Chemistry of Life

Chapter 4

Matter

• What all material is made

• Atoms p+, n0, e-

• Isotopes: – atoms w/same atomic number, different

atomic mass. – Decay at different rates – Used in historical dating

• Law of Conservation of Matter– Matter cannot be created or destroyed– Can only change forms– Basis for all chemical equations

• 116 Known Elements, 88 Naturally-occurring

• 24 are required for life, in varying amounts

• Many poisonous: Pb, As, Cd, Hg, U

Factors affecting life

• Ability of organisms to live and reproduce• Abiotic Factors: non-living

– Solar radiation– Rainfall/water availability– pH level– Level of pollution– Type of substrate/rock– Dissolved gasses– Minerals available

• Biotic Factors: living– Predation– Parasitism– Competition– Disease

Chemical Reactions

Reactants Products

H2O + CO2 H2CO3

Dissolving of CO2 into aquatic systems

Makes oceans largest reservoir of carbon

Makes water slightly acidic

Macronutrients:

• Required in large amount by all life forms• C • H • O • N: proteins, DNA• P: Forms ATP and ADP, transferring and use of

energy in cells, DNA • S: proteins and amino acids• Required to a lesser extent:

– Mg, K, Mn, Fe, Cu, Zn, Mo – Ca: structural element in bones and shells, cell walls

Form organic compounds

Micronutrients

• Required for some life forms in moderate amounts or all life in small amounts

• B, F, Na, Si, V, Co, Se, I

• Metals often used as catalysts (enzymes)

Limiting Factor

• An element that is not available in great enough quantity at the right time.

• Prevents growth of individual, population or species

• Terrestrial ecosystems: N primary, P secondary• Aquatic ecosystems: P primary, N secondary• Large additions of limiting factors can lead to

rapid growth. Ex: algae blooms

http://en.wikipedia.org/wiki/Algal_bloom

Red Tide in ocean

Algal bloom in a pond

http://nue.okstate.edu/

Use of Nitrogen Fertilizer to increase crop yield

Energy

• Can change position, state or temperature of matter

• Kinetic motion– Wind, hydroelectric power

• Potential stored– Chemical vs gravitational– Fossil Fuels, food– Water towers

1st Law of Thermodynamics:

• The total increase in heat of a system is the sum of the work done on it and the heat added to it.

or

• Energy is neither created or destroyed but changes forms (Law of Conservation of Energy).

2nd Law of Thermodynamics:

• Natural processes go in a direction that increases the total entropy.

• Entropy: disorder within a systemor

• Energy goes from a more usable form to a less usable form. (Heat)

or• It takes energy to keep molecules (and systems)

organized. There cannot be 100% efficiency. Not even close.

Things fall apart.

Photosynthesis

• Who: Autotrophs (primary producers)

• 6CO2 + 6H2O + sunlight C6H12O6 + 6O2

Sugar (Glucose)

Energy

•About 1% Efficient

Cellular Respiration

• Who: Every aerobic living organism (inc. plants)• Releases energy from glucose for cell repair and

to form chemical bonds

• C6H12O6 + 6O2 6CO2 + 6H20 + energy

Carbon Cycle

• Reservoirs– Geologic

• Uplifting, volcanic activity

– Atmosphere• Diffusion

– Plant/Animal life• Photosynthesis, respiration, combustion (forest fires)

• Anthropogenic sources– Combustion rxns, lack of photosynthetic uptake– Video clip

Chemosynthesis

• Use bond energy of H2S to form organic from inorganic carbon compounds

• Areas w/o sunlight—deep sea vents