Biology 4

The structure of emzymes and how they work

Proteins are made from chains of small molecules called amino acids. These long chains are folded into particular shapes. Is information is important in showing how emzymes and antibodies work.

Enzymes are biological catalysts - they are substances that increase the rate of chemical reactions without being used up. Enzymes are proteins folded into complicated shapes that allow smaller molecules to fit into them. The place where these substrate molecules fit is called the active site.

Proteins are polymers they are built up in a cell when monomers called amino acids join together at the ends. There are only about 20 different naturally occurring amino acids. However, each protein molecule has hundreds, or even thousands, of them joined together in a unique sequence. This gives each protein its own individual properties.

  1. Polymers- A polymer is a large molecule formed from many identical smaller molecules (monomers).
  2. Monomers- Atom or small molecule that bonds with other monomers to form a polymer eg amino acid monomers forming a protein polymer.

If the shape of an enzyme changed it might not work in its active state- we call this denatured. Enzymes can be denatured by high temperatures or dramatic changes in PH. The enzymes will not be 'killed' although they are made by living things they are no alive, they are proteins.

Lock and key theory

Thetheory that the specific action of any enzyme with a single substance can be expressed using a lock and key diagram produced in 1894 by Emil Fischer. Enzymes are specific. Only molecules with the correct shape can fit into the enzyme. Just like only one key can open a lock, only one type of enzyme can speed up a specific reaction. This is called the lock and key model.


Created with images by USDAgov - "20150320-OSEC-LSC-0082"

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