Biological Molecules: Proteins

Question 1

what are amino acids?

Answer 1

amino acids are the monomers from which proteins are made

Question 2

what are dipeptides?

Answer 2

formed by the condensation reaction of two amino acids

Question 3

what are polypeptides?

Answer 3

formed by the condensation reaction of many amino acids

Question 4

what is the general structure of amino acids?

Answer 4

• c in centre
• h at bottom
• cooh to the right
• h2n to the left
• r at the top

Question 5

what is COOH?

Answer 5

carboxyl group

Question 6

what is H2N?

Answer 6

amine group

Question 7

what are the levels for protein structure?

Answer 7

primary, secondary, tertiary, quaternary

Question 8

what is the primary structure?

Answer 8

the sequence of amino acids in the polypeptide chains

Question 9

what are the shapes in the secondary structure?

Answer 9

• alpha helix
• beta pleated sheet

Question 10

why doesn’t the polypeptide chain remain straight and flat?
(secondary structure)

Answer 10

hydrogen bonds form between the amino acids in the chain and this causes them to automatically coil

Question 11

what bonds are included in the dipeptide chain?

Answer 11

hydrogen bonds and ionic bonds
(attraction between negative and positive charges on different parts of the molecule)

Question 12

when do disulfide bridges form?

Answer 12

whenever two molecules of amino acid cysteine come close together (sulfur in one cysteine bonds with sulfur in the other)

Question 13

what is the final 3D structure for proteins made of a single polypeptide chain?

Answer 13

tertiary structure

Question 14

what is the quaternary structure?

Answer 14

the way the several different polypeptide chains are assembled together

Question 15

what are some examples of proteins with more than one polypeptide chain?

Answer 15

insulin, collagen and haemoglobin

Question 16

what determines a proteins functions?

Answer 16

its shape

Question 17

how is a peptide bond formed?

Answer 17

• the condensation reaction of two amino acids which releases H2O
• the peptide bond forms between the amine group (nitrogen) of one amino acid and the carboxyl group (carbon) of the other

Question 18

what are the two types of proteins?

Answer 18

• globular: e.g. enzymes
• fibrous

Question 19

how do you test for proteins?

Answer 19

• biuret solution
• protein is present the solution turns from blue to lilac

Question 20

how many polypeptide chains do functional proteins contain?

Answer 20

one or more

Question 21

how many amino acids are common in all organisms?

Answer 21

20