Dr Vijaya Marakala M.D
IMS, MSU | MANAGEMENT AND SCIENCE UNIVERSITY, SHAH ALAM, MALAYSIA
TUTORIAL MBBS YEAR 1
MEDICAL AND BIOLOGICAL IMPORTANCE OF
1. Carbohydrates are the major source of energy for man. For example,
glucose is used in the human body for energy production.
2. Some carbohydrates serve as reserve food material in humans and in
plants. For example, glycogen in animal tissue and starch in plants serves
as reserve food materials.
3. Carbohydrates are components of several animal structure and plant
structures. In animals, carbohydrates are components of skin, connective
tissue, tendons, cartilage and bone. In plants, cellulose is a component of
wood and fiber.
4. Some carbohydrates are components of cell membrane and nervous
5. Carbohydrates are components of nucleic acids and blood group
6. Carbohydrates are involved in cell-cell interaction.
7. Derivative of carbohydrates are drugs. For example, a glycoside ouabain
is used in clinical medicine. Streptomycin an antibiotic is a glycoside.
8. Aminosugars, derivatives of carbohydrates are components of antibiotics
like erythromycin and carbomycin.
9. Ascorbic acid, a derivative of carbohydrate is a water-soluble vitamin.
10.Bacterial invasion involves hydrolysis of mucopolysaccharides.
11.Survival of Antarctic fish in icy environment is due to presence of anti-
freeze glycoproteins in their blood
MEDICAL AND BIOLOGICAL IMPORTANCE OF PROTEINS
Proteins perform wide range of essential functions in mammalians.
1. Proteins are involved in the transport of substances in the body. Example:
Haemoglobin transports oxygen.
2. Enzymes which catalyze chemical reactions in the body are proteins.
3. Proteins are involved in defence function. They act against bacterial or
viral infection. Example: Immunoglobulins.
4. Hormones are proteins. They control many biochemical events
5. Some proteins have role in contraction of muscles. Example: Muscle
6. Proteins are involved in the gene expression. They control gene
expression and translation. Example: Histones.
7. Proteins serve as nutrients. Proteins are also involved in storage function.
Examples: Casein of milk, Ferritin that stores iron.
8. Proteins act as buffers. Example: Plasma proteins.
9. Proteins function as anti-vitamins. Example: Avidin of egg.
10.Proteins are infective agents. Example: Prions which cause mad cow
disease are proteins.
11.Some toxins are proteins. Example: Enterotoxin of cholera
12.Some proteins provide structural strength and elasticity to the organs and
vascular system. Example: Collagen and elastin of bone matrix and
13.Some proteins are components of structures of tissues. Example: α-
keratin is present in hair and epidermis
MEDICAL AND BIOLOGICAL IMPORTANCE OF LIPIDS
1. Fat under skin serve as thermal insulator against cold.
2. Fat around kidney serve as padding against injury.
3. Fat serve as a source of energy for man like carbohydrates.
4. Fat is an ideal form for storing energy in the human body compared to
carbohydrates and proteins because:
(a)Energy content of fat is higher.
(b)Only fat can be stored in a concentrated water free form which is
not possible with carbohydrates and proteins
5. Lipids are structural components of cell membrane and nervous tissue.
6. Some lipids serve as precursors for the synthesis of complex
molecules. For example, acetyl-CoA is used for the synthesis of
7. Lipoproteins, which are complexes of lipids and proteins are involved
in the transport of lipids in the blood and components of cell
8. Some lipids serve as hormones and fat soluble vitamins are lipids.
9. Fats are essential for the absorption of fat soluble vitamins.
10. Fats serve as surfactants by reducing surface tension.
11. Eicosanoids which have profound biological actions are derived
from the essential fatty acids.
12. Lipids present in myelinated nerves act as insulators for
propagation of depolarization wave