Chapter 4

http://www.youtube.com/watch?v=V4P2z2RQwWs

http://www.youtube.com/watch?v=ggNI76hF6HQ

AP Biology

Carbon and the Molecular Diversity of Life

Carbon: The backbone of Life? Wait, what? Isn’t it water? Well yes and no.

Water is the universal medium for life

Most living organisms are made up of chemicals that are based on the element carbon

Carbon and the Molecular Diversity of Life Carbon enters the biosphere through

the action of plants Plants use solar energy to transform

atmospheric CO2 into the molecules of life

Molecules are then passed to animals that feed on plants

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=6NsZQ0LV82NBLM&tbnid=_0lTj5WbQ3F7LM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.nar.ucar.edu%2F2008%2FNCAR%2Fhighlights%2Fenergizing%2Fcarboncycle.php&ei=TOQ3Ur7qMsPmyQGdkIDYCw&bvm=bv.52164340,d.aWc&psig=AFQjCNE68vu1V_fQz9PgFLmWTl_BSTCpRw&ust=1379480978304904

Carbon and Diversity

Carbon is able to form molecules that are large, complex and diverse

It makes possible the diversity of organism that have evolved on earth

History of looking at carbon 1800’s: Theory of vitalism A belief that a life force outside of

the jurisdiction of physical and chemical laws

1950’s: U.S. Stanley Miller. Theory of mechanism

The view that physical and chemical laws govern all natural phenomena including the processes of life.

History of looking at carbon In order to prove that

spontaneous life could occur, he did an experiment

Primordial soup idea went from speculation to empirical science!

History of looking at carbon Methane, ammonia,

and hydrogen and subjected it to steam

It was then exposed to an electrical charge

This caused a chemical reaction

The result: proteins and amino acids

Back to carbon…

Carbon has 6 electrons Carbon usually shares its electrons

to complete the valence shell Creates covalent bonds Each carbon atom acts as an

intersection point and can branch off in as many as four directions

This allows carbon to form complex bonds.

Some examples

Methane Ethane Ethylene

Carbon Experiment

Balloon 40 ml of water Soft drink bottle Drinking straw Lemon juice or vinegar 1 teaspoon baking soda

Carbon experiment

Stretch out the balloon Pour 40 ml of water into the soft

drink bottle Add the teaspoon of baking soda and

stir it around with the straw till it is dissolved

Pour the vinegar or lemon juice in and quickly put the stretched balloon over the bottle

Carbon experiment If all goes well then your balloon should

inflate! Adding the lemon juice to the baking soda creates a chemical reaction. The baking soda is a base, while the lemon juice is an acid, when the two combine they create carbon dioxide (CO2). The gas rises up and escapes through the soft drink bottle, it doesn't however escape the balloon, pushing it outwards and blowing it up. If you don't have any lemons then you can substitute the lemon juice for vinegar.