Overall Summary
Living systems are composed of complex molecules including
carbohydrates, proteins, nucleic acids, and lipids.
Carbohydrates and proteins are essential components of food,
while vitamins and minerals play crucial roles in organism
functions.
Carbohydrates
Definition: Naturally occurring organic substances found in plants
and animals, formed by photosynthesis in plants.
Old Definition: Hydrates of carbon, with the general formula
Cx(H2O)y.
New Definition: Optically active polyhydroxy aldehydes or
ketones, or compounds that yield such units upon hydrolysis.
Types:
o Monosaccharides: Simple sugars (e.g., glucose, fructose).
o Disaccharides: Composed of two monosaccharides (e.g.,
sucrose, maltose).
o Polysaccharides: Long chains of monosaccharides (e.g.,
starch, cellulose).
Sugars
Reducing Sugars: Contain free aldehyde or ketone groups; can
reduce Fehling's and Tollen's reagents (e.g., glucose, maltose).
Non-reducing Sugars: Do not have free aldehyde or ketone
groups (e.g., sucrose).
Monosaccharide Types:
o Aldose: Contains an aldehyde group.
o Ketose: Contains a ketone group.
Examples of Monosaccharides:
o Triose: 3 carbon atoms (e.g., glyceraldehyde).
o Tetrose: 4 carbon atoms (e.g., erythrose).
o Pentose: 5 carbon atoms (e.g., ribose).
o Hexose: 6 carbon atoms (e.g., glucose).
o Heptose: 7 carbon atoms (e.g., sedoheptulose).
Structure of Glucose
Molecular Formula: C6H12O6 (aldohexose).
Open Chain Structure: Initially proposed but later found
incorrect due to the presence of a free aldehyde group.
Cyclic Structure: Exists in two forms (α and β) due to the
anomeric carbon (C1).
Mutarotation: Change in optical rotation due to the
interconversion of α and β forms.
Disaccharides
Definition: Composed of two monosaccharides linked by
glycosidic bonds.
Examples:
o Sucrose: Glucose + Fructose (non-reducing).
o Maltose: Glucose + Glucose (reducing).
o Lactose: Galactose + Glucose (reducing).
Polysaccharides
Definition: Long chains of monosaccharides linked by glycosidic
bonds.
Types:
o Starch: Polymer of α-glucose; consists of amylose (water-
soluble) and amylopectin (insoluble).
o Glycogen: Animal starch, similar to amylopectin but more
branched.
o Cellulose: Straight-chain polymer of β-glucose.
Amino Acids
Definition: Compounds containing both -NH2 (amino) and -
COOH (carboxyl) functional groups.
Classification:
o Essential Amino Acids: Cannot be synthesized by the body
and must be obtained from the diet.
o Non-Essential Amino Acids: Can be synthesized by the
body.
Physical Properties: Colorless, crystalline, water-soluble, high
melting solids; behave like salts due to dipolar ions (zwitterions).
Proteins
Definition: Polymers of amino acids linked by peptide bonds.
Structure:
o Primary Structure: Sequence of amino acids.
o Secondary Structure: Local folding patterns (α-helix and β-
pleated sheet).
o Tertiary Structure: Overall 3D shape of the protein.
o Quaternary Structure: Arrangement of multiple
polypeptide chains.
Denaturation: Loss of biological activity due to unfolding of
protein structure.
Enzymes
Definition: Biological catalysts that speed up chemical reactions.
Cofactors: Non-protein components required for enzyme activity,
can be inorganic ions or organic molecules (coenzymes and
prosthetic groups).
Temperature Dependence: Enzymes have an optimal temperature
range for activity.
Vitamins
Definition: Organic compounds required in small amounts for
normal health and nutrition.
Classification:
o Fat-Soluble Vitamins: A, D, E, K.
o Water-Soluble Vitamins: B complex and C.
Deficiency Diseases: Lack of vitamins can lead to various health
issues.
Nucleic Acids
Definition: Biopolymers made of nucleotide units; responsible for
heredity.
Components:
o Nitrogenous Bases: Purines (adenine, guanine) and
pyrimidines (cytosine, thymine, uracil).
o Pentose Sugar: Ribose in RNA, deoxyribose in DNA.
o Phosphate Group: Attached to the sugar, forming the
backbone of nucleic acids.
Structure: DNA is a double helix, while RNA can be single-
stranded or form secondary structures.
Functions: DNA stores genetic information; RNA is involved in
protein synthesis.
Key Takeaways
Carbohydrates, proteins, and nucleic acids are essential
biomolecules with distinct structures and functions.
Understanding the classification and properties of these
biomolecules is crucial for studying biological processes and
functions.
Vitamins and enzymes play significant roles in maintaining health
and facilitating biochemical reactions.
