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Chapter 4 Notes Cell Physiology

Learn about the selective permeability of the cell membrane and how it helps maintain homeostasis in organisms. Explore passive transport mechanisms like diffusion, osmosis, facilitated diffusion, and ion channels. Discover active transport processes like ion channel pumps, endocytosis, and exocytosis.

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Chapter 4 Notes Cell Physiology

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  1. Chapter 4 NotesCell Physiology Biology Hamilton Science Department

  2. Homeostasis • Organisms must maintain a balance of materials that enter and leavetheir cells. • Without this ability, they will die.

  3. The Cell (Plasma) Membrane • The property of a membrane to allow only certain particles through while keeping others out is known as selective permeability. • One way cells maintain homeostasis is by having a selectively permeable cell membrane.

  4. The Plasma Membrane

  5. PASSIVE TRANSPORT-no energy required #1 DIFFUSION: • THE MOVEMENT OF PARTICLES FROM HIGHER CONCENTRATION TO AN AREA OF LOWER CONCENTRATION

  6. Diffusion occurs with CONTINUOUS MOVEMENT until EQUILIBRIUM is reached • EQUILIBRIUM: equal amounts of substance are on both sides of the cell membrane

  7. PASSIVE TRANSPORT continued.. • #2 OSMOSIS: • DIFFUSION OF WATER MOLECULES THROUGH A SELECTIVELY PERMEABLE MEMBRANE.

  8. 3 TYPES OF SOLUTIONS AROUND A CELL(3 Possibilities for the Direction of Water Movement around a Cell) • 1. ISOTONIC: CONCENTRATION OF DISSOLVED SUBSTANCES AND WATER SAME ON BOTH SIDES OF MEMBRANE • 2. HYPOTONIC: CONCENTRATION OF DISSOLVED SUBSTANCES IS LOWER THAN IN THE CELL (high concentration inside the cell—cell swells) • 3. HYPERTONIC: CONCENTRATION OF DISSOLVED SUBSTANCES IS HIGHER THAN IN THE CELL (low concentration inside the cell—cell shrinks)

  9. Hypertonic Solution–HypotonicSolution- If a cell is placed in a……. Water moves out of the cell (Balloon shrivels) Water moves into the cell!! (Balloon overfull) ISOTONIC SOLUTIONS ARE BALANCED !!

  10. #3 FACILITATED DIFFUSION: • Diffusion of substances from area of high concentration to area of low concentration with help of carrier proteins.

  11. #4 DIFFUSION THROUGH ION CHANNELS • Movement of ions ( Na+, K+, Cl-) through cell membrane by means of ion channel • Ion Channel: a transport protein with a polar pore through which ions can pass • Some ion channels have gates that open/close • Channels are specific to a certain kind of ion

  12. ACTIVE TRANSPORT • *REQUIRES ENERGY* • Energy used is from ATP • MOVEMENT OF SUBSTANCES FROM LOW CONCENTRATION. TO ALREADY HIGH CONCENTRATION • Opposite of Passive Transport • Substances move AGAINST GRADIENT (or opposite of equilibrium)

  13. Active Transport: #1 Ion Channel Pumps • Uses ion channel (aka: carrier proteins)-allows sodium, calcium, and potassium ions to enter and leave the cell against gradient • called Membrane Pumps • Most noteable Ion Pump is the Sodium-Potassium Pump

  14. Active Transport: • #2 Endocytosis and Exocytosis • For substances that are too big to be moved across cell membrance by carrier proteins • Examples: Proteins and Polysaccharides

  15. ENDOCYTOSIS: • USE ENERGY TO TAKE IN LARGE PARTICLES. CELL SURROUNDS THE PARTICLES – Forms vesicle around particles.

  16. EXOCYTOSIS: • RELEASE OF WASTES FROM CELL VESICLE. VESICLE FUSES WITH MEMBRANE AND CONTENTS ARE RELEASED TO OUTSIDE.

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