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 in R?

Answer 7

variable group (side chain)

Question 8

what is R for glycine?

Answer 8

H

Question 9

what is R for alanine?

Answer 9

CH3

Question 10

what is R for valine?

Answer 10

2 CH3s on a CH

Question 11

what are the levels for protein structure?

Answer 11

primary, secondary, tertiary, quaternary

Question 12

what is the primary structure?

Answer 12

the sequence of amino acids in the polypeptide chains

Question 13

what are the shapes in the secondary structure?

Answer 13

• alpha helix
• beta pleated sheet

Question 14

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

Answer 14

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

Question 15

what bonds are included in the dipeptide chain?

Answer 15

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

Question 16

when do disulfide bridges form?

Answer 16

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

Question 17

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

Answer 17

tertiary structure

Question 18

what is the quaternary structure?

Answer 18

the way the several different polypeptide chains are assembled together

Question 19

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

Answer 19

insulin, collagen and haemoglobin

Question 20

what determines a proteins functions?

Answer 20

its shape

Question 21

how is a peptide bond formed?

Answer 21

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

Question 22

what are the two types of proteins?

Answer 22

• globular: e.g. enzymes
• fibrous

Question 23

how do you test for proteins?

Answer 23

• add sodium hydroxide solution (solutions needs to be alkaline)
• add copper(II) sulfate solution
• protein is present the solution turns from blue to lilac

Question 24

how many polypeptide chains do functional proteins contain?

Answer 24

one or more

Question 25

how many amino acids are common in all organisms?

Answer 25

20