Ch. 4/5 Diffusion, Osmosis and Enzymes

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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


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