1.6: Proteins

Question 1

Monomers of proteins

Answer 1

amino acids

Question 2

Dipeptide

Answer 2

formed when 2 amino acids join together

Question 3

Polypeptide

Answer 3

formed when more than 2 amino acids join together

Question 4

Proteins made up of

Answer 4

one or more polypeptides

Question 5

general structure of an amino acid

Answer 5

C
single bond to COOH group (carboxyl group)
single bond to H
single bond to H2N (amine group)
single bond to R group (variable group)

Question 6

How many amino acids

Answer 6

20

Question 7

Polypeptide formed by a

Answer 7

condensation reaction

Question 8

Bonds formed between amino acids

Answer 8

peptide bonds

Question 9

4 structural levels of proteins

Answer 9

primary
secondary
tertiary
quaternary

Question 10

Primary structure of proteins

Answer 10

The sequence of amino acids in the polypeptide chain

Question 11

Secondary structure of proteins

Answer 11

Hydrogen bonds form between the amino acids making the chain coil into an alpha helix or beta pleated sheet

Question 12

Tertiary structure of proteins

Answer 12

Ionic bonds, more hydrogen bonds and sometimes disulfide bridges form in the chain, making it coil or fold more.
For proteins made from one polypeptide chain = final 3D structure

Question 13

Quaternary structure of proteins

Answer 13

The way several differnet polypeptide chains are assembled.

For proteins made from more than one polypeptide chain = final 3D structure

Question 14

Structural proteins

Answer 14

Consist of long polypeptide chains which are parallel to each other and have cross-links between them.
eg: keratin and collagen

Question 15

Test for proteins

Answer 15

Biuret test

Question 16

Biuret test steps

Answer 16

add NaOH to make the solution alkaline
add copper sulphate solution
protein present = purple
no protein present = remains blue