Biology I:

Homeostasis and Transport (Part 2)

Mr. Nettles

Agenda – Wed., Sept. 14, 2011

Warm-Up (3 min)

Today’s Objectives (2 min)

Lesson (40 min)

Wrap-Up (5 min)

Warm-Up1. When both sides of a concentration gradient

have an equal concentration of molecules on each side ______________ has been reached.

2. _________________involves the use a protein carrier to move molecules from an area of higher concentration to an area of lower concentration.

a) osmosis, b) diffusion, c) facilitated diffusion, d) active transport

3. In your own words, define homeostasis. (1 point Bonus!!) Explain an example related to the

human body.

Warm-Up1. When both sides of a concentration gradient

have an equal concentration of molecules on each side __equilibrium__ has been reached.

2. _________________involves the use a protein carrier to move molecules from an area of higher concentration to an area of lower concentration.

a) osmosis, b) diffusion, c) facilitated diffusion, d) active transport

3. In your own words, define homeostasis. (1 point Bonus!!) Explain an example related to the

human body.- the ability to maintain a stable internal (inside)

environment- People sweat to keep from overheating while exercising

Today’s Objectives

I will describe three types of passive transport.– Osmosis, Diffusion, Facilitated

Diffusion I will articulate one example of

active transport I will define: solvent, solute,

solution, hypertonic, hypotonic, and isotonic.

Think!!

If the molecules can’t get through the membrane, how else could it become less crowded?

Osmosis

Osmosis: WATER moves across a membrane to create more space.

Osmosis always moves water toward the side that has MORE molecules

Osmosis does NOT need energy.

Osmosis Osmosis moves WATER from higher

concentration [OF WATER] to lower concentration [OF WATER].

– Moves from more water to less water

Hypertonic vs. Hypotonic

Key Vocabulary Solute = what is being dissolved (salt,

Koolaid, other molecules) Solvent = what molecules are dissolved in

(water or other liquid) Solution = an even mixture of solute and

solvent (Koolaid drink) Hypertonic = high concentration of solute,

low concentration of solvent Isotonic = equal concentration of solute and

solvent Hypotonic = low concentration of solute, high

concentration of solvent

Hypertonic vs. Hypotonic If you place a normal cell in a

hypertonic solution, water will flow _?_ of the cell

If you place a normal cell in a hypotonic solution, water will flow _?_ the cell

Hypertonic vs. Hypotonic If you place a normal cell in a

hypertonic solution, water will flow OUT of the cell

If you place a normal cell in a hypotonic solution, water will flow INTO the cell

If water moves INTO a cell, the cell gets bigger = swells, expands, grows

- (Hypotonic solution)

If water moves OUT OF a cell, the cell gets smaller = shrinks

- (Hypertonic solution)

Active Transport

Using energy to move materials in and out of the cell is called active transport.

Molecules move from areas of low concentration to areas of high concentration.

– Move from less crowded to more crowded

Active Transport: Example: Na2+/K+ Pump

Sodium-Potassium Pump moves sodium out of the cell and potassium into the cell using energy.

Important for electric signal between neurons.

Moving Across a Membrane

Steps to tell what kind of transport:

1. Ask: what moves?– If molecules move , it is Diffusion.– If water moves, it is Osmosis.

Moving across a membrane2. Which way do the molecules

move?– If molecules move from higher

concentration to lower concentration, it is diffusion

– If molecules move from lower concentration to higher concentration, it is active transport.

Moving Across a Membrane

Osmosis Diffusion Active

What moves

Energy

Toward which side?

Example

Moving Across a Membrane

Osmosis Diffusion Active

What moves Water Molecules Molecules

Energy

Toward which side?

Example

Moving Across a Membrane

Osmosis Diffusion Active

What moves Water Molecules Molecules

Energy No No Yes

Toward which side?

Example

Moving Across a Membrane

Osmosis Diffusion Active

What moves Water Molecules Molecules

Energy No No Yes

Toward which side?

Water moves to the side with

more molecules

Molecules move to less concentrated

side

Molecules move to more concentrated

side

Example

Moving Across a Membrane

Osmosis Diffusion Active

What moves Water Molecules Molecules

Energy No No Yes

Toward which side?

Water moves to the side with

more molecules

Molecules move to less concentrated

side

Molecules move to more concentrated

side

ExampleCell in a

hypertonic solution

Smell of perfume

Na++/K+ pump

Wrap-Up If a cell that contains a 10% salt solution

is placed in a 90% salt solution, will water flow into or out of the cell? Is the cell hypertonic or hypotonic?

Identify the description as osmosis, diffusion, or active transport?1. Water moves into a cell from high

concentration to low concentration2. Iodine molecules move into a cell from high

concentration to low concentration3. Sodium molecules are moved from a low

concentration to a high concentration