Chemical Basis of Life

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Chemical Basis of Life
Chapter 2
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• All life processes involve chemical reactions
• Ex. Ca in muscle contraction
• Na, K in nerve impulses

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• Matter- anything that has mass and takes up space

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link

• Energy- the capacity to do work

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• 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)

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• Atoms- smallest complete unit of an element

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• 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

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• 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)

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• Ions- charged particles (form ionic bonds)

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Find the Face (in the Beans)
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• 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

Ionic bond
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Bonds

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

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• Hydrogen bonds- attraction of H to partial
  negative charge (due to
• polar covalent
• bonds between
• oxygen and
• hydrogen)

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

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• Isomer- molecules with the same chemical formula
  and with the same kinds of bonds between atoms,
  but in which the atoms are arranged differently.
  Isomers typically share similar if not identical
  properties in most chemical contexts.

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Different molecular and chemical properties!
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Chemical Reactions

• Metabolism sum of all chemical reactions in the
  body
• Synthesis (anabolism) A B AB
• Decomposition (catabolism) AB A B
• Single replacement AB C AC B
• Double replacement AB CD AD CB

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

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Inorganic Compounds

• Water (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)

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

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• Inorganic salts- provide Na, Cl-, K, Ca,
  Mg, PO4---, CO3--, etc.

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• Electrolytes- substances that release ions in
  water (will conduct an electrical current)
• Acids- release H ions
• Bases- release OH- ions

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• 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

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Organic Compounds

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

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• Monosaccharides- 3 to 7 carbons
• Ex. Glucose, fructose, galactose

• Carbohydrate
• utilized by the
• cell

Many C6H12O6
fructose
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• Disaccharides- 2 monos combine by dehydration
  synthesis (condensation)
• Ex. Sucrose
• Broken apart by hydrolysis (add water)

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

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

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

liquid
solid
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• Phospholipids- polar head and 2 non-polar tails
  (membrane)

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

cholesterol
testosterone
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• 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)

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Levels of Structure
Secondary
Primary
Tertiary
Quaternary
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• Nucleic acids
• Base sugar phosphate
• DNA and RNA
• ATP- provides energy for the cell

RNA
ATP
DNA
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Are these globes moving?