1 Biological Molecules: Proteins

Question 1

What is an amino acid?

Answer 1

• a monomer which makes up proteins

Question 2

What are the components of an amino acid?

Answer 2

• central carbon
• carboxyl group
• amine group
• hydrogen atom
• R group

Question 3

What is an amino group?

Answer 3

• the NH2 group of an amino acid

Question 4

What is a carboxyl group?

Answer 4

• the COOH group of an amino acid

Question 5

What is a disulphide bridge?

Answer 5

• bond formed between sulphur atoms in R groups of amino acids

Question 6

What is an ionic bond?

Answer 6

• bond between a positive ion which has a lost an electron and a negative ion which has gained an electron

Question 7

What is a peptide bond?

Answer 7

• type of bond formed between 2 amino acids

Question 8

What is a polypeptide?

Answer 8

• many amino acids joined by peptide bonds

Question 9

What is a protein?

Answer 9

• polymer made of amino acids linked by peptide bonds
• may also contain prosthetic groups as part of its quaternary structure

Question 10

What is an R group?

Answer 10

• variable group
• determines bonding that that the amino acid can carry out
• each of the 20 amino acids has a different R group

Question 11

What does the amine group contain?

Answer 11

• hydrogen
• oxygen
• nitrogen

Question 12

What does the R group?

Answer 12

• carbon
• exception of glycine ( one hydrogen atom)
• can contain other elements e.g sulphur (cysteine)

Question 13

What is two amino acids joined together called?

Answer 13

• dipeptide

Question 14

What is it called when more than 2 amino acids are joined?

Answer 14

• polypeptide

Question 15

How many levels of protein structure are there?

Answer 15

• 4

Question 16

What are the different levels of protein structure?

Answer 16

• primary
• secondary
• tertiary
• quaternary

Question 17

What levels can single chain polypeptides have?

Answer 17

• primary
• secondary
• tertiary

Question 18

What structure do proteins made of multiple polypeptide chains have?

Answer 18

• quaternary

Question 19

Describe the primary structure of a protein

Answer 19

• number and sequence of amino acids in the polypeptide chain
• this can determine 3D shape/ tertiary structure
• can therefore effect the shape of the active site in the enzymes

Question 20

Describe the secondary structure of a protein

Answer 20

• hydrogen bonds form between amino acids in the chain which causes it to coil into an alpha helix or fold into a beta pleated sheet
• many hydrogen bonds make structures stable
  -most channel proteins are made of alpha helixes

Question 21

Describe the tertiary structure of a protein

Answer 21

• 3D shape of the polypeptide chain
• creates specific shape due to the sequence of amino acids in the chain as hydrogen bonds, ionic bonds and disulphide bridges (covalent bonds) form between R groups
• there’s a change to the sequence of amino acids that would effect secondary and tertiary structure as these bonds would from in different places
• all enzymes, antibodies and some hormones have tertiary structures

Question 22

Describe the quaternary structure of a protein

Answer 22

• made of more than one polypeptide chain they are joined to create a quaternary structure
• antibodies and haemoglobin are examples

Question 23

How is the original source of amino acids obtained?

Answer 23

• hydrolysis of peptide bonds