Download Slide 1 In this lesson, we will give you a general

Slide 1
In this lesson, we will give you a general introduction to some of the organic molecules.
Slide 2
At the end of this lesson, you should be able to,
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Describe carbon bonding and organic compounds
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Explain alkanes, alkenes, and alkynes
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Describe the functional groups
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Discuss the organic molecules in living beings
Slide 3
Let us look at the definition of organic molecules.
Organic Molecules are the compounds containing carbon atoms. We do not include Carbon dioxide and
diamonds under this category.
Early Thoughts were that only living things could synthesize organic compounds. But, in 1800, an
organic compound was synthesized in the lab. This rejected the idea that organic compounds can only
be synthesized in living things.
Slide 4
All organic compounds contain carbon atoms. The carbon is the 6th element in the periodic table.
This means,
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There are 6 protons in the nucleus and 6 electrons surrounding that nucleus. The atomic
number of carbon is six.
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Carbon has three naturally occurring isotopes – C12, C13, and C14. C14 is a radioactive isotope.
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Isotopes are the elements with the same atomic number, but different atomic mass. C12 , C13 ,
and C14 have 6, 7, and 8 neutrons respectively in the nucleus in addition to the protons.
Therefore, these isotopes have different atomic masses since the atomic mass is the total value
of protons and neutrons in the nucleus.
Slide 5
Carbon has four electrons in the outermost shell. This means it needs four more electrons to complete
the octet rule. In order to get four more electrons, carbon makes four bonds.
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The four electrons in the outermost shell make 4 bonds by sharing with another four electrons
from different atoms or other carbon atoms.
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A carbon compound with four bonds forms a tetrahedron. E.g. Carbon Tetrachloride (CCl4)
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Organic compounds form long chains and rings.
Slide 6
The shape of a tetrahedron is given here. The compound on this PowerPoint is methane.
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Carbons can also make long chains. They can be a continuous chain like the one shown here
with repetitive CH2 groups and/or a combination of other branched chain with other atoms
attached to it. It could also have double or triple bonds which brings unsaturation to the
compound.
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Carbon also from ring structures. The example given here is cyclohexane.
Slide 7
Hydrocarbons are a group of carbon compounds consisting only of carbon and hydrogen atoms.
There are three types:
1) Alkane - This is the saturated form (all single bonds) of hydrocarbon.
2) Alkene – This group has double bonds.
3) Alkyne – This group has triple bonds.
Slide 8
Alkanes are also known as paraffins or saturated hydrocarbons.
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Alkanes belong to a homologous series. This means the series has a general formula, similar
chemical properties due to the same functional group and increasing physical properties as a
result of increasing mass and molecular size.
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The common formula for this series is CnH2n+2
Slide 9
Alkenes belong to the unsaturated hydrocarbons.
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These are also known as Olefine.
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The simplest acyclic form has one double bond in the structure.
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This series has the common formula CnH2n
Some examples are,
Ethene - C2H4
Propene - C3H6
Slide 10
Alkynes also belong to unsaturated hydrocarbon groups. They have at least one triple bond.
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Simplest member of the series is known as ethyne (acetylene)
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The acyclic homologous series formula with one triple bond is Cn H2n-2
Slide 11
A functional group is a group of atoms that performs a specific function. They can be hydrophilic ( (water
attracting)or hydrophobic ( water repelling).
Some examples of functional groups are:
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Alcohol with hydroxyl as its functional group; commonly written as ROH
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Carboxylic Acid with carboxyl group as its functional group; commonly written as RCOOH
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Aldehyde with aldehyde as its functional group; commonly written as RCHO
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Ketone with Carbonyl group as it functional group; commonly written as RCOR’
R is known as the alkyl group. The smallest alkyl group is CH3.
Slide 12
Alcohol is an organic compound with the functional group – OH, also known as hydroxyl group. Some
examples are:
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Methanol or Methyl Alcohol - CH3OH
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Ethanol or Ethyl Alcohol – C2H5OH
Slide 13
Carboxylic acid is an organic group with the functional group – COOH
Some examples are:
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Formic acid – HCOOH which is the simplest form of carboxylic acid.
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Acetic acid – CH3COOH found mainly in vinegar.
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Benzoic acid – C6H5COOH which is a cyclic compound.
Slide 14
Aldehydes are organic compounds with the functional group - CHO
An example is:
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Formaldehyde – HCOH used mainly as a preservative in laboratories and morgues.
Slide 15
Ketones are organic compounds with the functional group – CO –
An example is:
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Acetone CH3COCH3 which is mostly the base of nail polish remover.
Slide 16
Now we will cover some of the organic molecules found in human body cells.
They are:
1) Carbohydrates (sugars and starch)
2) Proteins
3) Lipids
4) Nucleic Acids
These are found in living things. All of the above types are combinations of several sub units that have
produced polymers. This means they are macromolecules.
Slide 17
Monomers of carbohydrates are monosaccharides.
Examples are glucose, fructose, and galactose. These are the basic units and combinations of these
compounds give different types of sugars and carbohydrates.
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Carbohydrates are used as a source of energy.
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These are made up carbon, hydrogen, and oxygen
Slide 18
Two monosaccharides combine to give a disaccharide. In this combination the basic sugars we described
earlier would combine to give different disaccharides.
Some examples, glucose and fructose give sucrose which is table sugar. Here we have given the
structures of the two monomers separately and then the structure of the combined product.
Slide 19
The combination of glucose and galactose gives lactose. This is found in milk.
You may have heard of lactose intolerance. This means the body can’t break this sugar down.
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A combination of glucose and glucose gives maltose.
Slide 20
Polysaccharides are chains of monosaccharides.
One example is starch. This is the way glucose is stored by plants.
Another example is amylose which is a non-branched polysaccharides
Amylopectin is an example of a branched polysaccharides
Glycogen is another polysaccharide. The glucose is stored in animals as glycogen.
Cellulose is polysaccharide produced by plants that make up the cell wall and Chitin polysaccharide
forms animal exoskeletons.
In the body, when stored glycogen needs to be converted to sugar, the hydrolytic enzymes break these
polymers to sugar molecules
Slide 21
Protein is a polymer. Its monomer is amino acid with the functional groups amine (NH2) group at one
end and carboxyl (COOH) group at the other end.
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Two amino acids combine to produce dimer known as a Peptide
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The polymeric form of amino acids is called protein
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Amino acids combine by the elimination of a water molecule to form a peptide bond. The bond
is between amine and carboxyl group of two different amino acid monomers.
Slide 22
Protein goes through four structures before it becomes a protein. The primary structure is just a
sequence of amino acids combined by peptide bonds.
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The secondary structure is of two types. Alpha helix and Beta strand.
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The tertiary structure is given when secondary structures are combined by hydrogen, disulphide,
hydrophobic bonds, and ionic bonds.
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The quaternary structure is given when two or more polypeptides are folded together.
Slide 23
Some uses of protein in the body are as follows:
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It provides primary structure.
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Supports the formation of keratin (nails) and collagen, tendons, and skin.
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Actin and myosin proteins Support motion
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All enzymes are proteins and support reactions in the body.
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Hemoglobin is a protein in blood that supports transport.
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Antibodies and antigens are proteins helping defense system.
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Hormones are proteins that help metabolism.
Slide 24
Lipids are long hydrocarbons chains. These are insoluble in water.
An example is triglycerides. This consists of:
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Three fatty acids ( long hydrocarbon chain with a carboxylic functional group) linked to a
glycerol ( three hydroxyl groups)
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Fatty acids can be saturated or unsaturated (double or triple bonds)
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Fats are solid that originate in animals.
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Oils are liquid that originate in plants.
Slide 25
Examples of some other lipids are:
Phospholipids – These are found in cell membrane. They have a hydrophilic head and a
hydrophobic tail
Steroids – These are lipids with four fused carbon rings. E.g. Cholesterol, testosterone, estrogen
Waxes – These are long chain fatty acids combines with long chain alcohols
Slide 26
Nucleic acids are made up of nucleotides. Each nucleotide consists of a pentose sugar (ribose or
deoxyribose), a phosphate, and a nitrogen containing bases
An example of a nucleic acid is DNA known as Deoxyribonucleic acid. It has:
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Double strands (also known as a double helix) (A with T and G with C base pairings.)
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The two nitrogen containing bases are,
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Purine which is a structure with a double ring. Examples are Adenine and Guanine
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Pyrimidine has only a single ring. Examples are Cytosine and Thymine.
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Adenine combines with Thymine and Guanine with Cytosine in the human body.
Slide 27
RNA or Ribonucleic Acid is another example of a nucleic acid.
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It has only one strand
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The base Purine consist of Adenine and Guanine
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The Pyrimidine consist of Cytosine and Uracil
AMP or Adenosine monophosphate is a nucleotide. Adenosine consists of adenine and ribose.
ATP or Adenosine triphosphate would lose its phosphate and become a AMP and in the
process produces energy.