Cell membranes

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Slide 1

AS Biology FOUNDATION Chapter 4 CELL MEMBRANES and TRANSPORT

Slide 2

The Cell

Slide 3

Learning Objectives

Describe the fluid mosaic model of membrane structure and explain the underlying reasons for this structure.

Outline the roles of phospholipids, cholesterol, glycolipids, proteins and glycoproteins in membranes.

Outline the roles of the plasma membrane, and the roles of membranes within cells.

Describe and explain how molecules can get in and out of cells (cross cell membranes) by the processes of diffusion, facilitated diffusion, osmosis, active transport, endocytosis and exocytosis.

Describe the effects on animal and plant cells of immersion in solutions of different water potential.

Describe the features of the gaseous exchange surface of mammalian lung.

Describe the features of root hairs that enable the uptake of ions by active transport.

Slide 4

Key words you should know

Phospholipids Solution Pinocytosis

Polar Solute Micropinocytosis

Hydrophilic Solvent Exocytosis

Hydrophobic Partially permeable Gaseous exchange

Micelles Water potential Alveoli

Phospholipid bilayer Solute Potential Root hair

Fluid mosaic model Pressure Potential Surface area

Glycoproteins Turgid Epidermis

Glycolipids Plasmolysis Passive transport

Cholesterol Plasmolysed

Proteins Incipient plasmolysis

Transport proteins Active transport

Enzymes Carrier protein

Receptor molecules Bulk transport

Diffusion Endocytosis

Concentration gradient Phagocytosis

Facilitated diffusion Phagocytes

Osmosis Phagocytic vacuoles

Slide 5

Cell membrane

All living things are surrounded by a membrane.

A cell membrane is also known as plasma membrane.

Controls exchange of materials such as nutrients and waste between cells and their environment.

Has other important functions for example to enable cells to receive hormones.

To understand the function of anything in biology, you must study the structure first!

Slide 6

Cell Membranes from Opposing Neurons (TEM x436,740).

} cell membrane

7nm wide

Cell membrane {

Nerve cell

Nerve cell

Gap between cells

Slide 7

HYDROPHILIC heads (water liking) -Attracted to the water

called POLAR

HYDROPHOBIC tails (water fearing) -Not attracted to the water