Biochemistry of proteins

Question 1

what do proteins exclusively contain?

Answer 1

carbon hydrogen oxygen and nitrogen (some proteins contain sulfur)

Question 2

the monomers that repeat to make up the polymer are called

Answer 2

amino acids

Question 3

the r group is always opposite …

Answer 3

a lone hydrogen off the central carbon

Question 4

how do amino acids join together

Answer 4

a condensation reaction where a molecule of water is removed

Question 5

when two amino acids are joined a …. is formed

Answer 5

dipeptide

Question 6

the bond between the carbon and nitrogen is known as ..

Answer 6

the peptide bond

Question 7

the condensation reaction is said to be

Answer 7

reversible , the reverse reaction is known as hydrolysis

Question 8

primary structure is the ..

Answer 8

amino acid sequence, peptide bonds are present in this level of the structure

Question 9

secondary structure is how..

Answer 9

the primary structure folds for the first time

Question 10

what are the two most common secondary structures

Answer 10

alpha helix

beta pleated sheet

Question 11

the secondary structure is held in place by

Answer 11

hydrogen bonds which are WEAK attractions between oxygen and hydrogen atoms in the primary structure

Question 12

tertiary structure is..

Answer 12

the 3D shape that the secondary structure folds into

Question 13

what is the shape of the tertiary structure determined by

Answer 13

the amino acid sequence, the tertiary structure is unique for each different protein

Question 14

3 types of bond that are present in the tertiary structure (and strengths)

Answer 14

hydrogen bonds- weak
ionic bonds- quite strong
disulphide bridges (covalent)- very strong

Question 15

why does an enzyme stop working after it has been heated

Answer 15

the enzyme has denatured
weak hydrogen bonds have been broken
3D tertiary structure is unravelled- loss of shape
active site is no longer complementary to the substrate

Question 16

quaternary structure is only found in…

Answer 16

proteins containing more than one polypeptide chain

Question 17

a prosthetic group is a

Answer 17

non polypeptide

Question 18

the final 3D structure of a protein can be classified as either

Answer 18

globular or fibrous

Question 19

globular proteins are mostly used for

Answer 19

metabolic processes

Question 20

fibrous proteins are mostly used for

Answer 20

structural processes

Question 21

testing for proteins (the buiret test)

Answer 21

1. Add an equal volume of a strong base (such as KOH) to the sample.
2. Add a few drops of Copper (II) Sulphate solution.
3. Mix gently.
4. Colour change from blue to lilac indicates presence of protein