Protein

Question 1

What is the primary structure of proteins?

Answer 1

The number and sequence of amino acids in the polypeptide chain.

Question 2

What is the secondary structure of proteins?

Answer 2

The coiling or regular folding of the polypeptide chain, held together by hydrogen bonds.

Question 3

What is the tertiary structure of proteins?

Answer 3

The further folding of the polypeptide chain to form a precise, compact and geometric shape. It is held together by hydrogen bonds, disulfide bonds, ionic interactions and hydrophobic and hydrophilic interactions.

Question 4

What is the quaternary structure of proteins?

Answer 4

Proteins which contain two or more polypeptide chains.

Question 5

What are the monomers of a polypeptide chain called?

Answer 5

Amino acids.

Question 6

What are 2 types of proteins?

Answer 6

Globular proteins and fibrous proteins.

Question 7

What is the shape of a globular protein?

Answer 7

Roughly circular/spherical

Question 8

What is the shape of a fibrous protein?

Answer 8

Long and thin strands

Question 9

What determines the function of a protein?

Answer 9

The shape, so the type and number of amino acids within a polypeptide chain.

Question 10

What is the general structure of an amino acid?

Answer 10

A central carbon atom bonded to an amine group (NH2), a carboxylic acid group (COOH), a hydrogen atom and an R group.

Question 11

What is the covalent bond called that forms between an amino acid?

Answer 11

Peptide bond.

Question 12

How is a peptide bond formed?

Answer 12

A hydroxyl (-OH) is lost from the carboxylic group of one amino acid and a hydrogen atom is lost from the amine group of another amino acid. The remaining carbon atom (with the double-bonded oxygen) from the first amino acid bonds to the nitrogen atom of the second amino acid.

Question 13

What is the reaction called when the bond is formed?

Answer 13

Condensation reaction.

Question 14

What is the primary structure of a polypeptide chain determined by?

Answer 14

The DNA of the cell.

Question 15

What are the 2 types of secondary structures of a protein?

Answer 15

Alpha helix and Beta pleated sheet.

Question 16

When does the alpha helix occur?

Answer 16

When the hydrogen bonds form between every fourth peptide bond.

Question 17

When does the beta pleated sheet form?

Answer 17

When the protein folds so that two parts of the polypeptide chain are parallel to each other enabling hydrogen bonds to form between parallel peptide bonds.

Question 18

What are the additional bonds that can form between the R groups?

Answer 18

Hydrogen bonds, disulfide bonds, ionic bonds and weak hydrophobic interactions.

Question 19

Where do disulfide bonds form?

Answer 19

Between two cysteine R groups as they are the only amino acid with a sulfur atom.

Question 20

Where do ionic bonds form?

Answer 20

Between positively charged and negatively charged R groups.

Question 21

When do hydrogen bonds form?

Answer 21

Between strongly polar R groups.

Question 22

When do hydrophobic interactions form?

Answer 22

Between the non-polar R groups within the interior of the protein.

Question 23

What is the structure of haemoglobin?

Answer 23

Has a tertiary structure with 4 polypeptide chains. These chains are globin proteins and all contain a prosthetic haem group. The chains are held together by disulphide bonds and by hydrophobic and hydrophilic interactions.

Question 24

How does the structure of haemoglobin help its function?

Answer 24

The haem groups contain Iron 2+ ions which is able to reversibly combine with oxygen to form oxyhaemoglobin.

Question 25

What type of protein are enzymes?

Answer 25

Globular proteins.

Question 26

What is the structure of collagen (fibrous protein)?

Answer 26

Has a quaternary structure with 3 polypeptide chains closely held together by hydrogen bonds to form a triple helix structure. Each polypeptide chains is a helix shape and contains about 1000 amino acids, most commonly glycine, proline and hydroxyproline. Covalent bonds are also present which forms cross links between R groups of amino acids. This then creates fibrils.