proteins

Question 1

When you join 2 amino acids by a peptide bond what is this called

Answer 1

Dipeptide

Question 2

how many types of amino acids are there

Answer 2

20 amino acids

Question 3

What are the 4 structures of proteins called

Answer 3

Primary structure of a protein
Secondary structure of a protein
Tertiary structure of a protein
Quaternary structure of a protein

Question 4

Explain what happens during the primary structure of a protein

Answer 4

The sequence of amino acids in a polypeptide chain is determined by the sequence of bases in a gene

The primary structure of a protein determines the shape of the protein and the function of the protein

Question 5

Explain what happens during the secondary structure of a protein

Answer 5

is when the polypeptide chain twists/coils

into an alpha helix

or

folds into beta pleated sheets

These are held together by hydrogen bonds (which are between the amino group of 1 amino acid and the carboxyl group of another)

Question 6

Explain what happens during the tertiary structure of a protein

Answer 6

When the alpha helices and beta pleated sheets of the secondary structure further coil and fold forming a 3D specific shape held in place by 3 types of bonds

Question 7

What are the 3 types of bonds that hold the 3d shape of a tertiary structure protein together and explain each bond

Answer 7

• hydrogen bonds = weak but are collectively strong
  Form between the slightly positive H on an amino group and slight negative O on a carboxyl group
• ionic bonds = attraction between positive and negative charges on amino and carboxyl groups in R groups
• disulfide bridges = only form between 2 cystenine amino acids (strong)

Question 8

Explain what happens during the quaternary structure of a protein

Answer 8

are formed from multiple polypeptide chains joined together
they can have non protein groups associated with the protein (e.g: haemoglobin)

Question 9

give 3 examples of the quaternary structure of a protein

Answer 9

• antibodies
• haemoglobin
• insulin

Question 10

write a method for the testing of proteins

Answer 10

• place sample of solution that is being tested into a test tube
• add an equal volume of NaOH at room temperature
• add a few drops of copper (11) sulfate solution and mix gently
• if it turns purple there are peptide bonds and therefore a protein
• if no protein is present the solution remains blue