USF PCB 3023 Exam 2
Composition of Lipid Bilayer - 50% lipids (outnumber all other molecules 50:1), proteins (50% of
mass of membranes), cholesterol
Plasma Membrane (Function) - Enclose Cells, Organelles
1. Defines Boundaries to regulate chemical composition and environment
2. Define malleable borders
Saturated - Single Bonded
Unsaturated - Double Bonded
Fatty Acids - Monomers for Lipids
Function of Lipids - 1. energy storage
2. cell membranes
Why Do Mitochondria have a double membrane? - Prehistoric cells absorbed mitochondria (as a
bacteria)
Why do lipids self-assemble in water? - To prevent hydrophobic tails from touching water.
Hydrophillic heads protect. This lowers free energy (delta G).
If hydrophillic heads are exposed... - Delta G will increase
Glycolipids - lipid with glycosidic bond to glucose in hydrophillic head.
Antigens on Red Blood Cells are..? - Glycolipids
,Cholesterol - A lipid steroid ring attached to glycerol. Fills gaps in Plasma Membrane left by
unsaturated hydrocarbon tails. Rigid.
How many pints of Blood are in the body? - 10 pints, on average. When you donate blood you
donate a pint. 7,000,000,000 RBCs in a single liter. Body has trillions of cells
What is Fluidity? - How easily lipids can move within a membrane
Are cells symmetrical or asymmetrical? - Asymmetrical. Asymmetry established at 'birth' of the
cell
What is flipase? - Specific catalyzed Transfer. Uses fatty acids from cytosolic monolayer to add new
membrane. Responsible for 'flip-flop' of lipids
What is scramblase? - Random Catalyzed Transfer.
Where are lipids synthesized? - Endoplasmic Reticulum.
How are lipids synthesized in the ER transported across the cell? - Via vesicles.
(EXCEPTION: Lipids for Mitochondrial Membrane and Plasmid Membrane)
Why are cells asymmetrical? - 1. To distinguish living and dead cells (Phosphatadylserine (-) is
transferred across membrane during apoptosis)
2. Signal Transduction. So that extracellular signals can be relayed through cell membrane
Types of Movement in Membrane Lipids - 1. Lateral Diffusion (~10^8 cm^2/sec at 310K)
2. Transverse Fluctuation
3. Rotation
4. Flexion
, 5. Flip-Flop (RARE for lipids. Common for cholesterol)
Planar (Black) Membrane - Technique to study a lipid bilayer
Liposome - Organelle. Good for studying lipid bilayers
FRAP- fluorescence recovery after photo-bleaching - FRAP measures membrane fluidity- the
ability of a cell to shuffle lipids laterally to replace the photo bleached portion. Revealed that cells are
typically consistency of olive oil
Transmembrane Proteins - Have hydrophillic and hydrophobic regions
Types of Transmembrane Proteins - 1. Single Alpha Helixes
2. Multiple Alpha Helixes
3. Rolled up Beta Sheets
Lipid-Anchored Proteins - Simply anchored to lipids in one layer of the membrane
Types of Lipid-Anchored Proteins - 1. Lipid Anchored via Non-Covalent Interaction
2. Covalently Attached to Lipid Chain
3. Covalently Attached to Oligosaccharide link
Types of Periphreal proteins - Attach to other membrane proteins non-covalently
Function of Membrane Proteins - 1. Transport (protons, ions, small molecules, proteins, RNA)
2. Signal Transduction (Chemical to Mechanical) or (Chemical to Chemical)
3. Cell to Cell Recognition
4. Cytoskeletal and ECM attachment
5. Catalysis
Composition of Lipid Bilayer - 50% lipids (outnumber all other molecules 50:1), proteins (50% of
mass of membranes), cholesterol
Plasma Membrane (Function) - Enclose Cells, Organelles
1. Defines Boundaries to regulate chemical composition and environment
2. Define malleable borders
Saturated - Single Bonded
Unsaturated - Double Bonded
Fatty Acids - Monomers for Lipids
Function of Lipids - 1. energy storage
2. cell membranes
Why Do Mitochondria have a double membrane? - Prehistoric cells absorbed mitochondria (as a
bacteria)
Why do lipids self-assemble in water? - To prevent hydrophobic tails from touching water.
Hydrophillic heads protect. This lowers free energy (delta G).
If hydrophillic heads are exposed... - Delta G will increase
Glycolipids - lipid with glycosidic bond to glucose in hydrophillic head.
Antigens on Red Blood Cells are..? - Glycolipids
,Cholesterol - A lipid steroid ring attached to glycerol. Fills gaps in Plasma Membrane left by
unsaturated hydrocarbon tails. Rigid.
How many pints of Blood are in the body? - 10 pints, on average. When you donate blood you
donate a pint. 7,000,000,000 RBCs in a single liter. Body has trillions of cells
What is Fluidity? - How easily lipids can move within a membrane
Are cells symmetrical or asymmetrical? - Asymmetrical. Asymmetry established at 'birth' of the
cell
What is flipase? - Specific catalyzed Transfer. Uses fatty acids from cytosolic monolayer to add new
membrane. Responsible for 'flip-flop' of lipids
What is scramblase? - Random Catalyzed Transfer.
Where are lipids synthesized? - Endoplasmic Reticulum.
How are lipids synthesized in the ER transported across the cell? - Via vesicles.
(EXCEPTION: Lipids for Mitochondrial Membrane and Plasmid Membrane)
Why are cells asymmetrical? - 1. To distinguish living and dead cells (Phosphatadylserine (-) is
transferred across membrane during apoptosis)
2. Signal Transduction. So that extracellular signals can be relayed through cell membrane
Types of Movement in Membrane Lipids - 1. Lateral Diffusion (~10^8 cm^2/sec at 310K)
2. Transverse Fluctuation
3. Rotation
4. Flexion
, 5. Flip-Flop (RARE for lipids. Common for cholesterol)
Planar (Black) Membrane - Technique to study a lipid bilayer
Liposome - Organelle. Good for studying lipid bilayers
FRAP- fluorescence recovery after photo-bleaching - FRAP measures membrane fluidity- the
ability of a cell to shuffle lipids laterally to replace the photo bleached portion. Revealed that cells are
typically consistency of olive oil
Transmembrane Proteins - Have hydrophillic and hydrophobic regions
Types of Transmembrane Proteins - 1. Single Alpha Helixes
2. Multiple Alpha Helixes
3. Rolled up Beta Sheets
Lipid-Anchored Proteins - Simply anchored to lipids in one layer of the membrane
Types of Lipid-Anchored Proteins - 1. Lipid Anchored via Non-Covalent Interaction
2. Covalently Attached to Lipid Chain
3. Covalently Attached to Oligosaccharide link
Types of Periphreal proteins - Attach to other membrane proteins non-covalently
Function of Membrane Proteins - 1. Transport (protons, ions, small molecules, proteins, RNA)
2. Signal Transduction (Chemical to Mechanical) or (Chemical to Chemical)
3. Cell to Cell Recognition
4. Cytoskeletal and ECM attachment
5. Catalysis
