3.6 Structure Of Proteins

Question 1

How many amino acids are there in an organism

Answer 1

20

Question 2

How are amino acids joined together?

Answer 2

By condensation reactions
A peptide bond is formed between two amino acids, producing a dipeptide
A polypeptide is firmed when many amino acids bond together

Question 3

What is the primary structure of a protein?

Answer 3

The polypeptide produced during translation

Question 4

What is the secondary structure of a protein?

Answer 4

A coiled or pleated sheet protein structure
Alpha helix - coiled
Beta helix - pleated

Question 5

What is the tertiary structure of a protein?

Answer 5

A specific 3D shape as a result of hydrogen bonds, ionic bonds, disulfide bridges and hydrophobic interactions

Question 6

What is the quartenary structure of a protein?

Answer 6

When two or more polypeptides associate

Question 7

What test identifies proteins?

Answer 7

The biuret test

Question 8

How is the biuret test carried out?

Answer 8

1. Add sodium hydroxide (NaOH) to the sample (equal volumes)
2. Add drops if copper sulphate solution (which is blue) and mix
3. A purple colour shows the presence of protein

Question 9

What is the difference between DNA and ATP?

Answer 9

-The base in ATP is always adenine whereas in DNA the base is either adenine, thymine, cytosine and guanine
-There are 3 phosphate groups in ATP and only one in DNA
-The sugar in ATP is ribose but in DNA it is deoxyribose
(Similarities both contain a nitrogenous base and a sugar. They also have phosphate groups involved