Download Building Blocks of Life

Building Blocks of Life
An Introduction
Carbon is unparalleled in its ability to form
large, complex, and diverse molecules
• Proteins, DNA, carbohydrates, and other
molecules that distinguish living matter
are all composed of carbon compounds
•
Carbon—The Backbone of
Biological Molecules
Electron configuration determines the
kinds and number of bonds an atom will
form with other atoms
 With four valence electrons, carbon can
form four covalent bonds with a variety of
atoms

◦ makes large, complex molecules possible
Carbon atoms can form diverse molecules by
bonding to four other atoms

The valences of carbon and its most
frequent partners (hydrogen, oxygen, and
nitrogen) are the “building code” that
governs the architecture of living
molecules
Within cells, small organic molecules are
joined together to form larger molecules
 Macromolecules are large molecules
composed of thousands of covalently
connected atoms

Macromolecules
Monomers build polymers linked together
by covalent bonds
• Three of the four classes of life’s organic
molecules are polymers:
•
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Carbohydrates
Proteins
Nucleic acids
Lipids
polymers built from monomers
Monomers form larger molecules by
condensation reactions called dehydration
reactions
 Polymers are disassembled to monomers
by hydrolysis, a reaction that is
essentially the reverse of the dehydration
reaction

The Synthesis and Breakdown of
Polymers
Short polymer
Unlinked monomer
Dehydration removes a water
molecule, forming a new bond
Longer polymer
Dehydration reaction in the synthesis of a polymer
Hydrolysis adds a water
molecule, breaking a bond
Hydrolysis of a polymer
Sugars and sugar polymers
 Monosaccharides

◦ Simple sugars
◦ glucose
Carbonyl
group
Hydroxyl
group
Carbohydrates

Disaccharides
◦ 2 or more monosaccharides joined by
glycosidic linkage, covalent bond by
dehydration reaction
◦ Glucose + fructose
sucrose
Carbohydrates

Storage
◦ Plant starch
◦ Stored energy can be broken down by
hydrolysis into glucose
◦ Animal polysaccharide
 Glycogen
◦ Stored in liver and muscles
◦ Used for short term energy
Carbohydrates

Structure
◦ Cellulose: cell walls
 Requires an enzyme for animals to break it down
◦ Chitin: exoskeleton of arthropods and fungi
Carbohydrates

Fats, oils, waxes
◦ Mix poorly with water
◦ Fats
 Large molecules of glycerol and fatty acid chains
connected by dehydration
Lipids

Cell Membranes
◦ Phospholipid bi-layer
Lipids


Polymer of amino acids called polypeptides
Functions
◦
◦
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Enzymes
Storage of amino acids
Hormones
Motor
Defense
Transport
Receptors for chemical stimuli
structure
Proteins

Amino acids
◦ 20 amino acids from 1000’s of proteins
◦ Side chains “R” determines the properties
 Hydrophillic:polar
 Hydrophobic: non polar
 Hydrophillic: electric charge
Proteins

Structure
◦ 1°
 Linear chain
Proteins

2°
◦ Alpha helix: hair
◦ β pleated sheets: spider web
◦ Held together by hydrogen bonds between
amino groups
Proteins

3°
◦ Interactions between side chains “R”
 Hydrogen bonds
 Ionic bonds
 Disulfide bonds
 Van der Waals
Proteins

4°
◦ Aggregation of polypeptide subunits
 Collagen
 hemoglobin
Proteins

Denaturation
◦ Weak chemical bonds and interactions can be
destroyed
 Heat
 pH
Proteins

Polymer of nucleotides
◦ DNA and RNA
Nucleic Acids