What is a Genome?QUESTION: What is a genome?ANSWER:
The word "genome" has gone from obscurity to a very common word over the last several years. However, the answer to the question, "what is a genome?" is still somewhat obscure in many of our minds. Except for those very familiar with biological genetics, how a genome relates to DNA, chromosomes, genes, proteins, and amino acids, is still not clear.
The origin of the word "genome," is a combination of two words. Gen is taken from the German word "genom" meaning gene and ome is taken from the word "chromosome." To understand what genome means and how it relates to the body and other genetic entities, let's start with the body and work toward smaller genetic entities.
A human body is made up of about 50,000,000 to 100,000,000 cells. Each cell contains, in its nucleus, all the coding instructions necessary to direct the cell's activities and manufacture the required proteins. A complete set of those raw coding instructions is referred to as a genome. In humans, the genome is made up of 24 distinct DNA molecules called chromosomes. In bacteria and other more simple forms of life, the genome only contains one chromosome.
Human chromosomes vary widely in size and how much genetic information they contain. Human chromosome #1 has the most genes with 2968. Human Y chromosome has the fewest with 231 genes. Genes are isolated information segments along the DNA molecule between what appears to be informationless coding. Scientists have been able to able to identify the information containing gene sections from the informationless coding sections along the DNA molecule through information theory techniques. This is similar to what the SETI (Search for Extraterrestrial Intelligence) program does to identify potential radio information from outer space as opposed to informationless noise.
A good analogy of a chromosome would be a huge encyclopedia with many books written in English using our 26-letter alphabet. The books that would be understandable to someone that knows English are the genes. Other books would be nothing but gibberish. These books are like the sections between the genes. This seems easy to someone that knows English, but it wouldn't be as obvious to someone that doesn't know English. However, although scientists know the DNA alphabet, they don't know the words in the DNA coded language. Currently only God, the designer, knows the language and what the words mean. However, this is what scientists are trying to learn.
DNA is the acronym for deoxyribonucleic acid. Geometrically it is a long double helix
molecule. A good analogy would be a very long spiral staircase with a pair of amino acid nucleotide coding letters as each step. These nucleotides include only four chemical building blocks. They include adenine (A), guanine (G), cytosine (C), and thymine (T). If these nucleotides could bond across the double helix in any combination, the coding alphabet would be more than four letters. However, because of the chemical geometry and affinity, bonding pairs only include A bonding with T and G bonding with C. This makes the opposite side of the double helix a negative of the other side. Consequently, all the information comes from one side of the helix with the other side being redundant.
A human genome contains about 3,000,000,000 nucleotide pairs and a bacterium contains about 600,000 pairs. Although we do not know the meaning of the words, sentences, etc., each cell knows how to read the code and only reads the part that is relevant to their type and function. This selective reading process creates many different kinds of cells, such as skin, muscle, neural, and bone cells, all of which develop from many cells of the embryo produced by the growth and division of one cell: the fertilized egg.
What we have learned about this whole process reveals the incredible design that has resulted in human life and other life forms. Although scientists have made great progress, we are just getting a glimpse of this incredible design. We should be in awe of the design and have a respectful fear of the powerful designer. Let's not be fooled by evolutionary thinking that claims random chance creates incredible design. Imagine you were the designer and the people you designed with great intellect and free will, came up with a theory that discredited your design and claimed that your incredible design was due to random natural forces. Think about it!