Answers to the Quickies
367
adjusted. Sulfur bridges form between
the polyisoprene chains, resulting in a
three-dimensionally crosslinked elastomer.
9. The rubber becomes permanently elastic
and has increased tensile strength. It can be
stretched more. After vulcanization, it essentially retains its shape, does not become
sticky when heated and does not become
brittle when cold.
10. Vulcanized natural rubber is poorly resistant
to heat, weather, UV radiation and ozone.
It is also not resistant to fats, hydrocarbons
and mineral oils. These disadvantages can
be partially compensated by the addition
of aromatic amines as heat stabilizers or
paraffins to protect against the ozone effect.
Stabilizers such as hydroquinone or zinc
oxide are added to reduce oxidation by
atmospheric oxygen under the influence of
UV light.
Answers to 7 Chap. 14
1. Proteinogenic amino acids are found in
proteins. Some of them are essential, i.e.
they must be consumed with food because
the human body cannot produce them itself.
There are also many non-proteinogenic
amino acids in nature.
2. There are four groups: uncharged with
non-polar rests, uncharged with polar rests,
negatively charged at pH 7 and positively
charged at pH 7.
3. Asn = asparagine, Asp = aspartic acid,
Arg = arginine, Gln = glutamine, Glu = glutamic acid, Ile = isoleucine, Trp = tryptophan.
4. The starting materials for Strecker synthesis
are aldehydes, hydrogen cyanide and ammonia. In addition, a mineral acid is required
for the hydrolysis of the formed aminonitrile to the amino acid. To produce valine,
isobutyraldehyde (isobutanal) is used as the
starting material, thus the (dl)-racemate of
valine is formed.
5. Casein is an important protein component
of milk. It can be obtained from cow’s milk,
for example, by denaturation, leaving behind
the whey. In the investigation of casein,
for the first time, important amino acids
were found, such as l-tyrosine (by Justus
von Liebig), l-lysine, l-methionine and
l-tryptophan.
6. Methionine is an important amino acid for
animal nutrition and is therefore added
to animalfeed, in particular poultry feed.
Glutamic acid and its sodium salt are used -
especially in Asia - as flavor enhancers in
foods.
7. The four main production methods are:
Protein hydrolysis, chemical synthesis, enzymatic synthesis and fermentation.
8. l-Dopa is the precursor of dopamine, which
controls human motor function. Dopamine
deficiency causes Parkinson’s disease, which
is treated with l-dopa.
9. In peptides, amino acids are linked by an
amide bridge. When only a few amino acids
are connected, this is called oligopeptide.
Longer chains are polypeptides. Chains with
more than 150 amino acids are referred to as
proteins.
10. The primary structure represents the amino
acid sequence. In the secondary structure,
the preferred conformation is given, e.g. a
helix arrangement of the peptide chain. In
the tertiary structure, a distinction is made
between several folding possibilities, in
particular between proteins with a leaflet
structure (sclerotic or fibrous proteins) and
with a spherical structure (spheroidal proteins). The quaternary structure describes
the association of different peptide chains,
e.g. in hemoglobin.
Answers to 7 Chap. 15
1. Well-known natural colorants are Tyrian
purple, madder red, saffron, indigo and
Indian yellow.
2. The synthesis of dyes began in the nineteenth century. The starting materials of
the syntheses were mostly aromatic hydrocarbons and their derivatives from coal tar,
which was formed as a by-product during
the coking of coal to coke and coke oven
gas.
3. Tyrian purple is obtained from the glandular secretion of the “purple snail”. The
secretion is soaked in salt for several days
and boiled in urine. A colorless solution
367
adjusted. Sulfur bridges form between
the polyisoprene chains, resulting in a
three-dimensionally crosslinked elastomer.
9. The rubber becomes permanently elastic
and has increased tensile strength. It can be
stretched more. After vulcanization, it essentially retains its shape, does not become
sticky when heated and does not become
brittle when cold.
10. Vulcanized natural rubber is poorly resistant
to heat, weather, UV radiation and ozone.
It is also not resistant to fats, hydrocarbons
and mineral oils. These disadvantages can
be partially compensated by the addition
of aromatic amines as heat stabilizers or
paraffins to protect against the ozone effect.
Stabilizers such as hydroquinone or zinc
oxide are added to reduce oxidation by
atmospheric oxygen under the influence of
UV light.
Answers to 7 Chap. 14
1. Proteinogenic amino acids are found in
proteins. Some of them are essential, i.e.
they must be consumed with food because
the human body cannot produce them itself.
There are also many non-proteinogenic
amino acids in nature.
2. There are four groups: uncharged with
non-polar rests, uncharged with polar rests,
negatively charged at pH 7 and positively
charged at pH 7.
3. Asn = asparagine, Asp = aspartic acid,
Arg = arginine, Gln = glutamine, Glu = glutamic acid, Ile = isoleucine, Trp = tryptophan.
4. The starting materials for Strecker synthesis
are aldehydes, hydrogen cyanide and ammonia. In addition, a mineral acid is required
for the hydrolysis of the formed aminonitrile to the amino acid. To produce valine,
isobutyraldehyde (isobutanal) is used as the
starting material, thus the (dl)-racemate of
valine is formed.
5. Casein is an important protein component
of milk. It can be obtained from cow’s milk,
for example, by denaturation, leaving behind
the whey. In the investigation of casein,
for the first time, important amino acids
were found, such as l-tyrosine (by Justus
von Liebig), l-lysine, l-methionine and
l-tryptophan.
6. Methionine is an important amino acid for
animal nutrition and is therefore added
to animalfeed, in particular poultry feed.
Glutamic acid and its sodium salt are used -
especially in Asia - as flavor enhancers in
foods.
7. The four main production methods are:
Protein hydrolysis, chemical synthesis, enzymatic synthesis and fermentation.
8. l-Dopa is the precursor of dopamine, which
controls human motor function. Dopamine
deficiency causes Parkinson’s disease, which
is treated with l-dopa.
9. In peptides, amino acids are linked by an
amide bridge. When only a few amino acids
are connected, this is called oligopeptide.
Longer chains are polypeptides. Chains with
more than 150 amino acids are referred to as
proteins.
10. The primary structure represents the amino
acid sequence. In the secondary structure,
the preferred conformation is given, e.g. a
helix arrangement of the peptide chain. In
the tertiary structure, a distinction is made
between several folding possibilities, in
particular between proteins with a leaflet
structure (sclerotic or fibrous proteins) and
with a spherical structure (spheroidal proteins). The quaternary structure describes
the association of different peptide chains,
e.g. in hemoglobin.
Answers to 7 Chap. 15
1. Well-known natural colorants are Tyrian
purple, madder red, saffron, indigo and
Indian yellow.
2. The synthesis of dyes began in the nineteenth century. The starting materials of
the syntheses were mostly aromatic hydrocarbons and their derivatives from coal tar,
which was formed as a by-product during
the coking of coal to coke and coke oven
gas.
3. Tyrian purple is obtained from the glandular secretion of the “purple snail”. The
secretion is soaked in salt for several days
and boiled in urine. A colorless solution