Life in acid: pH homeostasis in acidophiles
... impermeable cell membrane to restrict proton influx into the cytoplasm [13] (Figure 1). Because the membrane proton permeability determines the rate at which protons leak inward, the balance between proton permeability, proton influx through energetic and transport systems, and the rate of outward p ...
... impermeable cell membrane to restrict proton influx into the cytoplasm [13] (Figure 1). Because the membrane proton permeability determines the rate at which protons leak inward, the balance between proton permeability, proton influx through energetic and transport systems, and the rate of outward p ...
CONDUCTION INTRODUCTION
... an electrical signal from one part of an excitable cell to another. The essentially simultaneous contraction of all parts of a skeletal muscle cell requires the rapid spread of electrical depolarization over the sarcolemma and along the transverse tubules. The reflex that allows one to withdraw his ...
... an electrical signal from one part of an excitable cell to another. The essentially simultaneous contraction of all parts of a skeletal muscle cell requires the rapid spread of electrical depolarization over the sarcolemma and along the transverse tubules. The reflex that allows one to withdraw his ...
Extracellular Polyvalent Cation Block of Slow Na+ Channels in
... also exhibit marked differences in current kinetics, gating properties and pharmacological affinities (for review, see Fozzard and Hanck 1996) Their distinct pharmacological profiles allow classifying the sodium channels into three main classes according to their sensitivity to tetrodotoxm (TTX), sa ...
... also exhibit marked differences in current kinetics, gating properties and pharmacological affinities (for review, see Fozzard and Hanck 1996) Their distinct pharmacological profiles allow classifying the sodium channels into three main classes according to their sensitivity to tetrodotoxm (TTX), sa ...
Ch 48 49 Notes - Dublin City Schools
... • In a mammalian neuron at resting potential, the concentration of K+ is greater inside the cell, while the concentration of Na+ is greater outside the cell • Sodium-potassium pumps use the energy of ATP to maintain these K+ and Na+ gradients across the plasma membrane • These concentration gradient ...
... • In a mammalian neuron at resting potential, the concentration of K+ is greater inside the cell, while the concentration of Na+ is greater outside the cell • Sodium-potassium pumps use the energy of ATP to maintain these K+ and Na+ gradients across the plasma membrane • These concentration gradient ...
Differences in Whole-Cell and Single
... Because single-channel recordings are likely to reflect the differences in the kinetics observed in whole-cell measurements, we recorded singlechannel activity in excised outside-out patches isolated from both Thlaspi spp. (Fig. 5). However, there were no significant differences in the steady-state ...
... Because single-channel recordings are likely to reflect the differences in the kinetics observed in whole-cell measurements, we recorded singlechannel activity in excised outside-out patches isolated from both Thlaspi spp. (Fig. 5). However, there were no significant differences in the steady-state ...
ATP-Sensitive K+ Channels in the Brain: Sensors of
... During seizure, the cerebral metabolic rates of O2 and glucose uptake increase more than under any other circumstance (2). This massive energy demand causes a rapid fall in ATP that, if prolonged, leads ultimately to irreversible cell damage (5) due to intracellular ionic derangements such as Na+ an ...
... During seizure, the cerebral metabolic rates of O2 and glucose uptake increase more than under any other circumstance (2). This massive energy demand causes a rapid fall in ATP that, if prolonged, leads ultimately to irreversible cell damage (5) due to intracellular ionic derangements such as Na+ an ...
Cochlea and Auditory Pathways
... Hearing begins with pressure waves impacting the tympanic membrane, causing it to vibrate. The vibration is transmitted from malleus to incus to stapes. The stapes rocks in & out, causing the membrane of the oval window to produce pressure waves within perilymph of the scala vestibuli. Pressure is t ...
... Hearing begins with pressure waves impacting the tympanic membrane, causing it to vibrate. The vibration is transmitted from malleus to incus to stapes. The stapes rocks in & out, causing the membrane of the oval window to produce pressure waves within perilymph of the scala vestibuli. Pressure is t ...
Standard Half Cell Potentials
... Since a cell is made from two half cells, it is useful to identify the contribution of each half cell to the cell potential. It is impossible to measure the potential of a single half cell, this is because every attempt to take a measurement using a voltmeter will introduce a wire (metal/solution in ...
... Since a cell is made from two half cells, it is useful to identify the contribution of each half cell to the cell potential. It is impossible to measure the potential of a single half cell, this is because every attempt to take a measurement using a voltmeter will introduce a wire (metal/solution in ...
Neurons in Action: Passive Axon Tutorial
... The length constant tells you how far voltage will spread along the axon before it decays away. An axon will a large length constant will allow voltage to spread further along it than an axon with a small length constant. Since voltage decays down an axon exponentially, you can calculate the length ...
... The length constant tells you how far voltage will spread along the axon before it decays away. An axon will a large length constant will allow voltage to spread further along it than an axon with a small length constant. Since voltage decays down an axon exponentially, you can calculate the length ...
Activation parameters for ET
... Due to entropy mixing, the slope of the pH-dependence should be negative. Observed (total) activation entropy change The slope of the pH-dependence of the observed (total) entropy change is positive (or in some cases slightly negative) Our data indicate that the magnitude of ΔGET is at least as larg ...
... Due to entropy mixing, the slope of the pH-dependence should be negative. Observed (total) activation entropy change The slope of the pH-dependence of the observed (total) entropy change is positive (or in some cases slightly negative) Our data indicate that the magnitude of ΔGET is at least as larg ...
PDF
... Regarding the second phenomenon, a number of intracellular studies have shown that the membrane potential of neurons does not take on any value between rest and threshold with equal probability but rather that it assumes either a depolarized state, associated with spiking activity, or a resting stat ...
... Regarding the second phenomenon, a number of intracellular studies have shown that the membrane potential of neurons does not take on any value between rest and threshold with equal probability but rather that it assumes either a depolarized state, associated with spiking activity, or a resting stat ...
Bidirectional propagation of Action potentials
... porebuilding proteins called ion channels. Consequently K+ ions diffuse down the ion gradient and leed to a negative charge inside the cell, consequently maintain the resting potential. If it is possible to change the membrane potential rapidly, the cell is excitable, such as nerves and muscles. A r ...
... porebuilding proteins called ion channels. Consequently K+ ions diffuse down the ion gradient and leed to a negative charge inside the cell, consequently maintain the resting potential. If it is possible to change the membrane potential rapidly, the cell is excitable, such as nerves and muscles. A r ...
Monte Carlo simulations of peptide–membrane interactions with the
... membrane-induced conformational changes in the peptide. At constant temperature (T), it can be calculated as Gcon ¼ E TS, where DE is the internal energy difference between the peptide in the aqueous phase and in the bilayer. The internal energy is a statistical potential derived from available ...
... membrane-induced conformational changes in the peptide. At constant temperature (T), it can be calculated as Gcon ¼ E TS, where DE is the internal energy difference between the peptide in the aqueous phase and in the bilayer. The internal energy is a statistical potential derived from available ...
L egionella pneumophila
... major fracture plane occurred through the hydrophobic region of the plasma (inner) membrane revealing both the protoplasmic (PFim)and extracellular (EF,,) faces (Fig. 1 c), the PF,, being seen more often. For each strain studied, the distribution of particles on both the PF,, and EF,, was unaffected ...
... major fracture plane occurred through the hydrophobic region of the plasma (inner) membrane revealing both the protoplasmic (PFim)and extracellular (EF,,) faces (Fig. 1 c), the PF,, being seen more often. For each strain studied, the distribution of particles on both the PF,, and EF,, was unaffected ...
Chapter 24 Electric Potential
... 24-12 Potential of a Charged Isolated Conductor m2-042 Which of the following statements are CORRECT: (1) The electric flux through a Gaussian surface depends on the shape of the surface. (2) The electric flux through a closed surface depends on the net charge enclosed by the surface. (3) The elect ...
... 24-12 Potential of a Charged Isolated Conductor m2-042 Which of the following statements are CORRECT: (1) The electric flux through a Gaussian surface depends on the shape of the surface. (2) The electric flux through a closed surface depends on the net charge enclosed by the surface. (3) The elect ...
Membrane potential
Membrane potential (also transmembrane potential or membrane voltage) is the difference in electric potential between the interior and the exterior of a biological cell. With respect to the exterior of the cell, typical values of membrane potential range from –40 mV to –80 mV.All animal cells are surrounded by a membrane composed of a lipid bilayer with proteins embedded in it. The membrane serves as both an insulator and a diffusion barrier to the movement of ions. Ion transporter/pump proteins actively push ions across the membrane and establish concentration gradients across the membrane, and ion channels allow ions to move across the membrane down those concentration gradients. Ion pumps and ion channels are electrically equivalent to a set of batteries and resistors inserted in the membrane, and therefore create a voltage difference between the two sides of the membrane.Virtually all eukaryotic cells (including cells from animals, plants, and fungi) maintain a non-zero transmembrane potential, usually with a negative voltage in the cell interior as compared to the cell exterior ranging from –40 mV to –80 mV. The membrane potential has two basic functions. First, it allows a cell to function as a battery, providing power to operate a variety of ""molecular devices"" embedded in the membrane. Second, in electrically excitable cells such as neurons and muscle cells, it is used for transmitting signals between different parts of a cell. Signals are generated by opening or closing of ion channels at one point in the membrane, producing a local change in the membrane potential. This change in the electric field can be quickly affected by either adjacent or more distant ion channels in the membrane. Those ion channels can then open or close as a result of the potential change, reproducing the signal.In non-excitable cells, and in excitable cells in their baseline states, the membrane potential is held at a relatively stable value, called the resting potential. For neurons, typical values of the resting potential range from –70 to –80 millivolts; that is, the interior of a cell has a negative baseline voltage of a bit less than one-tenth of a volt. The opening and closing of ion channels can induce a departure from the resting potential. This is called a depolarization if the interior voltage becomes less negative (say from –70 mV to –60 mV), or a hyperpolarization if the interior voltage becomes more negative (say from –70 mV to –80 mV). In excitable cells, a sufficiently large depolarization can evoke an action potential, in which the membrane potential changes rapidly and significantly for a short time (on the order of 1 to 100 milliseconds), often reversing its polarity. Action potentials are generated by the activation of certain voltage-gated ion channels.In neurons, the factors that influence the membrane potential are diverse. They include numerous types of ion channels, some of which are chemically gated and some of which are voltage-gated. Because voltage-gated ion channels are controlled by the membrane potential, while the membrane potential itself is influenced by these same ion channels, feedback loops that allow for complex temporal dynamics arise, including oscillations and regenerative events such as action potentials.