Chapter 1 Biomolecules
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Transcript of Chapter 1 Biomolecules
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SBK1013Introduction to Biochemistry
CHAPTER 1: BIOMOLECULES
Learning Outcomes
State the common functional groups of
organic biomolecules
Describe major classes of biological molecules
Draw the general molecular structure of
biomolecules
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What is organic molecules?
Organic molecule is one that containsatoms of carbon and hydrogen
Organic molecules make up portions
of cells, tissues and organs
What is inorganic molecules?
Inorganic molecules does not contain carbon.
Water (H2O) and salt (NaCl) are examples of
inorganic molecule
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Carbon Atom and CarbonSkeleton
Carbon, with total of six electrons, has four electron
in the outer shell
To complete outer shell carbon atoms shares
electron with CHNOPS elements
Carbon chain of an organic molecule is called its
skeleton or backbone
Functional Groups
A functional group is a specific combination of
bonded atoms that always has the same chemical
properties
Therefore always react in the same way, regardless
of the particular carbon skeleton to which it is
attached
Functional group of organic molecule help to
determine its chemical properties
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Common Functional Groups
Functional Groups Found in
Hydroxyl Alcohol, sugars
Carboxyl Amino acids, fatty acid
Carbonyl Aldehydes, ketones
Amino Amino acids, proteins
Phosphate ATP, nucleic acids
Sulfhydryl Amino acids, cystein,
proteins
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Aldehydes: the carbonyl is placed at the end of a
carbon skeleton
Ketones: the carbonyl is placed between two carbon
atoms
Aldehydes vs Ketones
Carbonyl vs Carboxyl
Carbonyl: A carbon atom double bonded to an oxygen
atom
Carboxyl: A carbonyl (RR'C=O) and a hydroxyl (R-O-H),
which has the formula -C(=O)OH, usually written as -
COOH
CarbonylCarboxyl
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Major Classes of BiologicalMolecules
Carbohydrates
Lipids
Proteins
Nucleic Acids
Carbohydrates
Universally used as an immediate energy source
Carbohydrate can be found in the form of:
Monosaccharide a monomer of the carbohydrate
which is a single sugar molecule i.e glucose
Disaccharide two bonded sugar molecules
Polysaccharide- many sugar molecules bondedtogether
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Monosaccharide
All have the formula (CH2O)n,where n is between 3 and 7.
The most common & important
monosaccharide is glucose, which
is a six-carbon sugar.
It's formula is C6H12O6
Glucose forms a six-sided ring. The
six carbon atoms are numbered as
shown.
Glucose Isomers
There are many monosaccharides, with the same chemical
formula (C6H12O6), but different structural formulae. These
include fructose and galactose.
Glucose (C6H12O6)
(anan aldehydealdehyde)Fructose (C6H12O6)
(aa ketoneketone))
Galactose (C6H12O6)
(anan aldehydealdehyde)
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Glucose Isomers
Common five-carbon sugars (where n = 5, C5H10O5) include
ribose and deoxyribose (found in nucleic acids and ATP).
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Disaccharide
Disaccharides areformed when two
monosaccharides
are joined together
by a glycosidic
bond.
The reaction
involves the
formation of a
molecule of water(H2O)
Disaccharide
Two monosaccharide
bonded together
Sucrose derived from sugar
beet and sugar cane
Lactose found in milk
Maltose derived from barley
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Polysaccharide
Polysaccharides are long chains of many monosaccharides joinedtogether by glycosidic bonds.
There are three important polysaccharides:
i. Starch
Plant storage polysaccharide.
Consist of amylose and amylopectin.
Ii. Glycogen
Contain similar structure to amylopectin.
It is made by animals as their storage polysaccharide, and is found
mainly in muscle and liver. Iii. Cellulose
Only found in plants, where it is the main component of cell walls
Starch
amylose
amylopectin
Glycogen
Cellulose
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Lipids Lipids contain fats and oils (fats are solid at room
temperature, whereas oils are liquid)
Triglycerides
Triglycerides are commonly called fats or oils.
They are made of glycerol and fatty acids.
Glycerol is a small, 3-carbon molecule with three hydroxyl
groups.
Fatty acids are long molecules with a polar, hydrophilic end
and a non-polar, hydrophobic "tail"
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Triglyceride molecule
Insoluble in water
The structure can pack a lot of energy into one molecule
Long term energy storage
Saturated vs Unsaturated Fatty Acids Saturated fatty acid
No C=C double bonds in the hydrocarbon chain,
These fatty acids form straight chains, and have a high melting
point.
Unsaturated fatty acid
There are C=C double bonds in the hydrocarbon chain
These fatty acids form bent chains, and have a low melting point.
Fatty acids with more than one double bond are called poly-
unsaturated fatty acids
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Proteins
Proteins are made of amino
acids.
Amino acids are made of the
five elements C H O N S.
The general structure of an
amino acid consists of:
hydrogen atom
amino group
carboxyl group
a variable "R" group (or side
chain)
Amino Acids There are 20 different R groups, and so 20 different amino
acids.
Since each R group is slightly different, each amino acid has
different properties.
Example:
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Polypetides
Amino acids are joined together by peptide bonds When two amino acids join together a dipeptide is formed.
Three amino acids form a tripeptide.
Many amino acids form a polypeptide.
Nucleic Acids
Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are the
nucleic acids in cells.
Nucleic acids are polymer in which the monomer is called a
nucleotide.
DNA or RNA, both consists of:
A phosphate
A 5-carbon sugar
Nitrogen containing base
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DNA vs RNA
DNA RNA
Sugar Deoxyribose Ribose
Bases A, G, C, T A, G, C, U
Strand Double
stranded
Single
stranded
Helix Yes No