AEROBIC RESPIRATION

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Early Human Technology

What earliest technology makes homo unique among animals?

Homo neanderthalis Ardipithicus (4.4 MYA)

Pan troglodyte

Not Tools… Chimpanzees use those too

FIRE!!! Archaeological

sites in Asia and Europe indicate the first controlled use of fire occurred about 1,500,000 years ago.

The location of these ancient campfires coincides with the discovery of Homo erectus remains.

The Importance of Fire

Chemically speaking, fire is a product of the oxidation of biomass. It is a very exothermic process.

CH2O + O2 CO2 + H2O

Fire releases the energy stored by plants during photosynthesis

Fire & Cellular Respiration – Same Thing!!!

The examples shown have different amounts of energy stored in them. Rank them from least energy to greatest

What Fire Represents

The discovery of fire represented an increase in the amount of energy available to humans.

We have used this energy to increase our numbers and colonize every continent!

Fire, and the combustion of fossil fuels, is nothing but an extension of our metabolic processes by other means.

Burning = “Oxidation”

Oxidation state measures changes in the electronic structure of an atom

In general, a lower oxidation number represents a higher energy state.

Take carbon, for example:CO2 = +4 ; C = 0 ; CH4 = -4

Oxidation State of Carbon in:

Carbohydrates 0

Lipids and Protein< -1 Hydrocarbons

< -2

Less EnergyMore Oxidized

More EnergyLess Oxidized

Oxidation and Reduction

Whenever something gets oxidized, the thing that oxidizes it gets reduced.

2Fe +3O2 2Fe2O3

Before the reaction, Fe = 0, O = 0 After, Fe = +3, O = -2

For every yin, there is a yang.

What Does All This Mean???

As usual, it’s all about the electrons.

So… The bottom line

When a substance is oxidized, it:Releases energy (exothermic)Looses electronsIncreases oxidation state

Carbon is oxidized when burned, or used in cellular respiration.

Carbon is reduced during photosynthesis.

Example: Burn Sugar and Follow the Carbon

C6H12O6 + 6O2 6CO2 + 6H2O

Before the exothermic reaction, the carbon in C6H12O6 has an oxidation number of 0.

During the reaction, carbon looses electrons. After the reaction, the carbon (now in CO2) has

an oxidation number of +4.

Carbon has been oxidized.

Carbon Oxidation = Aerobic Life

The oxidation of carbon is the biochemical basis upon which almost all life rests.

The rate at which an individual or population can survive, grow, and reproduce is limited by how quickly it can get energy by oxidizing carbon.

The Fire Outside… Fire greatly increased

homo’s access to energy. With it, humans and their

ancestors could:Cook food, making new

sources of nutrition available

Heat shelters, allowing them to live in colder climates

Carry a portable source of light.

Growth requires Carbon