proteins : protein structure and bonding
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what is the primary structure ?
the sequence of amino acids in a polypeptide chains
what is a quaternary structure ?
a protein structure where a protein consists of more than one polypeptide chain
what is an example of a quaternary structure ?
insulin
what is secondary structure ?
the coiling and folding of an amino acid chain
why does the secondary structure arise in the way it is ?
often as a result of hydrogen bond formation between different parts of the chain
what are the main forms of secondary structure ?
the helix and the pleated sheet
what is the tertiary structure ?
the overall 3-dimensional shape of a protein molecule
why does the tertiary structure arise in the way it is ?
due to interactions including -hydrogen bonding, -disulfide bridges, -ionic bonds -hydrophobic interactions
why is the number and order of amino acids in a protein chain important ?
as changing just one amino acids can alter the function of protein
the fact that there are 20 amino acids means.. (alternatives)
at every point in the chain there are 20 alternatives
how much possible ways of ordering 100 amino acids is there ?
20 to the power of 100
what does the function of the protein determine ?
it’s structure
what does the order of amino acids in the primary structure determine ?
the shape of the protein molecule through its secondary , tertiary and quaternary structure
draw amino acids bonded together in a long chain (labelled with amino acid and what the R-group represents)
find elsewhere :)
what shape does a chain of amino acids turn into (secondary structure) ?
a twist
what does some chains coil into ?
alpha-helix
how much amino acids and per turns on the a-helix ?
36 amino acids per 10 turns of the helix
what is the helix held together by ?
• hydrogen bonds between -NH group of 1 amino acid • the -CO group of another 4 places ahead of it in the chain
how do other chains fold ?
in a zig-zag structure
how is a beta-pleated sheet produced ?
one chain folds over on itself
how is the sheet held together ?
• hydrogen bonds between -NH group of 1 amino acid • the -CO group of another further down the strand hold the sheet together
hydrogen bonds are weak but when ..
-many are formed –> both alpha and beta structures are at optimal temperature and pH