activation energy - ANSWER-the minimum amount of energy required to start a
chemical reaction
active site - ANSWER-The site on an enzyme that attaches to a substrate.
active transport - ANSWER-energy-requiring process that moves material across a cell
membrane against a concentration difference
ADP - ANSWER-A molecule composed of adenosine and two phosphate groups. The
molecule ATP is made by combining a molecule of ADP with a third phosphate in an
energy-consuming reaction.
ATP - ANSWER-A molecule composed of adenosine and three phosphate groups; the
main energy source for cells.
calorie - ANSWER-The amount of energy that raises the temperature of 1 g of water by
1°C.
chemical energy - ANSWER-Energy stored in the chemical bonds of molecules; a form
of potential energy.
concentration gradient - ANSWER-An increase or decrease in the density of a chemical
substance within a given region. Cells often maintain concentration gradients of
hydrogen ions across their membranes. When a gradient exists, the ions or other
chemical substances involved tend to move from where they are more concentrated to
where they are less concentrated.
conservation of energy - ANSWER-The principle that energy can neither be created nor
destroyed.
diffusion - ANSWER-The spontaneous movement of particles of any kind down a
concentration gradient; that is, movement of particles from where they are more
concentrated to where they are less concentrated.endocytosis
endocytosis - ANSWER-The movement of materials into the cytoplasm of a cell via
vesicles or vacuoles.
, Energy - ANSWER-The capacity to perform work, or to move matter in a direction it
would not move if left alone.
Entropy - ANSWER-A measure of disorder, or randomness. One form of disorder is
heat, which is random molecular motion.
enzyme inhibitors - ANSWER-A chemical that interferes with an enzyme's activity by
changing the enzyme's shape, either by plugging up the active site or binding to another
site on the enzyme.
enzymes - ANSWER-A protein that serves as a biological catalyst, changing the rate of
a chemical reaction without itself being changed in the process.
exocytosis - ANSWER-The movement of materials out of the cytoplasm of a cell via
membranous vesicles or vacuoles.
facilitated diffusion - ANSWER-The passage of a substance across a biological
membrane down its concentration gradient, aided by specific transport proteins.
feedback regulation - ANSWER-A method of metabolic control in which the end product
of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.
hypertonic - ANSWER-In comparing two solutions, referring to the one with the greater
concentration of solutes.
induced fit - ANSWER-The interaction between a substrate molecule and the active site
of an enzyme, which changes shape slightly to embrace the substrate and catalyze the
reaction.
isotonic - ANSWER-Having the same solute concentration as another solution.
kinetic energy - ANSWER-Energy of motion. Moving matter performs work by
transferring its motion to other matter, such as leg muscles pushing bicycle pedals.
metabolism - ANSWER-The total of all the chemical reactions in an organism.
osmoregulation - ANSWER-The control of the gain or loss of water and dissolved
solutes in an organism.
osmosis - ANSWER-The diffusion of water across a selectively permeable membrane.
passive transport - ANSWER-The diffusion of a substance across a biological
membrane without any input of energy.
phagocytosis - ANSWER-Cellular "eating"; a type of endocytosis whereby a cell engulfs
large molecules, other cells, or particles into its cytoplasm.
pinocytosis - ANSWER-Cellular "drinking"; a type of endocytosis in which the cell takes
fluid and dissolved solutes into small membranous vesicles.
plasmolysis - ANSWER-A phenomenon that occurs in plant cells in a hypertonic
environment. The cell loses water and shrivels, and its plasma membrane pulls away
from the cell wall, usually killing the cell.
Potential energy - ANSWER-Stored energy; the energy that an object has due to its
location and/or arrangement. Water behind a dam and chemical bonds both possess
potential energy.
receptor-mediated endocytosis - ANSWER-The movement of specific molecules into a
cell by the inward budding of vesicles. The vesicles contain proteins with receptor sites
specific to the molecules being taken in.
signal transduction pathway - ANSWER-A series of molecular changes that converts a
signal on a target cell's surface to a specific response inside the cell.
chemical reaction
active site - ANSWER-The site on an enzyme that attaches to a substrate.
active transport - ANSWER-energy-requiring process that moves material across a cell
membrane against a concentration difference
ADP - ANSWER-A molecule composed of adenosine and two phosphate groups. The
molecule ATP is made by combining a molecule of ADP with a third phosphate in an
energy-consuming reaction.
ATP - ANSWER-A molecule composed of adenosine and three phosphate groups; the
main energy source for cells.
calorie - ANSWER-The amount of energy that raises the temperature of 1 g of water by
1°C.
chemical energy - ANSWER-Energy stored in the chemical bonds of molecules; a form
of potential energy.
concentration gradient - ANSWER-An increase or decrease in the density of a chemical
substance within a given region. Cells often maintain concentration gradients of
hydrogen ions across their membranes. When a gradient exists, the ions or other
chemical substances involved tend to move from where they are more concentrated to
where they are less concentrated.
conservation of energy - ANSWER-The principle that energy can neither be created nor
destroyed.
diffusion - ANSWER-The spontaneous movement of particles of any kind down a
concentration gradient; that is, movement of particles from where they are more
concentrated to where they are less concentrated.endocytosis
endocytosis - ANSWER-The movement of materials into the cytoplasm of a cell via
vesicles or vacuoles.
, Energy - ANSWER-The capacity to perform work, or to move matter in a direction it
would not move if left alone.
Entropy - ANSWER-A measure of disorder, or randomness. One form of disorder is
heat, which is random molecular motion.
enzyme inhibitors - ANSWER-A chemical that interferes with an enzyme's activity by
changing the enzyme's shape, either by plugging up the active site or binding to another
site on the enzyme.
enzymes - ANSWER-A protein that serves as a biological catalyst, changing the rate of
a chemical reaction without itself being changed in the process.
exocytosis - ANSWER-The movement of materials out of the cytoplasm of a cell via
membranous vesicles or vacuoles.
facilitated diffusion - ANSWER-The passage of a substance across a biological
membrane down its concentration gradient, aided by specific transport proteins.
feedback regulation - ANSWER-A method of metabolic control in which the end product
of a metabolic pathway acts as an inhibitor of an enzyme within that pathway.
hypertonic - ANSWER-In comparing two solutions, referring to the one with the greater
concentration of solutes.
induced fit - ANSWER-The interaction between a substrate molecule and the active site
of an enzyme, which changes shape slightly to embrace the substrate and catalyze the
reaction.
isotonic - ANSWER-Having the same solute concentration as another solution.
kinetic energy - ANSWER-Energy of motion. Moving matter performs work by
transferring its motion to other matter, such as leg muscles pushing bicycle pedals.
metabolism - ANSWER-The total of all the chemical reactions in an organism.
osmoregulation - ANSWER-The control of the gain or loss of water and dissolved
solutes in an organism.
osmosis - ANSWER-The diffusion of water across a selectively permeable membrane.
passive transport - ANSWER-The diffusion of a substance across a biological
membrane without any input of energy.
phagocytosis - ANSWER-Cellular "eating"; a type of endocytosis whereby a cell engulfs
large molecules, other cells, or particles into its cytoplasm.
pinocytosis - ANSWER-Cellular "drinking"; a type of endocytosis in which the cell takes
fluid and dissolved solutes into small membranous vesicles.
plasmolysis - ANSWER-A phenomenon that occurs in plant cells in a hypertonic
environment. The cell loses water and shrivels, and its plasma membrane pulls away
from the cell wall, usually killing the cell.
Potential energy - ANSWER-Stored energy; the energy that an object has due to its
location and/or arrangement. Water behind a dam and chemical bonds both possess
potential energy.
receptor-mediated endocytosis - ANSWER-The movement of specific molecules into a
cell by the inward budding of vesicles. The vesicles contain proteins with receptor sites
specific to the molecules being taken in.
signal transduction pathway - ANSWER-A series of molecular changes that converts a
signal on a target cell's surface to a specific response inside the cell.
