Download Macromolecules

Macromolecules
The building blocks of life…
Macromolecules
Cells are composed of several types of
biological macromolecules.
 These function as energy-storage
molecules, structural components, and in
information storage, and are primarily
composed of carbon, hydrogen and
oxygen.

Carbohydrates
carbon, hydrogen & oxygen in a 1:2:1 ratio
 exist as monosaccharides, disaccharides
and polysaccharides
 among the most abundant molecules on
Earth

Monosaccharides
OH



“single sugars”
general formula is
(CH2O)n
glucose (top) and
ribose (bottom) are
monosaccharides
O H
H
H
OH
H
HO
OH
H
OH
HO
H
O
H
H
OH
OH
OH
H
Disaccharides
“double sugars”
 formed by dehydration synthesis from two
monosaccharides
 sucrose, maltose, and lactose are all
disaccharides

Synthesis of Maltose
OH
OH
O H
H
O H
H
H
OH
H
H
HO
OH
OH
H
H
HO
OH
OH
H
OH
- glucose
-glucose
OH
OH
O H
H
H
OH
HO
H
O
H
O H
H
H
OH
H
OH
OH
H
maltose
OH
Polysaccharides
straight or branched chains of
monosaccharides connected by glycosidic
linkages
 storage (e.g. starch, glycogen) or
structural (e.g. cellulose, chitin)

Polysaccharide Structure
Proteins
proteins are chains of amino acids
connected by peptide linkages
 order of amino acids for a particular
protein is determined by the gene which
codes for it

Amino Acid Structure


all amino acids have
the same basic
structure
“R” group is different
for each amino acid
amino
group
H2N
H
R
OH
O
carboxyl
group
Peptide Linkages
O
HS
O
H2N
OH
OH
NH2
cysteine
glycine
peptide
linkage
HS
O
O
H2N
N
H
OH
Levels of Protein Structure



Primary
the specific sequence
of amino acids
coded by DNA





Secondary
the folding or coiling
of the amino acid
chain
caused by
interactions between
“R” groups
-Helix
-Pleated Sheet




Tertiary
the unique threedimensional shape of
the protein
enzymes are globular
proteins
collagen is a fibrous
protein



Quaternary
interactions between
separate polypeptide
chains, or “subunits”
hemoglobin is
composed of four
subunits
Lipids
lipids are a group of hydrophobic
molecules
 “neutral fats” are uncharged lipids
composed of glycerol and fatty acids
 fats are solid at room temperature
 oils are liquid at room temperature
 steroids and phospholipids are amphiphilic

Steroid Structure


steroids all have the
same basic structure
of four fused
hydrocarbon rings
cholesterol is used to
synthesize many
other steroids in the
body
H3C
CH3
CH3
CH3
H3C
HO
cholesterol
Phospholipid Structure
glycerol backbone
has two fatty acids
and one charged
inorganic phosphate
group attached
 primary component
of cell membranes

Triglycerides
triglycerides are neutral fats
 glycerol is the “backbone” molecule
 fatty acids attach to glycerol by ester
linkages
 saturated fatty acids have no double
bonds between carbons
 unsaturated fatty acids have at least one
double bond between carbons

Triglyceride Synthesis
O
HO
H3C
OH O
H3C
HO
OH O
H3C
HO
OH
3 fatty acids
glycerol
ester
linkage
O
H3C
O
O
H3C
O
O
H3C
O
triglyceride
Nucleic Acids
Deoxyribonucleic Acid (DNA) and
Ribonucleic Acid (RNA)
 composed of nitrogen-containing “bases”
attached to a backbone of alternating
pentose sugars and inorganic phosphate
 function in information storage (DNA) and
transfer (RNA)

“Bases” of DNA & RNA
Purines
NH2
adenine
O
thymine
CH3
N
N
HN
O
N
H
N
O
guanine
N
H
NH2
cytosine
N
HN
H2N
Pyrimidines
N
N
O
N
H
N
H
O
uracil
HN
O
N
H
DNA



deoxyribose sugar
adenine, guanine, cytosine, thymine bases
arranged in a double helix
RNA



ribose sugar
adenine, guanine, cytosine, uracil bases
single-stranded
References



MIT Biology Hypertextbook(1996) http://esgwww.mit.edu:8001/esgbio/lm/sugars/sugars.html
(3/9/2001)
Farabee, M.J., (2001) An Online Biology Book.
Chemistry 2: Water and Organic Molecules
http://gened.emc.maricopa.edu/bio/bio181/BIOBK/BioBo
okCHEM2.html (3/9/2002)
A.C.D. Labs (2002) ChemSketch (Freeware), available
for download at http://www.acdlabs.com/. Used for
molecular structure diagrams.