BIOMOLECULES

BIOMOLECULES

• A. Carbohydrates. Carbohydrates are compounds

made up of carbon, hydrogen, and oxygen. They are also
known as saccharides. They have the general formula
Cx(H2O)y. Carbohydrates function as the energy source of
the body. A simple general classification of carbohydrates
is according to the number of sugar units (saccharides)
present in the molecule: monosaccharides, disaccharides,
and polysaccharides.
Monosaccharides are the building blocks or monomers of
carbohydrates. The simplest monosaccharide contains
three carbon atoms (such as glyceraldehydes and
dihydroxyacetone).
 EXAMPLES OF POLYSACCHARIDES
• Starch is composed of glucose monomers linked by
alpha-glycosidic bonds and has a general formula of
(C6H12O5)x It is the cheapest main energy source of
humans, as it is present in a wide array of sources such
as rice, corn, potatoes and wheat.
• It has two major components: a) Amylose is a straight
chain that contains 100 to 1000 glucose units and b)
Amylopectin is the part responsible for the branching out
of chain polymers and contains 500 to 5000 glucose
units.
 EXAMPLES OF POLYSACCHARIDES
• Cellulose is the structural component of cell walls
that forms the fibers present in plants and wood.
Similar to starch, it also comprises glucose units as
monomers. However, its glucose units are
connected in alternating patterns known as beta
linkages. This pattern of connection is responsible
for the stiffness of cellulose.
• Glycogen is the stored form of glucose that’s made
up of many connected glucose molecules.
 PROTEINS
• Proteins are natural polymers. They are very large
molecules that are critical for the functions of the human
body. They are made from the linkage of monomers
called amino acids. Amino acids have the following
structure:
 PROTEINS
• Amino acids have two functional groups: a. Carboxylic
group (—COOH) and b. Amine group (—NH2)
• There are 20 kinds of amino acids depending on the —R
group. The simplest amino acid is glycine where R is a
hydrogen atom. The body cannot make all the amino
acids required by the body and is dependent on protein
taken through food.
 PROTEINS
• Two amino acids can link together through a
condensation reaction with the removal of a water
molecule. The linkage is called a peptide bond. Take the
case of two amino acids reacting to form a dipeptide.
 PROTEINS
When many amino acids are linked together through
peptide bonds, the resulting molecule is called a
polypeptide. A very large number of amino acids linked
together results in a protein. Some proteins are made up
of only one polypeptide while most proteins involve
assemblies of two or more polypeptides. The term
polypeptide is usually used for shorter, unstructured chains
while proteins fold into fixed structures.
 PROTEINS
It is therefore possible to think of a protein as a
strong of beads strung together where each bead
is an amino acid.
 PROTEIN FUNCTIONS
a. Antibodies - proteins involved in defending the body against
antigens. They are the molecules of the immune system.
b. Contractile proteins – responsible for body movement such
as muscle contraction
c. Enzymes – proteins that catalyze (speed up) or facilitate
biochemical reactions
d. Hormonal proteins – serve as messenger proteins to help
coordinate some body functions. An example is insulin (which
controls blood sugar concentration).
 PROTEIN FUNCTIONS
e. Structural proteins – are fibrous and provide
support. An example is collagen which provides
support to connective tissues.
f. Storage proteins – store amino acids like casein in
milk.
g. Transport proteins – are carrier proteins which
move molecules from one place to another in the
body. An example is hemoglobin which transports
oxygen.
 PROTEIN DENATURATION
• Denaturation is a process in which a protein loses its
secondary, tertiary, or quaternary structures. This may be
caused by physical or chemical agents like strong acid,
base, inorganic salt, heat, or solvent which disrupt the
bonds that hold the protein structures together.
Denaturation does not cause the cleavage of the peptide
bond (the primary structure). Note that a protein will lose
its biological activity if it loses its 3-dimensional shape.
PROTEIN DENATURATION
 NUCLEIC ACID
• Nucleic acids are natural polymers with very large molar
masses. The two main types of nucleic acids are
deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
DNA and RNA are polymers made up of monomers in the
form of nucleotides. When these nucleotides combine,
they form polynucleotides. DNA carries the genetic
information passed on from parents to children. RNA
plays an important role in protein synthesis.
 NUCLEIC ACID
• Each nucleotide is made up of three parts:
1. A nitrogen base
a. Purines - adenine (A), and guanine (G)
b. Pyrimidines - cytosine (C), thymine (T), uracil (U)
2. A five-carbon sugar
a. Deoxyribose
b. Ribose
3. Phosphate
FEATURES OF DNA AND RNA
 LIPIDS

• Lipids are a class of naturally occurring organic

compounds distinguished by their solubility in an organic
solvent (and not in water). Lipids are hydrophobic,
nonpolar, and made up mostly of hydrocarbon chains.
Some of the more important lipids are: triglycerides
(fats), saturated and unsaturated fatty acids, waxes,
phospholipids, and steroids.
 EXAMPLES OF LIPIDS
1. Fatty Acids. Fatty acids consist of a long hydrocarbon
chain (typically about 12 – 18 carbons) attached to a
carboxyl group.
A. Saturated fatty acid – contains only single C-C bonds
because the carbon atoms are saturated or filled up with
hydrogens. Because their structure is straight, they can
pack well and are solid at room temperature (e.g. fat in
butter).
 EXAMPLES OF LIPIDS
B. Unsaturated fatty acids – contain carbon-carbon double
bonds. When there is only one C-C double bond, it is called
monounsaturated; if there are several C-C double bonds, they
are called polyunsaturated. Remember that when there are
double bonds, there will be geometric isomers (cis and trans).
• Because of the double bonds, they do not pack as tightly as
saturated fatty acids. They are usually liquids at room
temperature. An example of an unsaturated fatty acid is olive
oil.
 EXAMPLES OF LIPIDS

b. Fats and Oils. Fat molecules have two parts: a glycerol

backbone and three fatty acid chains. The resulting
molecule is called a triglyceride.
 EXAMPLES OF LIPIDS

2. Waxes – are nonpolar lipids that plants and animals use

for protection and have many functions in society. Natural
waxes are typically esters of fatty acids and long chains of
alcohol.
3. Steroids – are another class of lipid molecules,
identifiable by their structure of four fused rings.
 TYPES AND EXAMPLES OF LIPIDS

▪ sterols- steroids, hormones

▪ waxes- bee, furniture, ear, car, plant
▪ cholesterol- egg yolks, red meat
▪ fats- from animals
▪ oils- from plants
▪ phospholipids- cell membranes
▪ pigments- plants