Ch. 4/5 Diffusion, Osmosis and Enzymes
Diffusion across a biological membrane is called ______________________.
Passive transport
The nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles make up the __________.
endomembrane system
The _____ between an active site and its substrate often strains bonds and helps the reaction proceed.
induced fit
Most enzymes are
proteins
What are the main components of cellular membrane?
proteins and phospholipids
Cofactor
A nonprotein molecule or ion that is required for the proper functioning of an enzyme.
active site
A pocket or groove on the surface of the enzyme.
Product
A substance produced in a chemical reaction
Inhibitor
A substance that slows down or stops a chemical reaction
Enzyme
A type of protein that speeds up a chemical reaction in a living thing
Metabolism
All of the chemical reactions that occur within an organism
When cells are placed in hypotonic solutions, both animal and plant cells accumulate water as a result of osmosis. This causes the cells to swell. Why can plant cells better tolerate hypotonic solutions?
Animal cells can burst in such situations. In plants, however, rigid cell walls limit how far cells can expand and exert a back pressure to limit further water uptake.
Hydrolysis
Breaking down complex molecules by the chemical addition of water
An enzyme is considered a(n)________because it speeds up a chemical reaction without being used up.
Catalyst
Osmosis
Diffusion of water through a selectively permeable membrane
Hypertonic
Having a higher concentration of solute than another solution.
Hypotonic
Having a lower concentration of solute than another solution
Coded genetic information is produced in the nucleus and transferred to the cytoplasm in a molecule called _____.
Messenger RNA
Diffusion
Movement of molecules from an area of higher concentration to an area of lower concentration.
What name is given to the process by which water crosses a selectively permeable membrane?
Osmosis
What name is given to the reactants in an enzymatically catalyzed reaction?
Substrate
Osmoregulation
The control of water balance.
passive transport
The movement of materials through a cell membrane without using energy
Reactant
a substance that takes part in and undergoes change during a reaction.
An enzyme is specific because the shape of its __________ matches only particular reactants.
active site
Catalysis
an enzyme makes a reaction run much faster than it would on its own
coenzyme
an organic cofactor
A(n) ______, which is often a vitamin, binds to an enzyme and plays a role in catalysis.
coenzyme
High temperatures or changes in pH can ______ an enzyme, causing it to lose its shape and biological activity.
denature
In osmosis, water always moves toward the __________ solution, that is, toward the solution with the __________ solute concentration.
hypertonic ... greater
As a result of its involvement in a reaction, an enzyme _____.
is unchanged
An animal cell placed in a hypertonic solution will __________.
lose water by osmosis and shrivel
An enzyme speeds up a reaction by _____________________________________.
lowering the activation energy
When molecules move down their concentration gradient, they move from where they are _____________________ to where they are________________________.
more concentrated, less concentrated
An enzyme is an
organic catalyst
Enzymes work by _____.
reducing activation energy
In a catalyzed reaction, a reactant is often called a(n)_______________
substrate
Tonocity
the ability of a solution to cause a cell to gain or lose water
active transport
the movement of materials through a cell membrane using energy
Isotonic
when the concentration of two solutions is the same
