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Plasma Membrane Structure and Function Chapter 4
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Plasma Membrane Structure and Function Chapter 4.

Dec 18, 2015

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Lenard Cobb
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Page 1: Plasma Membrane Structure and Function Chapter 4.

Plasma Membrane Structure and

FunctionChapter 4

Page 2: Plasma Membrane Structure and Function Chapter 4.

Outline• Phospholipid Bilayer

• Fluid Mosaic Model

• Membrane Proteins

• Diffusion

• Facilitated Diffusion

• Osmosis

• Bulk Transport

• Active Transport

Page 3: Plasma Membrane Structure and Function Chapter 4.

Membrane Functions

• Protection

• Communication

• Selectively allow substances in

• Respond to environment

• Recognition

Page 4: Plasma Membrane Structure and Function Chapter 4.

Plasma Membrane• Boundary that separates the living cell from

it’s non-living surroundings.• Phospholipid bilayer• Amphipathic - having both:

hydrophilic heads

hydrophobic tails• ~8 nm thick• Is a dynamic structure

PhospholipidPhospholipid

Page 6: Plasma Membrane Structure and Function Chapter 4.

Proteins—For Function

• Transport

• Receptors

• Enzymes

• Signal Transducers

• Support

Page 8: Plasma Membrane Structure and Function Chapter 4.

Channel protein

Page 9: Plasma Membrane Structure and Function Chapter 4.

Carrier protein

Page 10: Plasma Membrane Structure and Function Chapter 4.

Cell recognition protein

Page 11: Plasma Membrane Structure and Function Chapter 4.

Receptor protein

Page 13: Plasma Membrane Structure and Function Chapter 4.

Permeability of the Cell Membrane-Differentially PermeableDifferentially Permeable

Page 14: Plasma Membrane Structure and Function Chapter 4.

Permeability of the Cell Membrane

Page 15: Plasma Membrane Structure and Function Chapter 4.

• Diffusion – the passive movement of molecules from

a higher to a lower concentration until equilibrium is reached.

– How can we explain diffusion?

– Gases move through plasma membranes by diffusion.

• Osmosis– A special case of diffusion

DIFFUSION

Page 16: Plasma Membrane Structure and Function Chapter 4.

Process of diffusion

Page 17: Plasma Membrane Structure and Function Chapter 4.
Page 18: Plasma Membrane Structure and Function Chapter 4.
Page 19: Plasma Membrane Structure and Function Chapter 4.

Gas exchange in lungs by diffusion

Page 20: Plasma Membrane Structure and Function Chapter 4.

OsmosisThe diffusion of water across a

differentially permeable membrane due to concentration differences

Page 21: Plasma Membrane Structure and Function Chapter 4.

Question:What’s in a Solution?

Answer:

• solute + solvent solution

• NaCl + H20 saltwater

Page 22: Plasma Membrane Structure and Function Chapter 4.

TONICITY

• Refers to the concentration of SOLUTES

• Is a RELATIVE term, comparing two different solutions

• Hypertonic

• Hypotonic

• Isotonic

Page 23: Plasma Membrane Structure and Function Chapter 4.

Hypertonic

• A solution with a greater solute concentration compared to another solution.

3% NaCl97% H2O

Red Blood Cell

5% NaCl

95% H2O

solutionsolution

Which way will the water move?

Page 24: Plasma Membrane Structure and Function Chapter 4.

Hypotonic

• A solution with a lower solute concentration compared to another solution.

3% Na97% H2O

Red Blood Cell

1% Na99% H2O

solutionsolution

Which way will the water move?

Page 25: Plasma Membrane Structure and Function Chapter 4.

Isotonic

• A solution with an equal solute concentration compared to another solution.

3% Na97% H2O

Red Blood Cell

3% Na97% H2O

solutionsolution

Which way will the water move?

Page 26: Plasma Membrane Structure and Function Chapter 4.

ISOTONIC SOLUTION

Page 27: Plasma Membrane Structure and Function Chapter 4.

HYPOTONIC SOLUTION

Page 28: Plasma Membrane Structure and Function Chapter 4.

HYPERTONIC SOLUTION

Page 29: Plasma Membrane Structure and Function Chapter 4.

• Function—Transport. Are specific, combine with only a certain type of molecule.

• Types

–Facilitated transport--passive

–Active transport—requires energy

Carrier Proteins

Page 32: Plasma Membrane Structure and Function Chapter 4.

The sodium-potassium pump

Page 33: Plasma Membrane Structure and Function Chapter 4.

• Exocytosis---Cellular secretion• Endocytosis—

–Phagocytosis— “Cell eating”–Pinocytosis– “Cell drinking”–Receptor-mediated endocytosis-

specific particles, recognition.

Exocytosis and Endocytosis

Page 34: Plasma Membrane Structure and Function Chapter 4.

Exocytosis

Page 35: Plasma Membrane Structure and Function Chapter 4.

Phagocytosis

Phagocytosis 1

Phagocytosis 2

Page 36: Plasma Membrane Structure and Function Chapter 4.

Pinocytosis

Page 37: Plasma Membrane Structure and Function Chapter 4.

Receptor-mediated Endocytosis

Page 38: Plasma Membrane Structure and Function Chapter 4.

SUMMARY• Phospholipid Bilayer

• Fluid Mosaic Model

• Membrane Proteins

• Diffusion

• Facilitated Diffusion

• Osmosis

• Bulk Transport

• Active Transport