Chemistry of Life

Keyword:Biology120Chem

Topics

Review of Chemistry
Biologically Important Macromolecules

Review of Chemistry

Definitions

• matter
  
  
  
• atoms
  
  
  
  
  

SPONCH-sulfur, phosphorous, oxygen, nitrogen,carbon, hydrogen
C HOPKiNS CaFe Mg ("C. Hopkins Cafe mighty good")-carbon, hydrogen,oxygen, phosphorous, potassium, nitrogen, sulfur, calcium, iron, magnesium


Subatomic and elemental structure:

• atoms: protons, neutrons, electrons

  protons and neutrons responsible for most of the atomic mass
  
  
  
  
  
  

• Bohr model
  
  
  
  
  
  
  
  
  
  
• number of protons determines atomic number, eg H = 1
  
  
  
  
  
• number of protons in element is constant ( H=1, Ur=92) but neutron number may vary, so mass number (protons+neutrons) variable
  
  
  
  
  
• Elements may contain varying numbers of neutrons; these forms of an element are called isotopes
  
  
  
  
  
• Some isotopes are radioactive-meaning they "radiate" energy as they decay to a more stable form, perhaps another element
  
• half-life: time required for half of the atoms of an element to decay into stable form
  

"SPONCH" elements in detail

Almost never found singly-form molecules, two or more chemically joined atoms

• compounds
  
  
  
  
  
  

Why do compounds form ???


Energetic tendencies:

• +/- charges tend to balance, usually by balancing the number of electrons and protons
• electrons within atoms and molecules tend to pair
• Electron shells tend to fill

How are these competing electrical tendencies met?
"Compromise" through chemical bonds
Chemical bonds

Types of Chemical Bonds

• Ionic bonds
  
  
  
  
  
  
  
  
  
  
  
  
  
  
• Covalent bonds-sharing electrons

  
  
  
  
  
  
  
  
  
  
  
  

Water

Water is ubiquitous on earth on the surface and in living organisms; humans are 90+ % water, water is an absolute necessity for survival-why is it so important ?

• Unique chemical structure
  
  
  
  
  
  
  
• hydrogen bonds
  
  
  
  
  
  
  
  
• heat capacity
  
  
  
  
  
  
  
  
• Solvent
  
  
  
  
  
  
  
  
  • hydrophilic
    
    
    
    
  • hydrophobic
    
    
    
    
    
    

Reactions in water

all of the chemistry of organisms takes place in a watery milieu, the characteristics of which affect the reactions

• 
  
  
• acids
  
  
  
  
  
  
  
  
  
  
• bases
  
  
  
  
  
  
  
  
  
  
  

What is acidity and how is it measured ?

• pH scale
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
• Buffers
  
  
  
  
  
  
  
  
  
  
  
  

Biologically Important Macromolecules

Carbon-one of the central, most important molecules for all living organisms; forms the framework on which organism build the structural, metabolic etc. molecules needed to make a living-"carbon-based units"

• chemically very versatile
  
  
  
  
  
  

polymers







hydocarbons









hydrolysis/condensation reactions






Carbohydrates: sugars, starches etc.
basic unit is (CH2O)n repeated n times=CARBOhydrATE

• monosaccharide
  
  
  
  
  
  
  
  
  
• Disaccharides
  
  
  
  
  
  
  
  
  
• Polysaccharides
  
  
  
  
  
  
  
  
  
  

Lipids
are a very diverse group of molecules, defined more by their insolubility than structure
important as energy storage cmpds, insulators, lubricants, hormones-chains formed by cov dehydr links

• Triglycerides: fats and oils, 3 fatty acid chains + glycerol
  
  
  
  
  
  
  
  
  
  
  
• Saturated vs. unsaturated
  
  
  
  
  
  
  
  
  
  
• Phospholipids-2 fatty acids s + glycerol+ (-)phosphate group
  
  
  
  
  
  
  
  
  
  
  
• Waxes: fa + long chain molecule/OH
  very water repellent
  
  
  
  
  
  
  
• Sterols

Proteins
often huge molecules with important 3D structure
structural molecules, enzymes, antibodies, etc.
long chains of amino acids (covalent dehyd links)
amino acids-20 naturally occuring
all have carboxyl group, amino group, H and the "R" group which makes each aa distinctive

Protein structure

• 1 degree(primary)
  
  
  
  
  
  
  
  
• 2 degree(secondary)
  
  
  
  
  
  
  
• 3 degree(tertiary)
  
  
  
  
  
  
  
  
  
• 4 degree(quaternary)
  
  
  
  
  
  
  
  
  

Nucleic acids
DNA, RNA, huge polymers
repeated units called nucleotides: pentose sugar, with phosphate group and one of 5 N bases
hydrogen bonded into double helix

DNA-adenine, guanine, cytosine, thymine-genetic mat. + oxyribose RNA-AGC, uracil-messenger, protein production + deoxyribose




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Last Modified: Oct. 24, 1995
All contents copyright (C) 1995.
Western Kentucky University.