The cell membrane and cell wall The Cell Boundaries The cell membrane and cell wall

The borders The most important parts of a cell are its borders, which separate the cell from its surroundings. All cells are surrounded by a thin flexible barrier known as ____________

The Cell Membrane

The borders --- Some cells produce a strong supporting layer around the membrane known as the cell wall. What type of cell would have these?

Plant Cells

Cell Membrane The cell membrane regulates what enters and leaves the cell --- Cell membranes are made of a double layer sheet called a lipid bilayer.

Lipids REMEMBER!!!! What is a lipid?

Definition of a Lipid A lipid is a type of organic compound found in all living things. Lipids are not soluble in water and are made of carbon and hydrogen atoms.

Lipid Bilayer The lipid bilayer gives the cell membrane a flexible structure that forms a strong barrier between the cell and its surroundings

Proteins Most cell membranes contain protein , which are embedded in the lipid bilayer. ---- Some of the proteins form channels and pumps that help to move material across the cell membrane.

Important **** One of the most important functions of the cell membrane is to regulate the movement of dissolved molecules to the liquid side on the other side.

Transport Across Membranes What is Diffusion, Osmosis, Facillated diffusion and Active Transport

Cellular Transport Cellular transport is the process of molecules or material moving in and out of the cell There are two types of transport within the cell. Passive Transport Active Transport

Passive Transport Passive transport is the movement of molecules in or out of the cell without the use of energy Can only occur if the molecules moving in and out of the cell are: Small Uncharged (meaning they contain NO + or – which are ions) Move from an area of high concentration to an area of low concentration There are three types of passive transport: diffusion, osmosis, and facilitated diffusion

Diffusion Movement of particles from an area of higher concentration to an area of lower concentration until an equilibrium is established doesn’t require energy

Note: In the cell membrane if a substance has an unequal concentration on either side the particles will move to the area of low concentration until an equilibrium is established

Here is example

Lets Review What is diffusion in your own words

Osmosis Diffusion of water across a selectively permeable membrane (some substances can pass through and some can’t)

Think, Pair, Share Think for a moment about Cellular Transport. What do you think would be a good method to help a 4th grade student understand what cellular transport means?

Pair Pair with someone who's the same or similar height as you. Talk with them about your method.

Share some of your ideas with the class

Think You learned about Passive Transport last week. What is a major characteristic of Passive Transport? Think of the two types of passive transport you learned about, ho could you teach this to the 4th grade student using a diagram?

Pair Pair with your neighbor, using an expo marker draw your diagrams on the desk.

Share Share your diagrams with the class

Watch the Example

Osmotic pressure For an organism to survive it must have a way balance the intake and loss of water. Pressure produced by osmosis can sometimes be fatal to plant an animal cells Keep in mind water follows the solute

Before we begin. What do the prefixes mean: a. iso b. hyper c. hypo

Hypertonic Solution solution has a higher solute concentration outside the cell; too much outside of the cell In plant cells, - cell will become plasmolyzed (shrink) In animal cells, - cell will lyse (shrink)

Hypotonic Solution lower solute concentration outside of the cell than inside In animal cells - cell will become swollen and burst In plant cells, - cell will become turgid (very firm, swollen and hard) - this is normal for plant cells

Isotonic Solution there is the same solute concentration inside and outside of the cell In animal cells - the cell will be normal In plant cell - will be flaccid (limp) **green parts of the plant droop and are unable to hold their leaves towards the sun**

Let’s watch another example

Facilitated Diffusion Movement of specific molecules across cell membranes through protein channels. These specific molecules bind to a protein and are channeled from the outside of the cell to the inside Is fast and specific Will still only occur if concentration is higher on one side of the membrane than the other.

Molecular Transport Small molecules and ions are carried across membranes as in facilitated diffusion, but require energy because they are going against the concentration gradient These proteins behave as pumps that require energy to move molecules and ions sometime against the concentration gradient of diffusion.

Active Transport The passing of molecules across a membrane against the concentration gradient Requires energy Small molecules are transported by pumps (molecular transport) Larger molecules are transported by endocytosis and exocytosis.

Endocytosis Process of taking material into the cell by means of forming a vesicle or pockets of the cell membrane This takes material into the cell and it forms a vacuole in the cell Large molecules of food and whole cells can be taken this way

Two Types of Endocytosis Phagocytosis Means “cell eating” An extension of cytoplasm surrounds a particle and package it into a food vacuole requires an enormous amount of energy Pinocytosis Means” cell drinking” Tiny pockets form along the cell membrane fill with liquid and form vacuoles with in the cell Requires enormous amounts of energy

Exocytosis The process where cells release large amount of materials Vacuole surrounding material fuses with the cell membrane, forcing the contents out of the cell Also requires energy

Cell Wall Cell walls are not found in animal. --- They are located outside the cell membrane. ---- They are porous, which allow water, oxygen, carbon dioxide and other substances to pass through.

Cell Wall Plant cell walls are made mostly of cellulose , a tough carbohydrate fiber.

Solutions The cytoplasm of a cell contains a solution of many different substances in water.

Solution What is a solution? A solution is a mixture of two or more substances in which the molecules of the substance are evenly distributed

So let’s wrap it all up First video

Compare an contrast diffusion and osmosis. Give me and example of what happens to a cell if an isotonic, hypotonic, or hypertonic solution is present? What is facillated diffusion? Explain active transport What happens during molecular transport Describe endocytosis Contrast phagocytosis and exocytosis? What happens during exocytosis?