NUCLEIC ACIDS
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- Consists of hydrogen, oxygen, carbon, nitrogen and phosphate.
- Nucleotides as monomers.
- These nucleotides are made of three parts:
1. A five-carbon sugar
2. A base that has nitrogen (N) atoms
3. An ion of phosphoric acid known as phosphate (PO43-) - The nitrogenous bases are adenine, guanine, thyamine, cytosine and uracil.
- Though only four different nucleotide bases can occur in a nucleic acid, each nucleic acid contains millions of bases bonded to it.
- The order in which these nucleotide bases appear in the nucleic acid is the coding for the information carried in the molecule. In other words, the nucleotide bases serve as a sort of genetic alphabet on which the structure of each protein in our bodies is encoded.
- The amines that form nucleic acids fall into two categories: purines and pyrimidines. There are three pyrimidines (cytosine, thymine, and uracil) and two purines (adenine and guanine).
There are two common nucleic acids:
1. DNA (deoxyribonucleic acid)
1. DNA (deoxyribonucleic acid)
- Stores genetic information.
- Made and resides in the nucleus of living cells.
- A DNA molecule consists of two long polynucleotide chains (double stranded) composed of four types of nucleotide subunits.
- Two chains are held together by hydrogen bonding between the bases on the different strands, all the bases are on the inside of the double helix, and the sugar-phosphate backbones are on the outside.
- Four different nucleotide bases occur in DNA: adenine (A), cytosine (C), guanine (G), and thymine (T).
- Sugar is deoxyribose attached to a single phosphate group (hence the name is deoxyribonucleic acid), and the base may be either adenine (A), cytosine (C), guanine (G), or thymine (T).
- The nucleotides are covalently linked together in a chain through the sugars and phosphates, which thus form a “backbone” of alternating sugar-phosphate-sugar-phosphate.
- Has the unique ability that it can make exact copies of itself, or self-replicate. When more DNA is required by an organism (such as during reproduction or cell growth) the hydrogen bonds between the nucleotide bases break and the two single strands of DNA separate. New complementary bases are brought in by the cell and paired up with each of the two separate strands, thus forming two new, identical, double-stranded DNA molecules.
2. RNA (Ribonucleic acid)
- Single-stranded molecule.
- Contains the bases adenine (A), cytosine (C), and guanine (G); however, RNA does not contain thymine, instead, RNA's fourth nucleotide is the base uracil (U).
- Main genetic material used in the organisms called viruses, and RNA is also important in the production of proteins in other living organisms.
- Can move around the cells of living organisms and thus serves as a sort of genetic messenger, relaying the information stored in the cell's DNA out from the nucleus to other parts of the cell where it is used to help make proteins.