Chapter 7-3 Cell Boundaries Part 1

Focus Questions What are the main functions of the cell membrane and cell wall? What happens during diffusion? What is osmosis?

“I can…” statements I can... Describe the function of the cell membrane. I can… Compare and contrast active and passive transport I can… differentiate between hypotonic, hypertonic, and isotonic.

1. Cell Membranes: ALL cells have one! A. Outer boundary of the cell B. Functions 1) Separates a cell from other cells 2) Protection and support 3) Controls what enters and exits the cell, to maintain homeostasis

C. Structure: (described as) Lipid Bilayer 1) 2 layers of phospholipids a) polar head: forms outside of bilayer Described as hydrophilic: water loving, attracts water b) non-polar tail: forms inside of bilayer Described as hydrophobic: water fearing, avoids water (polar)HEAD Hydrophilic (nonpolar) TAIL Hydrophobic

2) Proteins with carbohydrate chains are wedged between Phospholipid molecules. 3) Proteins act as pores, channels or pumps to move substances into or out of cell. 4) Carbohydrates are markers which are used for cell identification.

D. Selectively permeable: allows certain substances to pass through The structure allows it to be selective. Protein pores allow small thing insoluble in lipids pass( Ex. H20) Ex. Glucose can pass through Things soluble in Lipids can pass (Ex. Alcohol)

Molecules can pass through IF: They are soluble (able to dissolve) in lipids, they can easily pass through bilayer (ex. Alcohol, CO2, O2, steroids) They are NOT soluble (unable to dissolve) in lipids (water, glucose, amino acids, ions: May be small enough to get through protein pores (ex. water) May be able to go through a protein channel (ex. Glucose) May be able to get pushed through by a protein pump Ex. Na+(sodium ion), K+(potassium ion)

Examples of substances that need to pass into cell: 1. water 2. glucose 3.oxygen Examples of substances that need to pass out of cell: 1. carbon dioxide 2. water

1) Plants 2) Algae 3) Bacteria 4) Fungi Cell Walls A. Found in: 1) Plants 2) Algae 3) Bacteria 4) Fungi (Have both cell membrane AND cell wall) B. NOT IN ANIMAL CELLS C. Function: EXTRA Support and protection, and gives strength to cells D. Composed of fibers of carbohydrates: 1. Cellulose in _____________ 2. Chitin in _______________ 3. Peptidoglycan in ___________________ Plants Fungi Eubacteria

REVIEW QUESTIONS How does water move through the cell membrane? _______________ What does semi-permeable mean? ___________________________________ What molecule is the lipid bilayer made of? ___________ Which part is polar? _______Which is nonpolar?_________ How does one cell recognize that a cell is part of that tissue or organ? _____________ What is a substance that is soluble in lipids, that would pass through the lipid bilayer of the cell membrane easily?_______ True or False: All cells have cell walls? ______________ Through PROTEIN pores Only allows certain substance through Phospholipid Head tail Carbohydrate chain Alcohol False –animal cells don’t

Chapter 7-3 Notes Part 2 Types of Transport

TRANSPORT CAN BE EITHER

Passive Transport DOES NOT REQUIRE ENERGY!!! On top of the hill DRAW Passive Transport On top of the hill Movement of molecules from areas of high concentration to areas of lower concentration. DOES NOT REQUIRE ENERGY!!! high low Weeee!!!

OR

This is gonna be hard work!! DRAW Active Transport Bottom of the hill Movement of molecules from areas of low concentration to areas of high concentration. REQUIRES ENERGY! high low This is gonna be hard work!!

Animations of Active Transport & Passive Transport Types of Passive Transport cell does not use energy Diffusion Facilitated Diffusion Osmosis All 3 types of PASSIVE transport occur until equilibrium is reached. Equilibrium: when the concentration of a solute is the same throughout a closed system. (i.e. Inside and outside of a cell.)

Types of Active Transport cell uses energy Protein Pumps Endocytosis Exocytosis

Three Types of Passive Transport Defined Ch 7-3 Notes Part 3 Three Types of Passive Transport Defined

1. Diffusion: movement of molecules FROM areas of HIGH concentration TO areas of LOW concentration through the lipid bilayer. Examples: Alcohol, CO2, O2

GO TO DIFFUSION ANIMATION

Simple Diffusion Animation http://bio.winona.edu/berg/Free.htm

2. Facilitated Diffusion B Diffusion of specific particles through transport proteins found in the cell membrane Example:Glucose Transport Proteins are specific – they “select” only certain molecules to cross the membrane Transports molecules that are large or insoluble in lipids. Facilitated diffusion (Channel Protein) Diffusion (Lipid Bilayer) Carrier Protein http://bio.winona.edu/berg/Free.htm

Osmosis animation 3. Osmosis diffusion of water through a selectively permeable membrane. a. Water moves from high concentration of (H2O)to low concentration(of H2O) Water moves freely through special pores. Solute (green) soluble in lipids.

Effects of Osmosis on Life Cells cannot control the movement of water (Osmosis). ii. If too much water moves into the cell it can burst (die). If too much water moves out it can shrivel up (die).

HOW DO SOLUTIONS AFFECT OSMOSIS???

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypotonic: has a lower concentration of solutes and a higher concentration of water compared to inside the cell. (Low solute; High water) Result: Water moves from the solution into the cell. Osmotic pressure increases and causes the cell to grow until equilibrium is reached or the cell bursts. Hint: HYPO=HIPPO(grow)

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Hypertonic Solution Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water) Result: Water moves out of the cell into the solution: Cell shrinks/shrivels.

Isotonic Solution(Iso=Equal) Osmosis Animations for isotonic, hypertonic, and hypotonic solutions Isotonic Solution(Iso=Equal) Isotonic: The concentration of solutes and water in the solution is equal to the concentration of solutes and water inside the cell. Result: Water moves equally in both directions (Dynamic Equilibrium) and the cell remains same size!

2 3 1 What type of solution are these cells in? Hypertonic Isotonic TOO MUCH OSMOTIC PRESSURE!!! 2 3 1 Hypertonic Isotonic Hypotonic *Which of these solutions do you think is used in an IV?

How Organisms Deal with Osmotic Pressure Paramecium (protist) removing excess water video How Organisms Deal with Osmotic Pressure 1. A protist, like paramecium, has contractile vacuoles that collect water flowing in and pump it out to prevent them from over- expanding. Contractile Vacuole:

2. Bacteria and plants have cell walls that keep the membrane from bursting when osmotic pressure increases.

3. Animal cells are bathed in blood 3. Animal cells are bathed in blood. Kidneys keep the blood isotonic by removing excess salt and water.

Part 4: Active Transport Ch 7-3 Notes Part 4: Active Transport

1. Three Types of Active Transport Protein Pumps Endocytosis Exocytosis

D. 3 Types of Active Transport Sodium Potassium Pumps (Active Transport using proteins) Protein Pumps –Require energy transport molecules across membrane. Example: Ions such as Na+ and K+ in Sodium / Potassium Pumps, which are important in nerve responses. Protein changes shape to move molecules: this requires energy!

Endocytosis: taking bulky material into a cell a. Uses energy b. Cell membrane folds in around food particle “cell eating” c. forms food vacuole & digests food d. This is how white blood cells eat bacteria!

Endocytosis & Exocytosis animations 3. Exocytosis: Forces material out of cell in bulk a. membrane surrounding the material fuses with cell membrane b. Cell changes shape – requires energy EX: Hormones or wastes being released from the cell Endocytosis & Exocytosis animations Exocytosis