Biomolecules
H
H
C
H
H
Structural formula
Ball-and-stick model
Space-filling model
Models of Methane
The Molecular Logic of Life
Small molecules, common to all
organisms, are arranged into
unique macromolecules
(Campbell p. 62)
Macromolecules
Many complex biological activities require
large macromolecules
Macromolecules are polymers
poly: “many”
mer: “units”
ex: proteins, nucleic acids, starches
Polymers are built by covalently linking
together small similar (or in some cases,
identical) subunits/building blocks called
monomers
mono: “one”
mer: “unit”
ex: amino acids, nucleotides,
monosaccharides
4 Classes of Organic Compounds
“Biomolecules”
Proteins are polymers of amino acids
Nucleic acids are polymers of nucleotides
Starches are polymers of simple sugars called
monosaccharides
Lipids aren’t REALLY polymers, since they don’t
have repeating chains. BUT they are important
biomolecules. The building blocks (monomers)
of some types of lipids are glycerol and fatty
acids
Macromolecules- why are
they so important?
• Each macromolecule performs complex
tasks with precision
• The basic structure and function of each
class of macromolecules is similar in all
organisms (from the simplest bacteria to
complex humans)– indicates an
evolutionary link.
Basic Function
Carbo’s
Lipids
N. Acids
Energy
Storage
Structure
Strength
Long term
storage
Insulation
Protection
Hormones
Sugars
Fats
DNA
Oils/Waxes
RNA
Phospholipids ATP
Steroid
hormones
(glucose)
Starch/
Glycogen
Cellulose/
Chitin
Inheritance
Blueprint for
metabolism
Proteins
Catalysts
Hormones
Structure
Defense
Proteins
Enzymes
Carbohydrates
•
•
•
•
•
•
Sugars
Monomer =(CH2O)n
Monosaccharides:Glucose
Oligosaccharides: Sucrose
Polysaccharides: Cellulose
Energy storage and structure
Sugars
• Monosaccharides
– Five carbon: Ribose
– Six carbon: glucose and fructose
•Disaccharides
–Sucrose
–Lactose
•Polysaccharides
–Starch
–Glycogen
–Chitin
–Cellulose
fructose
glucose
sucrose
+ H2O
Cellulose chains
Starch chain
cellulose
glycogen
amylose (a starch)
Two Types for Storage
1. Glycogen – animal energy storage
• animal energy storage product that
accumulates in the liver/muscles
• Highly branched
2. Starch – plant energy storage
• Helical
• Easily digested by animals through
hydrolysis
Lipids
Functions:
1. Long-term energy
storage/insulation (fats)
2. Structural components of cells
(phospholipids)
3. Cellular messengers (hormones)
Lipids
•
•
•
•
•
•
Fats and oils
Monomer = CH2
Fats 1,2 or 3 fatty acids attached to
glycerol
Sterols- Cholesterol, Steroids
Waxes- Beeswax
Used for waterproofing, insulation and
cell membranes
Figure 2.21c
Page 29
FATS
• 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.
hydrophilic
head
hydrophobic tails
stearic acid
oleic acid
linolenic acid
hydrophilic
head
two
hydrophobic
tails
one layer
of lipids
one layer
of lipids
cell membrane section
Sterol backbone
Cholesterol
Proteins
50% dry weight of body
Mammal cell contains 10,000 proteins
Enzymes (regulate chemical reactions)
Structural elements (cell membrane,
muscles, ligaments, hair, fingernails)
• Carriers (regulate what goes into/out
of cells)
• Send and receive messages
(hormones)
• Movement
•
•
•
•
Proteins
• Monomer= Amino Acid
• Enzymes- Catalyze metabolic reactions
• Transport proteins- move things across
membranes
• Structural proteins-keep the structure
of cells
Amino
group
(basic)
Carboxyl
group
(acidic)
R group
(20 kinds with distinct properties)
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
http://www.biotopics.co.uk/
as/aminocon.html
Protein Structure
• Primary structure
– Specific linear sequence of AA’s in a
polypeptide
– Determined from code in inherited
genetic material
– Changes in primary structure can
alter proper functioning of the protein
one
peptide
group
Linear primary structure
• Secondary structure
- the tendency of the
polypeptide to coil or
pleat due to H-bonding
between R- groups
- -helix, -pleated
sheet, or random coil
Secondary
structure
Tertiary
structure
Secondary
structure
Tertiary
structure
• Tertiary structure
- shape of entire chain; folded, twisted, or
– globular
- shape related to function and properties
• Quaternary structure
- more than one polypeptide chain
heme group
helically coiled
globin molecule
alpha chain
beta chain
beta chain
alpha chain
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)
Nucleic Acids
• Monomer: Nucleotide
– ATP is a Nucleotide
• Molecules of inheritance: hold the code for
how to make proteins
• Deoxyribose Nucleic Acid- DNA
• Ribose Nucleic Acid- RNA
nitrogencontaining
base
Ball-and-stick model of ATP
sugar
3 phosphate groups
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
Adenine
(a base)
phosphate
group
Thymine
sugar
(deoxyribose)
Guanine
Cytosine
Single strand of DNA or RNA
phosphate
connected by
covalent bond
sugar
base
covalent bonding
in carbon backbone
hydrogen bonding between bases