1.
Fats
generally are solid while the oil is liquid phase,however both are equally
triglyceride.explain why the form of two different triglyceride, and point out
important factors that determine the form of fat?
Answer :
Triglycerides
in the fat oil
Can be
either solid or liquid depending on the composition of the constituent fatty
acids. Liquid vegetable oil because it contains unsaturated fatty acids, while
animal fats are generally solid at room temperature because it contains
unsaturated fatty acids.
Fat oil
Triglycerides
are composed of a mixture of esters of glycerol and long chain fatty acids. Fat
if the oil will produce three molecular hydrolyzed long-chain fatty acids and a
glycerol molecule.
Triglycerides
oil fatty
Derived
from various sources have physico-chemical properties are different from each
other that occurs because of differences in the number and types of esters
contained therein.
Triglycerides
in the fat oil
Did not
differ in their chemical composition differing only in shape or form.
Triglycerides are called oils when melted at room temperature and is called
solid if it freezes at room temperature.
There
are many different kinds of fats, but each is a variation on the same chemical
structure. All fats are derivatives of fatty acids and glycerol. The molecules
are called triglycerides, which are triesters of glycerol (an ester being the
molecule formed from the reaction of the carboxylic acid and an organic
alcohol). As a simple visual illustration, if the kinks and angles of these chains were straightened out,
the molecule would have the shape of a capital letter E. The fatty acids would
each be a horizontal line; the glycerol "backbone" would be the
vertical line that joins the horizontal lines. Fats therefore have
"ester" bonds.
The properties of any
specific fat molecule depend on the particular fatty acids that constitute it.
Different fatty acids are composed of different numbers of carbon and hydrogen
atoms. The carbon atoms, each bonded to two neighboring carbon atoms, form a
zigzagging chain; the more carbon atoms there are in any fatty acid, the longer
its chain will be. Fatty acids with long chains are more susceptible to
intermolecular forces of attraction (in this case, van der Waals forces), raising its melting point.
Long chains also yield more energy per molecule when metabolized.
Saturated
and unsaturated fats
A
fat's constituent fatty acids may also differ in the C/H ratio. When all three
fatty acids have the formula CnH(2n+1)CO2H,
the resulting fat is called "saturated".
Values of n usually range from 13 to 17. Each carbon atom in the chain is
saturated with hydrogen, meaning they are bonded to as many hydrogens as possible.
Unsaturated fats are derived from fatty acids with the formula CnH(2n-1)CO2H.
These fatty acids contain double bonds within carbon chain. This results in
an "unsaturated" fatty acid. More specifically, it would be amonounsaturated fatty acid. Polyunsaturated fatty acids would be fatty acids with more than
one double bond; they have the formula, CnH(2n-3)CO2H
and CnH(2n-5)CO2H. Unsaturated fats can be
converted to saturated ones by the process of hydrogenation.
This technology underpinned the development of margerine.
Saturated and unsaturated
fats differ in their energy content and melting point. Since unsaturated fats
contain fewer carbon-hydrogen bonds than saturated fats with the same number of
carbon atoms, unsaturated fats will yield slightly less energy during metabolism
than saturated fats with the same number of carbon atoms. Saturated fats can
stack themselves in a closely packed arrangement, so they can freeze easily and
are typically solid at room temperature. For example, animal fats tallow and lard are high in saturated fatty acid
content and are solids. Olive and linseed oils on the other hand are highly
unsaturated and are oily.
Trans
fats
There are two ways the
double bond may be arranged: the isomer with both parts of the chain on the
same side of the double bond (thecis-isomer), or the isomer with the
parts of the chain on opposite sides of the double bond (the trans-isomer). Most trans-isomer fats (commonly
called trans fats)
are commercially produced. Trans fatty acids are rare in nature. The cis-isomer introduces a kink
into the molecule that prevents the fats from stacking efficiently as in the
case of fats with saturated chains. This decreases intermolecular forces
between the fat molecules, making it more difficult for unsaturated cis-fats to
freeze; they are typically liquid at room temperature. Trans fats may still
stack like saturated fats, and are not as susceptible to metabolization as
other fats. Trans fats may significantly increase the risk of coronary heart disease.
2.
How a primary metabolite can be converted in the mecto secondary
metabolites. What is the basic idea and how the machanism could be described?
Answer:
Primary metabolite can be converted into secondary metabolisme
from the reaction the fundamental processes of photosynthesis, glycolysis, and
the Krebs cycle are tapped off from energy-generating processes to provide
biosynthetic intermediates.To make biosynthesis intermediets needs the
buillding blocks. By far the most important building blocks employed in the
biosynthesis of secondary metabolites are derived from the intermediates acetyl
coenzyme A (acetyl-CoA), shikimic acid, mevalonic acid, and methylerythritol
phosphate. These are utilized respectively in the acetate, shikimate,
mevalonate, and methylerythritol
phosphate pathways, Acetyl-CoA
is formed by oxidative decarboxylation of the glycolytic pathway product
pyruvic acid. It is also produced by the β-oxidation of fatty acids,
effectively reversing the process by which fatty acids are themselves synthesized
from acetyl-CoA. Important secondary metabolites formed from the acetate
pathway include phenols, prostaglandins, and macrolide antibiotics, together with
various fatty acids and derivatives at the primary–secondary metabolism
interface. Shikimic acid is
produced from a combination of phosphoenolpyruvate, a glycolytic pathway
intermediate, and erythrose 4-phosphate from the pentose phosphate pathway. The
reactions of the pentose phosphate cycle may be employed for the degradation of
glucose, but they also feature in the synthesis of sugars by photosynthesis.
The shikimate pathway leads to a variety of phenols, cinnamic acid derivatives,
lignans, and alkaloids. Mevalonic acid
is itself formed from three molecules of acetyl-CoA, but the mevalonate pathway
channels acetate into a different series of compounds than does the acetate
pathway. Methylerythritol phosphate arises
from a combination of two glycolytic pathway intermediates, namely pyruvic acid
and glyceraldehyde 3-phosphate by way of deoxyxylulose phosphate. The
mevalonate and methylerythritol phosphate pathways are together responsible for
the biosynthesis of a vast array of terpenoid and steroid metabolites.
In addition to acetyl-CoA, shikimic
acid, mevalonic acid, and methylerythritol phosphate, other building blocks
based on amino acids are frequently employed in natural product synthesis.
Peptides, proteins, alkaloids, and many antibiotics are derived from amino
acids, and the origins of some of the more important amino acid components of
these are briefly indicated in Figure 2.1. Intermediates from the glycolytic
pathway and the Krebs cycle are used in constructing many of them, but the aromatic
amino acids phenylalanine, tyrosine,
and tryptophan are
themselves products from the shikimate pathway. Ornithine, an amino acid not found in proteins, and its homologue lysine, are important alkaloid
precursors and have their origins in Krebs cycle intermediates. Of special
significance is the appreciation that secondary metabolites can be synthesized
by combining several building blocks of the same type, or by using a mixture of
different building blocks. This expands structural diversity and, consequently,
makes subdivisions based entirely on biosynthetic pathways rather more difficult.
A typical natural product might be produced by combining elements from the
acetate, shikimate, and methylerythritol phosphate pathways.
3.
Hormone
progesterone is essential for survival tha pregnancy,these hormones are derived
from a steroid biogenetically.Explain the logic of chemical reactions which may
occur in the formation of progesterone?
Answer:
In
mammals, progesterone (6), like
all other steroid hormones, is synthesized
from pregnenolone (3), which in turn is derived fromcholesterol (1) (see the upper half of the figure to the right).
Cholesterol (1) undergoes double oxidation to produce
20,22-dihydroxycholesterol (2).
This vicinal diol is then further oxidized with loss of
the side chain starting at position C-22 to produce pregnenolone (3). This reaction is catalyzed by cytochrome P450scc. The conversion of
pregnenolone to progesterone takes place in two steps. First, the 3-hydroxyl group is oxidized to a keto group (4) and second, the double bond is moved to C-4, from C-5 through a
keto/enol tautomerizationreaction.[14] This reaction is catalyzed by 3beta-hydroxysteroid
dehydrogenase/delta(5)-delta(4)isomerase.
Progesterone in turn (see lower half of
figure to the right) is the precursor of the mineralocorticoid aldosterone,
and after conversion to17-hydroxyprogesterone (another natural progestogen) of cortisol and androstenedione.
Androstenedione can be converted totestosterone, estrone and estradiol.
4.
Many
alkaoid are toxic to other organisms. Thay often have pharmacological effects
and are used as medication,as recreational drug,or in entheeogenic ritual.
Answer:
Isoquinoline alkaloids are tyrosine-derived plant alkaloids
with an isoquinoline skeleton. Among them benzylisoquinoline alkaloids form an important
group with potent pharmacological activity, including analgesic compounds of
morphine and codeine, and anti-infective agents of berberine, palmatine, and
magnoflorine. Biosynthesis of isoquinoline alkaloids proceeds via
decarboxylation of tyrosine or DOPA to yield dopamine, which together with
4-hydroxyphenylacetaldehyde, an aldehyde derived from tyrosine, is converted to
reticuline, an important precursor of various benzylisoquinoline alkaloids.
biosintesis alkaloid tirosin
biosintesis alakoid piperidin
biosintesis alkaoid dari nikotin
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