Anonymous Candidate Code:
Joseph Fourier University
2014-2015
BIO 121 Final Exam (Session 1)
---------------------------------------------------------------------------------------------------------
Exam conditions:
- 2H,
- no document allowed,
- no calculator allowed,
- no cell phone allowed.
The exam subject is composed of two parts:
Part A: answer in the provided squares below.
Part B consists in multiple choice questions: tick the correct or the wrong
answer(s) as requested.
---------------------------------------------------------------------------------------------------------------------------
PART A
(You should be answering to these questions in 60 minutes or less)
Drepanocytosis (sickle-cell anemia) is a genetic disease largely spread all over the world. It is
caused by a mutation on chromosome 11 resulting in a mutation of the globin part of
hemoglobin. Comparison of the nucleotide sequence of the mutated allele (allele S) to that of
the normal allele revealed a point mutation, as described in the following table:
Partial DNA sequence of a
wild-type (healthy) individual
Partial DNA sequence of a
mutated (sick) individual
GAG
GTG
1 Use the “square/triangle/circle’ code to schematize below the various parts of a nucleotide.
Do not forget to completely annotate this schematic representation.
1
2 Using the same “square/triangle/circle’ code, schematize below the double stranded DNA of
a healthy individual at the GAG codon. Orient and annotate this double stranded DNA.
The point mutation described above results in a modification of the amino acid sequence of
the globin protein. The table below compares the amino acid sequence of the globin A from a
healthy individual with the corresponding amino acid sequence of the globin S from an
individual suffering from drepanocytosis.
Portion of the globin A amino acid
sequence from a healthy individual
Portion of the globin S amino acid
sequence from a sick individual
Val His Leu Thr Glu Leu
Val His Leu Thr Val Leu
2
4 Write below the developed formula of the tripeptide Thr Glu Leu (from globin A) at pH1.
Threonine
Glutamate
Leucine
pKa (α-COOH)
2,6
2,2
2,4
pKa (α-NH3+)
10,4
9,7
9,6
pKa (lateral chain)
4,3
5 Write the dissociation equilibria of the tripeptide Thr Glu Leu from globin A and calculate
its isoelectric point.
3
The modification of the globin amino acid sequence resulting from the point mutation leads to
a modification of the protein isoelectric point.
6. Which method would you use to separate globin A from globin S? (Describe the principle
of this separation method and name it.)
The modification of the globin amino acid sequence resulting from the point mutation also
leads to a modification of the protein 3D structure. Hemoglobin S indeed polymerizes into
rigid fibers, which deform the red blood cell plasma membrane of sick individuals.
7 Draw below a schematic representation of a portion of a normal cell plasma membrane,
including all the components of this plasma membrane. Do not forget to completely annotate
this scheme, including the various compartments that you have represented.
4
The lipidomic analysis performed on this plasma membrane showed the presence of
1 palmityl 2 oleyl 3 β D-glucopyranosyl glycerol among the lipid components.
8 Write below the semi-developed formula of β D-glucopyranose.
9 Write below the semi-developed formula of palmitic acid at pH 1. Do not forget to number
the carbons and provide its fatty acid nomenclature.
10 Write below the semi-developed formula of oleic acid at pH 1. Do not forget to number the
carbons and provide its fatty acid nomenclature.
5
11 Write the semi-developed formula of 1 palmityl 2 oleyl 3 β D-glucopyranosyl glycerol.
To which lipid family does it belong?
12 On the formula written in question 11, draw a hydrogen bond that can be established
between the lipid and one water molecule.
6