Chapter 4 Notes Cell Physiology Biology Hamilton Science Department

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

The Plasma Membrane The property of a membrane to allow only certain particles through while keeping others out is known as selective permeability.

Permeability Non-permeable- no materials can get into or out of the membrane Semi-permeable- based upon size of the material, some molecules can get through while other can’t. Permeable- Most or all molecules can move through the membrane

The FLUID MOSAIC MODEL of the Plasma Membrane

Polar Head Non polar Tails

Plasma Membrane Structure Marker Protein Channel Protein Receptor Protein Lipid Bi-Layer

PASSIVE TRANSPORT- no energy required DIFFUSION: THE NET MOVEMENT OF PARTICLES FROM HIGHER CONCENTRATION TO AN AREA OF LOWER CONCENTRATION

Diffusion is a CONTINUOUS MOVEMENT UNTIL DYNAMIC EQUILIBRIUM IS REACHED. Until EQUAL AMOUNTS OF SUBSTANCE ARE ON BOTH SIDES OF THE MEMBRANE

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

3 TYPES OF SOLUTIONS 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 CONTRACTILE VACUOLES: PROTISTS HAVE THESE ORGANIELLES - COLLECT EXCESS WATER AND EXCRETE IT SO CELL DOESN’T BURST 3. HYPERTONIC: SOLUTION. CONCENTRATION OF DISSOLVED SUBSTANCES IS HIGHER THAN IN THE CELL.

Hypertonic Solution– Hypotonic Solution- If a cell is placed in a……. Hypertonic Solution– Hypotonic Solution- Water moves out of the cell Water moves into the cell!! ISOTONIC SOLUTIONS ARE BALANCED !!

TURGOR PRESSURE – The water pressure inside a plant cell. HIGH TURGIDITY = CRISPNESS LOW TURGIDITY = WILTEDNESS

PLASMOLYSIS: LOSS OF WATER FROM A CELL RESULTING IN A DROP IN TURGOR PRESSURE CYTOLYSIS: GAINING OF WATER IN THE CELL CYTOPLASM,,,THUS AN INCREASE IN TURGOR!

FACILITATED DIFFUSION: TRANSPORT PROTEINS PROVIDE OPENINGS FOR PARTICLES TO PASS THROUGH – EX: SUGARS FROM HIGH TO LOW CONCENTRATION.

The Plasma Membrane The “ion channel” allows sodium, calcium, and potassium ions to enter and leave the cell. called Ion Pumps

ACTIVE TRANSPORT REQUIRES ENERGY MOVEMENT OF SUBSTANCES FROM LOW CONCENTRATION. TO ALREADY HIGH CONCENTRATION EXAMPLE: MINERALS INTO CELL - SCARCE Substances move AGAINST GRADIENT

ENDOCYTOSIS: USE ENERGY TO TAKE IN LARGE PARTICLES. CELL SURROUNDS THE PARTICLES - DOESN’T PASS THROUGH CELL MEMBRANE

PHAGOCYTOSIS: “CELL EATING” TAKE IN WHOLE PIECES BY PINCHING IN MEMBRANE

PINOCYTOSIS: “CELL DRINKING” TAKE IN FLUID BY PINCHING IN MEMBRANE

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