First 320 words of the document:
Rearrange the following statements into the correct sequence.
1. A piece of steak is bitten, chewed, and swallowed.
The tertiary structure allows enzymes to be complementary to their substrates by induced fit,
and allows antibodies to be complementary to their antigens.
The hydrochloric acid is neutralised by bile from the liver to provide the optimum pH for
trypsin from the pancreas.
The amino acids are absorbed by facilitated diffusion into the capillaries of the villi in the
The polypeptides are further hydrolysed to dipeptides, then amino acids.
The first amino acid in any protein is always methionine, this is then usually removed when
the protein is complete.
The amino acids are joined by peptide bonds formed in a condensation reaction, the order
(primary structure) is determined by the base sequence of the DNA.
Disulphide bridges form between the R groups of cysteine
The blood transports them to all cells, where they are absorbed.
Eventually a complete chain of amino acids is produced, and the protein has its tertiary or
The individual amino acids are attached to molecules of tranfer RNA (tRNA) which take
them to the ribosomes on the rough endoplasmic reticulum.
As the peptide chain grows, reactions between the R groups cause secondary structures
such as alpha helix and betapleated sheet.
Pepsin in the stomach hydrolyses peptide bonds in the protein to produce polypeptides. The
hydrochloric acid provides the optimum pH for the reaction.
Proteases form an enzymesubstrate complex with polypeptides and dipeptides that are
complementary to their active site, then lower the activation energy for hydrolysis.
15. Proteins are usually taken in vesicles to the golgi apparatus to be modified for use eg. as
membrane proteins such as carriers or hormone receptors, or secretion via exocytosis.