Ivan Qu
BBS1001 THE LEGO BRICKS OF LIFE CASE 1
LEARNING GOALS:
1. WHAT IS A SUGAR?
2. WHAT IS A FAT?
3. WHAT ARE NATURAL AND REFINED FATS AND SUGARS?
4. WHAT ARE THE STRUCTURES OF FATS AND SUGARS?
5. THE NOMENCLATURE OF FATS AND SUGARS
6. HOW DOES THE BODY DIGEST FATS AND SUGARS?
7. WHAT HAPPENS WITH THE NUTRIENTS?
8. WHY DO WE NEED NUTRIENTS?
9. WHAT ARE THE DIFFERENCES BETWEEN ESSENTIAL AND NON -ESSENTIAL FATS?
10. CHYLOMICRONS AND MICELLES
RESEARCH
1. A sugar is a sweet-tasting carbohydrate. Sugars are also referred as
saccharides, because of their taste. Simple sugars,
monosaccharides, include glucose, fructose and galactose. There
are also compound sugars, disaccharides, such as sucrose, lactose.
Longer chains, such as oligosaccharides and polysaccharides, also
exist. Sugars are poly-alcohols.
2. A fat is part of the lipids. Fats are not soluble in water. Animal fats
and plant oils are triglycerides. It is a tri-ester of fatty acids with
glycerol. Fats can be made into hormones, can be stored as energy
and can be used as energy.
3. Refined sugars are those that have been processed, as opposed to natural sugars in fruit and
milk. Refined sugars mostly come from sugar canes or sugar beets. These are processed in a
way that the color and impurities are removed, which then results in for example the white,
crystal-like table sugar, also known as sucrose (a disaccharide of glucose and fructose).
Refined sugars tend to be easier to digest but increase insulin levels at a faster pace.
Natural sugars are sugars that occur in fruits, vegetables, grains and diary.
Refined fats, more or less processed fats, are generally speaking the trans-fats as a result of
hydrogenation. Fatty acids mostly have double bonds in cis isomers, but those are sometimes
reduced into trans isomers, extending the shelf life of the fat and creating a more wanted
consistency. However, trans fats are not healthy and can cause health problems.
Natural fats are triglycerides found naturally in meats, vegetables, fruits and other plants.
4. Monosaccharides have hydroxyl (-OH) and carbonyl (-HC=O) groups in the same molecule,
which then react, resulting in a 5 or 6 C atomic ring structure, also known as a cyclic
hemiacetal. When the monosaccharides are in an “open”
structure, like a chain, and it has an aldehyde-group, it is
called an aldose. When it has a ketone group, it is called a
ketose. Monosaccharides have asymmetric carbon atoms,
but when the ring-structure is formed, there will be a new
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asymmetric carbon atom and that carbon atom is called the
anomeric carbon. From there on the counting of the carbon will start
(clockwise). This results in an alpha-position (OH is below the C) and
a beta-position (OH is above the C). Monosaccharides can bind with
each other, creating longer molecules. The OH groups from both
monosaccharides will bond into a glycosidic bond, with
an alpha (when the OH from the first C atom is below
the C) and a beta variation. Mutarotation is a change in
the optical rotation of a solution due to a change in
equilibrium between alpha and beta anomers, upon
dissolution in the aqueous solution.
Fat consists of glycerol and fatty acids. The fatty acids can differ but have similarities
(unbranched carboxylic acids, 10-20 carbons, even number of carbons, apart from the -COOH
group they have no other functional group aside from the occasional
double bonds, when double bonds are present, the cis isomer is
dominant). Such triglycerides are insoluble in water (ester groups are
polar, but the environment is nonpolar). However, mono- and diglycerides
also exist. When double bonds are present in fatty acids, the FA are called
unsaturated, as the double bonds can open up. Conversely, when no
double bonds are present, it is called saturated. Having
double bonds or not also affect the consistency of the
triglyceride in for example room temperature.
5. Most simple monosaccharides have 3-9 carbon atoms.
Simple monosaccharides can be named after the
amount of such atoms: triose, tetrose, pentose, hexose etc. The suffix -ose suggests a
carbohydrate. Monosaccharides are classified as aldoses or ketoses, depending on the
presence of the aldehyde or ketone group. The prefixes aldo- and keto- can be combined with
triose, pentose etc. (ketotriose for example). An alternative nomenclature uses -ose only for
aldoses and -ulose for ketoses (pentulose). Carbohydrates have multiple stereocenters, which
then leads to more molecules and different names. The Fisher projection is a 2D-projection
showing the configuration of a stereocenter. When the OH-
group on the lowest chiral carbon is on the left, it is the L-
configuration, when it is on the right, it’s the D-configuration.
There is also an alpha or beta variation, when looking at the
cyclic form of carbohydrates, that depends on the orientation
of the OH on the first C-atom. Pyranose is a collective term for saccharides that have the
chemical structure that includes a six-membered ring, consisting of 5 C and 1 O. Furanose is
the same as pyranose, but with a five-membered ring, consisting of 4 C and 1 O.
Haworth projection is used to represent the cyclic structure of monosaccharides. It has the
following characteristics: C1 is the anomeric carbon and C and H are implicit (not explicitly
shown), it is a 3D projection so the thicker line indicates atoms closer to the observer and the
groups below the plane of the ring in Haworth projections correspond to those on the right-
hand side of a Fisher projection (rule does not always apply)
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For fatty acids, the C next to the carboxyl group is the alpha carbon, the beta carbon is next to
it etc. The last C atom is the omega-carbon. Counting from that omega-carbon is done (for
example to determine whether the FA is an omega-3 or omega-6), but according to the IUPAC
naming, the name is based on the C atoms counted from the carboxylgroup. Fatty acids can
have multiple or one double bond (polyunsaturated
and monounsaturated). Double bonds can be noted
with a Δx, y etc. (double bonds are always counted
starting from the carboxylgroup). Due to the presence of double bonds, either a cis- or
transconfiguration will be present.
Code name→ x carbons: x double bonds: position of the double bonds (omega or delta
variation) –> exam question: you are given the FA and link the code
6. Fats are broken down into glycerol and fatty acids. Glycerol can be converted to glucose by
the liver. Fats are somewhat broken down in the stomach, but most of the digestion is in the
small intestine. Lipases (pancreatic, hepatic, endothelial and lipoprotein lipases) produced by
the pancreas can break down fats. Bile (bile salts, lecithin, substances derived from
cholesterol), coming from the liver, can emulsify
the fats, making it easier for the lipase (increase
contact surface and enzyme and fat don’t mix) to
reach the fats. When the fat is broken down into
monoglycerides and fatty acids. Bile salts envelop
these to form micelles. Micelles have a fatty acid
core and a water-soluble exterior, making it able to
pass the microvillus of the small intestine. The fatty
content is released and the monoglycerides and
fatty acids reassemble into triacylglycerols. These can join together with cholesterol,
phospholipids, and a protein to form a chylo-micron (biggest lipoproteins), which makes
transportation of the fats possible.
Sugars are broken down by enzymes to their basic units, in other words, down to
monosaccharides. This happens mechanically (chewing) and chemically (enzymes). The
digestion starts in the mouth, but primarily takes place in the small
intestines. (Lactose intolerance is a disturbance of the sugar break
down)
7. Carbohydrates, when digested, end up in the bloodstream, making
it easily transportable throughout the whole body.
When fats are broken down into fatty acids, they are transported
via the chylomicron, which then can release these FAs to the places
where they are needed. The chylomicrons are transported through
the lymphatic system. Chylomicrons enter the lymphatic system
through the lacteal, a lymphatic capillary that absorbs fat in the villi of the small intestine.
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Both the fats and the sugars and up in places where they are needed for a certain goal, be it as
an energy source, a building block for the formation of a cell or they are simply transported to
a place where it needs to be stored.
8. There are 6 essential nutrients that the body needs to function properly. Nutrients are
compounds in foods essential to life and health, providing us with energy, the building blocks
for repair and growth (DNA, membrane (phospholipids: polar and apolar and cholesterol) etc.)
and substances necessary to regulate chemical processes.
9. The fatty acids that our body can produce via conversion (of for example amino acids) are
called non-essential fatty acids. Conversely, the FA that our body can’t “create” are regarded
as essential fatty acids as those have to be supplied via our food intake. Those FA are also vital
for the human health. The essential FA are linoleic acid (which makes the synthesis of omega 6
FA possible) and alpha linoleic acid (omega 3: ALA, DHA and EPA).
10. Free fatty acids and monoglycerides are enveloped by bile salts and it forms a micelle. A
micelle has a water soluble outside and a fatty core. This makes it able to pass to content into
to epithelial cell layer of the small intestine. When the fatty content is released into the cell,
chylomicrons are formed.
Chylomicrons (ultra-low-density lipoproteins (ULDL)) consist of triglycerides, phospholipids,
cholesterol and proteins. These transports and release the FA so that it can be absorbed by
the tissues. When it is mostly drained of the triglyceride content, it is taken up by the liver
(HDL, LDL?), providing the liver with some FA as well. The chylomicrons are transported via
the lymphatic system.