Welcome Back!Please do the following:• pick up the handouts from

the front table • pick up glue• if you did the extra credit

assignment, it is due in the tray

• have out your notebook• get started on your bell

ringer

We will investigate & explain the transport of molecules.

I will be able to explain the direction water will move through celery.

CELL TRANSPORTHow molecules get in and out of cells

To discuss how nutrients get in and out of a cell, you’ll need to know these words.

Solute: _____________________________________

Solvent: ____________________________________

water

salt

saltwatersolution

The substance doing the dissolving

The substance being dissolved

solute

solvent

In aqueous solutions, the solvent is always water. The cytoplasm in the cell is an aqueous solution.

We need to move molecules because…

• People need nutrients

• People need to get rid of waste

• Cells also need nutrients

• Cells also need to get rid of waste

What part of the cell regulates the entry and exit of molecules?

The Cell Membrane is made of…• Proteins and Lipids and some Carbohydrates

The Cell Membrane is Semi-Permeable

• Semi-Permeable means that only certain sized molecules can pass through the cell membrane

• Think of the cell membrane as a chain link fence!

The cell membrane maintains homeostasis…

• By allowing proper nutrients into the cell

• By getting rid of wastes from within the cell

• Membranes also allow cells to communicate with other cells & the outside world. This allows the cells to respond to their environment & each other!

Quick Review

• What protective barrier of cells controls the entry and exit of molecules? What is this barrier made of?

• The cell membrane is semi-permeable. Explain what this means.

• How does the cell membrane maintain homeostasis?

Two Types of Transport

• Cells move substances through the cell membrane by a process called transport.

1. Passive Transport• For small, uncharged molecules

2. Active Transport• For large molecules

Energy

Energy

Diffusion is Passive Transport

• Requires no energy from the cell

• Molecules move from high → low concentration

• Molecules move with the concentration gradient

Energy

High Concentration

Low Concentration

Examples of Diffusion

• Dye added to liquid • Odors

In both cases, molecules move from areas of high concentration to

low concentration until a balance is reached!

We call this balance on both sides EQUILIBRIUM!

How does diffusion happen in a cell?

How does diffusion happen in a cell?

Osmosis is the diffusion of waterWater travels from where it is purest

to where it is least pureCell Membrane

Osmosis is the diffusion of water

Cell Membrane

Water has to be able to move…

• We are over 75% water• Water is an important solvent in our body

(water dissolves a lot of stuff in our body)

• If our cells are in an environment that robs them of water, we dehydrate! YIKES!

• Can you die from drinking too much water?

Effects of Passive Transport

100% Distilled Water

80% H2O

70% Water30% Dissolved

Substances

80% H2O

80% Water20% Dissolved

Substances

80% H2O

Which way did the water move?

70% Water30% Dissolved

Substances

80% H2O

Why did the cell get so small?

HYPERTONICSolution

Which way did the water move?

80% Water20% Dissolved

Substances

80% H2O

Why did the cell stay the same size?

ISOTONICSolution

Which way did the water move?

100% Distilled Water

80% H2O

Why did the cell get so big?

HYPOTONICSolution

Real life example with red blood cells

A change in cell shape is a change in

cell function!

Facilitated Diffusion I’m a Channel, I can help!

Channel and carrier proteins help substances (glucose) pass through the cell membrane. Still passive transport - no energy required.

Facilitated Diffusion I’m a Channel, I can help!

Channel and carrier proteins help substances (glucose) pass through the cell membrane. Still passive transport - no energy required.

Quick Review

• What are the two types of transport and which one requires the input of ATP energy?

• How is osmosis and facilitated diffusion different from each other?

• How are hypotonic and hypertonic solutions different from each other?

Active Transport

• Requires energy from the cell

• Molecules move from low → high concentration

• Molecules move against the concentration gradient

Energy

High Concentration

Low Concentration

Endocytosis

• Cells take in large particles changing the shape of the cell membrane.– Phagocytosis (cell eating)– Pinocytosis (cell drinking)

Exocytosis

• How the cell gets rid of waste

Quick Review

• What type of transport requires energy and moves molecules from low to high concentration?

• What process allows cells to get rid of large particles like waste?

• What process allows cells to get take in large molecules?

SUMMARYCompare Passive Transport

to Active Transport

• ENERGY OR NO ENERGY• LOW TO HIGH OR HIGH TO LOW• WITH OR AGAINST CONCENTRATION GRADIENT

http://www.youtube.com/watch?v=wO1yq6YTJDI