3.1 BIOLOGICAL MEMBRANES 3.1.1 Properties of Cell Membranes • Separates living cell from its nonliving surroundings. • 8 nm thick. • Selectively permeable - allows some substances to cross more easily than others. 4.1.2 Fluid Mosaic Model • Singer and Nicolson (1972) - plasma membrane is a mosaic of proteins dispersed within lipid bilayer‚ with only bilayer‚ the hydrophilic regions exposed to water. Hydrophilic region of protein Phospholipid bilayer Hydrophobic region of protein
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MOVEMENT ACROSS MEMBRANES Intracellular fluid Extracellular fluid Pond water Blood plasma K+ A- ClNa+ Cl+ K+ Na+ Cl- Na+ Na+ Gill epithelial cell Intestinal epithelial cells Cl- Cell membrane Anionic proteins (a) Ion concentration inside a single animal cell (b) Ion concentration across gill epithelium of a freshwater fish Blood capillary Intestinal lumen Glucose from meal Cross section of small intestine (c) Glucose transport across intestinal epithelium into
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1 Experiment Membrane Transport Objectives ► Referring to energy‚ what two ways can substances enter a cell? What is active transport? What is passive transport? How is osmosis related to diffusion? How can we demonstrate active transport? How can we demonstrate Brownian movement? How can we demonstrate diffusion (2 ways)? How can we demonstrate osmosis (3 ways)? In terms of relationships between substances‚ how can we define “hypertonic”‚ “isotonic”‚ and “hypotonic”? What is the relationship
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effects of stressful experimental treatments on living membranes we are going to examine how fresh beets roots react when they are exposed to different temperatures. Membranes are an important feature of plant cells and they act as a barrier that separates the interior of the cell from the external environment (Campbell 133). They organize specific chemicals and reactions into specific compartments within the cell. Generally‚ cell membranes consist of phospholipids bilayer that is impermeable to
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Cell Membranes and Transport Hands-On Labs‚ Inc. Version 42-0033-00-01 Lab Report Assistant This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions‚ diagrams if needed‚ and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing
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The Nervous System: Membrane Potential 1. Record the intracellular and extracellular concentrations of the following ions (mM/L): Intracellular Extracellular Sodium (Na+) Potassium (K+) Chloride (Cl–) 2. Excitable cells‚ like neurons‚ are more permeable to ___________ than to ___________. 3. How would the following alterations affect the membrane permeability to K+? Use arrows to indicate the change in permeability. a. An increase in the number of passive K+ channels
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The Cell: Transport Mechanisms and Cell Permeability 1. Molecular motion: A and D 2. Velocity of molecular movement: B and C 4. Size of pores. Solubility in the lipid portion of the membrane and/or presence of membrane “carriers” for the substance(s). 5. Glucose- (a) move into the sac Albumin- (c) no movement Water- (b) move out of the cell NaCl- (a) move into the celll 7. Hypertonic- C- crenated Isotonic- B Hypotonic- A- hemolysis‚ bursting open due to swelling
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13 THE MEMBRANES OF DIFFERENT TYPES OF CELLS ARE INVOLVED IN MANY DIFFERENT FUNCTIONS – 25 MARKS Membranes are found in all organisms‚ around and within cells. They control the movements in and out of cells‚ as well as protecting cells. They also allow different functions to occur. They have the same basic structure called the plasma membrane. All plasma membranes‚ around or inside cells have a same phospholipid bilayer structure. Phospholipids contribute to the flexibility of membranes and transfer
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LAB REPORT 1 - LAB 7 CELL MEMBRANE FUNCTION Marisela Camacho Legarreta June 30‚ 2013 ACTIVITY 1 INTRODUCTION Be aware that all molecules have kinetic energy‚ which means that is an active energy that is always in motion. Molecules move in all different ways and this create an evenly distributed movement which is best known as diffusion. Diffusion is the movement of molecules from a region of their higher concentration to a lower concentration. METHODS Check the reaction of different
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Lecture: Plasma Membrane and Transport I. Structure of the Plasma Membrane A. plasma membrane - the surface encapsulating a cell B. Fluid Mosaic Model 1. bilayer of phospholipids a. hydrophilic heads - P04 end "water" "loving" attracted to water on inner/outer parts of cell b. hydrophobic tails - fatty acids "water" "fearing" attracted to each other on inside of bilayer c
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