1.3 Proteins

Question 1

Draw the structure of an amino acid

Answer 1

• Correct structure drawn

Question 2

What is the bond which holds two amino acids in place

Answer 2

Peptide bond

Question 3

How do two amino acids bond together, via what reaction ?

Answer 3

Condensation reaction

Question 4

Explain a condensation reaction

Answer 4

When two hydrogen atoms and one oxygen atom is removed to join two things. Water is REMOVED

Question 5

Draw the structure of a dipeptide

Question 6

Where are the two proteins joined in the cell

Answer 6

• In the ribosome, where translation occurs and amino acids are joined together

Question 7

What is known as three or more amino acids joined together

Answer 7

Polypeptide

Question 8

What kind of reaction must take place to break a peptide bond ?

Answer 8

Hydrolysis reaction, where you add water back to break the peptide bond

Question 9

What enzyme carries out this reaction, the breaking of a peptide bond?

Answer 9

Protease

Question 10

What is known as the primary structure of proteins, and what are its bonds ?

Answer 10

A linear sequence of amino acids joined together by peptide bonds

Question 11

What is known as the secondary structure of proteins, and what are its bonds

Answer 11

Repeated pattern in the structure of the peptide chain such as alpha helix or beta pleated sheats, held together via hydrogen bonds

Question 12

Describe the tertiary structure of a protein

Answer 12

• The folding of the secondary structure into a 3D shape, held by hydrogen bonds, ionic bonds and disulphide bonds

Question 13

Describe the quaternary structure of a protein

Answer 13

3d arrangement of more than one tertiary polypeptide chain. Held together via hydrogen bonds, ionic bonds and disulphide bonds

Question 14

Why is the primary structure of a protein important

Answer 14

• It determines the final 3D shape of the protein

Question 15

What do some quaternary structure protein contain which make it useful for its purpose ?

Answer 15

• Prosthetic group
• In red blood cells this is Haem which binds to oxygen

Question 16

How is the structure of collagen related to its function ?

Answer 16

• Fibrous protein that gives strength to bones, skin and tissue
• Hydrophobic R groups which make them insoluble in water
• Polypeptide chains in collagen wrap tightly together to form a triple helix
• Hydrogen bonds form between polypeptide chains which helps stabilise the the quaternary structure of the protein , cross links