoming NADH. NADH temporarily stores electrons during cellular respiration... important in shuttling electrons to the electron transport chain (ETC)!!!

NADH

The reduced form (= electrons added) of nicotinamide adenine dinucelotide that temporarily stores electrons during cellular respiration. Important in shuttling electrons to the electron transport chain (ETC)... acts as an electron donor to the ETC.

exergonic reaction

A spontaneous chemical reaction in which there is a net release of free energy.

endergonic reaction

A non-spontaneous chemical reaction in which free energy is absorbed from the surroundings.

fermentation

A catabolic process that makes a limited amount of ATP from glucose (or other organic molecules) without an electron transport chain and that produces a characteristic end product, such as ethyl alcohol or lactic acid.

cellular respiration

The catabolic pathways of aerobic and anaerobic respiration, which break down organic molecules and use an electron transport chain for the production of ATP.

glycolysis

A series of reactions that ultimately splits glucose into pyruvate. This process occurs in almost all living cells, serving as the starting point for fermentation or cellular respiration.

citric acid cycle

A chemical cycle involving eight steps that completes the metabolic breakdown of glucose molecules (begun in glycolysis) by oxidizing acetyl CoA (derived from pyruvate) to carbon dioxide; occurs within the mitochondrion in eukaryotic cells and in the cytosol of prokaryotes; together with pyruvate oxidation, the second major stage in cellular respiration.

oxidative phosphorylation

The production of ATP using energy derived from the redox reactions of an electron transport chain; the third major stage of cellular respiration.

electron transport chain

A sequence of electron carrier molecules (membrane proteins) that shuttle electrons down a series of redox reactions that release energy used to make ATP. This process uses products (electrons from NADH!!!) from the first two acts of glycolysis and the citric acid cycle to complete the chemical reaction that turns our food into usable cellular energy (ATP).

chemiosmosis

An energy-coupling mechanism that uses energy stored in the form of a hydrogen ion gradient (HIGH to LOW) across a membrane to drive cellular work, such as the synthesis of ATP. Under aerobic conditions, most ATP synthesis in cells occurs by this process. [the perfect analogy for this process is a hydroelectric dam... the water "gradient" turns the turbines which generates electricity]

ATP synthase

A complex of several membrane proteins that functions in chemiosmosis with adjacent electron transport chains, using the energy of a hydrogen ion (=proton) concentration gradient (HIGH to LOW) to make ATP. These complexes are found in the inner mitochondrial membranes of eukaryotic cells and in the plasma membranes of prokarytoes. [analogy.... these are the turbines generating electricity in a hydroelectric dam]