Metabolic Pathways and their Control Flashcards
Active transport
Movement of molecules or ions through a cell membrane from a region of lower concentration to a region of higher concentration.
Alternative route
Step(s) in a metabolic pathway that allow the regular steps to be bypassed.
Anabolism
Type of metabolic pathway that brings about the biosynthesis of complex molecules and requires energy.
Carrier
Type of protein molecule that actively pumps specific ions into and/or out of a cell.
Catabolism
Type of metabolic pathway that brings about the breakdown of complex molecules and releases energy.
Channel – forming
Type of protein molecule in the cell membrane containing a pore through which specific substances are able to diffuse.
Chloroplast
Membrane – bound organelle containing enzymes responsible for the Calvin cycle.
Concentration gradient
Difference that exists between two regions resulting in diffusion.
Diffusion
Movement of molecules or ions from a region of higher concentration to a region of lower concentration.
Metabolism
Sum of all the biochemical reactions occurring within a living organism.
Reversible
Step in a metabolic pathway that can operate in both a forward and backward direction.
Activation energy
Energy needed to break the chemical bonds in the reactants in a chemical reaction.
Active site
Region of an enzyme molecule where the complementary surface of its substrate molecule becomes attached.
Affinity
Degree of chemical attraction between reactant molecules.
Catalyst
Substance that increases the rate of a chemical reaction and remains unaltered by the reaction.
End product
Substance formed as a result of an enzyme acting on its substrate.
Enzyme
Protein made by living cells that acts as a biological catalyst.
Induced fit
State of close molecular contact resulting from change in shape of an enzyme’s active site to accommodate its substrate.
Orientation
Way in which molecules of two reactants are held together as determined shape of the enzyme’s active site.
Reaction rate
Amount of chemical change that occurs per unit of time.
Specificity
Complementary relationship of a molecular structure allowing an enzyme to combine with one type of substrate only.
Substrate
Substance upon which an enzyme acts, resulting in the formation of an end product.
Transition
State of reactant molecules that have absorbed enough energy to break and allow the reaction to occur.
Allosteric site
Non-active location on an enzyme molecule to which an inhibitor or an activator may become attached.
Competitive
Type of inhibitor with a molecular structure similar to an enzyme’s substrate enabling it to become attached to the enzyme’s active site.
End – product inhibition
Process by which a metabolite at a later stage in a pathway builds up and prevents the activity of an enzyme controlling an earlier stage.
Inhibitor
Regulatory molecule that halts or decreases the rate of an enzyme – controlled reaction.
Non– competitive
Type of inhibitor that becomes attached to a non-active site on an enzyme and changes the enzyme’s molecular shape.
