patch-clamp electrophysiology‚ investigators have recently cloned‚ expressed‚ and characterized the genes encoding many of these proteins. Ion-channel proteins are under intense scrutiny in an effort to determine their roles in pathophysiology and as potential targets for drugs. Defective ion-channel proteins are responsible for cystic fibrosis‚1 the long-QT syndrome‚2 heritable hypertension (Liddle’s syndrome)‚3‚4 familial persistent hyperinsulinemic hypoglycemia of infancy‚5‚6 hereditary nephrolithiasis
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substances across the cell membrane without the use of energy by the cell. During passive transport‚ substances move down their concentration gradient‚ hence no energy is required. Passive transports can happen through three different channels‚ namely 1. lipid bilayer 2. pore protein 3. carrier protein SIMPLE DIFFUSION What is diffusion? Diffusion is the movement of particles from a high density region to a low density region. No energy is needed and no membrane involves in diffusion
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Suggested answers to Practical Workbook for SBA Ch 1 Introducing biology Practical 1.1 Design an investigation of the effect of fresh pineapple on the setting of jelly Propose a hypothesis (p. 1-2) It is the fresh pineapple that causes the jelly to remain in liquid form. Design and perform an experiment (p. 1-2) 1 (Answer varies with Ss. The recommended quantity of jelly powder and water is stated on the packet of the jelly powder. Jelly will not set if it is too dilute.)
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and (+) ions (Ca++) can pass into the muscle fiber which depolarizes the membrane potential. As this happens the voltage-gated sodium channels are triggered opens and allows sodium ions (NaCl-) enters the fiber and action potential spreads along the entire membrane to initiate excitation-contraction coupling. Following the depolorization of the membrane‚ repolarization occurs‚ which reestablishes the negative membrane potential. The ACh within the synaptic cleft is also degraded by AChE so that ACh
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Osmosis is the spontaneous net movement of solvent molecules through a partially permeable membrane into a region of higher solute concentration‚ in the direction that tends to equalize the solute concentrations on the two sides. It may also be used to describe a physical process in which any solvent moves‚ without input of energy‚ across a semipermeable membrane separating two solutions of different concentrations. Although osmosis does not require input of energy‚ it does use kinetic energy and
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Describe the pathways AND mechanisms by which water passes from the soil to the xylem vessels in the root. (7 marks) As there is a higher water potential in the soil‚ and there is a lower water potential in the root hair cells‚ the water molecules move from the area of high potential to the area of low potential. From the soil into the roots. The process by which the molecules of water move into the root hair cells is ’osmosis’. This is a passive process‚ meaning that no energy (in the form of
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respiration * N – Nutrition = synthesis of organic materials * R – Reproduction = asexual (cell division) * R – Response = to change (environmental) * * 2.1.4 * Compare relative sizes * 1 nm = molecule * 10nm = Membrane * 100nm = Virus * 1 um = Bacteria * 10um (or less) = organelle * 100um (or less) = cell * * 2.1.5 * Calculating Linear Magnification (answer = magnification) 1. Measure scale bar on page e.g. 15mm 2. Convert
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the nerve impulse would travel at a much slower speed. d) What is d? Explain what happens when an action potential reaches d. The structures labeled d are synaptic knobs. When an action potential reaches the knobs‚ they release neurotransmitters that carry the signal across the synapse. These neurotransmitters usually work by binding to receptor proteins in the membrane of the receiving neuron. This binding opens gates that allow sodium ions to enter the cell. 3. Name two ways
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Chapter 48 Nervous Systems Lecture Outline Overview: Command and Control Center The human brain contains an estimated 1011 (100 billion) neurons. Each neuron may communicate with thousands of other neurons in complex information-processing circuits. Recently developed technologies can record brain activity from outside the skull. One technique is functional magnetic resonance imaging (fMRI)‚ which reconstructs a 3-D map of the subject’s brain activity. The results of brain imaging and other
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the selective diffusion of water and other molecules across membranes‚ which in the case of living organisms‚ the solvent (water) would have net movement across a selective permeable membrane. Osmosis only occurs when a membrane such as that of a cell is permeable to water molecules but not to specific solutes (Tortora & Derrickson 2014). Certain simple molecules such as oxygen‚ water and carbon dioxide can travel across the cell membrane by osmosis‚ a passive process similar to other forms of diffusion
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