Exam 2 Flashcards
What does the plasma membrane do?
defines the cell and separates the inside from the outside
In eukaryotes, what else does the plasma membrane do?
defines intracellular organelles
What does the plasma membrane consist of?
a lipid bilayer that is semipermeable
What does the plasma membrane regulate?
the transport of materials into and out of the cell
What are the functions of the plasma membrane?
-hold structure
-protection
-transport
-communication through cell-cell signaling
-energy transportation
What is the basic structural unit of biological membranes?
phospholipid bilayer
What prevents water-soluble substances from crossing the membrane?
its hydrophobic core
What does the fluid mosaic model do?
keeps organelle shape and enables membrane budding and fusion/fission
What things give mosaic structure and fluid character?
phospholipids
cholesterol
proteins
carbohydrates
What are the principal building blocks of membranes?
phospholipids
What is the most common phospholipid in membranes?
phosphoglycerides
What does amphipathic mean?
molecules consists of 2 different properties
What makes phospholipids amphipathic?
hydrophobic tail made of fatty acids
hydrophilic head
What are the 3 amphipathic lipids in membranes?
phospholipids, glycolipids, cholesterol
What determines the structure of membranes?
the interactions between phospholipids with each other and water
How do phospholipids form bilayers?
hydrophobic tails align tightly together in the center, forming a hydrophobic core
hydrophilic heads face the outside
What stabilizes the close packing of non polar phospholipid tails?
van der Waals interactions
What stabilizes the interactions of the polar phospholipid head groups with water and each other?
ionic and hydrogen bonds
Exoplasmic face of bilayer
faces the outside
Cytosolic face of bilayer
faces the inside (cytosol)
What organelles are surrounded by two membranes (2 lipid bilayers)?
nucleus, chloroplast, mitochondria
Structure of phosphoglycerides
hydrophobic tail with 2 fatty acyl chains
polar head group attached to phosphate
What are plasmalogens?
a group of phosphoglycerides that contain one chain attached to C2 of glycerol by ester linkage and the other chain attached to C1 of glycerol by ether linkage
Where are plasmalogens abundant?
brain and heart tissue