Chemistry as basis of life.

1. CHEMICAL BASIS OF
LIFE
DR. ROSEMARIE D. COSUE

2. • All life processes involve chemical reactions
• Ex. Ca in muscle contraction
• Na, K in nerve impulses
•

3. • There are 92 naturally occurring elements (112
known)
• Living organisms require about 26 of
these elements (table 2.1)
• About 96 (by mass) comes from Oxygen (O),
Carbon (C), Hydrogen (H), and Nitrogen (N)
•

4. • Atoms- smallest complete unit of an element
• Subatomic particle Charge Location
• proton nucleus
• neutron none nucleus
• electron - surrounds
• nucleus
• Atomic number () number of protons (number of
electrons in neutral atom)
• Mass number (AM) number of protons number of
neutrons
•

5. • Isotopes- atoms of same element, different mass
(due to neutrons)
• Ex. C-12 and C-14
• Radioactive isotopes used in many medical tests
(ex. I-131 for thyroid activity)

6. • Ions- charged particles (form ionic bonds)
• Bonds (ionic and covalent)- lose, gain or share
electrons in order to fill valence shell
(stability)
• All atoms want 8 e- in their outermost shell

7. • BondsDue to electronegativity!
• Ionic- gt1.7
• Polar covalent- 0.4- 1.7
• Covalent- lt 0.4
•

8. • Molecular formula- represents the numbers and
types of atoms in a molecule
• Ex. H2O , C6H12O6
•

9. • Catalyst- effect the rate of reaction without
being changed by the reaction
• Biological catalyst enzyme (-ase)

10. • Inorganic CompoundsWater (60 RBC, 75 muscles, 92 plasma)
• Participates in chemical reactions
(ex. Hydrolysis)
• Carries chemicals within body (good solvent)
• Can absorb and transport heat (homeostasis) heat
capacity
• Requires large amount of heat
• to change state heat of
• vaporization
• Serves as lubricant
• Protective function (cushioning)

11. • Oxygen- used to release energy from glucose
• Carbon dioxide- waste of metabolic processes

12. • Inorganic salts- provide Na, Cl-, K, Ca,
Mg, PO4---, CO3--, etc.
• Electrolytes- substances that release ions in
water (will conduct an electrical current)
• Acids- release H ions
• Bases- release OH- ions

13. • pH scale measures hydrogen ion concentration
• pH 7 neutral
• pH gt7 basics (more OH- than H)
• pH lt7 acidic (more H than OH-)
• Normal blood pH for humans is 7.35 to 7.45
• If gt , alkalosis
• If lt , acidosis
• Buffers- maintain pH

14. • Organic CompoundsCarbohydrates- sugars, starches, glycogen,
cellulose 2-3 body weight
• Plants- starches and cellulose (cannot digest)
• Animals- source of energy- stored as glycogen

15. • Monosaccharides- 3 to 7 carbons
• Ex. Glucose, fructose, galactose
• Carbohydrate
• utilized by the
• cell
•
Many C6H12O6
fructose

16. • Disaccharides- 2 monos combine by dehydration
synthesis (condensation)
• Ex. Sucrose
• Broken apart by hydrolysis (add water)
•

17. • Polysacchride- 10-100s of monos
• Ex. starch
•

18. • Lipids- 18-25 in lean adults
• Contain C, H, O - neutral
• Fats- concentrated energy stored in adipose tissue
•

19. • Triglycerides
• Glycerol 3 fatty acids
• Monounsaturated- one double bond
• Polyunsaturated- more than one double bond
• Saturated- no double bonds
•
liquid
solid

20. • Phospholipids- polar head and 2 non-polar tails
(membrane)
•

21. • Steroids- cholesterol, sex hormones, cortisol,
etc.
•
cholesterol
testosterone

22. • Proteins- 12-18 in lean adults
• Structural and physiological enzymes
• Made of amino acids (20)- held by peptide bonds
• 3D shape held by H-bonds (denatured with heat)
• Fibrous (structural) or globular (functional)
•

23. • Levels of Structure
Secondary
Primary
Tertiary
Quaternary

24. • Nucleic acids
• Base sugar phosphate
• DNA and RNA
• ATP- provides energy for the cell
•
RNA
ATP
DNA