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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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