Slide 1
Carbon has four electrons in its outermost orbital - but there is
room for 8 electrons in this shell. This valence of four allows each carbon
atom to form stable associations with up to four other atoms, including other
carbon atoms.
Slide 2
Carbon can form single, double, or triple bonds. That is, it can
share one, two, or three of its valence electrons with another atom.
This allows carbon to serve as the backbone for an almost endless array of organic molecules.
Slide 3
Long chains of carbon atoms are common. The chains may be branched
or form rings.
Slide 4
Metabolism is the set of chemical reactions that happen in living
organisms to maintain life.
These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments.
Anabolism uses energy to construct components of cells and
catabolism
breaks down organic matter, for example to harvest energy.
Slide 5
The normal functioning of cells and organisms requires both
anabolic and catabolic reactions.
Most macromolecules are polymers - long chains of repeating units. These polymers are built up during anabolic dehydration reactions (sometimes referred to as condensation reactions). During dehydration synthesis - a molecule of water is lost as covalent bond is formed between the exising polymer and a monomer.
Polymers are broken down during catabolic hydrolysis reactions. A hydrolysis reaction uses a molecule of water to break a covalent bond between two units in a polymer.
As we talk more about the activities inside a cell we will see that polymers are always being built up and broken down to maintain life.