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Are involved in: cellular sturcture, movement,defence,transport and communication (hormones)

made up of amino acids= 20 naturally accuring amino acids

Amino acids are the monomers that link together to form polymers called polypeptide chains: the basis of proteins.

the structure of amino acids

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Amino acids

Amino acids can be linked by peptide bonds

cells link amino acids together

the bonds are between amino acids momomers are called peptide bonds

strings of amino acids from polypeptide chains

when 2 amino acids join together water and a peptide bond are formed

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Primary structure of protein

A striaght chain

linear sequence of amino acids form primary structure

sequence will determine the secondary and teritiary structures and functions of the protien

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secondary sturcture of protein

peptide chains fold into secondary structures

  • Alpha- helix = storage
  • Beta - pleated sheets
  • random coil

produced by hydrogen bonding (weak)

shape is maintain by hydrogen bonds between C=O and N - H groups in the back bone

R group directed outward from coil

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teritary sturcture of protein

secondary structure fold and pack together to form teritiary structure  usually globular shape

teritary structure stablised by bonds between R groups

Teritary sturcture H bonds

Hydrogen bonds are weak allowing to be broken and reformed easily (folded in) structual change

produces 'functional' molecules

Teritary sturctureionic bonds

ions on R group form salt bridges through ionic bonds. ionic bonds = form between ionised amino and carboxylic groups broken by PH extreme. 

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sturcture of protien

teritary sturcture of protein = disulfide bonds

sulphur to sulphur in adjacent cysteine amino acids, weak bonds broken by reducing agents

covalent bonds between sulphur atoms on two cysteine amion acids

Quaternary structure

Arragement of multiple teritary sturctures into single functional complex

Often associated with other molecules

Allows for changes in structure and function

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