1. Chapter 7 Membrane Structure and Function
Days 8
Objectives
-You will understand that membranes are fluid
-The structure results in a semi-permeable membrane
-Passive transport requires no energy
-Active transport requires energy
-Bulk transport of molecules either by exocytosis or by endocytosis.
Lab 1: Diffusion and Osmosis
p. 127

2. Cell Membranes Are Made up of Macromolecules
Lipids -Specifically Phospholipids
-Form a bilayer with nonpolar, hydrophobic region in the middle.
Proteins -Various proteins are embedded.
Carbohydrates -Carbohydrates extend out and old the cell in place to the ECM

3. Factors That Affect The Fluidity Of The Membrane
Cell membranes are mainly held together by nonpolar attractions --- Much weaker then covalent bonds
Movement of lipids
Saturated Vs
Unsaturated fats
Cholesterol
**Cell Membrane Sidedness
P 130

5. Cellular Proteins Functions: Types: 1. Integral 1. Transport
-Hydrophobic Channel
-Shuttle uses ATP
2. Enzymes
-Use of Active Site
-Often grouped together
3. Signal Transduction
-Acts in cellular comunication
-Uses a receptor site
4. Cell Recognition
-Glycoproteins
-Immune system
5. Inter Cellular Joining
-Used in various types of junctions
6. Attachment proteins
-Stablize internal organelles and cell
Types: 1. Integral
2. Peripheral
Cellular Proteins

6. Membranes are Selectively Permeable
What?
Ions (K, Na, Ca, and C
Water
Sugars
Amino Acids
Proteins
Cellular Respiration
To create gradients
Why?
Maintain homeostasis, balance
Protein synthesis
Where?
Aquaporins allows water to diffuse through
Channel proteins (hydrophillic channel)
Carrier proteins are specific to what it is moving
How? What directs movement?
Active transport needs energy
Passive transport doesn’t need energy
When?
When the cell needs anything
Constantly

7. Passive Diffusion: Movement of solutes from a high concentration to a lower concentration.
-Takes No Energy to move
-In Cell Biology we are talking about movement across the cell membrane
Osmosis: Passive diffusion of water.
Facilitated Diffusion: Passive diffusion of large solutes through protein channels

8. Active Transport Passive Transport Takes Energy Increases gradient
Gradient is used for cellular work
Passive Transport
-Takes no energy
-Common property of life
-The goal is homeostasis

9. Active Transport Ion pump Co-transport
Na/K pump makes use of protein shape and changing ion affinity
ATP reacts – Phophate changes shape of protein
Membranes can have a electronic potential based on their electrochemical gradient
Electrogeneic pump is a membrane protein that increases the electrochemical gradient
Ion pump
Co-transport
-Pump creates a gradient
-Use of property of homeostasis to transport large molecules like sucrose

10. Exocytosis
-Transport vesicles inside cell combine with cell membrane and release contents to the exterior of the cell.
-Transport occurs along microtubules
Endocytosis
Phagocytosis
Engulf food particles into a food vacuole for digestion
Ameobas and pseudopods
Pinocytosis is gulping of extracellular fluid
Receptor Mediated Endocytosis
-Ligands attach to specific
-LDL (Low Density Lipoproteins)
p. 138