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 individual segments of a DNA molecule. Genes are further broken down into smaller, linear building blocks called nucleotides. Nucleotides are aptly named for the nitrogenous base they contain. Much of biology hinges on the chemistry of DNA.
Nucleotides are made of three separate chemical units. The first unit is a pentose sugar made of five carbon atoms. The second unit is a phosphate group made of four oxygen atoms bonded to a central phosphate atom. The third unit is one of four nitrogenous bases, adenine, thymine, cytosine, or guanine.
The four nitrogen-containing bases are sometimes represented as T, C, A, or G, and are always from of one of two chemical categories: Purines or pyrimidines. Purines form a double-ring, while pyrimidines are chemically a single ring. Guanine and adenine are classified as purines, whereas the pyrimidines are thymine and cytosine.
The chemical structure of DNA depends on the correct chemical interaction between purines and pyrimidines. This interaction allows certain bonding to occur that holds two strands of DNA together. The result is what is known as a double helix.
A DNA molecule is termed a double helix due to its twisted shape. The chemical structure is essentially two strands of DNA held together by weak hydrogen bonds. Each DNA strand looks like one half of a ladder sliced down the middle, but together the strands unite to form a single ladder.
Each strand is a chemical complement of the other. The nucleotides that pair together represent the rungs of the ladder. So, when the halves of the ladder bond, a single ladder is formed.
For genes to properly function, the nucleotides must pair 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 a purine always pairs with a pyrimidine. In other words, adenine always pairs with thymine and cytosine always pairs with guanine.
The bonds formed as a result of nucleotide pairing are weak hydrogen bonds that also play an important part in the chemistry of DNA. Each molecule looks like a twisted ladder due to these and other complex chemical bonds between different molecular units. This unique shape is why a DNA molecule is termed a double helix. - 16459
Genes are individual segments of a DNA molecule. Genes are further broken down into smaller, linear building blocks called nucleotides. Nucleotides are aptly named for the nitrogenous base they contain. Much of biology hinges on the chemistry of DNA.
Nucleotides are made of three separate chemical units. The first unit is a pentose sugar made of five carbon atoms. The second unit is a phosphate group made of four oxygen atoms bonded to a central phosphate atom. The third unit is one of four nitrogenous bases, adenine, thymine, cytosine, or guanine.
The four nitrogen-containing bases are sometimes represented as T, C, A, or G, and are always from of one of two chemical categories: Purines or pyrimidines. Purines form a double-ring, while pyrimidines are chemically a single ring. Guanine and adenine are classified as purines, whereas the pyrimidines are thymine and cytosine.
The chemical structure of DNA depends on the correct chemical interaction between purines and pyrimidines. This interaction allows certain bonding to occur that holds two strands of DNA together. The result is what is known as a double helix.
A DNA molecule is termed a double helix due to its twisted shape. The chemical structure is essentially two strands of DNA held together by weak hydrogen bonds. Each DNA strand looks like one half of a ladder sliced down the middle, but together the strands unite to form a single ladder.
Each strand is a chemical complement of the other. The nucleotides that pair together represent the rungs of the ladder. So, when the halves of the ladder bond, a single ladder is formed.
For genes to properly function, the nucleotides must pair 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 a purine always pairs with a pyrimidine. In other words, adenine always pairs with thymine and cytosine always pairs with guanine.
The bonds formed as a result of nucleotide pairing are weak hydrogen bonds that also play an important part in the chemistry of DNA. Each molecule looks like a twisted ladder due to these and other complex chemical bonds between different molecular units. This unique shape is why a DNA molecule is termed a double helix. - 16459
About the Author:
RJ Sullivan manages several successful online businesses and is a accomplished editor and writer. Ms. Sullivan also writes for In the Gno, a blog devoted to demystifying the science of genetics in an interesting and easy-to-understand manner. Visit In the Gno to learn more about genetics and DNA.
