pdt-4th chap(biological molecules)
TRANSCRIPT
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BIOLOGICAL MOLECULES
ATOMS
Submicroscopic particles that make up allmatter.
Pure substances that are made up of a single
kind of atom
Cannot be separated into different substances
by ordinary chemical methods.
- Examples: oxygen (O), hydrogen (H),
carbon (C).
ELEMENTS
Atoms that have lost or gained electrons
Examples: hydrogen ion (H+), hydroxide ion (OH-).
IONS
Molecules made up of atoms of different
elements
Example: water molecule (H2O), carbohydrates,
lipids and proteins
COMPOUNDS
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5 functional groups that are most important to thechemistry of life:
Hydroxyl group (-OH). Carboxyl group (-COOH).
Amino group (-NH2).
Sulphydryl group (-SH).
Phosphate group(-OPO32-).
FUNCTIONAL GROUP
FUNCTIONAL GROUP
Group with distinct chemical properties
Carbon is the skeleton holding groups of atoms
Chemical reactions within organisms involvethe transfer of a functional group
Give each molecule its unique properties.
A hydrogen atom is bonded to an oxygen atom
These in turn is bonded to the carbon skeleton ofthe organic molecule
Organic compounds with hydroxyl groups arealcohols
Their names typically end in -ol.
HYDROXYL GROUP (-OH)
When an oxygen atom is double bonded to acarbon atom that is also bonded to a hydroxylgroup
Organic compounds with carboxyl groups arecarboxylic acids.
CARBOXYL GROUP (-COOH)
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AMINO GROUP (-NH2)
Consists of a nitrogen atom bonded to twohydrogen atoms and to the carbon skeleton.
Organic compounds with amino groups are amines.
Consists of a sulphur atom bonded to an atom of
hydrogen. Help stabilise the structure of proteins.
Organic compounds with sulphydryl groups arethiols.
SULPHYDRYL GROUP (-SH)
PHOSPHATE GROUP (-OPO32-)
A phosphorus atom is bonded to four oxygen
One oxygen is bonded to the carbon skeleton
Two oxygen carry negative charges
Function is to transfer energy between organic
molecules.
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Organics compound
KEY TERMScarbohydrates monosaccharidesglucose disaccharides
maltose polysaccharides
cellulose lipids
fatty acid glycerol
steroid phospholipids
proteins amino acid
polypeptide nucleic acids
triglyceride condensation
hydrolysis glycosidic linkage
ester linkage peptide bond
CARBOHYDRATES
Contain C,H, & O
Ratio H:O = 2:1
Example: starch, glycogen, cellulose
Glucose
Carbohydrate:Structural formula of glucose
Molecular formula: C6H12O6
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CARBOHYDRATES
There are three groups of carbohydrates:
Monosaccharides (simple sugar)
Disaccharides
Polysaccharides
MONOSACCHARIDES
Simplest carbohydrates
Individual sugar molecules
Have a carbonyl group and multiple of hydroxylgroups.
Examples: glucose, fructose, galactose
Two types of glucose are:
1) -glucose
2) -glucose
MONOSACCHARIDES
-Glucose and -Glucose
-glucose and -glucose are six carbon
molecules.
Difference : The position of hydroxyl group at
carbon number one of the molecule.
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DISACCAHARIDES
2 monosaccharides linked together with a
glycosidic linkage
via condensation process.
Produce water molecule
DISACCAHARIDES
Example : maltose is formed by joining two
-glucose molecules.
Polymers of sugars (monosaccarides)
Hundreds to thousands of monosaccharides joined
by glycosidic linkages
Insoluble
Called complex carbohydrates
POLYSACCHARIDES
Example : cellulose.
Cellulose - a polymer of -glucose monomers.
- a major component of the plant cell
wall
POLYSACCHARIDES
Cellulose
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Monosaccharides :
Important fuel to gain energy to sustain life
the raw material for the synthesis of othermonomers.
Polysaccharides :
energy storage, e.g :glycogen (animal), starch(plants)
serve as building materials for the cell or wholeorganism.
Example : cellulose -plant cell wall material.
Functions of Carbohydrates
LIPIDS
Large molecules made up of hydrogen, carbon& oxygen.
H:O ratio higher than 2:1
Not dissolved in water, dissolved in oil and otherorganic solvents
3 important categories of lipids
Triglycerides (fats)
Phospholipids
Steroids
TRIGLYCERIDES
Non-polar
Built from two types of subunitsGlycerol
Fatty acids
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Triglycerides
Molecule with 3 fatty acids and 1 glycerol The linkage between each fatty acid and glycerol
is called ester linkage by condensation reaction
GENERAL STRUCTURE OFTRIGLYCERIDE
PHOSPHOLIPIDS
Similar to triglyceride- but one of the fatty acidsis replaced by phosphate group
Key component of cell membrane
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PHOSPHOLIPIDS
STEROIDS
With 4 carbon rings
As a precursor for steroid hormones
cholesterol
Energy storage (more energy than equivalentamounts of carbohydrates)
Cushion vital organs.
As insulation.
Phospholipids :component of membranes.
Cholesterol (steroid) : a component in animal cellmembranes.
Functions of Lipids
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PROTEINS
Consist of carbon, hydrogen, nitrogen, oxygenand sometimes sulphur and phosphorus.
The most structurally complex molecules known.
Basic unit of protein is amino acids.
Chain of amino acids are linked by peptidebonds.
Two amino acids can be joined by acondensation reaction to form a dipeptide.
COOH
H
NH2
R
AMINO ACIDS
Basic unit of proteins
Contain : R group
amino group(-NH2)
carboxyl group(-COOH)hydrogen atom
carbon atom
C
DIPEPTIDE
Two amino acids are linked together forming
dipeptide. Linked by peptide bond
Polymers of proteins are called polypeptides.
PROTEINS
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Functions of Proteins
Digestive enzymes
Transport of respiratory gases - haemoglobin.
Immunity antibodies.
Coordination hormones.
Growth and repair membrane proteins. Support and movement muscle (myosin-actin)
Protection - keratin
NUCLEIC ACIDS
Composed of nucleotides (basic unit)
NUCLEIC ACIDS
Individual nucleotide comprises of:
a. Phosphate group
b. Pentose sugar
c. Organic bases- nitrogenous base
Nucleic acid NUCLEIC ACIDS
There are 2 types:
DNA = deoxyribonucleic acid
RNA = ribonucleic acid
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Organicbases
Pentose sugars DNA MOLECULE
Stores the information forproteins synthesis.
Long, thin and double strandedpolymer of nucleotides.
4 types of bases:
a. Thymine (T)b. Cytosine (C)
c. Adenine (A)
d. Guanine (G)
pyrimidines
purines
RNA MOLECULE
Long, thin and single strandedpolymer of nucleotides.
Directs the manufacture ofproteins using the code fromDNA
4 types of bases:
a. Uracil (U)
b. Cytosine (C)
c. Adenine (A)
d. Guanine (G)
pyrimidines
purines
There are 3 types of RNA with different functions:
1. Messenger RNA (mRNA)
2. Ribosomal RNA (rRNA)
3. Transfer RNA (tRNA)
RNA MOLECULE
tRNA
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RNA MOLECULE
DNA : information for all the cells activities.
RNA : important in protein synthesis
Functions of Nucleic Acids
A reaction in which two monomers becomecovalently bonded to each other
Loss of a water molecule. Also known as dehydration reaction.
Condensation
CONDENSATION
Example 1 : combination of two glucosemolecules to form a maltose and a
water molecule
Condensation
CONDENSATION
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CONDENSATION
Example 2 : combination of 1 glycerol moleculeand 3 fatty acids molecules to forma triglyceride and 3 molecules ofwater
Example 3 : combination of two amino acids molecules to form a dipeptide and
a molecule of water
CONDENSATION
A chemical process that lyses, or splits moleculesby the addition of water.
Water is added to the bond that links adjacentmonomers
Breaking the bond between the molecules
Separates the molecules into individual monomers.
HYDROLYSIS
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HYDROLYSIS
Example 2: The splitting of protein to its monomers,amino acids.
H2O
Hydrolysis
HYDROLYSIS
Example 1: The splitting of maltose to its monomers,
glucoses.