Chapter 5 Flashcards
metabolism
The sum of all chemical reactions within a living organism, Because chemical reactions either release or require energy, metabolism can be viewed as an energy-balancing act. Accordingly, metabolism can be divided into two classes of chemical reactions: those that release energy and those that require energy.
catabolism
The enzyme-regulated chemical reactions that release energy. The breakdown of complex organic compounds into simpler ones. These reactions are called catabolic, or degradative, reactions. Catabolic reactions are generally hydrolytic reactions (reactions which use water and in which chemical bonds are broken), and they are EXERGONIC (produce more energy than they consume). EX: Cells break down sugars into carbon dioxide and water.
anabolism
The enzyme-regulated energy-requiring reactions. The building of complex organic molecules from simpler ones. These reactions are called ANABOLIC, or BIOSYNTHETIC, reactions. Anabolic processes often involve DEHYDRATION SYNTHESIS reactions (reactions that release water), and they are ENDERGONIC (consume more energy than they produce). EX: Formation of proteins from amino acids, nucleic acids from nucleotides, and polysaccharides from simple sugars.
metabolic pathways
A cell’s sequences of chemical reactions are determined by its enzymes, which are in turn determined by the cell’s genetic makeup
collision theory
Explains how chemical reactions occur and how certain factors affect the rates of those reactions. The basis of the collision theory is that all atoms, ions, and molecules are continuously moving and colliding with one another. The energy transferred by the particles in the collision can disrupt their electron structures enough to break chemical bonds or form new bonds.
activation energy
The collision energy required for a chemical reaction, which is the amount of energy needed to disrupt the stable electronic configuration of any specific molecule so that the electrons can be rearranged.
reaction rate
the frequency of collisions containing sufficient energy to bring about a reaction - depends on the number of reactant molecules at or above the activation energy level. In living systems, enzymes increase the reaction rate without raising the temperature.
catalysts
Substances that can speed up a chemical reaction without being permanently altered themselves
enzymes
Serve as biological catalysts. As catalysts, each enzyme acts on a specific substance, called the enzyme’s SUBSTRATE (or SUBSTRATES, when there are two or more reactants), and each catalyzes only one reaction. As catalysts, enzymes typically accelerate chemical reactions by lowering their activation energy.
substrate
Any compound with with an enzyme reacts
