Transport NotesTransport Notes

HomeostasisHomeostasis How does your cells keep homeostasis How does your cells keep homeostasis

(internal stable condition)?(internal stable condition)? By transporting molecules in and out of By transporting molecules in and out of

the cell, like water, sugar, salt, and the cell, like water, sugar, salt, and electrolytes.electrolytes.

This is done by the passive or active This is done by the passive or active transports.transports.

TransportsTransports To transport molecules in and out of the To transport molecules in and out of the

cell, these molecules will have to pass cell, these molecules will have to pass through the cell membrane.through the cell membrane.

So let’s learn more about the function So let’s learn more about the function and structure of the cell membrane!!!and structure of the cell membrane!!!

Cell OrganelleCell Organelle Cell MembraneCell Membrane – is – is

the organelle that the organelle that surrounds the cell surrounds the cell and is made up of and is made up of phospholipids and phospholipids and proteins.proteins.

Cell MembraneCell Membrane Function: Function: is to control what goes in and is to control what goes in and

out of the cell. out of the cell. This means cell membranes are This means cell membranes are

selectively permeable.selectively permeable.

Cell MembraneCell Membrane Selectively Selectively

PermeablePermeable – means – means some substances some substances can pass through can pass through while others cannot, while others cannot, the membrane the membrane selects what can selects what can permeate through it. permeate through it.

The cell membrane is made The cell membrane is made up of lipids and proteinsup of lipids and proteins

Membrane LipidsMembrane Lipids PhospholipidsPhospholipids – the tail is hydrophobic – the tail is hydrophobic

(fears water) and the head is hydrophilic (fears water) and the head is hydrophilic (loves water).(loves water).

Membrane LipidsMembrane Lipids Cells are surrounded by a water Cells are surrounded by a water

environment (both inside the cell and environment (both inside the cell and outside) sooooooutside) sooooo

cell membranes are made out of a lipid cell membranes are made out of a lipid bilayer (2-layers) where the hydrophobic bilayer (2-layers) where the hydrophobic tails point toward each othertails point toward each other

Important PartsImportant Parts Fluid Mosaic Model Fluid Mosaic Model - - This best This best

describes the cell membrane, because the describes the cell membrane, because the lipid bilayer acts more like a fluid than a lipid bilayer acts more like a fluid than a solid (think of Jello)solid (think of Jello)

Important PartsImportant Parts The cell membrane changes with the The cell membrane changes with the movementmovement of phospholipids and proteins of phospholipids and proteins

TransportTransport Cells have to transport substances in or out Cells have to transport substances in or out

of the cell to maintain homeostasis. of the cell to maintain homeostasis. So, cells are constantly fighting So, cells are constantly fighting

concentration gradients.concentration gradients.

TransportsTransports Concentration GradientConcentration Gradient – is the difference – is the difference

in concentration across an area divided by a in concentration across an area divided by a membrane. membrane.

One side has a high percent than the otherOne side has a high percent than the other

TransportsTransports So, the job of transports are to get rid of So, the job of transports are to get rid of

concentration gradients by moving concentration gradients by moving molecules from one side of the cell molecules from one side of the cell membrane to the other.membrane to the other.

When the sides have an equal When the sides have an equal concentration you have now reach concentration you have now reach equilibrium (Homeostasis).equilibrium (Homeostasis).

EquilibriumEquilibrium EquilibriumEquilibrium – is the state when the – is the state when the

concentration of molecules are equal on concentration of molecules are equal on both sides of the membrane.both sides of the membrane.

TransportTransport There are 2 types of transports.There are 2 types of transports. 1. 1. Passive TransportPassive Transport – movement of – movement of

substances down their concentration gradient substances down their concentration gradient (high concentration to low concentration); no (high concentration to low concentration); no energyenergy

2. 2. Active Transport: Active Transport: movement of movement of substances up their concentration gradient substances up their concentration gradient (low concentration to high concentration); (low concentration to high concentration); requires ENERGYrequires ENERGY