Protiens

Question 1

What is the structure of an amino acid

Answer 1

Draw this molecule
The r group is different chemical groups
The 20 naturally occurring amino acids differ on in their R

Question 2

Formation of the peptide Bond

Answer 2

amino acid monomers can combine to form a peptide bond The water is made by combining an —OH from the carboxyl group of one amino acid with an —H from the amino group of another amino acid.

Question 3

Primary structure of proteins

Answer 3

Through a series of condensation reactions, many amino acid monomers can be joined together. The resulting chain of many hundreds of amino acids is called a polypeptide

Question 4

Changes in primary

Answer 4

It is the primary structure of a primary protein that determines the ultimate structure and a single change in an amino acid could lead to a change in the shape of the function and shape of the protein

Question 5

The secondary structure of proteins

Answer 5

The linked amino acids that make up a polypeptide have both —NH and —C=0 groups on either side of every peptide bond. The hydrogen of the —NH group has an overall positive charge while the 0 of the
—C=0 group has an overall negative charge. These two groups therefore readily form hydrogen bonds. This causes the long polypeptide chain to be twisted into a 3-D shape, such as the coil known as an a-helix.

Question 6

Tertiary structure of proteins

Answer 6

The alpha helixes of the secondary protein structure can be twisted and folded even more to give the complex 3-D structure of each protein.This is the tertiary structure. This structure is maintained by a number of different bonds.
• disulfide bridges - which are fairly strong and therefore not easily broken.
• ionic bonds - which are formed between any carboxyl and amino groups that are not involved in forming peptide bonds. They are weaker and are easily broken by changes in pH.
• hydrogen bonds - which are numerous but easily broken.

Question 7

Quaternary structure of proteins

Answer 7

Large proteins often form complex molecules containing a number of individual polypeptide chains that are linked in various ways.
There may also could be non protein groups associated oh the molecules . Remember that, although the 3-D structure is important to how a protein functions, it is the sequence of amino acids that determines the 3-D shape in the first place.

Question 8

Protein test

Answer 8

Place a sample of the solution to be tested in a test tube and add an equal volume of sodium hydroxide solution at room temperattre
• Add a few drops of very dilute (0.05%) copper(II) sulfate solution and mix gently.
• A purple coloration indicates the presence of peptide bonds and hence a protein. If no protein is present, the solution remains blue.