KEGS Biology Blog

Monday 8th October Section 1
October 7, 2012, 10:13 pm
Filed under: Uncategorized

Tertiary and quarternary structure protein


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Quarternary Structure Proteins

Quarternary Structure
– Instead of one polypeptide bond, it is a combination of seperate polypeptide chains to form a larger complex
– The chains are held together by the same kind of bonds as tertiary structure proteins

Globular Proteins
– Globular proteins have many folds and twists
– Susceptible to temperature and pH changes
– Usually have hydrophobic, non-polar groups facing into the molecule
– Form hydrogen bonds with water molecules
– Tend to be soluble in water

– Found in red blood cells, carries 8 oxygen molecules
– Has 4 polypeptide chains: 2 alpha and 2 beta
– Each chain is associated with a ‘haem’ group containing iron
– Anaemia can be caused by slight mutations to the haemoglobin genes which reduce its oxygen-carrying capacity

Fibrous Proteins – structural
– Peptide chains are extended and inter-twined to form long, thread-like molecules
– Insoluble in water
– Relatively unaffected by changes in pH and temperatures
– Mainly structural in function e.g. keratin in hair and collagen in skin

– Found in skin, bones and tendons
– Forms the leather in a hide that has been tanned
– Gives bones ‘bendability’
– Greek for ‘glue-maker’ – glue can be made by boiling down bones
– Collagen is made of 3 polypeptide chains about 1000 amino acids each which twist around eachother
– Molecules of collagen are insoluble and tend to link up with eachother to form fibrils. They can be several mm long.

Comment by milliepaine

Tertiary Structure
-coiled or folded chains of amino acids are folded amd coiled further.
-More bonds from between different parts of the polypeptide chain such as-

-Ionic interactions
-Disulfide bonds
-Hydrophobic and Hydrophilic interactions
-Hydrogen bonds

Comment by roobennithi – explains Collagen quite well I think

Comment by charlieshah

– made up of a wide range of amino acids in the primary structure

– around 35% of the molecule’s primary structure is one type of amino acid (glycine)

Comment by sarahroche12

Structure of Haemoglobin:

Comment by meganbpotter

This is a good website on quarternary structure proteins:

Comment by eilishsmyth

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