Chapter 7 Flashcards
Ampiphatic
A molecule containing both hydrophilic and hydrophobic areas
What does the fluid mosaic model state?
That the membrane is a fluid structure with various proteins embedded into it
Why can phospholipids move within bilayer?
Hydrophobic interactions are weak
What are the two kinds of phospholipid movements?
Lateral (more often) and flip-flop
Why do phospholipids in membrane move around?
Create heat to prevent solidification
A membrane is fluid in ______ conditions
warmer
Cells in colder climates have more ______ to prevent ________
unsaturated hydrocarbon tails
solidificiation
How is cholesterol a buffer in both high and low temperatures?
High: cholesterol makes bilayer less fluid by restraining phospholipid movement
Low: cholesterol hinders close packing of proteins, lowering temperature required for solidification
What determines the function of the membrane?
Proteins
Integral proteins
Proteins that penetrate through whole bilayer
Peripheral proteins
Proteins loosely binded to membrane surface
Transmembrane proteins
Peripheral proteins that span membrane
What does the hydrophobic region of integral proteins consist of?
1 or more stretches of non polar amino acids coiled into alpha helices
Major functions of membrane proteins
Transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to cytoskeleton and extracellular matrix
How do cells recognize eachother?
By binding to surface molecules (often carbs) on membrane
Membrane carbs may be bonded to ______, creating _______, or more commonly bonded to _______, creating ____________
- bonded to lipids, forming glycolipid
- bonded to proteins, forming glycoprotein
Exchange of material with surroundings is controlled by what?
Membrane
______ molecules can pass through membrane easily
Hydrophobic
List hydrophobic molecules that can pass through membrane
Carbon dioxide, oxygen, hydrocarbons
_____ molecules can not cross membrane easily
Polar
List some molecules that cannot pass membrane easily
Sugar, water
What allows passage of hydrophilic substances
Transport proteins