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Chemistry of Life

John Dalton formulated in 1810 the

atomic theory:

All matter is composed of small particles

called ATOMS.

This is the basic building block of matter

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Atomic Structure

Protons

Positively charged

Neutrons

Neutral

Electrons

Negatively charged

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F

act: An atom has equal number of electrons and

protons

When an atom loses or gains electrons it

becomes a positively or negatively chargedION

CATION

Positively charged ion

ANION

Negative charged ion

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Elements

Atoms with identical numbers of electronsand protons

Same chemical properties exist together

About 30 essential elements for organismsbut

Only four make up 99% of the mass of cells

Hydrogen

Oxygen

Nitrogen

Carbon

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Molecules

When two or more atoms of the same or

different elements combine Example:

Water

Consists of two hydrogen atoms bonded togetherto one oxygen atom

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Chemical Bond

3 types:

1. Eletrovalence or ionic bond Ex. NaCl

2. Covalence or covalent bond

Ex.H20

3. Hydrogen bond

Ex. In structural proteins and DNA

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Organic Molecules

Complex molecules that contain carbon atoms in

chains or rings

Inorganic Molecules

Do not contain carbon atoms in rings or chains

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Important Inorganic Molecules

1. Water Most abundant molecule in living cells

Essential for cell functions

Universal solvent

Excellent buffer against heat changes

2. Oxygen &Carbon Dioxide

Present as gases in respiratory organs

In tissue fluids such as blood and lymph

3. Minerals & Organic Salts

Present in skeletons

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Important Organic Molecules

1. Carbohydrates

Biomolecules composed ofCarbon,Hydrogenand Oxygen

CH20 (ratio of 1:2:1)

Primary products of photosynthesis in green

plants Source of energy

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Carbohydrates

Monosaccharides (simple sugars)

Oligosaccharides (two or more sugar units)

DISACCHARIDES (double sugar) Ex.Sucrose

Polysaccharides (complex sugar) To store energy when external food supply

is low

x Ex. Glycogen in animal cells

To provide tough molecule for structuralsupport and protection

x Ex.Cellulose in plant cells

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2. Lipids

Compounds consisting mainly ofC andH

Insoluble in water1. Simple lipids

2. Compound lipids

3. Precursor and derived lipids

3. Proteins

Substance of life (C, H, O,N)

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Amino Acids

Longs chains of chemical units of proteins

Functions of Proteins:

Form structural parts of cells

Serve as catalysts (ENZYMES)

Examples:

Keratin Collagen

Actin Myosin Antibodies Hemoglobin

Insulin

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NUCLEICACID

Polymers of nucleotides carry the code oflife

Funtions:

Protein synthesis

Heredity

Terms:

DNA RNA

ATP NucleotideCoenzyme

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