Anatomy and Physiology

Cell Transport

Types of TransportDiffusion

• Characteristics– Particles move from an area of high

concentration to an area of low concentration.

– Moves “down” or “with” the concentration gradient. (difference in concentration)

– Does not require energy.

Types of Transport

• Factors effecting the rate of diffusion– TemperatureTemperature - as temperature

increase, rate of diffusion increases.– PressurePressure - as pressure increases, rate

of diffusion increases.– Steepness of the concentration Steepness of the concentration

gradientgradient - - the steeper the gradient, the faster the rate of diffusion.

Types of Transport

• Diffusion will continue until dynamic equilibrium is reached.

• Dynamic equilibriumDynamic equilibrium - - continuous movement of particles, but no overall concentration change. (Everything is equally distributed).

Type of TransportOsmosis

• Characteristics– Movement of

water across a cell membrane.

– Cell has no control over movement of water. It continues to move until [inside] = [outside].

[ ] =concentration

AS Biology, Cell membranes and Transport

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Osmosis

Cell membrane partially permeable.

Inside cell Outside cell

VERY High concentration of water molecules.

VERY Low concentrationof water molecules.

Sugar molecule

DILUTE SOLUTIONCONCENTRATED SOLUTION

AS Biology, Cell membranes and Transport

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Osmosis

Cell membrane partially permeable.

Inside cell Outside cellHigh conc. of water molecules.

Low conc. of water molecules.

OSMOSIS

AS Biology, Cell membranes and Transport

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Osmosis

Cell membrane partially permeable.

Inside cell Outside cell

OSMOSIS

EQUILIBRIUM. Equal water concentration on each side. Equal water potential has been reached. There is no net movement of water – water moves in and out of cell at the same rate.

What is a solution?

2 Parts:

•Solvent – Usually a liquid like water•Solute – Usually a solid such as sugar, salt

Isotonic SolutionIsotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell.

ISO = THE SAME

Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

• Osmosis Animations for

isotonic, hypertonic, and hypotonic

solutions

Osmosis - Types of Osmosis - Types of SolutionsSolutions

IsotonicIsotonic• [water inside]

= [water outside]

• Dynamic equilibrium reached immediately.

Normal Red blood cells

Hypotonic SolutionHypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute (HYPO); High water)

Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

• Osmosis Animations for

isotonic, hypertonic, and hypotonic

solutions

Osmosis - Types of Osmosis - Types of SolutionsSolutions

HypotonicHypotonic

• [water inside] < [water outside]

• Solutes are higher inside the cell.

• Water flows in, cell swells.

• Cell could burst if water flow continues.

Swollen red blood cells

Hypertonic Solution

Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute (HYPER); Low water)

Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!

• Osmosis Animations for

isotonic, hypertonic, and hypotonic

solutions

shrinks

Osmosis - Types of Osmosis - Types of SolutionsSolutions

HypertonicHypertonic

• [water inside] > [water outside].

• Solutes are higher outside the cell.

• Water leaves the cell, cell shrinks.

Dehydrated red blood cells

Types of transport

Passive vs. Active Transport

• Passive - no energy required

• Active - energy required

Types of Cellular Transport

• Passive Transport cell doesn’t use energy

1. Diffusion2. Facilitated Diffusion3. Osmosis

• Active Transportcell does use energy

1. Protein Pumps2. Endocytosis3. Exocytosis

high

low

This is gonna

be hard work!!

high

low

Weeee!!!

•Animations of Active Transport & Passive

Transport

Types of Transport

• Passive TransportPassive Transport– Movement across

a membrane by diffusion.

– Facilitated diffusion - moves down the concentration gradient with the aid of a protein molecule.• Most glucose

moves this way

2. Facilitated diffusion: diffusion of specific particles through transport/carrier proteins found in the membrane a.Transport Proteins are

specific – they “select” only certain molecules to cross the membrane

b.Transports larger or charged molecules

Facilitated diffusion (Channel Protein)

Diffusion (Lipid

Bilayer)

Passive Transport: 2. Facilitated Diffusion

Carrier Protein

A B

• http://bio.winona.edu/berg/Free.htm

Types of Transport• Active Transport Active Transport

– moves from an area of low concentration to an area of high concentration.

– Moves up or against the concentration gradient.

– Glucose moving from blood stream into liver for storage.

Types of Transport

• Bulk TransportBulk Transport– Moving large particles across the cell

membrane.

– Endocytosis - movement – into the cell

– Exocytosis - movement out of the cell

• Cell changes shape – requires energy

• EX: Hormones or wastes released from cell

Contractile vacuole full

Contractile vacuole empty

Paramecium

Bulk Transport

• Endocytosis - 2 types

– Pinocytosis- bulk transport of liquids into the cell.

– Phagocytosis- “cell eating”- bulk transport of solids into the cell.

• Cell membrane in-folds around food particle• “cell eating”• forms food vacuole & digests food• This is how white blood cells eat bacteria!