Transcript The Living World

Lecture 3
Macromolecules
Forming Macromolecules
 An organic molecule consists of a
carbon-based core with special
groups attached
 These groups have special
properties and are referred to as
functional groups
 Organisms are primarily made of
four kinds of molecules
 Carbohydrates
 Lipids
 Proteins
 Nucleic acids
 These are termed
macromolecules
 They constitute the building
materials and machinery of
the cell
Macromolecule Formation & Breakdown
 Macromolecules are made by
a process termed dehydration
synthesis
 Macromolecules are broken
down by a process termed
hydrolysis
 Both types of processes require enzymes
Mechanism of Enzyme Action
 Enzyme binds with substrate
 Product is formed at a lower
activation energy
 Product is released
PLAY
How Enzymes Work
Types of Macromolecules
Types of Macromolecules
Carbohydrates
 Also referred to as sugars
 Provide building materials and energy storage
 Are molecules that contain carbon, hydrogen and oxygen in a
1:2:1 ratio
 Are of two main types:
 Simple carbohydrates
 Complex carbohydrates
Simple Carbohydrates
 Monosaccharides
 Consist of one subunit
 Disaccharides
 Consist of two subunits
Complex Carbohydrates
 Consist of long polymers of sugar subunits
 Also termed polysaccharides
 Examples:
 Starch provides energy storage in plants
 Glycogen provides energy storage in animals
 Cellulose is found in the cell walls of plants
 Chitin is found in the cell walls of fungi & insect
exoskeletons
Carbohydrate Functions
Carbohydrate Functions
Three Forms of Lipids
 Large nonpolar molecules that are insoluble in water
 Fats
 Used for long-term energy
storage
 Also termed triglycerides or
triacylglycerol
 Composed of three fatty
acid chains linked to
glycerol
 Phospholipids
 A modified fat
 One of the three fatty acids is
replaced by a phosphate and a
small polar functional group
 In water, phospholipids
aggregate to form a lipid bilayer
 Steroids
 Composed of four carbon rings
 Examples:
 Cholesterol
 Found in most animal cell
membranes
 Male and female sex hormones
Saturated & Unsaturated Fats
 Fatty acids can be saturated or unsaturated
Proteins
 Made up of subunits
called amino acids
 There are 20 common
amino acids, and they
fall into one of four
general groups
 Amino acids are
linked together by
peptide bonds
 Long chains of
amino acids are
called polypeptides
Protein Functions
Protein Functions
Protein Structure
 Determined by the sequence of its
amino acids
 There are four general levels
 Primary
 Secondary
 Tertiary
 Quaternary
Protein Structure

Primary structure
 The specific amino acid sequence of a protein

Secondary structure
 The initial folding of the amino acid chain by hydrogen bonding
PLAY Chemistry of Life:
Proteins: Secondary Structure

Tertiary structure
 The final three-dimensional shape of the protein
PLAY

Chemistry of Life:
Proteins: Tertiary Structure
Quaternary structure
 The spatial arrangement of polypeptides in a multi-component protein
PLAY
Chemistry of Life:
Proteins: Quaternary Structure
Protein Structure
 Proteins can be divided into two classes
1. Structural
 Long cables
 Provide shape/strength
2. Globular
 Grooves and depressions
 Enzymes
 Changes in a protein’s environment can
cause a protein to denature
 It loses its three-dimensional structure and
becomes inactive
Chaperone Proteins
 Help newly-produced proteins to fold properly
 Chaperone protein deficiencies may play a role in certain
diseases
 Cystic fibrosis and Alzheimer’s disease
Nucleic Acids
 Serve as information
storage molecules
 Long polymers of
repeating subunits
termed nucleotides
 A nucleotide is
composed of three parts
 Five-carbon sugar
 Nitrogen-containing
base
 Phosphate
DNA & RNA
RNA
Ribonucleic acid
DNA
Deoxyribonucleic acid
Sugar = Ribose
Bases = A, G, C, U
Sugar = Deoxyribose
Single-stranded
Double-stranded
Bases = A, G, C, T