ISNHS-SHS-STEM
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MELC:
Describe the structure of proteins, nucleic acids, lipids, and carbohydrates, and
relate them to their function. STEM_GC11OCIIg-j-95
Objectives:
üIdentify the monomers involved in the formation of the biopolymers
of carbohydrates, proteins, and nucleic acids.
üDistinguish the biomolecules of proteins, carbohydrates, nucleic
acids, and lipids.
üDiscuss the function of proteins, carbohydrates, nucleic acids, and
lipids.
üValue the importance of foods that are sources of biological
macromolecules.
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ISNHS-SHS-STEM
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Guide Questions
1. What can you say about the formula of glucose, fructose,
and galactose?
2. What do you call compounds with the same formula but
different structures?
3. What is the difference between the structure of glucose
and the structure of fructose?
4. How many carbon atoms do glucose, fructose, and
galactose have?
5. What functional groups are present in glucose, fructose,
and galactose?
ISNHS-SHS-STEM
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Biomolecules or biological molecules are molecules
present in organisms that are essential to one or more
biological processes. Biomolecules include large
molecules necessary for life that are built from smaller
organic molecules which are called biological
macromolecules. There are four major classes of
biological macromolecules and each is an important
component of the cell and performs a wide array of
functions. These molecules when combined make up most
of a cell’s mass.
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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.
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ISNHS-SHS-STEM
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Carbohydrates
Monosaccharides
- One sugar unit per
molecule.
- Ex: glucose,
fructose, galactose
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Disaccharides
- Two sugar units per
molecule.
- Ex: sucrose,
maltose, lactose
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Polysaccharides
- Many sugar units
per molecule.
- Ex: cellulose, starch,
glycogen
Proteins
Proteins are very large molecules critical for the human
body’s functions. They are made from the linkage of
monomers called amino acids.
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Proteins
There are 20 kinds of amino acids depending on the —R
group. An amino acid is a compound that contains at least
one amino group and at least one carboxyl group.
Twenty different amino acids are the building blocks of all
the proteins in the human body. 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.
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Protein Functions
ü Antibodies - proteins involved in defending the body against antigens. They are
the molecules of the immune system.
ü Contractile proteins – responsible for body movement such as muscle
contraction
ü Enzymes – proteins that catalyze (speed up) or facilitate biochemical reactions.
ü Hormonal proteins – serve as messenger proteins to help coordinate some
body functions.
An example is insulin (which controls blood sugar
concentration).
ü Structural proteins – are fibrous and provide support. An example is collagen
which provides support to connective tissues.
ü Storage proteins – store amino acids like casein in milk.
ü Transport proteins – are carrier proteins that move molecules from one place to
another in the body. An example is hemoglobin which transports oxygen.
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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 3dimensional shape.
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Nucleic Acids
Nucleic acids play an essential role in protein synthesis.
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. Each nucleotide is made up of three parts:
a nitrogen base; a five-carbon sugar; and a phosphate.
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Lipids
Lipids are molecules that contain hydrocarbons and make up the
building blocks of the structure and function of living cells.
Examples of lipids include triglycerides (fats), oils, axes, certain
vitamins (such as A, D, E, and K), hormones, and most of the cell
membrane that is not made up of protein.
Fatty Acids are the simplest form of lipids and are the building
blocks of the fat in our body and in the food we eat. During
digestion, the body breaks down fats into fatty acids, which can then
be absorbed into the blood. Fatty acids consist of a long
hydrocarbon chain (typically about 12 – 18 carbons) attached to a
carboxyl group.
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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).
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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.
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Triglycerides can be broken down by treatment with
aqueous sodium hydroxide. The products are glycerol and
the fatty acid salts; the latter are known as soaps. This
process is called saponification.
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Analogy
1.
2.
3.
4.
Monosaccharide: One sugar unit; Disaccharide: ______________
Glucose + Fructose: Sucrose; __________________: Lactose
Carbohydrates: saccharides; Proteins: __________________
________________: Glycosidic bond; Amino acids: Peptide bond
5. Lactose: _______________; Fructose: C6H12O6
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Identification
1. This type of carbohydrate is composed of only one sugar unit.
2. The monosaccharide is found in starch.
3. It is also known as “animal starch”.
4. The elements make up carbohydrates.
5. The carbohydrate that cannot be digested by humans.
6. They are called long chains of sugars.
7. The small repeating units that makeup proteins.
8. The polymer of glucose.
9. The type of proteins that speed up biochemical reactions.
10.The molecules of the immune system.
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TRUE or FALSE
1.Sucrose and maltose have the same structural
formula.
2.Glucose and galactose have the same chemical
formula.
3.DNA contains nitrogen base thymine.
4.Unsaturated fatty acids contain double C-C bond.
5.RNA are polymers made up of monomers in the
form of amino acids.
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Give It Some Thought
What are the side effects of having too
much or too little of carbohydrates,
proteins, nucleic acids, and lipids in
our body?
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