A look back at today


What’s cracking cyber people! lol… ok i did NOT think about that picture when i asked that question :p Today in Biochem1362 we focused on the structure of Proteins.

PROTEINS (Macromolecules) are made up of monomers (amino acids).


Photo credit- http://www.ucl.ac.uk/~sjjgsca/protStructTable.gif

Let’s take a look at Primary, Secondary and Tertiary Structures…

 Primary StructureThis is the order of the amino acids of which the polypeptide chain is made up of. The only bonds are covalent bonds between sucessive amino acids. Proteins differ in the variety, number and order of their constituent amino acids. The sequence of the amino acids in the polypeptide chain is controlled by the coded instructions stored in the DNA of the chromosomes in the nucleus.

Secondary StructureThis is the way in which the amino acid folds itself as a result of hydrogen bonding. There are 2 types, α helix and β pleated sheet.

A polypeptide chain often coils into an α helix. The helix is held in shape by attraction between the O2 of the CO group of 1 amino acid and the H of 1 amino acid four places ahead of it. This twists the chain into a spiral (helical form) where the twists are kept in place by hydrogen bonds. A small portion or the whole polypeptide chain can twist into an α helix.  Eg. Keratin, an example of an insoluble protein found in nails. In β pleated sheets, protein strands lie adjacent to each other. H bonds form from the interaction of different chains resulting in a flat structure that becomes folded like a sheet. Eg of such protein is silk

Tertiary Structure–  This is the precise 3Dshape that is unique to proteins and rises when the molecule is further folded and held in a particular complex shape. This shape is made permanent by four different types of bonding (ionic, hydrogen, hydrophobic, disulphide linkages) between adjacent parts of the chain.

That’s a wrap for now!

Thought for today! 😉

Other sources- http://www.rpi.edu/dept/bcbp/molbiochem/MBWeb/mb1/part2/protein.htm


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