Chemistry of Life Chapter 4

Matter What all material is made Atoms  p +, n 0, 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 H 2 O + CO 2  H 2 CO 3 Dissolving of CO 2 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

Red Tide in ocean Algal bloom in a pond

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 system or 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) 6CO 2 + 6H 2 O + sunlight  C 6 H 12 O 6 + 6O 2 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 C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 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 clipVideo clip

Chemosynthesis Use bond energy of H 2 S to form organic from inorganic carbon compounds Areas w/o sunlight—deep sea vents

Formation of Life on Earth Urey-Miller experiments –Mixture of gases in early atmosphere formed organic compounds and amino acids when hit by lightning Panspermia –Microbes came to earth on meteorites. –1969 Australian meteorite w/amino acids Chemoautrophs –Life originated in deep sea vents under 100s of kilometers of ice Single-cell bacteria present over 3 billion years ago