Page 96 - Medicinal Plants_PharmD general

Biosynthesis of proteins

Proteins are the macro-biomolecules which consist of large number
of polymers known as amino acids so amino acids are known as the
building blocks of protein. These polymers contain hydrogen, carbon,
nitrogen, oxygen atoms and Sulphur. Few proteins also have additional
elements like phosphorus and iron. Proteins differ from each other
depending on their amino acid sequences. Proteins are involved in many
metabolic pathways occurring in plants cells such as catalyzing reaction,
replication of DNA, transporting molecules inside and outside of the cell.
They can also be considered as building block of cell membranes. Proteins
are synthesized in the rough endoplasmic reticulum where the ribosomes
play an essential role.

Under normal conditions, the plant cell produces numerous proteins
that play a role in many metabolic pathways such as catalyzing chemical
reactions (enzymes), energy generating reactions involving electron
transport, replication of DNA, transporting molecules inside and outside of
the cell. They can also be storage proteins and important structural
components of the cell wall. In addition to the proteins commonly found in
plants that play a structural and metabolic role, plants produce other types
of proteins under specific conditions to cope with environmental factors.
Examples of these proteins are:

1. Heat shock protein
The heat shock protein is synthesized in plants under heat stress

conditions and hence also called stress induced protein. Heat shock protein
responds to heat stress on molecular level in plants where the stress initiates
gene expression and biosynthesis of heat shock proteins to cope with effect
of the stress. Heat shock proteins generally regulate the thermo tolerances
in plants.

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