Team “Insane in the Membrane”

Team members: Heather Addy, Anna Davis, Cindy Graham, Joan Marshall, Vesal Mahanian

Membrane Structure and

Function26 July 2012

Learning Goals Understand why phospholipids

spontaneously arrange into micelles and vesicles when mixed in water

Identify the properties/structure of phospholipid bilayers make them selectively permeable.

Collaborate with others to solve a problem Learn to communicate and defend a

scientific argument based on experimental evidence

After this session you will be able to…(1) Predict (and draw) the arrangements of

phospholipids in an aqueous solution, based on their chemical properties

(2) Deduce the properties that govern membrane permeability of molecules from experimental data

(3) Evaluate whether different compounds can diffuse across a simple lipid bilayer based on polarity, size and charge.

FoundationsPreviously we learned about the… Importance of intermolecular forces Relationship between polarity and

hydrophobicity How functional groups influence the

chemical properties of molecules Properties of water

Oil and water don’t mix

Oleic Acid (Lipid)

Water

Phospholipids are amphipathic

Properties of Phospholipids

If we mix phospholipids in

water, how will they organize?

In a group of 3, draw at least 2 arrangements

of phospholipid molecules in water...

2 minutes

Phospholipids spontaneously form micelles and bilayers in water

Fatty acid chains aggregate together

Phosphate-containing head groups associate with water

Is this arrangement possible?

What properties determine whether a molecule crosses a phospholipid bilayer?

Small Group Activity In a recent experiment, the

permeability coefficient of various molecules was determined

Organize the molecules in order of permeability and consider what structural/chemical features contribute to their permeability

5 minutes

Which can pass through a membrane more readily?

Why?

#1

#2

Summative Assessment:

Which can pass through a membrane more readily?

Why?

#1

#2

Summative Assessment: Answer#1 Vitamin B2: Water soluble, cannot pass

through a phospholipid bilayer because it’s large and polar

#2 Vitamin E: Fat soluble, is able to pass through the phospholipid bilayer because it’s non-polar (looks like a fat)

Thank you!

Supplemental Material

ProgesteroneP=3.5x10E-4 cm/s

OxygenP=42 cm/s

O=O

Small Group Activity Cards

AcetateP=1x10E-12 cm/s

Acetic acidP=2x10E-2 cm/s

GlycerolP=5x10E-5 cm/s

GlucoseP=2x10E-7 cm/s

Sodium ionP=1x10E-12 cm/s

Na+

WaterP=5x10E-2 cm/s