Topic Biomolecule (Protein) Essay - Main Points!

Q) Describe the main differences between a named globular protein and a named fibrous protein

Main points
Key idea:	Example and function
Collagen   · Performs structural function; main component in connective tissue e.g. ligaments Haemoglobin · In rbc; carries O2 to respiring tissues of body
Key idea:	Types of amino acids
Collagen · Mostly made up of glycine & proline; some hydroxyproline & hydroxylysine present Haemoglobin · Made up of a variety of aa
Key idea:	Sequence of amino acids
Collagen · Regular repetitive seq Haemoglobin · Irregular seq
Key idea:	Variation of the sequence of amino acids
Collagen · Seq of 2 collagen mol may vary slightly Haemoglobin · Seq is specific + never varies
Key idea:	Length and shape of each polypeptide
Collagen · Comprises of ~1000 aa residues, forms a kinked helical struc Haemoglobin · Contains fewer no. of aa, folds into a compact globular shape
Key idea:	Level of organization of each polypeptide
Collagen · Forms sec struc; no tertiary struc present Haemoglobin · Forms tertiary struc · Ref to R gps of aa residues may interact w each other throu H, ionic, disulfide bonds + hydrophobic interaction
Key idea:	Interaction between polypeptides
Collagen · 3 long parallel polypep coil tightly around each other, form triple helical struc of tropocollagen · Ref to each adjacent straight tropocollagen forms covalent cross linkages, to form collagen fibrils · Ref to fibrils further bundle to form collagen fibres  Haemoglobin · Comprises of 2 α subunits + 2 β subunits · Ref to 4 polypep subunits associate w each other throu H, ionic + hydrophobic interactions
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) Both proteins exhibit quarternary level of organization (v) You should also be able to explain how the structural features of the named proteins enable them to perform their respective roles in the organism (refer to N10 essay)