Proteins Question Booklet
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Unit 1- Woodford County High School
Question 1
Unit 1- Woodford County High School
Question 2
Unit 1- Woodford County High School
Unit 1- Woodford County High School
Question 3
Read through the following passage about protein structure, then write on the dotted
lines the most appropriate word or words to complete the passage.
All amino acids contain the elements carbon, hydrogen, oxygen and
................................................ The primary structure of a protein is formed when
amino
acids are joined together by ............................................... bonds. Chains of
amino acids
may then form a secondary structure such as a spiral shape called the
..............................................., which is maintained by
...............................................
bonding. The tertiary structure of a protein is maintained by bonding between the
............................................... of amino acids.
(Total 5 marks)
Question 4
a)
The diagram below shows the structures of two amino acids, alanine and serine.
H
H
N
H
C
O
C
CH 3
H
H
N
OH
H
C
CH 2
O
C
OH
OH
Alanine
Serine
In the space below, draw a diagram to show a dipeptide formed when
these two molecules bond together.
(2)
Unit 1- Woodford County High School
(b) Computer-generated models were used to measure the length in
nanometres (nm) of a polypeptide containing a large number of amino acids.
Measurements were made of the primary and secondary structure of the
polypeptide. The models were used to measure the length of the polypeptide at
25 °C and at 55 °C. The results are shown in the table below.
Length of polypeptide/nm
Structure of polypeptide
at 25 °C
at 55 °C
Primary
505
505
Secondary
48
70
(i)
Explain what is meant by the term secondary structure of a protein.
..............................................................................................................
..............................................................................................................
..............................................................................................................
..............................................................................................................
..............................................................................................................
..............................................................................................................
(2)
(ii)
Compare the results obtained at 25 °C with those obtained at 55 °C.
..............................................................................................................
............................................................................................................
............................................................................................................
.............................................................................................................
...........................................................................................................
..............................................................................................................
(2)
Unit 1- Woodford County High School
(iii)
Suggest why the increase in temperature has this effect on the length
of the secondary structure of the polypeptide.
.............................................................................................................
..............................................................................................................
.............................................................................................................
...........................................................................................................
.............................................................................................................
.............................................................................................................
(2)
(Total 8 marks)
Question 5. (a)
Insulin and collagen are both proteins that have a primary
structure made up of amino acids joined together by peptide bonds.
(i)
Explain what is meant by the term primary structure of a protein.
.............................................................................................................
..............................................................................................................
..............................................................................................................
..............................................................................................................
(1)
(ii)
Name the type of reaction that occurs when a peptide bond is broken
causing a dipeptide to split into two amino acids.
.............................................................................................................
(1)
Unit 1- Woodford County High School
(b)
Insulin and collagen both contain the amino acids glycine and serine. The
diagram below shows a dipeptide formed from these two amino acids.
Complete the diagram to show the structure of serine when the peptide
bond breaks.
H
H
O
H H
O
N—C—C—N—C—C
H
OH
H
CH2
OH
H
H
O
N—C—C
H
+
OH
H
Glycine
Serine
(1)
(Total 3 marks)
Unit 1- Woodford County High School
Mark Scheme
Question 1
Question 2
Unit 1- Woodford County High School
Question 3
Nitrogen / N;
Peptide;
{Alpha / α} helix;
Hydrogen / H;
R groups / side groups / side chains; [5]
Question 4
(a)
Peptide bond drawn correctly ;
Rest of both amino acids drawn correctly ;
(b)
2
Reference to α-helix / β-pleated sheet ;
(i)
Reference to hydrogen bonds ;
(ii)
1.
2.
3.
4.
(iii)
1.
2.
3.
4.
2
The primary structure is the same length at both temperatures ;
The secondary structure is shorter at 25 °C ;
Length decreases from primary to secondary at both
temperatures ;
Correct manipulation of figures ;
2
Reference to increase in kinetic energy at (55 °C) ;
(More) vibrations within molecule ;
Therefore hydrogen bonds (holding α-helix / β-pleated
sheet together) reak/eq;
(Molecule) starts to unwind ;
2
[8]
Question 5
.
(a) (i)
the {sequence / order} of amino acids;
(ii)
hydrolysis;
1
1
(b)
H
H
N
H
C
CH 2
OH
O
C
OH
;
1
[3]
Unit 1- Woodford County High School