B2.1. - Membranes and Membrane Transport

Phospholipid Structure

hydrophilic phosphate head, hydrophobic fatty acid tail, glycerol connects

_____ particles and _______ particles cannot pass directly through the phospholipid bilayer

Large particles and hydrophilic, charged particles cannot pass directly through the phospholipid bilayer

_____ theory states that particles are in constant motion. This applies to gases, liquids, and solutes and allows diffusion and osmosis to occur.

Kinetic theory states that particles are in constant motion. This applies to gases, liquids, and solutes and allows diffusion and osmosis to occur.

Diffusion is the ______ transport of particles from a region of _____ concentration to a region of ______ concentration.

Diffusion is the passive transport of particles from a region of high concentration to a region of low concentration.

_______ proteins are permanently attached to the plasma membrane, and penetrate into the centre of the phospholipid bilayer.They contain a _____ (hydrophobic/hydrophilic) section within the fatty acid tails and two _______ (hydrophobic/hydrophilic) sections at each surface of the bilayer.

Integral proteins are permanently attached to the plasma membrane, and penetrate into the centre of the phospholipid bilayer.They contain a hydrophobic section within the fatty acid tails and two hydrophilic sections at each surface of the bilayer.

_____ proteins are temporarily attached to one side of the membrane. They are _____ (hydrophobic/hydrophilic) and do not penetrate the phospholipid bilayer.

Peripheral proteins are temporarily attached to one side of the membrane. They are hydrophilic and do not penetrate the phospholipid bilayer.

Osmosis is the passive transport of water molecules from a region of ____ solute concentration to a region of ____ solute concentration through a semipermeable membrane.

Osmosis is the passive transport of water molecules from a region of low solute concentration to a region of high solute concentration through a semipermeable membrane.*water is polar but is so small that it can move through the membrane

_______ are integral channel proteins that selectively transport water rapidly through membranes

Aquaporins are integral channel proteins that selectively transport water rapidly through membranes

Solute concentration

Inside Cell: .5mM

Outside solution: .9mM

Is the solution outside the cell hypotonic, isotonic, or hypertonic?

What will happen to the cell?

Solute concentration

Inside Cell: .5mM

Outside solution: .9mM

Hypertonic solution; water will leave cell, and cell will shrink

Solute concentration

Inside cell: .5mM

Outside cell: .5mM

Is the solution outside the cell hypotonic, isotonic, or hypertonic?

What will happen to the cell?

Solute concentration

Inside cell: .5mM

Outside cell: .5mM

Isotonic; no net water movement

Solute concentration

Inside cell: .7mM

Outside cell: .2mM

Is the solution outside the cell hypotonic, isotonic, or hypertonic?

Solute concentration

Inside cell: .7mM

Outside cell: .2mM

Hypotonic solution; water will enter cell, and cell will swell and potentially burst

Facilitated diffusion is the ____ (active/passive) transport of molecules from a region of ___ concentration to a region of ___ concentration through channel proteins.

Facilitated diffusion is the passive transport of molecules from a region of high concentration to a region of low concentration through channel proteins.

Active transport is the movement of particles from a region of ____ concentration to a region of _____ concentration using protein pumps and ATP energy

Active transport is the movement of particles from a region of low concentration to a region of high concentration using protein pumps and ATP energy

Selective or nonselective:

a) facilitated diffusion

b) active transport

c) simple diffusion

Selective or nonselective:

a) facilitated diffusion - selective

b) active transport - selective

c) simple diffusion - nonselective

Phospholipids and membrane proteins can have carbohydrate chains attached by a process known as ________.

Phospholipids and membrane proteins can have carbohydrate chains attached by a process known as glycosylation.

______ are membrane proteins with a carbohydrate chain attached.______ are phospholipids with a carbohydrate chain attached.

Glycoproteins are membrane proteins with a carbohydrate chain attached.Glycolipids are phospholipids with a carbohydrate chain attached.

Draw a labeled diagram of the fluid mosaic model

refer to slides

_____ fatty acids have single bonds between the carbons on the hydrocarbon chain. They are linear and contribute to triglycerides with _______ (higher/lower) melting points. _______ fatty acids have at least one double bond between carbons on the hydrocarbon chain. They are bent at the position of the double bond and contribute to triglycerides with _____ (higher/lower) melting points.

Saturated fatty acids have single bonds between the carbons on the hydrocarbon chain. They are linear and contribute to triglycerides with higher melting points. Unsaturated fatty acids have at least one double bond between carbons on the hydrocarbon chain. They are bent at the position of the double bond and contribute to triglycerides with lower melting points.

_____ fatty acids make membranes stronger at higher temperatures.

Saturated fatty acids make membranes stronger at higher temperatures.

Cell membranes with more ______ fatty acids are more fluid.

Cell membranes with more unsaturated fatty acids are more fluid.

Cholesterol is located in the membranes of animal cells, and helps regulate the ______ of the membrane.

Cholesterol is located in the membranes of animal cells, and helps regulate the fluidity of the membrane.

At higher temperatures, cholesterol _____ (maintains/reduces) membrane fluidity.At lower temperatures, cholesterol _______ (maintains/reduces) membrane fluidity.

At higher temperatures, cholesterol reduces membrane fluidity.At lower temperatures, cholesterol maintains membrane fluidity.

_____ is the release of large particles from a cell, involving the fusion of a vesicle with the plasma membrane.______ is the process by which large particles enter the cell, involving the budding off of the plasma membrane inside the cell to form a vesicle.*Both processes require ___

Exocytosis is the release of large particles from a cell, involving the fusion of a vesicle with the plasma membrane.Endocytosis is the process by which large particles enter the cell, involving the budding off of the plasma membrane inside the cell to form a vesicle.*Both processes require ATP

_____ gated ion channels open in response to an increase in membrane potential.Sodium and potassium ____ gated channels are involved in the movement of action potentials along neurons.

Voltage gated ion channels open in response to an increase in membrane potential.Sodium and potassium voltage gated channels are involved in the movement of action potentials along neurons.

Acetylcholine is a _______ that opens sodium channels in the _______ membrane of neurons.Acetylcholine is a ligand which attaches to a sodium ion channel, opening the channel and allowing sodium ions to enter a neuron through the _______ membrane.

Acetylcholine is a neurotransmitter that opens sodium channels in the postsynaptic membrane of neurons.Acetylcholine is a ligand which attaches to a sodium ion channel, opening the channel and allowing sodium ions to enter a neuron through the postsynaptic membrane.

Sodium Potassium Pump mnemonics

321 NOKIA

3 Na+ Out

2 K+ In

1 ATP Used

"Salty Banana" (sodium moved outside, potassium moved inside)

The sodium potassium pump is an example of _____ (active/passive) transport.It works to maintain the resting potential / potential difference in a neuron. Their resting potential is usually about ______mV

The sodium potassium pump is an example of active transport.It works to maintain the resting potential / potential difference in a neuron. Their resting potential is usually about -70mV

In one mechanism of glucose tranposrt, glucose is passively transported through glucose channels from the small intestine into the epithelial cells. This is an example of which type of transport?

In one mechanism of glucose tranposrt, glucose is passively transported through glucose channels from the small intestine into the epithelial cells. This is an example of Facilitated Diffusion.

In sodium dependent glucose cotransporters, the movement of an ion (Na+) down its concentration gradient is linked with the movement of a solute (glucose) against its concentration gradient. This is an example of which type of transport?

In sodium dependent glucose cotransporters, the movement of an ion (Na+) down its concentration gradient is linked with the movement of a solute (glucose) against its concentration gradient. This is an example of indirect/secondary active transport.

_______ form a seal between cells, preventing substances leaking between the cells.

Tight junctions form a seal between cells, preventing substances leaking between the cells.

________ are channels between cells that allow molecules to pass between cells, allowing cell communication.

Gap junctions are channels between cells that allow molecules to pass between cells, allowing cell communication.

_______ use protein complexes to connect cells together.

Adherens junctions use protein complexes to connect cells together.

_______ use protein complexes to form strong connections between cells, providing tissues with structural integrity.

Desmosomes use protein complexes to form strong connections between cells, providing tissues with structural integrity.