Unit 1 – Cellular Functions

1. Unit 1 – Cellular Functions Movement of molecules through the cell membrane • The cell requires that its internal environment is maintained at a near constant condition • This steady state condition is referred to as homeostasis • Homeostasis is maintained inside a living cell mainly by the cell membrane

2. Unit 1 – Cellular Functions Movement of molecules through the cell membrane First a quick review of the cell membrane function • Boundary between cell’s internal and external environment • Strength and shape to cell • Concentrates chemical material • Regulates traffic by • Simple diffusion • Osmosis • Facilitated diffusion • Active transport • Endocytosis • Exocytosis

3. Unit 1 – Cellular Functions Movement of molecules through the cell membrane Movie Clip • What is the process that moves the odor around the elevator? Diffusion

4. Unit 1 – Cellular Functions Movement of molecules through the cell membrane Simple Diffusion • Passive – Does not require an input of energy • Movement of molecules from an area of high concentration to an area of low concentration (with the concentration gradient) • Leads to an equilibrium (uniform distribution) • Diffusion is the mode in which molecules move around inside cells and limits cell size

5. Unit 1 – Cellular Functions Movement of molecules through the cell membrane Demonstration Factors affecting the rates of diffusion inside the cell • Predict/Explain – for each demonstration predict what is going to happen and give plausible explanation • Observe/Explain – After observing each demonstration record observation and give a plausible explanation

6. Unit 1 – Cellular Functions Movement of molecules through the cell membrane Factors affecting the rates of diffusion inside the cell • Concentration – rate increases as concentration gradient increases • Temperature – rate increases as temperature increases • Molecule size – rate decreases as molecule size increases

7. Unit 1 – Cellular Functions Movement of molecules through the cell membrane Ozzmosis Osmosis The diffusion of water • The diffusion of a solvent across a semi-permeable membrane separating two solutions • The solvent in cells is water • The cell membrane cannot prevent the movement of water molecules

8. Unit 1 – Cellular Functions Movement of molecules through the cell membrane Osmosis

9. Unit 1 – Cellular Functions Movement of molecules through the cell membrane • Video of red blood cell in a hypertonic solution http://www.one-school.net/Malaysia/UniversityandCollege

10. Unit 1 – Cellular Functions Movement of molecules through the cell membrane • Video of red blood cells in a hypotonic solution http://www.one-school.net/Malaysia/UniversityandCollege

11. Unit 1 – Cellular Functions Movement of molecules through the cell membrane • Video of red blood cells in a isotonic solution http://www.one-school.net/Malaysia/UniversityandCollege