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    • Chemistry SL/HL >
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      • All Vocab Definitions
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      • Unit 1,2 & 12
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      • Unit 8 & 18
      • Unit 9 & 19
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      • Option D: Medicinal Chemistry >
        • D.1 PHARMACEUTICAL PRODUCTS AND DRUG ACTION
        • D.2 Aspirin and penicillin
        • D.3 Opiates
        • D.4 pH Regulation of the Stomach
        • D.5 Antiviral Medications
        • D.6 Environmental impact of some medications
        • D.7 Taxol- A Chiral Auxiliary Case Study
        • D.8 Nuclear Medicine
        • D.9 Drug Detection and Analysis
    • Biology SL >
      • Tips & Guides
      • TOPIC 1: CELL BIOLOGY >
        • 1.1 Introduction to cells
        • 1.2 Ultrastructure of Cells
        • 1.3 Membrane Structure
        • 1.4 Membrane Transport
        • 1.5 Origin of Cells
        • 1.6 Cell Division
      • TOPIC 2: MOLECULAR BIOLOGY >
        • 2.1 Molecules to metabolism
        • 2.2 Water
        • 2.3 Carbohydrates and Lipids
        • 2.4 Proteins
        • 2.5 Enzymes
        • 2.6 Structure of DNA and RNA
        • 2.7 DNA Replications, Transcription and Translation
        • 2.8 Cell Respiration
        • 2.9 Photosynthesis
      • Topic 3: Genetics >
        • 3.1 Genes
        • 3.2 Chromosomes
        • 3.3 Meiosis
        • 3.4 Inheritance
        • 3.5 Genetic Modification and Biotechnology
      • Topic 4: Ecology >
        • 4.1: Species, Communities and Ecosystems
        • 4.2 Energy Flow
        • 4.3 Carbon Cycling
        • 4.4 Climate Change
      • Topic 5: Evolution and Biodiversity >
        • 5.1 Evidence for evolution
        • 5.2 Natural Selection
        • 5.3 Classification and Biodiversity
        • 5.4 Cladistics
      • Topic 6: Human Physiology >
        • 6.1 Digestive System
        • 6.2 The blood system
        • 6.3 Defense against infectious disease
        • 6.4 Gas Exchange
        • 6.5 Neurons and Synapses
        • 6.6 Hormones, Homeostasis and Reproduction
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      • Topic 5: Electricity & Magnetism
      • Topic 6: Circular Motion & Gravitation
      • Topic 7: Atomic, Nuclear, & Particle Physics
      • Topic 8: Energy Production
      • Option D: Astrophysics
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      • Tips & guide
      • Unit 1: Changing population
      • Unit 2: Global climate—vulnerability and resilience
      • Unit 3: Global resource consumption and security
      • Unit 4: Power, Places and Networks
      • Unit 5: Human Development and Diversity
      • Unit 6: Global Risks and Resillience
      • Option A: Freshwater
      • Option B: Ocean and Coastal Margins
      • Option C: Extreme Environments
      • Option E: Leisure, tourism and sport
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      • Unit 1: Business Organization and Movement >
        • 1.1 Nature of Business
        • 1.2 Types of Organizations
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        • 1.5 External Environment
        • 1.6 Growth and evolution
      • Unit 2: Human Resource Management >
        • 2.1 The functions and evolution of human resource management
        • 2.2 Organizational structure
        • 2.3 Leadership and management
        • 2.4 Motivation
      • Unit 3: Finance and Accounts >
        • 3.1 Sources of Finance
        • 3.2 Costs and Revenues
        • 3.3 Break-even analysis
        • 3.4 Final accounts
        • 3.5 Profitability and liquidity ratio analysis
        • 3.7 cash flow
      • Unit 4: Marketing >
        • 4.1 The role of marketing
        • 4.2 Marketing Planning
        • 4.4 Market Research
        • 4.5 The four ps
        • 4.8 E-commerce
      • Unit 5: Operations Management >
        • 5.1 The role of operations Management
        • 5.2 Production methods
        • 5.4 Locations
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        • 1.1 Competitive Markets: Demand and Supply
      • macroeconomics
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      • Topic 1: Measurements and Uncertainties
      • Topic 2: Mechanics
      • Topic 3: Thermal Physics
      • Topic 4: Waves
      • Topic 5: Electricity and Magnetism
      • Topic 6: Circular Motion and Gravitation
      • Topic 7: Atomic, Nuclear and Particle Physics
      • Topic 8: Energy Production
      • Option D: Astrophysics
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1.3 MEMBRANE STRUCTURE

1.3 Syllabus
Picture

U1. Phospholipids form bilayers in water due to the amphipathic properties of phospholipid molecules.

Cell Membrane: Cell membranes are made of phospholipids, molecules composed of a phosphate head and a lipid tale 
Phospholipids: Molecules composed of a phosphate head and a lipid tale. This makes phospholipids amphipathic. 
    -Phosphate head: Hydrophilic (Polar) = Attracted to water
    -Tails: Hydrophobic (Non-polar)= Not attracted to water (Consists of 2 hydrocarbon chains)
- When phospholipids mixed with water, phosphate head is attracted to water and hydrocarbon tail is attracted to each other and not attracter to water. This forms double layer
-Membrane needs to be fluid enough for cell to move
- Properties of the Phospholipid Bilayer: The bilayer is held together by weak hydrophobic interactions between the tails. Hydrophilic / hydrophobic layers restrict the passage of many substances. Individual phospholipids can move within the bilayer, allowing for membrane fluidity and flexibility. This fluidity allows for the spontaneous breaking and reforming of membranes (endocytosis / exocytosis)


U2. Membrane proteins are diverse in terms of structure, position in the membranes and function.

-Primary Function: Form barrier through which ions and hydrophilic molecules do not easily pass. It is carried out by phospholipid bilayer.
- Integral Proteins (Carrier and channel protein): Permanently embedded in hydrocarbon chains in centre of membrane. Many go all way through. 
- Peripheral protein: Usually have temporary association with the membrane , 

 Related Question: 
Q. Write down functions of membrane protein

Answer: 
-Cell to cell communication
-Channels for passive transport
-Active transport
-Cell Adhesion
-Immobilized Enzymes embedded in the membrane
-Electron carriers
-Binding site for Hormone
​

U3. Cholesterol is a component of animal cell membranes

Cholesterol: Makes the phospholipids pack more tightly and regulate the fluidity and flexibility of the membrane. Mostly hydrophobic and restrict movement of phospholipid molecule. It reduces fluidity of membrane and permeability of membrane to hydrophilic particles ions.
  • Type of lipid: Steroids -> Interact with fatty acid tails of phospholipids to moderate properties of the membrane.
  • Disrupt regular packing of hydrocarbon tails of phospholipid molecules a
- Cholesterol functions to immobilize the outer surface of the membrane, reducing fluidity.
   →It makes the membrane less permeable to very small water-soluble molecules that would otherwise freely cross
   →It functions to separate phospholipid tails and so prevent crystallization of the membrane
   →It helps secure peripheral proteins by forming high density lipid 

S1. Drawing of the fluid mosaic model.

Picture

S2. Analysis of the falsification of the Davison-Danielli model that led to the Singer-Nicolson model.

Evidences that have falsified Davison-Danielli Model: 
​-Presence of globular proteins with phospholipid bilayer
-Non polar amino acids cause proteins to remain embedded in membranes 
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  • Home
  • IB STUDY MATERIALS
    • Psychology SL/HL >
      • Tips & Guide
      • Biological Approach >
        • Brain and Behaviour
        • Hormones and Pheromones
        • Genetics and Evolution
        • HL Animal Research
      • Sociocultural Approach >
        • Individual and the group
        • Cultural Origins
        • Cultural Influences
        • HL Globalization
      • Cognitive Approach >
        • Cognitive Processing
        • Reliability of Cognitive Processes
        • Emotion and Cognition
        • HL Digital World
      • B. Human Relationships >
        • Personal Relationships
        • Group Dynamics
      • D. Developmental >
        • Developing as a Learner
        • Developing an Identity
      • Studies >
        • Biological Approach
        • Sociocultural Approach
        • Cognitive Approach
        • B. Human Relationships
        • D. Developmental
    • Chemistry SL/HL >
      • Tips & Guide
      • All Vocab Definitions
      • ALL EQUATIONS
      • Unit 1,2 & 12
      • Unit 3 &13
      • Unit 4 &14
      • Unit 5,6,7 & 15,16,17
      • Unit 8 & 18
      • Unit 9 & 19
      • Unit 10 & 20
      • Unit 11 & 21
      • Option D: Medicinal Chemistry >
        • D.1 PHARMACEUTICAL PRODUCTS AND DRUG ACTION
        • D.2 Aspirin and penicillin
        • D.3 Opiates
        • D.4 pH Regulation of the Stomach
        • D.5 Antiviral Medications
        • D.6 Environmental impact of some medications
        • D.7 Taxol- A Chiral Auxiliary Case Study
        • D.8 Nuclear Medicine
        • D.9 Drug Detection and Analysis
    • Biology SL >
      • Tips & Guides
      • TOPIC 1: CELL BIOLOGY >
        • 1.1 Introduction to cells
        • 1.2 Ultrastructure of Cells
        • 1.3 Membrane Structure
        • 1.4 Membrane Transport
        • 1.5 Origin of Cells
        • 1.6 Cell Division
      • TOPIC 2: MOLECULAR BIOLOGY >
        • 2.1 Molecules to metabolism
        • 2.2 Water
        • 2.3 Carbohydrates and Lipids
        • 2.4 Proteins
        • 2.5 Enzymes
        • 2.6 Structure of DNA and RNA
        • 2.7 DNA Replications, Transcription and Translation
        • 2.8 Cell Respiration
        • 2.9 Photosynthesis
      • Topic 3: Genetics >
        • 3.1 Genes
        • 3.2 Chromosomes
        • 3.3 Meiosis
        • 3.4 Inheritance
        • 3.5 Genetic Modification and Biotechnology
      • Topic 4: Ecology >
        • 4.1: Species, Communities and Ecosystems
        • 4.2 Energy Flow
        • 4.3 Carbon Cycling
        • 4.4 Climate Change
      • Topic 5: Evolution and Biodiversity >
        • 5.1 Evidence for evolution
        • 5.2 Natural Selection
        • 5.3 Classification and Biodiversity
        • 5.4 Cladistics
      • Topic 6: Human Physiology >
        • 6.1 Digestive System
        • 6.2 The blood system
        • 6.3 Defense against infectious disease
        • 6.4 Gas Exchange
        • 6.5 Neurons and Synapses
        • 6.6 Hormones, Homeostasis and Reproduction
    • Physics SL >
      • Must-have Resources
      • Full Study Resources
      • Other Resources
      • Tips & Guide
      • IA, Lab Report
      • Topic 1: Measurements & Uncertainties
      • TOPIC 2: MECHANICS
      • TOPIC ​3: THERMAL PHYSICS
      • Topic 4: Waves
      • Topic 5: Electricity & Magnetism
      • Topic 6: Circular Motion & Gravitation
      • Topic 7: Atomic, Nuclear, & Particle Physics
      • Topic 8: Energy Production
      • Option D: Astrophysics
    • Geography SL/HL >
      • Tips & guide
      • Unit 1: Changing population
      • Unit 2: Global climate—vulnerability and resilience
      • Unit 3: Global resource consumption and security
      • Unit 4: Power, Places and Networks
      • Unit 5: Human Development and Diversity
      • Unit 6: Global Risks and Resillience
      • Option A: Freshwater
      • Option B: Ocean and Coastal Margins
      • Option C: Extreme Environments
      • Option E: Leisure, tourism and sport
    • Business SL/HL(pending) >
      • Tips & guides
      • Unit 1: Business Organization and Movement >
        • 1.1 Nature of Business
        • 1.2 Types of Organizations
        • 1.3 Organizational objectives
        • 1.4 Stakeholders
        • 1.5 External Environment
        • 1.6 Growth and evolution
      • Unit 2: Human Resource Management >
        • 2.1 The functions and evolution of human resource management
        • 2.2 Organizational structure
        • 2.3 Leadership and management
        • 2.4 Motivation
      • Unit 3: Finance and Accounts >
        • 3.1 Sources of Finance
        • 3.2 Costs and Revenues
        • 3.3 Break-even analysis
        • 3.4 Final accounts
        • 3.5 Profitability and liquidity ratio analysis
        • 3.7 cash flow
      • Unit 4: Marketing >
        • 4.1 The role of marketing
        • 4.2 Marketing Planning
        • 4.4 Market Research
        • 4.5 The four ps
        • 4.8 E-commerce
      • Unit 5: Operations Management >
        • 5.1 The role of operations Management
        • 5.2 Production methods
        • 5.4 Locations
    • Economics SL/HL (pending) >
      • Tips & guides
      • MICROECONOMICS >
        • 1.1 Competitive Markets: Demand and Supply
      • macroeconomics
    • Chinese B SL >
      • Oral Example
    • Extended Essay (EE) >
      • General Tips
      • Physics EE
    • Internal Assessment (IA) >
      • General Tips
    • Theory of Knowledge >
      • Essay Example
      • Presentation Example
    • Other notes >
      • Topic 1: Measurements and Uncertainties
      • Topic 2: Mechanics
      • Topic 3: Thermal Physics
      • Topic 4: Waves
      • Topic 5: Electricity and Magnetism
      • Topic 6: Circular Motion and Gravitation
      • Topic 7: Atomic, Nuclear and Particle Physics
      • Topic 8: Energy Production
      • Option D: Astrophysics
    • Other Citations
  • UNI application
    • United States
    • United Kingdom >
      • Academic Schools
      • Art & Design Schools
    • China
    • Japan
    • Hong Kong
    • Canada (pending)
    • Australia (pending)
  • our warm advice
    • academic advice!
    • Toxic Productivity
    • Finding Your Balance
    • Giving Up
    • YOLO?
    • Are grades important
    • Danger of Quotes
    • How to Destress
  • About us