Chapter 5 Enzymes, coenzymes & energy Flashcards
acetyl-CoA
The 2-carbon remainder of the carbon skeleton of pyruvic a Hacked to a coenzyme. A molecule acid that is able to enter the mitochondrion for oxidation in the Krebs cycle
activation energy
Energy required to start a reaction.
active site
The place on the enzyme that causes the substrate to change.
adenosine triphosphate (ATP)
blocks of adenine, ribose, and phosphates; it functions as the primary energy carrier in the cell.
anabolism
Metabolic pathways that result in the synthesis of new, larger compounds (e.g., protein synthesis).
binding site (attachment site)
A specific point on the surface of the enzyme where it can physically attach itself to the substrate.
biochemical pathway (metabolic pathway)
A major series of enzyme-controlled reactions linked together.
catabolism
Metabolic pathways that result in the breakdown of compounds (e.g., glycolysis).
catalyst
A chemical that speeds up a reaction but is not used up in the reaction
coenzyme
A molecule that works with an enzyme to enable the enzyme to function as a catalyst.
cofactors
Inorganic ions or organic molecules that serve as enzyme helpers.
competitive inhibition
No two species can occupy the same niche at the same time.
enzymatic competition
Competition among several different available enzymes to combine with a given substrate material.
enzyme
Molecules, produced by organisms, that are able to control the rate at which chemical reactions occur.
enzyme-substrate complex
A temporary molecule formed when an enzyme attaches itself to a substrate molecule.
flavin adenine dinucleotide (FAD)
A hydrogen carrier used in respiration.
gene-regulator proteins
Chemical messengers within a cell that inform the genes as to whether protein-producing genes should be turned on or off or whether they should have their protein producing activities increased or decreased (e.g., gene-repressor proteins and gene-activator proteins).
high-energy phosphate bond
The bond between two phosphates in an ADP or ATP molecule that readily releases its energy for cellular processes.
inhibitor
A molecule that temporarily attaches itself to an enzyme, thereby interfering with the enzyme’s ability to form an enzyme substrate complex.
negative-feedback inhibition
A regulatory mechanism in which an increase in the stimulus causes a decrease of the response and results in homeostasis.
nicotinamide adenine dinucleotide (NAD+ )
An electron acceptor and hydrogen carrier used in respiration.
nutrients
Molecules required by organisms for growth, reproduction, or repair.
substrate
A reactant molecule with which the enzyme combines.
turnover number
The number of molecules of substrate with which a single molecule of enzyme can react in a given time.
