1.3 Notes
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This document outlines key concepts of membrane structure in IB Biology, detailing definitions of terms like polar, non-polar, hydrophobic, and hydrophilic. It discusses the composition of cell membranes, including phospholipids and protein types, and explores historical models of membrane structure such as the Davson-Danielli and Singer-Nicholson models. Additionally, it addresses the role of cholesterol in membrane stability and permeability.
1.3 Notes
- 1. IB Biology Chapter 1 Notes: Membrane Structure (1.3) NAME: Word Definition Polar Having a charge or partial charge Non-polar Neutral—no charge Hydrophobic Fear of water or will not mix with water Hydrophilic Likes water or will mix with water Amphipathic Describes a molecule with both polar and nonpolar regions Cholesterol Help maintain membrane structure at a variety of temperatures Glycoproteins Proteins that have a sugar attached to them at the surface of the membrane. Integral proteins Proteins that span the membrane Peripheral proteins Proteins only on one side of the membrane Phospholipids Lipids made of two fatty acid chains and one phosphate group that make up the primary structure of the cell membrane. They have polar and non-polar sections Bilayer A double layer Semi-permeable Only allowing certain materials to cross
- 2. 1.3.1 Phospholipids form bilayers in water due to the amphipathic properties of phospholipid molecules. 1.3.6 Analysis of evidence from electron microscopy that led to the proposal of the Davson-Danielli model. 1.3.7 Analysis of the falsification of the Davison- Danielli model that led to the Singer-Nicolson model. 1.3.2 Membrane proteins are diverse in terms of structure, position in the membrane and function. Draw and label a phospholipid bilayer (including hydrophilic and hydrophobic regions): Describe the membrane structure suggested by Davson and Danelli and their evidence: Outline evidence that led to the disproving of the Davson-Danielli model: 1. Freeze-etched electron micrographs: 2. Structure of membrane proteins: 3. Fluorescent antibody tagging: Functions of Membrane Proteins
- 3. 1.3.5 Draw the fluid mosaic membrane model 1.3.3 Cholesterol is a component of animal cell membranes. 1.3.4 Cholesterol in mammalian membranes reduces membrane fluidity and permeability to some solutes. Draw and label the parts of the fluid mosaic membrane model: Describe the position of cholesterol in the structure of animal cell membranes: Describe the role/ function of cholesterol in animal cell membranes: