Like this study set? Create a free account to save it.

Sign up for an account

Already have a Quizlet account? .

Create an account

selective permeability

A property of biological membranes that allows some substances to cross more easily than others and blocks the passage of other substances altogether


Is passive transport. Solutes naturally diffuse from high to low concentrations, and the cell does not have to expend any energy. Small, non-polar molecules can easily cross a cell through simple diffusion (fig 5.3)

passive transport

The diffusion of a substance across a biological membrane with no expenditure of energy.


is the diffusion of water. Water tends to diffuse toward high solute concentrations, remember, "water follows salt." (fig 5.4)


The ability of a solution surrounding a cell to cause that cell to gain or lose water. Hypotonic, hypertonic, and isotonic.


Referring to a solution that, when surrounding a cell, will cause the cell to take up water.


Referring to a solution that, when surrounding a cell, will cause the cell to lose water.


Referring to a solution that, when surrounding a cell, has no effect on the passage of water into or out of the cell.

Facilitated diffusion

requires a transport protein to cross(FACILITATE) the cell membrane. However, it is still passive transport (no energy required). Water, sugars, amino acids, and many ions cross the membrane this way.

Active transport

____________ requires energy from the cell, and can push solutes "uphill" against their concentration gradients (fig 5.8). The sodium-potassium pump is a protein that "actively transport" ions across the cell membrane.

Exocytosis and endocytosis

are also active transport. These involve physical engulfing (endo-) or ejection (exo-) of materials in vesicles (fig 5.9)

Potential energy

is stored energy. The energy stored in the chemical bonds of organic molecules is a form of ____________.
(water behind a dam possesses ____________).

Kinetic energy

is energy released or set into motion. Heat, transport, and movement are forms of ____________.

Consume energy

All cells _______________, typically by breaking down organic molecules to release their chemical energy, and then storing or using that energy in other forms

Second law of thermodynamics

no energy conversion is perfectly efficient, and some energy is always lost as heat.


chemical reactions release energy (catabolism).


chemical reactions require an input of energy (anabolism).


The totality of an organism's chemical reactions. The sum of an organism's chemical reactions is the ______.

ATP (adenosine triphosphate)

is the universal energy "currency" of the cell; energy released from splitting (hydrolysis) of ______ powers all cellular work. Energy released from break-down of sugars (exergonic) is used to re-charge (phosphorylate) the cell's stock of ATP. (fig 5.12A,B,C)


a chemical reaction that breaks bonds between two molecules by the addition of water; process by which polymers are broken down and an essential part of digestion.

exergonic reaction

an energy-releasing chemical reaction in which the reactants contain more potential energy that the products. The reaction releases an amount of energy equal to the difference in potential energy between the reactants and the products.


The transfer of a phosphate group, usually from ATP, to a molecule. Nearly all cellular work depends on ATP energizing other molecules by _________.


are large, complex proteins that function as catalysts. As such, they speed up or facilitate biochemical reactions, but are not themselves consumed in the reaction (fig 5.13, 5.14)


A non-protein molecule or iron that is required for the proper function. Many enzymes require helper(COPILOT) pieces called cofactors. Vitamins are organic cofactors also known as coenzymes. Cofactors can also be mineral ions, like zinc, iron, magnesium, etc.

feedback inhibition

A method of metabolic control in which a product of a metabolic pathway acts as an inhibitor of an enzyme within the pathway.

Competitive/noncompetitive inhibitors of enzymes, concept of "feedback inhibition" (fig 5.15A,B)

Competitive inhibitors

A substance that reduces the activity of an enzyme by binding to the enzyme's active site in place of the substrate. A _____________s structure mimics that of the enzyme's substrate.

Noncompetitive inhibitor

A substance that reduces the activity of an enzyme without entering an active site. By binding elsewhere on the enzyme, a _____________ changes the shape of the enzyme so that the active site no longer effectively catalyzes the conversion of substrate to product.

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

Voice Recording