Question

Put together a life story of a protein molecule (where is it made, what does it do while functional, how is it degraded, etc.). Use bullet phrases to save time.

Answer 1

Protein is a macromolecule made up of a long chain of amino acids which is an essential part of life on earth. Protein is an important biological molecule which is complex in nature. A long chain of an amino acid is joined by peptide bond and makes a unique protein for particular bilogical function.

• Proteins are assembled from amino acid using information encoded in genes. Each protein has its own unique amino acid sequence that is specified by the nucleotide sequence of the gene encoding this protein.
• The process of synthesizing a protein from an mRNA template is known as translation. The mRNA is loaded onto the ribosome and is read three nucleotides at a time by matching each codon to its base pairing anticodon located on a transfer RNA molecule, which carries the amino acid corresponding to the codon it recognizes.
• Depending upon the complicity of protein it is characterised in primary, secondary, tertiary and quaternary structure.

Function of protein

Protein is involved in almost all type of biological reactions. Enzymes, hormones, receptors, ligands, chaperons and immunoglobulins all are different forms of proteins. Additionally protein works in combination with some other molecules, for example, it interacts with fatty acid and creates important complex molecules for cell membrane (lipoprotein).

Functions include:

• catalysing metabolic reactions
• DNA replication
• responding to stimuli
• providing structure to cells and organisms
• transporting molecules from one location to another
• cell signaling and signal transduction

The activities and structures of proteins may be examined in vitro, in vivo and in silico.

• In vitro studies of purified proteins in controlled environments are useful for learning how a protein carries out its function.
• In vivo experiments can provide information about the physiological role of a protein in the context of a cell or even a whole organism.
• In silico studies use computational methods to study proteins.

Once formed, proteins only exist for a certain period and are then degraded and recycled by the cell's machinery through the process of protein turnover. A protein's lifespan is measured in terms of its half- life and covers a wide range. They can exist for minutes or years with an average lifespan of 1-2 days in mammalian cells. Abnormal or misfolded proteins are degraded more rapidly either due to being targeted for destruction or due to being unstable.