PDT-4th Chap(Biological Molecules)

8/8/2019 PDT-4th Chap(Biological Molecules)

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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.

PDT-4th Chap(Biological Molecules)

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