Chapter5

chemical process that uses oxygen to convert the chemical energy stored in fuel molecules to a form of chemical energy that the cell can use to perform work

yield products that are rich in potential energy

• the total of an organisms chemical reactions.
• intersecting metabolic pathways.

a series of chemical reactions that either builds a complex molecule or breaks down a complex molecule into simpler compounds

• the use of energy released from EXERgonic reactions to drive essential ENDERgonic reactions
• a crucial ability of all cells

powers nearly all forms of cellular work

• the transfer of a phosphate group, usually from ATP, to a molecule.
• *nearly all cellular work depends on ATP energizing other molecules by phosphorylation

the amount of energy that reactants must absorb before a chemical reaction will start

proteins that function as biological catalysts, increasing the rate of a reaction without being consumed by the reaction

a specific reactant that an enzyme acts on

the region of an enzyme that the substrate fits into

the change in shape of the active enzyme, induced my entry of the substrate do that it binds more snuggly to the substrate

• reduces an enzyme's productivety by blocking substrates from entering the active site
• can be overcome by increasing the concentration of substrate

a description of a membrane structure, depicting a cellular membrane as a mosaic of diverse protein molecules embedded in a fluid bilayer made of phospholipid molecules

allow some substances to cross more easily than others

• an increase/decrease in the density of a chemical substance in an area.
• cells often maintain concentration gradients of ions across their membranes
• when a gradient exists, substances tend to move from where they are more concentrated to where they are less concentrated

the diffusion of a substance across a biological membrane, without any input of energy

the ability of a solution surrounding the cell to cause that cell to gain or lose water

has the same solute concentration as another solution, thus having no effect on passage of water into or out of the cell

• a solution with a concentration lower than that of the cell
• the cell gains water, swells, and may burst

• a solution with a higher solute concentration
• the cell shrivels and can die from water loss

the passage of a substance through a specific transport protein across a biological membrane down its concentration gradient

a transport protein that very rapidly diffuses water into and out of cells

a cell must expend energy to move a solute against its concentration gradient-that is, across a membrane toward the side where the solute is more concentrated. the energy molecule ATP supplies most of the energy

the movement of materials out of the cytoplasm of a cell by fusion of vesicles with the plasma membrane

cellular uptake of molecules or particles via formation of new vesicles from the plasma membrane

cellular "eating"; a type of ENDocytosis where a cell engulfs macromolecules, other cells, or particles into its cytoplasm

cellular "drinking"; a type of ENDocytosis in which the cell makes fluid and dissolved solutes into small membrane vesicles

• the movements of specific molecules into a cell by the inward budding of membrane vesicles
• the vesicles contain protein with receptor sites specific to the molecules taken in

• does not enter the active site, but instead binds to the enzyme somewhere else
• its binding changes the shape of the enzyme so that the active site no longer fits the substrate

a method of metabolic control in which a product of a metabolic pathway acts as an inhibitor of an enzyme within that pathway

the capacity to perform work

• the energy of motion
• transferring motion to other matter

stored energy that an object possesses as a result of its location or structure

the potential energy available for release in a chemical reaction

the study of energy transformation that occurs in a collection of matter

• the principle of the conservation of energy
• energy can be transferred and transformed, but cannot be created or destroyed

• a measure of disorder or randomness
• the more randomly arranged a collection of matter it, the greater its entropy

• the principle whereby every energy conversion reduces the order of the universe, increasing its entropy
• ordered forms of entropy are at least partly converted to heat

a chemical reaction that releases energy