Lecture 6- Membranes & Transport Flashcards
In which direction can a phospholipid bilayer move freely?
Laterally
True or false: Short hydrocarbon chains provide more fluidity to the plasma membrane than long hydrocarbons
False; long hydrocarbon chains provide more fluidity to a membrane
What is the difference between passive transport and active transport?
Active transport requires energy
What are the three main functions of membrane proteins?
Transport, enzymes, & signal transduction
What is the main function of cholesterol in a plasma membrane?
In warm temperatures, cholesterol holds membrane together (decreases fluidity). In cold temperatures, cholesterol acts as a spacer and provides space between tails (increases fluidity)
What is osmosis?
Diffusion of water across a selectively permeable membrane
What is the main function of glycoproteins and glycolipids on the plasma membrane?
Cell identification (blood types)
True or false: Bulk transport can be conducted passively or actively
False; bulk transport always requires ATP
What is diffusion?
Tendency for molecules to fill available space (due to entropy)
True or false: According to the fluid mosaic model, membrane fluidity increases with decreasing temperature
False; membrane fluidity decreases with decreasing temperature and increases with increasing temperature
What is exocytosis?
Process by which waste, proteins, and/or secretory products are secreted from a cell
True or false: Phagocytosis is a specific mechanism
False; phagocytosis and pinocytosis are nonspecific mechanisms
What is the difference between a saturated and unsaturated fatty acil tail?
Saturated tails have no double bonds and are straight, whereas unsaturated tails are bent and have one or more double bonds
True or false: As a vesicle undergoing exocytosis fuses with the plasma membrane, the plasma membrane grows larger in size
TRUE
Which type of endocytosis involves a cell engulfing a large particle?
Phagocytosis
