Lecture1 PPT

Living Cell an introduction

Life is complex and dynamic: All organisms are primarily composed of organic molecules that have intricate, three dimensional shapes. Living processes, such as growth and development, involve thousands of chemical reactions in which vast quantities and varieties of vibrating and rotating molecules interact, collide, and rearrange into new molecules. Life is organized and self-sustaining: Living organism are hierarchically organized systems; that is, each level is based on the one below. The molecules that make up living organism -> biomolecules -> subatomic particles!

LIFE IS CELLULAR

-The are oldest form of life on earth: 3.8 billion years - Until 1.8 billion years ago they were only form of life - If you combine all the cell mass of eukaryotic animals still it is

ten fold less than prokaryotes - They are everywhere!

Archaea: The archaea were only recognized as distinct group of organisms in 1977 when Carl woese analyzed specific nucleic acid molecules. A prominent features of many of the archaea is their capacity to occupy and even thrive in very challenging habitats. Referred as extremophiles Eukarya: Presence of nucleus alone is not only he difference with bacteria 1. Size: Eukaryotic cells are substantially larger than prokaryotic cells 2. Complexity: Structural complexity of eukaryotes s remarkable. With

compartmentalization or organelles they perform specialized tasks. 3. Multicellular: With development of intricate inter cellular communications

they have multicellularity.

Virus!

Almost of all the other kinds f molecules in living organism are organic made of six elements - Carbon - Hydrogen - Oxygen - Nitrogen - Phosphorus - Sulfur with trace amounts of certain metallic elements

Functional groups in Biomolecules: Biomolecules can be considered to be derived from simple hydrocarbons. Hydrocarbons Are carbon-hydrogen containing molecules.

Chemical properties of these derivative molecules are determined by specific arrangement of functional groups.

Most bimolecules contain more than one functional group

e.g., amino acid building block of proteins contain both amino group and carboxyl group

Metabolism

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Building block

Simple sugar

Amino acid

Nucleotide

Fatty acid

Macromolecule

Polysaccharide

Protein (peptide)

RNA or DNA

Lipid

Anabolic

Catabolic

Primary function of metabolism: 1. Acquisition and utilization of energy 2. Synthesis of molecules for cell structure and functioning 3. Growth 4. Removal of waste products

Though complex, Reactions types are few Are simple organic reactions catalyzed by one enzyme Most of the important pathways are conserved across the species

Reaction types:

1. Nucleophilic substitution 2. Elimination 3. Addition 4. Isomerization 5. Oxidation-reduction

Nucleophilic substitution:

Here A is called nucleophillic nucleus lover attacks B Electrophilies, forming a new bond. Outgoing X is called leaving group

Hydrolysis reactions: Kind of nucleophilic substiution reaction in which the oxygen of a water molcule Serve as the nucleophile. He electrophile is usually the carbonyl group of an Ester, amide or anhydride.

Example: Hydrolysis f ATP

Elimination reaction: A double bond is formed as atoms in a molecule are removed

Removal of water is commonly encountered reaction.

Other products include NH3, amides RNH2, alcohols ROH

Addition reactions: In addition reaction two molecules combine and form a single product. e.g., hydration is one of the common addition reaction. When water is added to alkene An alcohol results.

Isomerization: Intermolecular shift of atoms or molecule

Oxidation-reduction reactions: 1. Oxidation has occurred if a molecules gains a oxygen or losses a hydrogen

2. Reduction has occurred if a molecules losses a oxygen or gains a hydrogen

Who came first - DNA? - PROTEINS?

Evolution of Biomolecules

14000 years ago Modern human history starts

Prebiotic Evolution

Biomolecules first arose on the planet by chemical evolution

This process of chemical evolution can be simulated in the laboratory

The classical experiment of Urey and Miller (1953) combined mixtures of atmospheric gases (methane, ammonia, water, and hydrogen) along with electrical sparks

The resulting gas phase had carbon monoxide, carbon dioxide, and the starting materials

The water layer had organic compounds, amino acids, hydroxy acids, aldehydes, and hydrogen cyanide

Some amino acids could be produced:

Addition of nitrogen, carbon dioxide and carbon monoxide to the starting materials led to the formation of hundreds of organic compounds

Amino acids, mono-, di-, and tri- carboxylic acids, fatty acids, adenine, and formaldehyde

Formaldehyde can polymerize to form sugars made of 3, 4, 5, and 6 carbons

Nucleotides and small peptides also form

Other sources of energy such as x-rays and UV radiation led to the development of even more compounds

Three theories about evolution of biomolecules

compounds resulted from electric discharges and ultraviolet irradiation

First & oldest

the basic components of living organisms were formed in space outside the orbits of large planets and transferred to the Earths surface

Second

Third, at oceanic crust

water overheated to 400C containing strongly reducing FeS, H2, and H2S met cool water containing CO2