Chapter 3 Vocab Flashcards
free energy, G
energy that can be harnessed to do work, such as drive a chemical reaction.
free-energy change, delta G
difference in free energy between the reactants and products.
large - delta G means theres a strong tendency for the reaction to occur,
the free energy change is defined in pressure, concentration, and temp.
hydrolisis
chemical reaction involves cleavage of a covalent bond with the accompanying consumption of water (its -H being added to one product of the cleavage and its -OH to the other); the reverse of condensation
Km
the concentration of a substrate at which an enzyme works at half its maximum rate. large values of Km usually indicate that the enzyme binds to its substrate with relatively low affinity
metabolism
the sum of total chemical reactions that take place in the cells of a living organism
Michaelis constant (Km)
concentrat of an substrate at which an enzyme works at half its maximum velocity.
serves as a measure of how tightly the substrate is bound
NAD+(Nicotine Adenine dinucleotide)
active carrier that accepts a hydride ion from a donor molecule producing NADH.
widely used in the energy-producing breakdown of sugar molecules (figure 3-34)
NADH
active carrier. widely used in the energy-producing breakdown of sugar molecules (figure 3-34)
NADPH (Nicotine Adenine dinucleotide phosphate)
active carrier closely related to NADH and used as an electron donor in biosynthetic pathways. in the process it is oxidized to NADP+
oxidation
removal of electrons from an atom.
photosynthesis
the process by which plants, algae, and some bacteria use the energy of the sunlight to drive the synthesis of organic molecules from carbon dioxide and water
reduction
The addition of electrons to an atom
respiration
general term for any process in a cell i which the uptake of molecular oxygen (O2) is coupled into the production of CO2
substrate
a molecule on which an enzyme attacks
turnover number
the number of substrate molecules an enzyme can convert to product per second
Vmax
the maximum rate of an enzymatic reaction, reached when the active sites of the enzyme molecules in a sample are fully occupied by substrate
acetyl CoA
Activated carrier that donates the carbon atoms in its readily transferable acetyl group to many metabolic reactions, including the citric acid cycle and fatty acid biosynthesis; the acetyl group is linked to coenzyme A (CoA) by a thioesterbond thatreleases a large amount of energy when hydrolyzed.
activated carrier
A small molecule that stores energy or chemical groups in a form that can be donated to many different metabolic reactions. Examples include ATP, acetyl CoA, and NADH.
activation energy
The energy that must be acquired by a molecule to undergo a chemical reaction.
ADP
(adenosine 5’-diphosphate)
Nucleoside diphosphate produced by hydrolysis of the terminal phosphate of ATP.
anabolism
Set of metabolic pathways by which large molecules are made from smaller ones.
biosynthesis
An enzyme-catalyzed process by which complex molecules are formed from simple substances by living cells; also called anabolism.
catabolism
Set of enzyme-catalyzed reactions by which complex molecules are degraded to simpler ones with release of energy; intermediates in these reactions are sometimes called catabolites.
catalysis
The acceleration of a chemical reaction brought about by the action of a catalyst; virtually all reactions in a cell require such assistance to occur under conditions present in living organisms
catalyst
Substance that accelerates a chemical reaction by lowering its activation energy; enzymes perform this role in cells.
condensation reaction
Chemical reaction in which a covalent bond is formed between two molecules as water is expelled; used to build polymers such as proteins, polysaccharides, and nucleic acids
coupled reaction
Linked pair of chemical reactions in which free energy released by one reaction serves to drive the other reaction.
diffusion
Process by which molecules and small particles move from one location to another by random, thermally driven motion.
entropy
Thermodynamic quantity that measures the degree of disorder in a system.
enzyme
A protein that catalyzes a specific chemical reaction.
equilibrium
State in which the forward and reverse rates of a chemical reaction are equal so that no net chemical change occurs.
equilibrium constant, K
For a reversible chemical reaction, the ratio of substrate to product when the rates of the forward and reverse reactions are equal.
ATP
(adenosine 5’-triphosphate)
Molecule that serves as the principal carrier of energy in cells; this nucleoside triphosphate is composed of adenine, ribose, and three phosphate groups.