Diffusion – The movement of molecules in and out of cells

Why are we made of trillions of cells Instead of 1 large cell?

As cells get larger their volume increases and they can’t get food in and waste out effectively.

Cell size is limited by 2 factors: 1. When a cell gets too big the DNA gets overworked & fails this is called DNA overload. 2. Cells that are too large can not get food in and waste out and the cell dies. Cells don’t’ have intestines …how do the dispose of waste?

Cell division How do cells prevent getting too large?

What regulates what diffuses in & out of cells

What do you have to go through to get into a cells cytoplasm? That depends on what type of cell it is… plant or animal What is the difference?

Cell Part_Cell Membrane_ Structure Mostly phospholipids plus some Protein channels & carbs. Function Regulate what goes in and out Location Outside of cytoplasm _____________________________________ The Cell membrane is like a Analogy Drawing __________Because it___ _____________________ -= -- = Analogy: windowScreen lets air in ei oat But not the Sags. lit t 11ttIl'.aaXfre 0-cellmembrane

Molecules go through cell membranes using a process called diffusion. Everything is made of atoms and they are always moving ex. Your desk (this is why diffusion works) Soooo… what is diffusion

Diffusion: The movement of molecules from areas of high concentration to areas of lower concentration. What examples can you think of? hint: think of smells

Diffusion

Diffusion also happens with liquids. What examples can you think of?

What would happen if you put some drops of food coloring into a beaker of water, and did not stir? Solutions: are a mixture of 2 substances with their molecules evenly distributed What has to happen for this to become a Solution? What could make diffusion happen faster?

Heat speeds up diffusion

Diffusion Relative concentrations affect the direction of diffusion.

hypertonic: high concentration isotonic: is the same – the concentration is the same hypotonic: low concentration The following terms are used to compare 2 solutions.

When we refer to tonic levels it is always as a comparison

Diffusion works in open areas but our cells Are surrounded by a cell membrane…so How do molecules go in and out of the cell?

Our cell membrane are complex with lots of moving parts. This allows some things to enter while keeping other things out.

There are 2 main categories of diffusion. Passive transport Does not require an input of energy. Active Transport Requires an input or energy

What are 2 differences between passive and active transport?

When water diffuses through a cell membrane we call it osmosis. Osmosis is the flow of water through a semi permeable membrane to areas of lower concentration. What is the difference between osmosis and diffusion? Is this active or passive transport?

Osmosis is the diffusion of water through a semi permeable (also called selectively permeable) membrane. DiffusionOsmosis

Pictures of rbc and plant plasmolysis

Draw & Label : Cell Membrane

Equilibrium occurs when molecules are evenly distributed and there is no longer a net change. Molecules still flow in all directions. Our bodies try to maintain homeostasis Which means they try to maintain Equilibrium for nutrients, waste, and water, and heat.

Diffusion Once equilibrium is reached do the Molecules continue to move?

A suspension is a mix of water and nondissolved materials

The contents of our digestive system is a mix of solutions and suspensions Nutrients and wastes are added to blood Homeostasis must be maintained or the system fails (you get sick & die)

We digest food and release its energy in our Mitochondria. That process makes CO2 as Waste. What process causes CO2 to leave our cells go to our blood leave our blood & go into our lungs where it is exhaled?

Potato Diffusion Mini Lab Predict the direction of the flow of water through semi-permeable membranes when potato pieces are placed in different solutions.

1.Get a triple beam balance, 2 pieces of potato, 2 beakers (label one 60ml of salt water, one beaker 60ml pure [deionized]H 2 O 2.Weigh and record the weight of each potato & which piece you place in salt water and which piece you place in pure water. 3.Predict which way water will flow according to your osmosis diffusion notes For each of the following situations 1.potato into salt water. 2.potato into pure water.

Potato Diffusion Mini Lab make the following chart Weight of potato before soaking in solution Weight of potato after soaking in solution Distilled WaterSalt Water H2OH2O + NaCl