Table of Contents
What controls permeability of a membrane?
The results suggest that the permeability of human red cell membranes to sodium and potassium is regulated by internal calcium, which in turn is controlled by a calcium pump that utilizes ATP.
What factors influence permeability of the plasma membrane?
In this article, it is shown that membrane permeability to water and solutes is dependent on the temperature, medium osmolality, types of solutes present, cell hydration level, and absence or presence of ice.
What causes an increase in muscle membranes permeability?
The most widely accepted theory to explain the increased membrane permeability is that the absence of dystrophin makes the membrane more fragile so that the stress of contraction causes membrane tears which provide the increase in membrane permeability.
What is the permeability of the plasma membrane?
Permeability of cell membrane refers to the ease with which a molecule can pass through a cell membrane. It is the rate at which the passive diffusion occurs through the membrane. Transporting molecules across the cell membrane is one of the important functions of the cell membrane.
What determines permeability?
Permeability is determined by applying a head and determining the depth of penetration or the amount of liquid or gas passing through the sample.
What changes membrane permeability?
Overview. The action potential, the primary electrical signal generated by nerve cells, reflects changes in membrane permeability to specific ions.
What is the role of tropomyosin in skeletal muscles?
The main function of tropomyosin is to prevent muscle contraction by establishing a barrier between the actin and myosin protein filaments that cause muscle contraction. When myosin filaments come into contact with actin filaments as part of the actin-myosin complex, the muscle is forced to contract.
How is the plasma membrane selectively permeable?
The plasma membrane is capable of being selectively permeable because of its structure. It is composed of a bilayer of phospholipids interspersed with proteins. The phospholipid part of the plasma membrane renders the latter hydrophobic and therefore polar molecules would not be able to easily pass through this layer.
Which of the following help maintain the selective permeability of a plasma membrane?
This lipid bilayer is punctuated by cholesterol molecules, glycolipids, and proteins that are either anchored or traverse the entire membrane. These proteins form channels, pores or gates to maintain selective permeability of ions, signaling molecules and macromolecules based on the requirements of the cell.
How does calcium affect membrane permeability?
Calcium may affect the distribution of electrons on the protein and alter the atomic/intra-molecular bond angles. This could modify the structural conformation of the pore/channel proteins, creating differences in membrane permeability to specific ions.]
What factors affect membrane fluidity and permeability?
Cell permeability and cell fluidity are two essential properties, having roles in transporting molecules across the membrane. These properties are affected by physiological factors like temperature, pH, and the membrane’s composition.
What increases cell permeability?
Electroporation is a biophysical phenomenon in which cell membrane permeability is increased through externally applied pulsed electric fields. This membrane permeability increase is used for many applications in biotechnology, medicine and the food industry.
How do skeletal muscles depolarize?
Once ACh binds, a channel in the ACh receptor opens and positively charged ions can pass through into the muscle fiber, causing it to depolarize, meaning that the membrane potential of the muscle fiber becomes less negative (closer to zero.)
How does a muscle cell depolarize?
Activation of the nAChR leads to an influx of cations (sodium and calcium) that causes depolarization of the muscle cell membrane. This depolarization in turn activates a high density of voltage-gated sodium channels on the muscle membrane, eliciting an action potential.
How does permeability of the plasma membrane affect its function?
permeability of plasma membrane -allows some substances to pass in and out of the cell – in general small, uncharged molecules (i.e. CO2, O2, H2O,glycerol, alcohol) can all move freely across the plasma membrane While large molecules, ions and charged molecules cannot with out assistance.
How is the permeability transition pore regulated in skeletal muscle mitochondria?
We have investigated the regulation of the permeability transition pore (PTP), a cyclosporin A-sensitive channel, in rat skeletal muscle mitochondria. As is the case with mitochondria isolated from a variety of sources, skeletal muscle mitochondria can undergo a permeability transition following Ca2+ uptake in the presence of Pi.
What is the function of the charge on the plasma membrane?
-allows some substances to pass in and out of the cell. – in general small, uncharged molecules (i.e. CO2, O2, H2O,glycerol, alcohol) can all move freely across the plasma membrane While large molecules, ions and charged molecules cannot with out assistance. passively/active movement.
What are the characteristics of plasmatic membrane?
plasma membrane -is differentially permeable -Certain substances can move across the plasma membrane while others cannot. -no substances can go through -all substances can go through -allows some substances to pass in and out of the cell -When some substances can move freely cross the plasma membrane.