Plasma Membrane - Part 2 Western Sydney University PDF
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Western Sydney University
Dr Anna Maceri
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This document provides details about the structure and function of the plasma membrane, including processes like diffusion, facilitated diffusion, and osmosis. It discusses various types of transport across the membrane. The document is part of a larger educational resource from Western Sydney University.
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THE CELLULAR LEVEL OF ORGANISATION THE PLASMA MEMBRANE PART 2/2 Dr Anna Maceri School of Nursing and Midwifery Commonwealth of Australia Copyright Act 1968 WARNING This material has been reproduced and communicated to you by or on behalf of Western Sydney University under Part VB of the Copyright Ac...
THE CELLULAR LEVEL OF ORGANISATION THE PLASMA MEMBRANE PART 2/2 Dr Anna Maceri School of Nursing and Midwifery Commonwealth of Australia Copyright Act 1968 WARNING This material has been reproduced and communicated to you by or on behalf of Western Sydney University under Part VB of the Copyright Act 1968 (the Act). The material in this communication may be subject to copyright under the Act. Any further reproduction or communication of this material by you may be the subject of copyright protection under the Act. Do not remove this notice. The Plasma Membrane cholesterol Phospholipids bilayer Integral proteins Peripheral proteins Phospholipid molecule Hydrophilic head (polar) Hydrophobic tail (nonpolar) See page 95 & 96 Marieb & Hoehn (2019) The Plasma Membrane Integral protein Peripheral proteins Transport across the membrane Extracellular fluid Interstitial fluid plasma Blood vessel Cell Plasma Intracellular fluid ex See page 1045 Marieb & Hoehn (2019) (liquid part of blood) Terminology Salts- compounds that dissociate in water into ions. Eg NaCl, CaCO3, KCl See page 71 Marieb & Hoehn (2019) Ions- charged molecules eg Na+ ,K+, 2+ Ca ,Cl NaCl → Na++ Clsalt ions Proteins- Complex molecules present in the body. Eg hormones, enzymes, antibodies, collagen, keratin, hemoglobin. See page 81 Marieb & Hoehn (2019) Terminology ATP- (adenosine triphosphate) primary energy source for the cell. Made by mitochondria. Solute- substance being dissolved Solvent- dissolves the solute eg water Diffusion Molecules move from area of high concentration towards area of low concentrationconcentration gradient The Plasma Membrane Selectively permeable-allows some substances to pass through more readily than other. Restricts the movement of some substances. Passive- no energy input from the cell. Active- cellular energy (eg ATP) is used to drive the process. Passive Processes 1. Simple diffusion 2. Facilitated – Carrier mediated – Channel mediated 3. Osmosis 1. Simple Diffusion Passes directly through the plasma membrane. Unassisted passage of very small molecules (O2, CO2) or lipid soluble particles. Does not use cell energy (ATP). Driven by concentration gradient. 2. Facilitated Diffusion Channel mediated diffusion allows passage of ions (Na+, K+, Ca2+) Does not use cell energy (ATP). Driven by concentration gradient. Carrier mediated diffusion Sugars, amino acids Shape change to transport through membrane Does not use cell energy (ATP). Driven by concentration gradient. 3. Osmosis Movement of solvent (water). Does not use cell energy (ATP). Driven by concentration gradient. Greater concentration of water Lower concentration of water Osmosis The concentration of a solution can change the shape of a cell by altering its internal water volume. Many solutes can not diffuse across the plasma membrane so instead they can influence the movement of water across the membrane.....potentially changing the shape of the cell. Osmosis Isotonic solution same solute concentration as inside the cell Hypertonic solution greater solute concentration than inside the cell less water (solvent) Hypotonic solution lower solute concentration than inside the cell more water (solvent) Hypotonic Hypertonic Osmosis Osmosis 10% NaCl/ 90% H2O Hypertonic solution Red blood cell 0.9% NaCl / 99.1% H2O Osmosis 0.9% NaCl / 99.1% H2O Isotonic solution Red blood cell 0.9% NaCl / 99.1% H2O Osmosis 0.1% NaCl / 99.9% H2O Hypotonic solution Red blood cell 0.9% NaCl / 99.1% H2O Active Processes Uses cell energy (ATP) to drive the movement of solutes across the plasma membrane. Against concentration gradient. Primary Active Transport Vesicular Transport Primary Active Transport ATP is used to drive the transport of substances across plasma membrane. E.g. Na+/K+ pump. Greater concentration of in extracellular fluid. Lower concentration of Na+ in cytoplasm. Na+ Lower concentration of K+ in extracellular fluid. Greater concentration of K+ in cytoplasm. Primary Active Transport ATP is used to drive the transport of substances across plasma membrane. Na+/K+ pump. Greater concentration of in extracellular fluid. Greater concentration of K+ in cytoplasm. Na+ Lower concentration of K+ in extracellular fluid. Greater concentration of K+ in cytoplasm. Primary Active Transport ATP is used to drive the transport of substances across plasma membrane. Na+/K+ pump. Greater concentration of in extracellular fluid. Greater concentration of K+ in cytoplasm. Na+ Lower concentration of K+ in extracellular fluid. Greater concentration of K+ in cytoplasm. Vesicular transport Molecules or particles are transported across the plasma membrane in vesicles. Uses ATP to drive movement. EndocytosisTransport substances into the cell. Infolding of the plasma membrane fuses to create a vesicle. Phagocytosis- solids (eg bacteria). Pinocytosis- liquids. ExocytosisTransport substances out of the cell. Vesicle fuses with plasma membrane and releases contents. Please watch the following videos. Membrane Transport Animation https://www.youtube.com/watch?v=FZccM0B5P rE https://www.youtube.com/watch?v=YfoiHrv57b 0 Osmosis: http://www.youtube.com/watch?v=7-QJ-UUX0iY
