chapter 4 notes cell physiology biology hamilton science department
TRANSCRIPT
Chapter 4 NotesChapter 4 NotesCell PhysiologyCell Physiology
Chapter 4 NotesChapter 4 NotesCell PhysiologyCell Physiology
Biology Biology
Hamilton Science Hamilton Science DepartmentDepartment
HomeostasisHomeostasis• Organisms must
maintain a balance of materials that enter and leave their cells.
• Without this ability, they will die.
The Cell (Plasma) The Cell (Plasma) MembraneMembrane
• 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.
The Plasma MembraneThe Plasma Membrane
PASSIVE PASSIVE TRANSPORT-TRANSPORT-
no energy requiredno energy required
#1 DIFFUSION: • THE MOVEMENT OF
PARTICLES FROM HIGHER CONCENTRATION TO AN AREA OF LOWER CONCENTRATION
• Diffusion occurs with CONTINUOUS MOVEMENT until EQUILIBRIUM is reached
• EQUILIBRIUM: equal amounts of substance are on both sides of the cell membrane
• PASSIVE TRANSPORT continued..
• #2 OSMOSIS: • DIFFUSION OF WATER
MOLECULES THROUGH A SELECTIVELY PERMEABLE MEMBRANE.
• 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)
Hypertonic Solution–
HypotonicSolution-
Water moves outof the cell(Balloon shrivels)
Water movesinto the cell!!(Balloon overfull)
If a cell is placed in a…….
ISOTONIC SOLUTIONS ARE BALANCED !!
#3 FACILITATED DIFFUSION:
• Diffusion of substances from area of high concentration to area of low concentration with help of carrier proteins.
#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
• 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)
Active Transport: Active Transport: #1 Ion Channel Pumps #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
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
• ENDOCYTOSIS: • USE ENERGY TO TAKE IN LARGE
PARTICLES. CELL SURROUNDS THE PARTICLES – Forms vesicle around particles.
• EXOCYTOSIS: • RELEASE OF WASTES FROM
CELL VESICLE. VESICLE FUSES WITH MEMBRANE AND CONTENTS ARE RELEASED TO OUTSIDE.