The Transport of Materials Between Cells

Question: How are nutrients and wastes exchanged between cells? Answer: By a process called cellular transport

There are two types of transport… Passive transport Active transport

Passive vs Active transport Passive transport: movement from high concentration to lower concentration Without using energy (ATP) . Examples: Diffusion Facilitated diffusion Osmosis Active transport: movement of particles from low concentration to higher concentration by using energy (ATP)

Past learning: What is the function of the cell membrane?

1. DIFFUSION: The natural movement of molecules from an area of high concentration to an area of lower concentration.

Diffusion high concentration low concentration

In which direction will these molecules diffuse? high concentration low concentration

In which cell is diffusion occurring?

Why do molecules move from high concentration to low concentration?

All molecules are always in motion. Gas Solid Liquid The higher the temperature, the faster they move.

What will happen?

DIFFUSION STOPS WHEN EQUILIBRIUM IS REACHED. Eventually, the molecules will be evenly spread out. Equilibrium: When there is an even concentration of molecules. DIFFUSION STOPS WHEN EQUILIBRIUM IS REACHED.

Equilibrium is reached. Into the cell or Out of the cell? Out of the cell. Into the cell. until... Equilibrium is reached.

Why didn’t they diffuse? Because it’s TOO BIG!!

The Rate of Diffusion depends on: Concentration gradient: Difference between the two concentrations. Size of particles – Large Molecules Won’t Fit through Cell Membrane Temperature (Molecules move faster when they are hotter.)

Concentration Gradient: The amount of difference between the 2 concentrations. Larger Gradient

Which diffusion will occur more quickly? Why? Because there is a greater concentration gradient.

2. Facilitated diffusion Movement of molecules from high concentration to lower concentration with the help of cell membrane protein molecules.

3. Osmosis: The diffusion of water from high water concentration to low water concentration.

NOTE - Diffusion and Osmosis do not require energy (ATP) from the cell.

3. Osmosis -

Solutes Substances that are dissolved in a liquid. Ex: salt in water

Hypertonic: Having a higher solute concentration. (But a lower water concentration) Hypotonic: Having a lower solute concentration. But a higher water concentration.

Solution is hypertonic. Water will leak out.

Hypertonic

Solution is hypotonic. Water will rush in.

Hypotonic

Isotonic: Same concentration.

Isotonic

Diffusion Diffusion 80% water 40% water

Equilibrium 60% water 60% water

Selectively Permeable Membrane Starch Molecule Water Molecule

Can Equilibrium be reached?

Osmosis (passive)

Osmosis Water will rush towards the area that has more solute (salt, starch, etc.) in order to dilute it.

Salt will dehydrate and kill a slug.

Fresh Water More solute

Lysis: Cell bursts. Fresh Water

In Salt Water Animal cell will shrivel. Plant cell wall maintains its shape. The cell membrane and its insides will shrivel.

Salt Water Add salt water Water rushes out of the cell. Cell shrinks.

Cell Wall cytoplasm Cell Membrane

Fresh Water Salt Water

2 Ways to Look at it: 20% Salt 80% Water 100% Water 0% Salt

OSMOSIS: Which Way? 20% Water 80% Water

OSMOSIS: Which Way? 50% Water 50% Salt

OSMOSIS: Which Way? 30% Water 70% Salt 40% Salt

Water diffuses towards salt. Swell Shrink

Concentration gradient

2 Ways to Look at it: 20% Salt 80% Water 100% Water All Water

OSMOSIS: Which Way? 40% Salt 10% Salt

OSMOSIS: Which Way? 50% Water 55% Water

OSMOSIS: Which Way? 15% Salt 45% Salt

OSMOSIS: Which Way? 90% Water 70% Water

OSMOSIS: Which Way? 10% Water 30% Water

How? Active Transport – movement of particles from LOW concentration to HIGH concentration but requires energy (ATP)!!!!

The cell can use energy!

Active Transport Can use endocytosis (in) or exocytosis (out).

Endocytosis and Exocytosis Vacuole

Even though the cell membrane can control what enters the cell to an extent, poisons can still enter.

Active Transport diffusion

Active Transport diffusion

Passive or Active?

Passive or Active?

Passive or Active?

Passive or Active?

Which process requires energy from the cell and which does not? Fresh Water OSMOSIS Contractile Vacuole

Fresh Water Paramecium Fresh Water

Membrane Proteins Some membrane proteins help communicate with other cells. Other proteins do active transport.

Active Transport The cell uses energy (ATP) in order to move molecules from low concentration to high concentration.

PASSIVE TRANSPORT No energy

ACTIVE TRANSPORT Requires energy

Active Transport Passive Transport Equilibrium is reached. Requires energy (ATP) Low to High Equilibrium is NOT reached. Requires no energy High to Low Diffusion Osmosis Facilatated diffusion Equilibrium is reached.

Practice problems

Passive or Active? You soak a cell in iodine but the cell never fills with iodine.

Passive or Active? You soak a cell in methylene blue and eventually it becomes fully blue.

more salt moving out of the cell than into the cell The biologist added a 10% salt solution to the slide and observed the cell as shown in diagram B. The change in appearance of the cell resulted from……. more salt moving out of the cell than into the cell more salt moving into the cell than out of the cell more water moving into the cell than out of the cell more water moving out of the cell than into the cell

Go Over Quiz

starch sugar protein amino acid fat fatty acid Quiz Today! Diffusion is the movement of molecules from a _________________________. What is an indicator? Which molecules are small enough to pass through a cell membrane? starch sugar protein amino acid fat fatty acid

What will happen?

Cell Membrane

Does diffusion require energy from this cell?

Since cyanide is a poison that limits a cell's ability to manufacture ATP, a cell containing cyanide is least likely to carry on the process of….. passive transport active transport diffusion

Passive or Active? A red blood cell maintains a higher concentration of Potassium inside its cell than outside.

Passive or Active? You soak a cell in iodine but the cell never fills with iodine.

Passive or Active? You soak a cell in methylene blue and eventually it becomes fully blue.

Passive or Active? Equilibrium is reached.

Passive or Active? The cell stays out of equilibrium.

Passive or Active? ATP is used.

Passive or Active? No energy is needed.

Which process is best represented in this diagram? active transport diffusion

active transport diffusion With the passage of time, some molecules move from area B to area A. This movement is the result of the process of: active transport diffusion

ATP is being used to move the molecules out of which cell(s)? cell A, only cell B, only both cell A and cell B neither cell A nor cell B

Which process is directly responsible for the net movement of K+ and Mg++ into the cell? diffusion active transport

Which row represents Diffusion? (Passive Transport)

Which row represents ACTIVE TRANSPORT?

S A A S P P S P P A S A S