* * * * * *
Using Genetics to Personalize
Health and Wellness
What Is DNA?
Fragments of DNA
DNA molecules are shaped like a twisted ladder and have a unique name called a
"double helix"
DNA Recall that DNA is the inherited genetic material that controls gene expression through protein synthesis. This is a fancy way of saying that DNA is a chemical form of a genetic blueprint. The genetic instructions contained in DNA are housed in genes. Genes are smaller segments that, when strung together, comprise a DNA molecule. Genes are actually unique linear sequences of nucleotide monomers named for the nitrogenous base they contain. There is much chemistry intertwined in biology; in fact, they go hand in hand. A nucleotide monomer is a chemical unit that is made of a sugar with five carbon atoms (aptly named a “five-carbon sugar” or “pentose sugar”), a phosphate atom bonded to four oxygen atoms (called a phosphate group), and one of four possible nitrogen-containing bases called adenine (A), cytosine (C), thymine (T), or guanine (G). They are called bases because these chemical compounds, collectively made mostly of carbon, nitrogen, and hydrogen atoms, have basic properties as opposed to acidic properties. Acids and bases are a deeper lesson in chemistry; right now it is more important to focus on the fact that the four bases (A, C, T, or G) are categorized into two types: Purines and pyrimidines. Purines are chemically a double-ringed structure, whereas pyrimidines form a single ring. Adenine and guanine are classified as purines, while cytosine and thymine are pyrimidines. For genes to properly function, the nucleotides (the elements that stick together to form the "rungs" of the ladder) must pair up correctly. They do this by adhering to a strict set of base-pairing rules that were discovered by pioneers in the science of genetics, James Watson and Francis Crick. Base-pairing rules dictate that adenine (A) always pairs with thymine (T), and cytosine (C) always pairs with (G). When nucleotide bases pair correctly, that is, when A pairs with T or C pairs with G, the rungs on two halfs of the ladder (single DNA strands) come together to form a single ladder. The ladder appears twisted due to complex chemical bonding between the various elements in the DNA molecule itself.
CLICK HERE to visit "In the Gno" our blog dedicated to DNA and genetics
DNA is an acronym for that long word deoxyribonucleic acid (dee-ocks-ee-rhy-bow-noo-clay-ic acid) which is the name of the molecule that contains our own unique genetic code – a set of chemical instructions that tell our cells to manufacture proteins that make us look, think, feel, and behave the way we do. In technical terms, DNA is part of molecular biology, the study of life at the molecular level. Much has already been revealed about DNA through years of scientific research, including the completion of mapping the human genome – the primary goal of the Human Genome Project.
The chemical structure of DNA is one of its most important underlying principles. Chemical structure is what allows strands of DNA to stick together. It also accounts for the unique structure of the DNA molecule itself, which is termed a double-helix. If you looked at DNA under a microscope, it would look like a twisted ladder. The “double” in double-helix is because there are two strands of DNA joined together. The “helix” in double-helix represents the helical, or twisted shape, of DNA.
One strand of DNA might look like a straight ladder cut down the middle, making a left side of the ladder and a right side of the ladder. One strand complements the other in a way that is also related to chemical structure. The component nucleotide bases (the rungs of the ladder) of a DNA strand (one half of the ladder) pair with each other by chemically bonding to the nucleotide bases of the second DNA strand (the other half of the ladder). Together, the two DNA strands unite to form what looks like one single ladder.
Genes
Genes can be several hundred or several thousand nucleotides long. Genes are what actually contain the chemical instructions that tell our body to make certain proteins. When gene segments of DNA are "read" by RNA (ribonucleic acid), they are decoded in triplet. This means that RNA reads nucleotides in segments of three. When RNA "reads" a gene's instructions, each triplet of nucleotides, called a codon, equates to a particular amino acid. There are twenty possible amino acids that may be produced.
For instance, when RNA "reads" the codon "TTT" it will translate that into an amino acid called Phenylalanine. Individuals who lack a necessary enzyme to properly metabolize phenylalanine are afflicted with a rare disorder called phenylketonuria (PKU). PKU screening is now routinely performed at birth in all United States hospitals. On the other hand, if RNA "reads" the codon "GAG", it will translate that into an amino acid called Glutamic acid. Glutamic acid is the origin of the unique flavor given to certain ethnic foods. This flavor has recently been named "umami" (Japanese for "yummy") and has formally been added to the other four traditional flavors: Sweet, salty, bitter, and sour. Glutamic acid is believed to play a role in cognitive functions such as learning and memory. Further, it is a key molecule in the process of cellular respiration, the crucial metabolic process that converts what we eat into energy.
Proteins
Amino acids are the building blocks of proteins. So as RNA "reads" a gene, several strings of amino acids are produced. The end result is called a polypeptide. One or more polypeptides makes a protein. Because amino acids are all chemically different, they give proteins unique sizes, shapes, and structures. Some proteins are enzymes that help lower the amount of energy it takes to start a chemical reaction. Some proteins are transporters of certain substances within our circulatory system (like hemoglobin that carries oxygen). Some proteins are chemical messengers, or hormones. There are many other types of proteins in our bodies, and all play a vital role in proper body function and survival.
If you are interested in learning more about DNA or genetics, including:
