Module 4A - Membrane Transport Flashcards
Two main types of membrane transport proteins.
Transporters and channels
A group of protein transporters that utilizes the electrochemical potential (membrane potential) to transport molecules across the membrane bilayer.
SLC transporters
A type of protein transporter that uses the hydrolysis of ATP to move molecules across the membrane bilayer.
ABC transporters
The movement of ions are dictated by the:
Concentration gradient
Types of molecules that can diffuse directly to the lipid bilayer without the aid of transport proteins or channels.
Hydrophobic molecules/Lipid soluble molecules
Molecules with the lowest permeability and needs the aid of transport proteins to move in and out of the cell.
Ions
Factors that affect permeability
Size and hydrophobicity
Proteins that transfer solutes, specific molecular species, or a class of molecules.
Membrane transport proteins
Transport proteins that binds and conforms to the shape of the molecule it transports. Capable of reversible conformation changes.
Transporters
Transport of molecules downhill using the difference in concentration gradient.
Passive transport
Movement of uncharged molecules are based on the:
Concentration gradient
This is where the movement of charge molecules across the electrochemical gradient of the cell from the extracellular matrix relies on.
Membrane potential
A type of active transport that uses the energy stored in concentration gradients.
Coupled transport
Active transport pump that uses the hydrolysis of ATP to move molecules against the electrochemical gradient.
ATP-driven pump
Protein pumps that use the energy from light to move molecules across the membrane bilayer.
Light/redox-driven pumps
A transporter protein that carries only one single solute.
Uniporter
Coupled transport protein that moves a molecule and a co-transported ion towards the same direction.
Symporters
Transport protein that move a molecule depending on the transport of a secondary molecule and harvests the energy stored in the electrochemical gradient.
Couple transporters
Coupled transport protein that facilitates the transfer of two molecules in opposite directions.
Antiporters
Channels in the lipid bilayer that facilitates the movement of water molecules.
Aquaporins
The solute and binding sites are located _______ through the transport protein.
Midway
Four classes of ATP-driven pumps
- P-type pumps
- ABC transporters
- V-type pumps
- F-type pumps
Also known as ATP synthase, it uses the H+ gradient to synthesize ATP.
F-type pumps
A type of ATP-driven pump that move small molecules with the aid ATP hydrolysis
ABC transporters
Pump that moves molecules using the phosphorylation from ATP.
P-type pumps
ATP-driven pump that is made from multiple different subunits
V-type pumps
Intracellular storage of Ca2+ in muscle cells.
Sarcoplasmic reticulum
Protein transport pump that pumps out Ca2+ outside of the cell.
Ca2+ ATPase (Calcium pumps)
What is the effects of pumping Ca2+ into the cytosol?
Muscle contraption
10 transmembrane α-helices are connected to what three(3) cytosolic domains.
- Nucleotide-binding domain
- Phosphorylation domain
- Activator domain
First found in bacteria, it contains highly conserved ATPase domains that brings together two different domains.
ABC transporters
What is the importance of the sodium-potassium pump?
Regulates cytosolic pH levels; creating electric potential
Connects the cytoplasm of two different cells
Gap junctions
Channels that facilitate the transport of inorganic ions
Ion channels
Transporter protein that is associated with antigen processing.
TAP transporter
A narrow pore that allows water molecules to move rapidly and traverse the membrane in a single file.
Aquaporins
Regulates the flow of ions or molecules, opening briefly and closing again in response to specific stimuli.
Gated ion channels
Different types of gated channels
- Voltage-gated
- Ligand-gated (intra and extra)
- Mechanically gated
Gated ion channel that activates due to a change in the membrane potential and facilitates active electrogenic pumping and passive ion diffusion.
Voltage-gated channels
Selectivity filter that is present in voltage-gated channels.
Pore helix
Neuromuscular disorder caused by voltage-gated Na+ channels in skeletal muscle cells
Myotonia
A condition that occurs when the Na+ or K+ channels in the brain dysfunctions, causing the neurons to fire more faster than normal.
Epilepsy
Voltage-gated channels contains __ identical transmembrane subunits that forms a central pore through the membrane.
Four
When K+ ions pass through the selectivity filter, it loses almost all of its bound __________________
Water molecules
Causes the titling of K+ channels inner helices
Closed K+ channels
Mechanosensitive channels that are capable of responding to mechanical forces. Found in the bacterial plasma membrane.
Mechanically gated ion channels
Receives, conducts, and transmits signals
Neurons
Changes in the electrical potential across the neuron’s plasma membrane.
Action potential/Nerve impulse
Responsible for generating action potentials and depolarization of the plasma membrane.
Voltage-gated cation channel
Photosensitive ion channels that covalently bound retinal groups.
Channelrhodopsins
Increase the rate at which the axon can conduct an action potential.
Myelination
Two types of glial cells that form the myelin sheets.
Schwann cells and oligodendrocytes
Little leaks of neuron transmission current can leak from:
Axons
Neuronal signals are transmitted at:
Synapses
Ion channels and feature at fast chemical synapses
Ionotropic receptors
G-protein coupled receptors that bind to all other neurotransmitter.
Metabotropic receptors
neuromuscular transmission involves the sequential activation of ________ different sets of ion channels
Five
Open cation channels, influx of Na+ or Ca2+; firing an action potential.
Excitatory neurotransmitters
Flow of synaptic neuronal signals across the neuron.
Presynaptic cell – synaptic cleft – postsynaptic cell
Gaps in the myelin sheets that aid in the rapid conduction of nerve impulses
Nodes of Ranvier
