Cell Biology Module 2: Membrane Transport

A cell obtains energy in the form of:

glucose

Nonpolar molecules are

hydrophobic

Polar molecules are

hydrophilic

Nonpolar molecules pass through plasma membrane

True

Polar molecules and charged ions do not cross membrane easily

True

What are some examples of nonpolar molecules?

lipid, O2, CO2

What are some examples of polar molecules and charged ions?

Glucose and Na+

What are the four types of membrane proteins?

transporters, receptors, anchor proteins, and enzymes

What are the function of anchor proteins?

link intracellular and extracellular structures

What is the function of a receptor?

They bind extracellular molecules which activate an intracellular process

What is the function of a transporter?

They carry a molecule from one side of the plasma membrane to other

Does Passive transport require energy?

No

Does active transport require energy?

Yes

Passive transport movement is from

high to low concentration

Active transport movement is

against concentration gradient

Definition of Diffusion (simplest type of passive transport)

A substance from an area of high concentration moves down gradient

Definition of Osmosis

Water diffuses across a membrane from the region of lower solute concentration to the higher solute concentration

In Osmosis: water follows

SOLUTE

What is tonicity?

the ability of a surrounding solution to cause a cell to gain or lose water due to its solute concentration

Definition of Isotonic

solute concentration is same as inside cell

Definition of hypertonic

solute concentration is greater than inside cell

Hypertonic, the cell ____ water

loses

Hypotonic, the cell ____ water

gains

Definition of hypotonic

solute concentration is less than inside cell

Facilitated diffusion is passive transport through a

membrane protein

Definition of active transport

moves substances against their concentration

What are the 4 main functions of active transport?

1. uptake essential nutrients from fluids surrounding cells
2. removal of waste
3. maintenance of intracellular ion concentrations
4. contribute to electrical potential difference

What are the 4 ions that active transport maintain

H+
Na+
K+
Ca2+

In active transport, ATP is used anytime an ion or molecule is transported through membrance protein:

against its concentration gradient or against its electrochemical gradient

Secondary active transport is coupled to

primary active transport

Secondary active transport uses an electrochemical gradient to move a DIFFERENT substance against its

concentration gradient

Glucose transport is an example of

secondary active transport

In Exocytosis, the vesicle fuses with the plasma membrane to:

empty contents

In Endocytosis, a cell

engulfs a particle in a vacuole

Phagocytosis is “cell”

eating

Pinocytosis is “cell”

drinking

In Endocytosis, molecules are taken up when

extracellular fluid is gulped into tiny vesicles

A Ligand is

any molecule that binds specifically to a receptor site

A ligand is used to transport what molecule?

cholesterol

What does the bulk transport of large molecules across the membrane require?

ATP

In a Hypertonic solution, water moves out of the cell to chase after solute. So, the cell

shrivels

In a hypotonic solution, water moves into the cell to get the solute. So, the cell

bursts

In an isotonic solution, the net movement of water is zero. So, the cell is

normal