Transport Across Cell Membrane Flashcards
Membran Transport proteins
Cell membrane contain specialized membran transport protein that facilitate the passage of selected small water soluble molecules
Small and nonpolar molecules can diffuse the membrane without problems
There are two main classes of membrane transport proteins:
Transporters
Channels
Transport through the membrane
Solutes can be transported actively or passively through the membrane
Gradient
The concentration gradient and electrical gradient combine to form a net driving force: the electrochemical gradient for each solute
There are two gradients that effect the transport of ions
- Through their electricity the electrical gradient
- Through the numbers of molecules inside or outside the cell the chemical gradient
Osmosis
Water moves passively across cell membranes down its concentration gradient
Some cells contain aquaporin for the pass from water
Water pass from high to low water compartment (osmos)
The molecules in water are called osmolarite
Cell and their Transporters
Each cell membrane has its own characteristics set of transporters
So their are no ‘’traffic” by using their needed region
Exp. Mitochondria contain pruvat protein
Passive transport
Passive transport move a solute along its electrochemical gradient
A conformation change in a transporter could mediate the passive movement of a solute
Exp. Glucose get together with carrier protein (Na) and bind to the transporter
They get a conformation change and go into the cell
Active transport
Active transport can be driven in 3 different ways
- Coupled-pump (use a helper protein; one goes in the other goes out of the cell)
- ATP driven pump ( use ATP energy for the transport)
- Light driven pump( most by bacteria cells)
Na K Pump
The Na K Pump in animal cells uses energy supplied by ATP to expel Na and brin K in
Types of transport mediated movement
- Uniport ( only one molecule)
- Symport ( two molecules in the are transported in the same way)
- Antiport ( two molecules are transported in opposite sites)
Glucose Na symport
A Glucose Na symport uses the electrochemical Na gradient to drive the active import of glucose
They balance the membrane pH
Trans cellular transport of Na and Glucose in the gut
Two types of glucose transporters enable gut epithelial cells to transfer glucose across the epithelial cells of the gut
Glucose get with active transporter in the gut cell and out with passive transporter out of the gut cell
Ion channels
Ion channels are ion selective and gated not all ions in
They are not continuously open - they opened by change of voltage
Ion selectivity
Ion selectivity depends on the diameter and shape of the ion channel and on the distribution of the charged amino acids that line it
The molecules are around die with water molecules before the filter
When they came in the filter the H2O molecules are Filtrates and the ion pass the thin filter part without water molecules
After they pass the filter complete they became their old composition
Venus flytrap
A Venus flytrap catch his prey with electrical signals
They leads to a rapid change in the turgo pressure
Patch clamp
Recording measures the ion movements and the electrical charges in a single channel molecule
Ion channel gates
- Voltage gated
- ligand gated
- mechanical gated
Auditory hair cells are a example for mechanically gated channels
Sound vibration pull the channels open causing ions to flow into the hair cells
From hair cell to the auditory nerve which conveys the signal to the brain
Mimosa pudica
Work with voltage channel and also with mechanical channel
Voltage gated-channel evolutionaryly
- AP in neurons are primarily through voltage-gated Na channels
- AP in muscle egg and endokrine cells are through voltage gated Ca and K channels
Neuron
Has a cell body a single axon and multiple dendrites
AP allow Papier long distance communication along axons
AP is triggered by a depolarization of neurons plasma membrane
Nerve terminal
An electrical signal is converted in to a secreted chemical signal at a nerve terminal
Presinaptik cell secrete neuro transmitter to the postsinaptik one triggered them so to AP
Postsinaptik cell take the neurotransmitter with ligand channel
Then the postsinaptik cells chance the chemical signals to electrical signals…
Optogenetic
Optogenetics uses the light gated ion channel to transiently activate or inactivate neurons in living animals
Used to test the behavior of rates
