Key Questions
1. 12
2. The main isotope of carbon, carbon-14, s constantly being created by a bombardment of cosmic rays in the upper atmosphere. Living plants and animals incorporate this new 14C in their tissues through the nutrients they consume and the air they breathe. However, when they die, they stop incorporating new 14C into their tissues and the existing 14C decays at a constant rate, with a half-life of 5730 years. The decrease in the ratio of 14C to normal carbon after death acts as a clock to tell us when the organism died. The lower the ratio of 14C in the sample, the longer the tissue has been dead. However, after 40,000 years, less than 1% of the 14C is left in the tissue, so this isotope is not useful for dating very old material.
3. Types of Biochemical Reactions
1) Hydrolysis Water was polar covalent because it had “poles” or regions that had opposite charges. This polar nature of water allows it to stick together, as well as stick to other structures in your body. Water is often required to break down and join various molecules together. For example, here’s simple hydrolysis reaction that occurs ever second in your body, where water is used to break down a protein into it’s component amino acids.
Protein + water -> amino acid + amino acid
2)Condensation
Condensation reactions occur when two molecules combine to form one molecule. They are the opposite of hydrolysis reactions. In most biochemical condensation reactions, water is produced when two smaller molecules join to produce a larger molecule. This is also known as dehydration synthesis because water is removed in the synthesis of the new molecule.
3)Oxidation and Reduction (Redox)
The process of losing electrons is called oxidation and the process of gaining electrons is called reduction. An electron transfer between two substances always involves a reduction of one and an oxidation of the other, and so is commonly called a redox reaction. Cellular respiration is an important example of redox reaction in
