Download Biochemistry Homework

Biochemistry Classwork January 2014
1.
Polypeptides and proteins are formed by the condensation reactions of amino acids.
(a)
Give the general structural formula of a 2-amino acid.
(1)
(b)
Give the structural formula of the dipeptide formed by the reaction of alanine and glycine.
State the other substance formed during this reaction.
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(2)
(c)
State two functions of proteins in the body.
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(2)
(Total 5 marks)
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2.
Electrophoresis can be used to identify the amino acids present in a given protein.
The protein must first be hydrolyzed.
(i)
State the reagent and conditions needed to hydrolyze the protein, and identify the bond
that is broken during hydrolysis.
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(4)
(ii)
Explain how the amino acids could be identified using electrophoresis.
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(4)
(Total 8 marks)
3.
(a)
Draw the straight chain structure of glucose.
(1)
2
(b)
The structure of α-glucose is shown below.
6
5
CH 2 OH
O
C
H
H
4
C
H
OH
H
C
C
1
C
OH
HO
3
H
2
OH
Outline the structural difference between α-glucose and β-glucose.
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(1)
(c)
Glucose molecules can condense to form starch which can exist in two forms, amylose
and amylopectin. Describe the structural differences between the two forms.
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(2)
3
(d)
1.00 g of sucrose, C12H22O11, was completely combusted in a food calorimeter. The heat
evolved was equivalent to increasing the temperature of 631 g of water from 18.36°C to
24.58 °C. Calculate the calorific value of sucrose (in kJ mol–1) given the specific heat
capacity of water in Table 2 of the Data Booklet.
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(3)
(Total 7 marks)
4