Chapter 5: Cell Membranes And Membrane Transport

Front 1

What's selective permeability?

Back 1

Selective permeability is a characteristic of a barrier that can allow certain molecules to go through and disallow others from going in.

Front 2

What's diffusion?

Back 2

Diffusion is the net transport of particles along their gradient, meaning from high concentrations to lower ones.

Front 3

Describe simple and facilitated diffusion.

Back 3

Simple diffusion occurs by itself with no help. Facilitated diffusion require special protein transporters.

Front 4

What's a channel protein?

Back 4

A channel protein is a type of facilitated diffusion through a hydrophilic channel and facilitates the transport of materials. Aquaporins gated channels.

Front 5

What's a carrier protein?

Back 5

A carrier protein binds to the molecule and transports it to the other side.

Front 6

What's an integral protein?

Back 6

An integral protein is a protein that is embedded in the lipid bilayer and sometimes spans the membrane multiple times.

Front 7

What's a peripheral protein?

Back 7

Peripheral protein is a protein that is on the surface of the membrane and doesn't interact with the hydrophobic core of the membrane.

Front 8

What's active transport?

Back 8

Active transport is the transport of molecules against their concentration gradient and which requires energy.

Front 9

Primary and secondary active transports.

Back 9

Primary active transports only deal with positive ions. Secondary active transport occurs in two mechanisms symport and antiport. It is supplied by a different ion which is the driving force.

Front 10

What's osmosis, hypertonic and hypotonic?

Back 10

Osmosis is the passive diffusion of water. It goes from lower solute concentrations to high ones. Hypotonic means under or below.

Front 11

What's exocytosis and endocytosis?

Back 11

Active and passive transport can only move small and middle sized molecules and aminoacids, however for the transport of larger ones exocytosis and endocytosis are used.

Front 12

Describe the structure and common components of eukaryotic membranes.

Back 12

Eukaryotic membranes are made of a phospholipid bilayer and embedded proteins on them. It has a very fluid and assymetric structure.

Front 13

Describe the functions of the eukaryotic plasma membrane.

Back 13

1. Transport of ions and molecules.

2. Cell to cell communication.

3. Protective function

Front 14

Describe how the “fluid mosaic model” fits what is known about the plasma membrane, with respect tomembrane structure/characteristics.

Back 14

The fluid mosaic modle states that the membrane has a very fluid like viscosity and the proteins can move around on the membrane. This has been shown by an experiment where human and mouse cells where fused together and the proteins after some time came to a randomly arranged structure.

Front 15

Describe the factors affecting membrane fluidity.

Back 15

1. Temperature

2. More double bonds means more fluid.

3. Sterols also can affect membrane fluidity because they act like buffers.

Front 16

Predict the effects on the membrane/cell properties with changes in membrane fluidity

Back 16

If the membrane is becoming more solid it can affect the functionality of the proteins and inhibit the transportation of molecules across it.

On the other hand, too high temperature can also mean that ions can leak through the cell.

Front 17

Predict the impact of changes in different lipid types on membrane fluidity.

Back 17

Double bonds introduce kinks on the phospholipid molecule and the membrane becomes less packed therefore more fluid.Unsaturated

Front 18

Predict how the cell will respond to changes in temperature in order to maintain proper membranefluidity

Back 18

Cells will start to produce an enzyme called desaturases in order to regulate the fluidity of the membrane.

Front 19

Explain how the plasma membrane structure provides selective permeability