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General Chemistry II
Homework :
Polymers & Biochemistry
Answer Key
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General Chemistry II
Homework Sheet 3: Polymers and Biochemistry
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Q1: Look at the compounds P to Y. Which is…..…..
OHOH
O
P
OH
H O
H
H
H
H
HO
O
R
OH
H
H
H
H
O
Q
OH
O
H
H2N
H
C
C
HO
OH
H
O
H OH
T
O
HO
H
H
H
S
H
OH
O
O
OH
HO
NH2
-O
P
N
O
O HO
O
H2N
N
U
O
H
CH C
OH
H
H
H
CH2
O
OH
O
O-
HO
H
H
OH
H
H
l) Of the two fatty acids, which has the lower melting point? Why?
m) Draw the skeletal structures of the four products that result when T is
hydrolysed with lithium hydroxide solution.
n) Draw the skeletal structures of the two possible
dipeptides that we could make from combining Q with V.
OH
O
O
OH O
a) a chiral amino acid?
b) a disaccharide?
c) an unsaturated fatty acid?
d) a non-chiral amino acid?
e) a triacyl glyceride?
f) a tripeptide?
g) a nucleotide?
h) a pentose monosaccharide?
i) a saturated fatty acid?
j) a hexose monosaccharide?
W
V
H
O
Q2: a) Draw two repeating units of the condensation polymer C that results when A is
reacted with B
b) What type of covalent bond is formed when the building blocks are joined?
c) Is this a homopolymer or co-polymer?
d) Does polymerisation occur by chain growth or step growth?
e) What is the mass (Da to 6 s.f.) of the repeating unit?
f) Given that when 10 mg of C was dissolved in 5 mL DMSO the osmotic pressure
was found to be 14.14 Pa at 25 ºC, what is the average molar mass of the polymer?
g) What is the average number of repeating units in each polymer chain?
A
O
HO
H2N
NH2
B
NH2
O
(5’) GCCTATCTGCAAGTC (3’)
Q3: Look at the fifteen-nucleotide DNA sequence shown:
a) What is the percentage of A nucleotides? What is the percentage of C nucleotides?
b) What is the expected abundance of G residues in the complementary strand of DNA?
c) What is the expected abundance of A residues in the
complementary strand of DNA?
Q4: Complete the following statements complete with words chosen from the wordsearch box.
A
RN
nds
ide
ar
ch
cis
c
sa
no
ur
ides
leot
nuc
es
enzym
ester a
min
o ac
ids
five
mo
pepti
de b
o
es
α-helic
prote
ins
disa
cch
arid
e
fo
sta
rch
s
er
acid
fatty
lipids
d) Write out the eight-nucleotide DNA sequence is
complementary to (5’) CTTCGAGC (3’)
er
A pentapeptide consists of______________building blocks called____________ joined together. There are
four_____________in the pentapeptide. Longer polypeptides are called___________. In these biopolymers, the long
chains fold against each other to create____________structural features including___________and_____________.
Proteins with catalytic activity are called___________
DNA is a biolpolymer featuring many thousand_____________joined together, of which there
are___________different types.____________is a single-stranded nucleic acid of ________ molecular mass.
Glucose, sucrose and cellulose are _______________ Glucose is an example of a ____________. Galactose is a
____________ and _____________is an example
of a polysaccharide.
Triacylglycerides feature three____________functional groups. They can be hydrolysed to give glycerol and
three___________.
Saturated __________have a __________melting point than those featuring many __________double bonds.
es
at
dr
Y
y
oh
OH
rb
ca
HO
gh
hi
O
w
lo
HO
ond
ary
O
HO
X
NH
HN
sec
O
ts
ee
sh
β-
O
1
Q1: Look at the compounds below. Which is…..
a) a chiral amino acid? V
b) a disaccharide? R
c) an unsaturated fatty
acid? P
d) a non-chiral amino
acid? Q
e) a triacyl glyceride? T
f) a tripeptide? Y
g) a nucleotide? U
h) a pentose
monosaccharide? W
i) a saturated fatty acid? X
j) a hexose
monosaccharide? S
OHOH
O
OH
H O
H
P
H
R
H
HO
O
H
OH
H
H
H
H
O
H
H2N
H
C
Q
OH
O
C
HO
OH
H
O
H OH
T
O
HO
H
H
H
S
O
O
OH O
H
OH
O
O
OH
HO
NH2
-O
P
N
O
H2N
N
U
O
H
CH C
CH2
O
O
O-
H
H
OH
H
H
O HO
O
OH
H
H
H
V
OH
HO
W
H
NH2
O
O
O
X
HO
O
NH
HN
O
HO
HO
OH
Y
Q1:
l) Of the two fatty acids, which has the lower melting point? Why?
P. Both have similar van der Waals forces but cis double
bonds create rigidity that cause P molecules pack
together more poorly in the solid than they do in X.
m) Draw the skeletal structures of the four products that result
when T is hydrolysed with lithium hydroxide solution.
O
O
OH
OH
OH
HO
O
OH
HO
O
n) Draw the skeletal structures
of the two possible dipeptides
that we could make from
combining Q with V.
H
N
O
HO
O
HO
O
NH2
NH2
N
H
H-Gly-Phe-OH
H-Phe-Gly-OH
(17 marks)
2
Q2: a) Draw two repeating units of the condensation polymer C that
results when A is reacted with B
OH
A
O
O
O
HN
O
B
NH
O
HO
O
H2N
HN
NH2
NH
b) What type of covalent bond is formed when the building blocks
are joined? peptide bond
c) Is this a homopolymer or co-polymer? co-polymer
d) Does polymerisation occur by chain growth or step growth?
step growth
(4 + 2 + 2 + 2 + 2 + 4 + 3 marks)
Q2:
OH
A
O
O
O
O
B
HO
HN
NH
O
O
H2N
NH2
HN
NH
e) What is the mass (Da to 6 s.f.) of the repeating unit? 250.34 Da
(4 + 2 + 2 + 2 + 2 + 4 + 3 marks)
3
Q2: f) Given that when 10 mg of C was dissolved in 5 mL DMSO
the osmotic pressure was found to be 14.14 Pa at 25 ºC, what is the
average molar mass of the polymer?
M = Π/RT
= 14.14/ (8.314 x 298)
= 5.707 x 10-3 molm-3
10 mg in 5 mL
= 10 x 10-3 g in 5 x 10-6 m3
= 2000 gm-3
Mr = 2000 / 5.707 x 10-3
= 3.50 x 105 g/mol
g) What is the average number of repeating units in each polymer
chain?
No. of repeating units = molar mass / mass of each unit
= 3.50 x 105 g/mol / 250.34 g/mol
= 1400
units
(4 + 2 + 2 + 2 + 2 + 4 + 3 marks)
Q3:
Look at the fifteen-nucleotide DNA sequence below.
(5’) GCCTATCTGCAAGTC (3’)?
a) What is the percentage of A nucleotides? 20%
What is the percentage of C nucleotides? 33.33%
b) What is the expected abundance of G residues in the
complementary strand of DNA?
In DNA, G must pair with C and A must pair with T
so %G = 33.33%
(3 + 3 + 4 + 4 marks)
4
Q3:
Look at the fifteen-nucleotide DNA sequence below.
(5’) GCCTATCTGCAAGTC (3’)?
c) What is the expected abundance of A residues in the
complementary strand of DNA?
In DNA, G must pair with C and A must pair with T so %A = 100
x (4/15) = 26.67%
d) Write out the eight-nucleotide DNA sequence is complementary to
(5’) CTTCGAGC (3’)
| | | | | | | |
(3’) GAAGCTCG (5’)
(3 + 3 + 4 + 4 marks)
five
A pentapeptide consists of______________building
blocks called____________
amino acids
joined together. There are four_____________in
the
pentapeptide. Longer
peptide bonds
polypeptides are called___________.
proteins In these biopolymers, the long chains fold
against each other to create____________structural
features
secondary
α-helices
including___________and_____________.
β-sheets
Proteins with catalytic activity are called___________
enzymes
DNA is a biolpolymer featuring many thousand_____________joined
together, of
nucleotides
RNA
which there are___________different
types.____________is
a
single-stranded
four
nucleic acid of ________
lower molecular mass.
carbohydrates Glucose is an example of a
Glucose, sucrose and cellulose are _______________
____________.
Galactose
is
a
____________
an example
monosaccharide
disaccharide and _____________is
starch
of a polysaccharide.
Triacylglycerides feature three____________functional
groups. They can be
ester
lipids
hydrolysed to give glycerol and three___________.
Saturated
__________have
a
fatty acids
higher
cis
__________melting
point than those featuring many __________double
bonds.
(10 marks) TOTAL: 60 marks
Q4: Write out the following statements complete with words chosen
from the wordsearch. Circle words you choose.
5