every dynamic function of a living being depends on protein. More than 50% of
the dry mass of most cells compose of protein. Proteins are the most
structurally sophisticated molecules known, they are made up of one or more
polypeptides, and each folded into a specific three-dimensional structure. The
monomer of protein is amino acid, and proteins are constructed from same set of
20 amino acids. Bond between amino acids is called a peptide bond. Therefore a
polymer of amino acids is called a polypeptide.
Amino acid is an organic molecule
with both an amino group and a carboxyl group. At the center of the amino acid
is an asymmetric carbon atom called alpha-carbon. Surrounded by 4 different
partners which are amino group, carboxyl group, hydrogen atom, and a variable
group symbolized by R. R group is also known as the side chain, the physical
and chemical properties of the side chain determine the unique characteristic
of a particular amino acid. Hence affects its functional role in a polypeptide.
Generally, there are two types of amino acid. Firstly, essential amino acid,
which cannot be made by the body, and must be supplied by food. The second type
is non-essential amino acid which can be produced by the body, from the
essential amino acid.
are most abundant biomolecule with diverse function. Some of the functions are
they act as structural materials such as collagen and keratin. Besides that
proteins can act as specific carriers. Enzymatic proteins regulate metabolism
by acting as catalyst, chemical agents that speed up chemical reaction.
Proteins are also involved in all cell movements. For instance, actin, tubulin,
and cytoskeleton protein. Other than that, proteins are also important for
defense. Thrombin and fibrinogen are blood clotting protein which prevent blood
loss when wounded. Next, proteins are important for regulation. Insulin and
glucagon are peptide hormones to regulate blood glucose level. Lastly, another
function of protein is for transport. Hemoglobin is an example of protein which
acts as transport, it carries oxygen from tissues to lungs.
acids are macromolecules that exist as polymers called polynucleotides. Each
polynucleotide consist of monomers called nucleotides. In polynucleotide, each
monomer has only one phosphate group, a five-carbon sugar, and nitrogenous
base. The main role of nucleic acid is to store information to make protein.
There are two types of nucleic acid, deoxyribonucleic acid (DNA) and
ribonucleic acid (RNA). They enable living organisms to reproduce their complex
components from one generation to another. DNA directs RNA synthesis, and
through RNA, controls protein synthesis.
Gene consist of DNA, which belongs to the class of
compounds called Nucleic Acids. The polymers of nucleic acid that made of
monomers called Nucleotides.A nucleotide is composed of three parts :
five-carbon sugar(pentose), nitrogen base, and one or more phosphate groups.
Polymers of nucleic acids are chains of nucleotides joined by condensation
reactions.They are held together by covalent bonds between sugar of one
nucleotide and the phosphate of another by phosphodiester bonds.Nucleic Acid
act as information storage,information ransfer and energy transfer.There are
two types of nucleic acid which are Deoxyribonucleic acid(DNA) and Ribonucleic
acid(RNA) enable living oganisms to reproduce their complex components from one
generation to the next. DNA directs RNA synthesis and provides directons for
its own replication.DNA made of two strands of nucleotides which form a double
helix and found in cell’s nucleus.It stores hereditary information.
Each nucleotide is composed of sugar-phosphate
covalently link to base which the base are Adenine (A),Thymine(T),Guanine(G)
and Cytosine(C)..A polynucleotide has a sugar-phosphate backbone with variable
appendages,the nitrogenous base.Moreover,DNA molecule that is composed of two
strands held together by hydrogen bonds between paired bases that is
(A-T,G-C).The arrows indicate the polarity of two strands which run
antiparallel to each other.Besides,RNA is a single helix that transfers
information from DNA to ribosomes.It also carries a protein recipe to
ribosome.Note that in RNA, Adenine pairs with Uracil (A-U).The type of nucleic
acid are ATP called Adenine Tri-Phosphate and ADP called Adenosine
Di-Phosphate. ATP is a single nucleotide that produced by cellular respiration
and has high energy molecule.It act as transfers energy within cells.ADP is a
single nucleotide and has a lower energy than ATP.It is a rechargeable energy
transfer molecule and its cellular respiration converts ADP into ATP.
Carbohydrates is the main source of energy for most
of living things in this world. Plant, animal and human really need
carbohydrate in their life. Carbohydrates, also known as saccharides or carbs,
are sugars or starches. They consist of carbon, hydrogen, and oxygen atoms. It
is the major source of energy for almost all living things. Plants make
carbohydrate, including structural carbohydrates such as cellulose and
energy-storage carbohydrates such as starch. Animals use carbohydrates as food
and many including humans store energy in a carbohydrate called glycogen.
Carbohydrates has various function which is a
structural components in cell membranes. For cellulose in the cell walls of
plants and many protists, while for chitin it is in the exoskeleton of insects
and other arthropods. Chitin is also can used as a surgical thread as chitin had strong and flexible but it also
dissolves over time, thus allowing patients to avoid the painful removal of
purpose of chitin is to provide support for the organisms. The material allows
the stability rigidity and flexibility. The body will considers chitin a
foreign substance so it will reacts against it to remove it. There is an enzyme
called chitanase. The chitanase function is to produced in our body to help
breakdown chitin. Hydrolysis separates the individual chitin molecules from
each other. Chitin also can be used for is in treating burn patients. Chitin
has a remarkable compatibility with living tissue, and has been looked at for
its ability to increase the healing of wounds. When the chitin is applied to
human wounds and surgical cloths, it accelerates the skin healing process. An
acidic mixture of chitin, when applied to burns, also increase the healing
process. When it use for the longest time, it can heal a third-degree bun
completely. It also has been shown to support the immune system during certain
kinds of illness-blocking procedures.
There are three groups of carbohydrates which is
monosaccharides, disaccharides and polysaccharides. Monosaccharides is the
simplest sugar with multiples of OH groups, Disaccharides is two monosaccharides
covalently linked ant for polysaccharides is polymer that consisting of chains
of monosaccharides or disaccharides unit. There are two basic compounds of
carbohydrates which is aldoses and ketoses. An aldose is a monosaccharide (a
simple sugar) with a carbon backbone chain with a carbonyl group on the endmost
carbon atom, making it an aldehyde, and hydroxyl groups connected to all the
other carbon atoms. A ketose is a ketone with two or more
hydroxyl groups (-OH), where at least one of the hydroxyl group at each end.
Ketoses are a type of monosaccharide, which are important fuel molecules and
nucleic acid building blocks.
Polysaccharides is a carbohydrates molecule which composed with
large numbers of monosaccharide units, which can be hundreds to thousands units
of monosaccharides and being connected by a bond named glycosidic bond. There
are two types of glycosidic bonds which are 1-4 glycosidic bonds and 1-6
glycosidic bonds, it depends on the carbon atoms that are bonded to each other.
Characteristic of polysaccharides are large and complex, not sweet and
insoluble in water. The main function of polysaccharides are as storage forms
of energy or as structural
materials. There are two types of polysaccharides which are
homopolysaccharides and heteropolysaccharides. Homopolysaccharides which only
contain one types of monomer. It can be linear homopolysaccharides and branched
homopolysaccharides. In linear homopolysaccharides, the bond is named 1-4 glycosidic bonds whereas the branched homopolysaccharides is 1-6
glycosidic bonds. Heteropolysaccharides are made out two or more different
monosaccharides. The structure of the heteropolysaccharide has different
repeating units. Heteropolysaccharides are complex structure compared to
homopolysaccharides. The repeating unit in heteropolysaccharides determines its
chemical and physical properties.
There are two types of polysaccharides act as storage which are
starch for plant and glycogen for animal. Starch is the reservoir of energy in
plant cells which is made of glucose(monomer)
units. Starch can be found in the chloroplast as an insoluble granule. It is a
homopolysaccharides which made up of two components; amylose and amylopectin.
Amylose is a linear chain structure formed by 1-4 glycosidic bonds. Because of
the linear structure it increase the surface area for the storage function.
While, amylopectin is a glucose polymer with mainly ?-1,4 glycosidic bond, but it also has branches which is formed by ?-1,6 glycosidic bond. This gives it more
open structure and prevent helix formation. It also can easily be broken than
amylose because of its structure.
Glycogen is the polysaccharides storage for animals. It is mostly
found in muscle and liver cells. In the liver cell, glycogen maintain the
blood-glucose level in the human body. The structure of glycogen is always
branched-chain of ?-D glucose. It has a-1,4 glycosidic bond and a-1,6
glycosidic bond. Glycogen is similar to starch except
it is highly branched. As glycogen is so highly branched, it can be
mobilised (broken down to glucose for energy) very quickly. It is broken down
to glucose by the enzyme glycogen
Starch and glycogen can be digested. To produce glucose,
starch and glycogen must be hydrolyzed. These enzymes
are known as ?-amylase and ?-amylase which attack glycosidic
bonds. ?-amylase is an endoglycosidase
which can hydrolyzed glycosidic bond anywhere along the chain to produce
glucose and maltose. While ?-amylase is an exoglycosidase
that cleaves from non reducing end of
polymer to produce maltose.
The three types of structural polysaccharidesare
for plant, chitin (N-acetyl-?-D-glucosamine) for animal and peptidoglycan for bacteria cell walls.
Cellulose is an organic compound which make plants have rigid cell wall, thus
it withstand osmotic pressure. It gives
(mechanical/structural) support and strength to plant. The monomer of cellulose is ?-D-glucose. There bond in cellulose which is ?(1,4)glucose polymer form cellulose microfibrils.
Microfibrils are very strong and rigid which give strength to plant cells. The ?-glycosidic bond cannot be easily broken down by
amylase, but it needs a specific cellulase enzyme.
Chitin is the component of the
exoskeleton of invertebrates. The strength is similar to cellulose. Chitin is a
linear homopolysaccharides of ?(1,4)-linked N-acetyl-D-glycosamine (NAG). One of the function of chitin
is; it can extends the shelf life of fruits and meats. Lastly, peptidoglycan is
a major structural of cell wall for bacteria. It is also heteropolysaccharides
which contain two alternating amino sugar; N-acetylglucosamine (NAG) and
N-acetylmuramic acid (NAM). Gram staining is a method of staining bacteria.
There are two types of gram staining; gram-positive bacteria has thick
peptidoglycan (cell wall) while gram-negative bacteria has thin peptidoglycan
biological compound that consist of nonpolar group and have limited solubility
in water. But dissolve freely in organic solvents (chloroform or acetone). Fats and oil are lipids and lipids exhibit
greater structural variety than other classes if biological molecule.Some of
the function of lipids are it act as structural components of biological
membranes such as Phosphoglycerol and sphingolipids. Lipid containing
hydrocarbon chain serve as energy store, triacylglycerols is one of the
example. there is also many intra and intercellular signaling events involve
lipid molecules such as steroids and phospholipids. There is classification of
lipids based on chemical structure. It is saperated into two groups, open
chained compound with polar head group and nonpolar tail, the other class is
the one that consist of fused ring compound.
Fatty acid has
carboxyl group at polar end and hydrocarbod chain at the non polar tail. It is
an amphiphatic molecule because the head is hydrophilic and the tail is
hydrophobic. Saturated hydrocarbon only consist of single bond bun unsaturated
hydrocarbon consist of double bond(monosaturated or polysaturated). Melting
point of fatty acid is the temperature at which the fatty acid undergoes transition from solid to liquid state. The
melting point is affected by the length of the acylchainand the number of
double bonds. The longer the chain, the higher the melting point because it
consist more van der waals forces. More double bond will lowering the melting
point because the double bond inhibit packing into solid solid state and the
van der waals forces interaction is reduced.
Tryglycerols which also known as triglycerides is the compound that
consist of three fatty acid and one one glycerol(alcohol that contain hydroxide
group). The OH group can form ester linkages with fatty acids. The fatty acid
is differ in chain and number of double bonds. It can be hydrolyzed by
saponification, a treatment with base to yield glycerol and fatty acid salts.
Tryglycerols can be synthesized by dehydration and one water molecule is lost
per ester bond formed. The functions are it act as energy storage, water
repellent, insulator and soap making.
Glycerolphospholipid which also known as phosphoacylglycerol or
phosphoglycerides. It is major component of biological membrane. Biological
membrane or also known as plasma membrane composed mainly lipid and protein.
Plasma membrane plays an important role in our life as it saperate beteween the
inter and outer space of the cells. Its consist of phosphoglycerides.
Cholesterol, plycolipiods and phytosterol.
is constitute a class of lipids defined by their 18 carbon amino-alcohol
backbones which are synthesized in the ER from non-sphingolipid precursors. Modification of this
basic structure will gives rise to the vast family of sphingolipids that play
significant roles in membrane biology and produce many bioactive metabolites
that will regulate cell function. Another function of sphingolipids is their creation and
destruction are governed by common synthetic and catabolic pathways. In this
regard, sphingolipid metabolism can be imagined as an array of interconnected
networks that diverge from a single common entry point and converge into a
single common breakdown pathway. It is important in both plants and animal.
Only one major phospholipid that contains ceramide (N-acyl-sphingosine
phosphocoline), an important structural lipid of nerve cell membranes.
Most sphingolipids are sphingolycolipids, that is,
their polar head groups consist of carbohydrate units. The lipids providing the
carbohydrates that covers the external surfaces of eukaryotic cells are
sphingoglycolipids. The principal classes of sphingoglycolipids are
cerebrosides (ceramide monosaccharides), sulfatides (ceramide monosaccharide
sulfates), globosides (neural ceramide oligosaccharides), and gangliosides
(acidic, sialic acid-containing ceramide oligosaccharides). The carbohydrate
unit is glycosidically attached to the N-acylsphingosine at its C1 OH group. In
sphingomyelin, primary alcohol group of sphingosine is esterified to phosphoric
acid, which in turn, is esterified to amino alcohol, choline. Galactocerebroside
(1-?-galactosylceramide) and glucocerebroside (1-?- glucosylceramide) are the
two most common cerebrosides. Both are synthesized from ceramide by addition of
a glycosyl unit from the corresponding UDP-hexose.
Glucocerebroside, although relatively uncommon, is
the precursor of globosides and gangliosides and it is the common component of
brain lipids. Biosynthesis of both globosides and gangliosides is catalyzed by
a series of glycosyltransferases. The pathway begin with transfer of a
galactosyl unit from UDP-Gal to glucocerebroside to form a ?(1-4) linkage. The
bond is referred to as lactosyl ceramide. Lactosyl ceramide is the precursor of
both globosides and gangliosides. Gangliosides are the most complex
glycosphingolipids. They are ceramide with attached oligosaccharides that include
at least one sialic acid residue.
The steroid core structure is composed of seventeen
carbon atoms, bonded in four rings: three six-member cyclohexane rings and one
five-member cyclopentane ring. Steroids vary by the functional groups attached
to this four-ring core and by the oxidation state of the rings. Fused rings
give sterols a rigid hydrophobic structure. Examples of some steroids such as
testosterone, cortisone, Vitamin D, cholesterol and etc. Sterols, the major
class of steroids, have a hydroxyl
at C-3. The major sterol in animal cell is cholesterol. Cholesterol is referred
as an amphipathic molecule, that it contains its hydrophilic and hydrophobic
parts. The hydroxyl group (-OH) in cholesterol is aligned with the phosphate
head of the phospholipid on cell membrane, which the rest of the cholesterol
goes with the fatty acid of the membrane. It is very important that cholesterol
is present on all the cell membrane due to its properties keep the cell firm
and avoid being overly fluid.
The steroid core structure is composed of seventeen
carbon atoms, bonded in four fused rings: three six-member cyclohexane rings
and one five-member cyclopentane ring. Steroids vary by the functional groups
attached to this four-ring core and by the oxidation state of the rings.
Cholesterol is usually synthesized in animals and smaller cholesterol can be
generated in plants. They are important in the composition of cell membranes
and also steroid hormones. Cholesterol has played an important role on every
cell in our body, especially abundant on the cell membrane, which function as a
communicator with other cells in our body. Small amount of cholesterol can also
be found on the membrane of some organelles inside the cells, such as the
mitochondrion and the endoplasmic reticulum.