Wednesday, October 26, 2011

Topic Biomolecule (Protein) Essay - Main Points!

Q) Explain the different levels of organization of a named protein
Main points
Key idea:
Haemoglobin
· Ref to up to 4 diff levels of organization in proteins
· Haemoglobin (Hb) comprises of 4 polypep subunits – 2 identical α subunits + 2 identical β subunits
· Ref to α + β subunit differs slightly in their aa composition
Key idea:
Primary structure
· Refers to no., type, seq of aa that make up each diff polypep subunit
· Det its properties, overall 3D conformation, hence bio fn
Key idea:
Secondary structure
· Each Hb subunit comprises of localized struc called α-helices formed due to intra-chain H bonds b/w nearby aa
· Ref to H bonds formed b/w carbonyl gp (CO) of aa residue (n) w NH gp of residue (n+4) along polypep chain
Key idea:
Tertiary structure
· Ref to extensive infolding of polypep chain upon itself, form a compact globular shape
· Due to interactions (e.g. H, ionic, disulfide bonds, hydrophobic interactions) b/w R gps of aa residues far away fr each other
Key idea:
Quaternary structure
· Associaton of 4 subunits due to hydrophobic interactions, H, disulfide, ionic bonds
Comments:
(i) Visualize the answer with the aid of a labelled diagram.
(ii) Verbalize the answer + write down the main points w/o referring to the answer (use abbreviations)
(iii) Read again within the next 24h & once more within 72h (do not spend more than 10min)
(iv) Select haemoglobin instead of collagen since the latter does not exhibits tertiary level of organization

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