Biochemistry & Human Ecology

Trevor Craig

Energy Science 110

Biochemistry & Human Ecology, 10

9/28/11           

This lecture was about how communities and organisms use bio-chemicals. There are four main types of organic bio-chemicals; the four different types are carbohydrates, proteins, nucleic acids, and lipids. Plants, animals, and people use these 4 types of bio-chemicals to live, they polymerize these chemicals to exist. Plants and animals use their 21 amino acids to polymerize and make proteins, which are also needed for survival.

Automobiles and living organisms are very similar in nature. Cars need fossil fuels to work, which, in chemical structure is very close to lipids, which people need to live. When we think of fatty acids and lipids it is important to look at the chemical structure of these substances, because they can vary greatly, for example Butyric acid has only 4 carbon atoms and 0 double bonds, where Erucic acid has 22carbon atoms and 1 double bond, and DHA, found in fish oil, has 22 carbon atoms and 6 double bonds, obviously these vary. But back to cars and how they are close to living organisms; plants make sugars and oxygen which is then consumed by a living being and which then the being release CO2 and H2O, which the plants then take back in again to start the cycle over again, cars do a very similar thing, they take in, essentially, sugars and oxygen from plants and release CO2 and H20 as a result from running.

Breaking covalent bonds requires energy input and to form covalent bonds it releases energy. These bonds affect the energy change in a chemical equation, which in turn affects the combustion of the material and heating values. The heat of combustion from plants is typically lower than those of liquid fuels, the higher values of heat of combustion of plants is waxes and lipids, waxes at 45 MJ kg^-1, and lipids at 38-40 MJ kg^-1. Liquid fuels have a higher heat of combustion number typically, for example gasoline has a combustion heat of 44 MJ kg^-1 and diesel has a combustion heat of 43 MJ kg^-1, that is one reason why we use gasoline in our cars instead of things like coal that have a combustion heat of 17-30 MJ kg^-1 depending on the quality of the coal.

Humans cannot consume lignocellulose which is the majority of biomass on the earth, but some animals can like cattle, and then we can eat them. Cattle can eat things like bluegrass which is 65% structural carbohydrates, which humans are unable to digest, but cattle can for us. The energy input we put in to get our food must be lower that the energy we receive from eating the material. The highest gain from hunting is whale hunting, which returns 2000 fold for energy input vs output, a whale has 22 MJ/kg which is a lot of fat. Life can be simpler to look at when you look at it from the perspective of energy coming in and energy coming out.

Polymerize- The bonding of two or more monomers to form a polymer

Metabolism- the sum of the physical and chemical processes in an organism by which its material substance is produced, maintained, and destroyed, and by which energy is made available.

ENSC110 Biochemistry & Human Ecology 10