Biomolecules
The Chemical Building
Blocks of Life
The Chemistry of Carbon
• Organic molecules contain carbon
• Carbon’s four valence electrons allow
it to form up to four covalent bonds
• Hydrocarbons consist only of C and H
– Propane CH8
• It can easily bond to itself and form
long chains
– Linear
- Cyclic
- Branched
Functional Groups
• Chemical properties and reactivity are a
result of functional groups
• Functional groups maintain chemical
properties no matter where they occur
• Polar molecules are hydrophilic
• Nonpolar molecules are hydrophobic
• The degree to which organic molecules
interact with water affects their function
• Hydroxyl group (-OH) is one of the most
common functional groups, it will make a
molecule water soluble
Macromolecules – The
Sum of the Parts
• Many complex biological activities
require large macromolecules
• Macromolecules are polymers built by
linking together small subunits called
monomers
– Proteins are polymers of amino acids
– Nucleic acids are polymers of nucleotides
– Starches are polymers of simple sugars
Condensation
It’s not just for the water cycle anymore
• Macromolecules are constructed by
covalently bonding monomers by
condensation reactions where water is
removed from the functional groups of the
monomers
• Dehydration synthesis (water is removed)
• A hydroxyl (-OH) from one monomer and a
hydrogen (-H) from another are removed
• Anabolic reaction
Hydrolysis
• Hydrolysis is the reverse of condensation
• Results in the break down of polymers
• Hydration reactions add water and break
bonds releasing energy
Macromolecules
• Perform complex tasks with
precision
• Basic structure and function
of each family similar in all
organisms (bacteria –
humans)
Families of Biomolecules
• Carbohydrates
•Lipids
•Proteins
•Nucleic Acids
Basic Function
Carbo’s
Lipids
N. Acids
Proteins
Energy
Storage
Structure
Long term
storage
Insulation
Protection
Inheritance
Blueprint for
metabolism
Catalysts
Hormones
Structure
Starch
Glycogen
Glucose
Sucrose
Cellulose
Lipid
Fats
Oils
Waxes
DNA
RNA
ATP
Proteins
Enzymes
Carbohydrates
How Sweet It Is!
• General formula (CH2O)n
• Simple sugars or large
molecules made of sugar
monomers
• Monosaccharides (monomer)
are covalently linked by
condensation reaction to form
polysaccharides (polymers)
Sugars
• Monosaccharides
– Five carbon: Ribose
– Six carbon: glucose and fructose
•Disaccharides
–Sucrose
–Lactose
•Polysaccharides
–Starch
–Cellulose
–Glycogen
Polysaccharides
Three Types
• Glycogen – animal storage product that
accumulates in the liver
- Highly branched
GlucoseGlycogenglucosebloodstream
• Starch – plant energy storage
- Helical
- Easily digested by animals through
hydrolysis
Cellulose
• Polysaccharide found in plant cell walls
• For humans cellulose is indigestible and
forms dietary fiber
• Made up entirely of β glucoses
– Structure is constrained into straight
microfibrils
• Not an energy source for animals
• Chitin – insect exoskeletons
Lipids
• Long-term energy storage
• Generally insoluble in water
• Structural components of cells
(phospholipids)
• Cellular messengers (hormones)
More FAT
• Triglycerides are composed of three fatty
acids covalently bonded to one glycerol
molecule
•Fatty acids are composed of CH2 units and
are hydrophobic
•Fatty acids can be saturated (all single bonds)
or unsaturated (one or more double bonds)
•A fat (mostly saturated) is solid at room
temp. while an oil (mostly unsaturated) is
liquid at room temp.
Phospholipids
• Important structural component of
cell memranes
• Phosphate group (head) is polar
and water soluble (hydrophilic)
• Fatty acid tails are hydrophobic
•This allows the phospholipids to
form bilayers and membranes
• Steroids
Other Lipids
– Insoluble in water
– Built around a four ringed skeleton
• Cholesterol
– Component for animal cell membranes
– Formation of myelin sheath covering nerves
• Hormones
– Chemical messengers
• Waxes
– Many fatty acids linked to a long backbone
– Waterproofing in plants, ears, beehives
Proteins
• 50% dry weight of body
• Mammal cell contains 10,000 proteins
• Control elements (enzymes)
– Organic catalysts
– Mediators of metabolism
– Direct development, maintenance, and
growth
• Structural elements (cell membrane,
muscles, ligaments, hair, fingernails)
• Regulate what goes into/out of cells
Building Blocks of Proteins
Amino Acids
• Amino acids (monomers) are linked
together to form proteins (polymers)
– Each unique sequence of amino acids forms a
different protein
– All living things (even viruses) use the same 20
amino acids
• 20 different Amino Acids
–
–
–
–
Amino end (NH2)
Carboxyl end (COOH)
Hydrogen
R group – variable component
Amino Acids
• Amino Acids are grouped by
whether R- group is polar or nonpolar
•Positively charged side chain
•Negatively charged side chains
•Polar but uncharged side chains
•Hydrophobic side chains
•Special cases
Protein Assembly
• AA’s are linked together by joining
the amino end of one molecule to
the carboxyl end of another
•Peptide bond forms a chain called a
polypeptide
•Transcription in nucleus
–DNA code  mRNA
•Translation on ribosomes
–mRNA  protein
Protein Structure
Primarystructure
structure
structure
••Quaternary
••Tertiary
Secondary
structure
more
than
oneofsequence
polypeptide
Specific
of chain
AA’s
incoil
a or
the
tendency
the polypeptide
to
or
--–shape
of linear
entire
chain;
folded,
twisted,
polypeptide
pleat
due to H-bonding between R- groups
globular
–Determined
from code
in or
inherited
helix,

-pleated
sheet,
random
coil
- shape
related to function and properties
genetic material
– Changes in primary structure can
alter proper functioning of the protein
Nucleic Acids
• Polymers composed of monomer
units known as nucleotides
• Information storage
– DNA (deoxyribonucleic acid)
• Protein synthesis
– RNA (ribonucleic acid)
• Energy transfers
– ATP (adenosine tri-phosphate) and
NAD (nicotinamide adenine
dinucleotide)
Nucleotides
• Nucleotide structure
– Phosphate
– Nitrogenous base
 Purines (double-rings)
 Adenine and Guanine
Pyrimidines (single-rings)
 Cytosine, Thymine, and Uracil
– Sugar – either ribose or deoxyribose
 pentoses in ring form
Deoxyribose lacks one oxygen
Functions of Nucleic Acids
• DNA – Physical carrier of genetic
information
– Restricted to nucleus
• RNA – key component of protein
synthesis
– Messenger RNA (mRNA) – blueprint
for construction of a protein
– Ribosomal RNA (rRNA) – construction
site where the protein is made
– Transfer RNA (tRNA) – truck
delivering the proper AA to the site of
construction
The End