Carbohydrates part1

Page 1: Introduction to Carbohydrates

  • Topic: Biochemistry Topic 4 Part 1

Page 2: Learning Objectives

  • Describe the major structural features and functions of carbohydrates

  • Distinguish between aldoses and ketoses

  • Draw linear and Haworth structures of glucose and fructose

    • Glucose: Example of an aldose

    • Fructose: Example of a ketose

  • Describe anomerisation in simple sugars

Page 3: What are Carbohydrates?

  • Essential Nutrients

    • Together with fats and proteins, carbohydrates are crucial for human survival.

  • Sources

    • Found in foods such as:

      • Bread

      • Cereals

      • Potatoes

      • Rice

  • Function

    • Primarily used as an energy source and for structural purposes.

Page 4: Main Functions of Carbohydrates

  • Energy Source

    • Example: Glucose

  • Structural Elements

    • Example:

      • Cellulose (in plants)

      • Chitin (in insects)

  • Precursor for Other Biomolecules

    • Examples include:

      • Amino acids

      • Lipids

      • Purines

      • Pyrimidines

Page 5: Features of Monomeric Carbohydrates (Monosaccharides)

  1. Composition

  • Carbohydrates consist of carbon, hydrogen, and oxygen.

  • "Carbo" refers to carbon; "hydrate" refers to water.

  1. Formula

  • General formula for monosaccharides: (CH2O)n (where n >= 3)

  • Example: Glucose (C6H12O6)

Page 6: Classification of Carbohydrates

  • Based on the Number of Simple Sugars

    • Monosaccharides

      • Contains one sugar unit

      • Examples: Glucose, Galactose, Fructose

    • Disaccharides

      • Contains two monosaccharide units

      • Examples: Sucrose, Lactose, Maltose

    • Oligosaccharides

      • Contains 2 to 10 sugar units

      • Example: Fructo-oligosaccharides

    • Polysaccharides

      • Contains more than 10 sugar units

      • Examples: Starch, Glycogen, Chitin, Cellulose

Page 7: Test Yourself

  • Jun Feng is tasked to write down simple sugars used in a practical.Help him fill in the formulas:

  1. C? H12 O?

  2. C4 H? O?

  3. C? H? O3

Page 8: Answers for Test Yourself

Fill in the formulas:

  1. C6 H12 O6

  2. C4 H8 O4

  3. C3 H6 O3

Page 9: Test Yourself - Maltose

  • The following is the structure of Maltose sugar.

  • Maltose is a:

    • A) Monosaccharide

    • B) Disaccharide

    • C) Oligosaccharide

    • D) Polysaccharide

Page 10: Test Yourself - Maltose Answer

  • Maltose is a Disaccharide

Page 11: Starch Structure Question

  • Structure of Starch: It contains chains of sugar residues.

  • Starch is a:

    • A) Monosaccharide

    • B) Disaccharide

    • C) Oligosaccharide

    • D) Polysaccharide

Page 12: Starch Structure Answer

  • Starch is a Polysaccharide

Page 13: Monosaccharides - Aldose and Ketose

  • Functional Groups

    • Aldehyde and Ketone functional groups

  • Nomenclature

Page 14: Classification of Carbohydrates

  1. By Number of Units

  • Mono-, Di-, Oligo-, Poly-

  1. By Number of Carbon Atoms

  • Triose, Tetrose, Pentose

  1. By Functional Group

  2. By Stereochemistry

  3. By Chemical Properties

  • Reducing or Non-reducing

Page 15: IUPAC Terminology

  • Suffix “-ose” denotes sugar.

  • Classification by number of carbon atoms:

    • 3 Carbons = Triose

    • 4 Carbons = Tetrose

    • 5 Carbons = Pentose

    • 6 Carbons = Hexose

Page 16: Monosaccharides Classification by Number of Carbons

  • Simple Sugar Types:

    • Triose (3C)

    • Tetrose (4C)

    • Pentose (5C)

    • Hexose (6C)

Page 17: Stereochemistry in Carbohydrates

  • Classification by Stereochemistry:

  • Determining D- and L- Forms

    • Identify penultimate carbon - the furthest chiral carbon from the aldehyde or ketone.

    • D-sugars: OH on right of penultimate carbon

    • L-sugars: OH on left of penultimate carbon

  • Fischer Projection

    • Draw most oxidized end at the top.

Page 18: D- and L- Isomers

  • Examples: Glyceraldehyde

    • D-(+) and L-(-)

Page 19: Isomer Information

  • Monosaccharides can exist as D- or L- isomers.

  • D forms are of primary interest in nature.

Page 20: Aldoses vs Ketoses

  • Aldoses

    • Monosaccharides containing an aldehyde group at the terminal end.

  • Ketoses

    • Monosaccharides containing a ketone group located between two carbons.

Page 21: Aldose and Ketose Structures

  • Structural Definitions:

    • Aldoses: -CHO at end

    • Ketoses: C=O between carbons

Page 22: Naming the Sugar Structure

  • Steps:

    1. Identify if it contains aldehyde or ketone group.

    2. Determine the number of carbons.

    • Combine to name the sugar.

Page 23: Naming Example

  • Naming Case:

  1. Aldehyde group indicates aldose.

  2. Count carbons to classify.

Page 24: Example: Glyceraldehyde

  • Classification:

    • Aldose (aldehyde group)

    • Triose (3C)

    • Named: Aldotriose.

Page 25: Example: Glucose

  • Structural Representation

  • Classification:

    • Aldose

    • Hexose (6C)

Page 26: Glucose Classification Example

  • Glucose classified as**:

    • Aldohexose (aldehyde + 6 carbons)

Page 27: Example: Fructose

  • Structural Representation

  • Classification: Ketose

    • Hexose (6C)

Page 28: Fructose Classification Example

  • Fructose classified as:

    • Ketohexose (ketone + 6 carbons)

Page 29: Testing Yourself - Structure

  • Name the structure, identify aldose/ketose and number of carbons.

Page 30: Testing Yourself - Structure Answer

  • Sugar classified as Ketotriose (C3)