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How Cells are Affected by and Interact with Their External Environment. Definition: Solution. A uniform mixture of 2 or more substances. Can be solids, liquids, or gases, or a combination of these Dissolved substance: Solute Examples? Substance in which solute dissolves: Solvent
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How Cells are Affected by and Interact with Their External Environment
Definition: Solution • A uniform mixture of 2 or more substances. • Can be solids, liquids, or gases, or a combination of these • Dissolved substance: Solute • Examples? • Substance in which solute dissolves: Solvent • Examples?
Examples of Solutions • Chocolate milk • Tea • Milk • Cytoplasm! • Blood • Lymph
Types of Molecular Movement This type doesn’t • Diffusion • Passive Transport • Simple diffusion • Facilitated diffusion • Osmosis • Active Transport These types involve some sort of membrane
1. Diffusion • The random movement of molecules (liquid or gas) until they are evenly dispersed • Molecules will travel down their concentration gradient • from areas of high concentration to low concentration • Why? Molecules drift into a lessorderedstate unless some energy input keeps it orderly. https://www.youtube.com/watch?v=VY0mZUDvbH4
2. Osmosis • A special type of diffusion where water moves down its concentration gradient through a membrane (i.e., cell membrane) • Osmosis accounts for most material exchange between internal and external environments of the cell
Discuss with a neighbor: Based entirely on the definition of osmosis, in what direction will the water (solvent) move? Hint: Where is there more water? Where is there less water? thin membrane
Your Task Discuss with neighbor: Why does all of this matter for a cell? For an organism?
Questions? Homework due ThursdayWS, Diffusion, Osmosis, Water Balance