The Cell Membrane

Temperature -High temperatures cause the phospholipid bilayer to become extremely fluid because increased temperature increases the kinetic energy present in the bilayer, thus it is able to overcome the intermolecular forces that are holding it together, therefore increasing the fluidity -Low temperatures cause the kinetic energy present in the bilayer to decrease, causing the phospholipids to cluster together, thus strengthening the intermolecular forces, therefore decreasing the fluidity

Double Bonds in Fatty Acid "Tails" -Double bonds decrease the interaction of phospholipids due to the presence of kinks, thus the intermolecular forces are decreased, therefore increasing the fluidity

Fatty Acid "Tail" Length -Increase in length, increases the intermolecular forces between the "tails", thus the bilayer is held tightly together, therefore reducing fluidity

Cholesterol -In high temperatures, the phospholipids begin to pull apart, causing the cholesterol to pull the phospholipids back together, thus increasing intermolecular forces,therefore decreasing fluidity -In low temperatures, the phospholipids begin to cluster together, however the cholesterol begins to fill in the space between the phospholipids, thus disrupting the intermolecular forces present, therefore increasing fluidity

Passive Transport -The movement/transport of molecules ACROSS the concentration gradient -WITHOUT the use of energy

Diffusion -The net movement of ions/molecules from an area of high concentration of the specific ion/molecule to an area of low concentration of the ion/molecule

Osmosis - Specific type of diffusion involving water molecules -The net movement of water molecules across a membrane -Molecules travel from a high concentration of water molecules to a low concentration of water molecules (concentration gradient)

Isotonic Solution -Solution that determines osmosis -Occurs when the concentration of solute inside of a cell is equal to the concentration of solute outside of a cell -Results in the equal exchange of water molecules

Hypotonic Solution -Solution that determines osmosis -Occurs when the concentration of solute inside the cell is greater than the concentration of solute outside of the cell -Results in water molecules moving into the cell -Results in swelling of the cell

Hypertonic Solution -Solution that determines osmosis -Occurs when the concentration of solute outside the cell is greater than the concentration of solute inside of the cell -Results in water molecules moving outside of the cell -Results in shrinking of the cell

Facilitated Diffusion -The net movement of ions/molecules from an area of high concentration to an area of low concentration with the aid of specific membrane proteins

Active Transport -The movement/transport of molecules AGAINST the concentration gradient -REQUIRES the use of energy (ATP)

Molecular Active Transport -Molecules move against the concentration gradient, therefore cellular energy is required

Primary Active Transport -Active transport that is derived directly from the breakdown of ATP

Sodium-Potassium Pump -Process of moving sodium and potassium ions across the cell membrane -Uses the hydrolysis of ATP to provide necessary energy -Process remains a large concentration of sodium ions outside of the cell, and a large concentration of potassium ions inside of the cell -This unbalanced charge transfer contributes to the separation of charge across the membrane -Important contributor to action potential produced by nerve cells

Calcium Pump -Responsible for the active transport of calcium out of the cell -Play a crucial role in proper cell signalling by keeping the intracellular calcium concentration roughly 10,000 times lower than the extracellular concentration

Proton Pump -Transports protons -Active pump that generates a proton concentration gradient across the inner mitochondrial membrane due to the high concentration of protons outside of the matrix than the inside

Secondary Active Transport -Active transport that is derived secondarily from the energy that has been stored in the form of ionic concentration differences from the two sides of the membrane

Bulk Transport -The movement of macromolecues in or out of the cell -The movement of large quantities of smaller molecules in or out of the cell

Exocytosis -Bulk transport in which molecules are transported from inside the cell to the outside of the cell -Through the use of membrane-bound vesicles that fuse with the plasma membrane

Endocytosis -Bulk transport in which molecules are transported from outside of the cell to the inside of the cell -Through the use of vesicle made by plasma membrane

Phagocytosis -"Cell Eating" -The ingestion of large molecules

Pinocytosis -"Cell Drinking" -The ingestion of liquid

Receptor-Mediated Endocytosis -Selective process of importing molecules into the cell -Uses specific receptors to indicate what molecules can be transported

Selectively Permeable - allows some substances to cross the membrane and not others

"Fluid Mosaic" -Fluid = proteins and bilayer are free to move -Mosaic = proteins and carbs

Hydrophobic "Tails" -The "tails" of the phospholipid bilayer avoid interaction with water molecules

Hydrophilic "Heads" -The "heads" of the phospholipd bilayer are attracted to water molecules

Peripheral Proteins -Proteins that remain on the perimeter of the membrane and other proteins -They are loosely bound

Transmembrane Proteins -Proteins that span throughout the entirety of the cell -They are permanently attached to the cell (embedded)

Integral Proteins -Proteins that are integrated into the membrane -They are permanently attached the the cell membrane

Transport -Proteins allow large and hydrophilic molecules to pass through the cell

Enzymatic Activity -Proteins that are built into the membrane may be enzymes when their active side is exposed to a substances in the adjacent cell

Signal Transduction -Proteins that send signal to the cell, telling it to complete certain tasks

Cell-Cell Recognition -Proteins that distinguish neighboring cells

Intercellular Joining -Proteins that connect with proteins of adjacent cells in various intercellular junctions

Attachment to the cytoskeleton and extracellular matrix (ECM) -help maintain cell shape and fix the location of certain membrane proteins

-In an axon, the change in charge that occurs when the fates of the K+ close, and the gates of NA+ channels open after a wave of depolarization is triggered.

Depolarization -A process in which the inside of the cell becomes less negatively charged relative to the outside of the cell

Repolarization -The effect of the sodium-potassium pump and the small amount of naturally occurring diffusion on the cell membrane of a neuron, which returns to its normal resting potential

Resting Membrane Potential -The potential difference across the membrane in a resting neuron