Topic 3 - Membrane Protiens Flashcards
Plasma membrane consists of ________
Phospholipids and protein
Hydrophilic heads align to ______
Extracellulaur space or cytoplasm
Examples of hydrophobic molecules and how they pass though
O2/CO2/N2 and steroid hormones
Pass through readily
Examples of small uncharged polar molecules and how they pass thorough
H2O/urea/glycerol
Pass through readily BUT at a lower rate as they are capable of dissolving
Large uncharged polar molecules - examples and how they pass
Glucose/sucrose
Can not pass through
Transmembrane proteins act as ______or ______
Channels or transporters
What is the function of these channels or transporters
Aid and control the movement of substances. They help control ion concentrations and concentration gradients
Examples of protein free bilayers
H+/Mg2+/Ca2+/HCO3-
What is facilitated diffusion
Small molecules that could only move only slowly by passive diffusion speeded through the membrane using transmembrane channel proteins that are specifically shaped to that molecules
What are gated channels
Channels protein always open using the help of an change in confirmation of the protein to open the channel
Example of gated channel
Sodium potassium pump
What’s a ligand gated channel
Binding of a signal molecule to change the confirmation of the channel
An example of it
Sodium or potassium channels
What’s a voltage gated channel
Uses changes in ion concentration to determine the opening and closing of channel
Where are they found
Nerve cells
What is signal transduction
Uses receptor proteins on the surface that are altered by the binding of the signal then sets off he reaction within the cell
What are the two types of binding sites for glucose symport
One for sodium
One for glucose
What’s the effects of the binding of one
It enhances the binding of another
What’s drives the system and how is that generated
Driven by sodium gradient generated by the sodium/potassium ATPase
How is it described
Secondary active transport
What happens when all binding sites are filled
Conformational change delivers both molecules across the membrane
What happens next
Sodium is pumped back out of the cell by sodium/pottasium ATPase
Why is sodium pumped back out
The conformational change relies on both sets of sites being filled or not and the switch between stars only happens if all sites are full or empty
How does this transport protein exist
In two states, A and B
Why is glucose more likely to bind to the molecule in the A state rather than the B state
Much higher extracellulaur than intracellulaur sodium levels
_____ glucose and sodium enter the cell by _______ transitions
More
A-B
What is this an example of
Cooperative co-transport
The net flow results in ________ against the concentration gradient
Accumulation of glucose
Sodium ions flow ____ their electrochemical gradient while glucose molecules pumped ___ their concentration gradient
Down
Up
What is the sodium/glucose symport used for
Actively transport glucose out of the intenstine and into the kidney tables and back into the blood test
What does the sodium potassium ATPase pump do
Transports ions against a steep concentration gradient using emerged from ATP
What does it use ATPase to do
Remove phosphate from ATP and uses it to change the confirmation of the protein channel
Stage 1 of sodium potassium pump
Transporter has high affinity for sodium ions inside the cell
Stage 2 of sodium potassium pump
Binding occurs
Stage 3 of sodium potassium pump
Phosphorylation of ATP
Stage 4 of sodium potassium pump
Confirmation changes
Stage 5 of sodium potassium pump
Affinity for ions change
Stage 6 of sodium potassium pump
Sodium ions released outside of the cell
Potassium ions bind outside the cell
Stage 7 of sodium potassium pump
Dephosphorylation
Stage 8 of sodium potassium pump
Confirmation changes
Stage 9 of sodium potassium pump
Potassium ions taken into the cell
Stage 10 of sodium potassium pump
Affinity return to start
Functions of the pump
Maintain osmotic balance
Generates ion gradient in kidney tumbles/for glucose symport in the small intestine
Generates and maintains ion gradient for resting potential in neurons
Electrical impulses travel along a ___________ as channel proteins ____ to allow ______ to rush in down a ________ ________
Nerve cell
Open
Sodium ions
Concentration gradient
What’s the name of the tiny gaps that prevents nerve impulses jumping directly to the next nerve cell
Synapse
What is responsible for carrying the signal across the gap
Neurotransmitters
What on the other side of the gap
Protein receptorsinked to closed ion channel proteins
What does the binding of neurotransmitters cause
Opening o the ion channels to allow sodium ions to rush in and the signal travels down the next neuron
When a neurotransmitter binds to a protein receptor a _______ ________ causes _______
Confirmation change
Ion channel to open and allow sodium ions to rush in
The neurotransmitters binding to its red world is an example of
A ligand gated channel
The flow of ions into the post synaptic membrane as a result of ?
Neurotransmitters binding leads to a change in charge across the membrane
The change in charge is known as ?
Depolarisation
What does he change in charge trigger
Opening of further ion channels (sodium/potassium ATPase) along the axon of the nerve (voltage gated channels)
What is the result
Charge moving along the axon towards the next nerve
Charge moving along the axon towards the next nerve is known as
Propagating
The wave of depolarisation reaches the end and tiggers?
The release of a neurotransmitter
Once the wave has passed ____________ close and other open to move ions in the opposite direction
Sodium channels
This then rest the neuron to its ________
Resting potential
What is the resting potential
Charge before depolarisation
