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Membrane Structure and Function

Terms in this set (42)

What is the plasma membrane
The selective membrane that separates a living cell from its surroundings
Are lipids hydrophobic or hydrophilic
hydrophobic
Why are lipids hydrophobic?
they consist mostly of hydrocarbons which form nonpolar covalent bonds
Polar molecules are hydrophilic or hydrophobic
hydrophilic
The most abundant lipid in the PM are
phospholipids
Phospholipids are ____________ molecules containing hydrophobic and hydrophilic regions
amphipathic
What does the fluid mosaic model state?
a membrane is a fluid structure with a "mosaic" of various proteins embedded in it
In which direction are phospholipids more likely to move
laterally
As temperatures cool the membrane __________
solidifies
As temperatures rise, the membrane ______
becomes more fluid
How does cholesterol play a role in the PM as temperatures rise
They force phospholipids together to prevent them from getting too fluid
How does cholesterol play a role in the PM as temperatures cool
They act as spacers preventing the phospholipids from getting too packed
Membranes rich in which type of fatty acid causes it to be more fluid
unsaturated fatty acid
What must the consistency of the membrane be in order to function properly
Fluid
What are the two types of proteins associated with the membrane
integral membrane and peripheral proteins
what determines majority of the membranes function
proteins
What are the 5 different function of the membrane proteins
-Transport; Enzymatic activity
-Signal transduction
-Cell-cell recognition
-Intercellular joining
-attachment to the cytoskeleton and extracellular matrix (ECM)
The asymmetrical distribution of proteins, lipids and associated carbohydrates in the PM is determined when membrane is built by products made in the ________ and ___________
ER and Golgi Apparatus
What is the exchange of materials by a cell controlled by
the plasma membrane
What is passive transport
diffusion of a substance across a membrane with no energy investment
What is diffusion
the tendency for molecules to spread out evenly into the available space
What is dynamic equilibrium?
a state of balance between continuing processes
Diffusion of a substance across the PM is what type of transport
passive
What is osmosis
The diffusion of water across a selectively permeable membrane
Water diffuses across the membrane in which direction
from the region of lower solute concentration to higher until the solute concentration is equal on both sides
What is tonicity
the ability of a surrounding solution to cause a cell to gain or lose water
isotonic solution
solute concentration is the same as that inside the cell with no net water movement across PM
What is a hypertonic solution
solute concentration outside of cell is greater than that inside cell; cell loses water
What is a hypotonic solution
solution concentration is less outside the cell than that inside cell; cell gains water
What is osmoregulation
control of solute concentrations and water balance
Transport proteins allow passage of which type of substance across the membrane
hydrophilic substances
what type of proteins have a hydrophilic channel that certain molecules or ions may use as a tunnel
channel proteins
which type of proteins bind to molecules and change shape to shuttle the molecules across the membrane
carrier proteins
Facilitated diffusion is which type of transport
passive
What are aquaporins used for
facilitated diffusion of water
What type of transport uses energy to move solutes against their graident
active
What is cotransport
coupled transport by a membrane protein
What is the main electrogenic pump of plants fungi and bacteria
proton pumps
What do electrogenic pumps do
help store energy that can be used for cellular work
How does bulk transport across the PM work
exo- and endocytosis
Many secretory cells use _______ to export their products
exocytosis
How do cells take in macromolecules
cells take in macromolecules by forming vesicles from the plasma membrane
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