Importance of Carbon
Carbon permeates the world of life—from the energy-requiring activities and structural organization of cells, to physical and chemical conditions that span the globe and influence ecosystems everywhere.
Humans and Global Warming
• Fossil fuels are rich in carbon
• Use of fossil fuels releases CO2 into atmosphere
• Increased CO2 may contribute to global warming
Organic Compounds
Hydrogen and other elements covalently bonded to carbon
Carbohydrates
Lipids
Proteins
Nucleic Acids
Carbon’s Bonding Behavior
• Outer shell of carbon has 4 electrons; can hold 8
• Each carbon atom can form covalent bonds with up to 4 atoms
Methane: Simplest Organic Compound
Structural formula
Ball-and-stick model
Space-filling model
HH
H
H
C
Figure 3.2Page 36
Bonding Arrangements
• Carbon atoms can form chains or rings
• Other atoms project from the carbon backbone Glucose
(ball-and-stick model)
In-text figurePage 36
Functional Groups
• Atoms or clusters of atoms that are covalently bonded to carbon backbone
• Give organic compounds their different properties
Examples of Functional Groups
Methyl group - CH3
Hydroxyl group - OH
Amino group - NH3+
Carboxyl group - COOH
Phosphate group - PO3-
Sulfhydryl group - SH
Carbohydrates
Monosaccharides(simple sugars)
Oligosaccharides(short-chain carbohydrates)
Polysaccharides(complex carbohydrates)
• Most include fatty acids– Fats– Phospholipids– Waxes
• Sterols and their derivatives have no fatty acids
• Tend to be insoluble in water
Lipids
Phospholipids
• Main component of
cell membranes
• Hydrophobic head
• Hydrophilic tails
Fig. 3.14a,bPage 43
Sterols and Derivatives
• No fatty acids
• Rigid backbone of
four fused-together
carbon rings
• Cholesterol - most
common type in
animals
Figure 3.15aIn-text p43
Cholesterol
Waxes
• Long-chain fatty acids linked to
long-chain alcohols or carbon
rings
• Firm consistency, repel water
• Important in water-proofing
Protein Synthesis
• Peptide bond
– Condensation reaction links amino group of
one amino acid with carboxyl group of next
Water forms as a by-product
Fig. 3.18aPage 45
Primary Structure
• Sequence of amino acids
• Unique for each protein
• Two linked amino acids = dipeptide
• Three or more = polypeptide
• Backbone of polypeptide has N atoms:
-N-C-C-N-C-C-N-C-C-N-
Second and Third Levels
• Hydrogen bonding
produces helix or
sheet
• Domain formation
Secondary structure
Tertiary structure
Figure 3.19aPage 46
Fourth Level Structure
Some proteins
are made up of
more than one
polypeptide
chain
HLA-A2 quaternary structureFigure 3.20Page 47
• Sugar
• At least one
phosphate group
• Nitrogen-
containing base
Nucleotide Structure
ATP
Figure 3.23aPage 50
Nucleotide Functions
• Energy carriers
• Coenzymes
• Chemical messengers
• Building blocks for
nucleic acids
DNA
• Double-stranded • Sugar-phosphate
backbone• Covalent bonds in
backbone• H bonds between
bases
Figure 3.25Page 51