Dna and Rna

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  • Topic: DNA, RNA, Gene
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General Biology
DNA and RNA

Deoxyribonucleic Acid and Ribonucleic Acid

• DNA is deoxyribonucleic acid. It is located in the nuclei of cells, which make up the body. Consequently, DNA can be considered as one of the building blocks of the body.

Where is DNA found?

DNA, or deoxyribonucleic acid, is the hereditary material that lies within the nucleus of all cells in humans and other living organisms. Most of the DNA is placed within the nucleus and is called nuclear DNA. However, a small portion of DNA can also be found in the mitochondria and is called mitochondrial DNA or mtDNA.

What is DNA made of?

DNA contains four chemical bases:
• Adenine (A)
• Guanine (G)
• Cytosine (C)
• Thymine (T).

• RNA stands for ribonucleic acid. It is an important molecule with long chains of nucleotides. A nucleotide contains a nitrogenous base, a ribose sugar, and a phosphate. Just like DNA, RNA is vital for living beings.

Functions of RNA

The main job of RNA is to transfer the genetic code need for the creation of proteins from the nucleus to the ribosome. This process prevents the DNA from having to leave the nucleus. This keeps the DNA and genetic code protected from damage. Without RNA, proteins could never be made.

RNAs as enzymes

Some RNAs are enzymes. It was widely believed for many years that only proteins could be enzymes. RNAs are now known to adopt complex tertiary structures and act as biological catalysts. Such RNA enzymes are known as ribozymes, and they exhibit many of the features of a classical enzyme, such as an active site, a binding site for a substrate and a binding site for a cofactor, such as a metal ion. One of the first ribozymes to be discovered was  RNase P, a ribonuclease that is involved in generating tRNA molecules from larger, precursor RNAs. RNase P is composed of both RNA and protein; however, the RNA moiety alone is the catalyst.

DNA compared to RNA

DNA is defined as a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms. RNA molecules are involved in protein synthesis and sometimes in the transmission of genetic information. However unlike DNA, RNA comes in a variety of shapes and types. While DNA looks like a double helix and a twisted ladder, RNA may be of more than one type. RNA is usually single-stranded, while DNA is usually double-stranded. In addition, RNA contains ribose while DNA contains deoxyribose. Deoxyribose lacks one oxygen atom. RNA has the bases Adenine (A), Uracil (U) (instead of thymine in DNA), Cytosine (C) and Guanine (G). Deoxyribose sugar in DNA is less reactive because of C-H bonds. DNA is stable in alkaline conditions. DNA has smaller grooves where the damaging enzyme can attach which makes it harder for the enzyme to attack DNA. Ribose sugar however is more reactive because of C-OH (hydroxyl) bonds. RNA is not stable in alkaline conditions. RNA has larger grooves, which makes it easier to be attacked by enzymes. The helix geometry of DNA is of B Form. DNA can be damaged by exposure to Ultraviolet rays. The helix geometry of RNA is of A-Form. RNA strands are continually made, broken down and reused. RNA, however, is more resistant to damage by Ultra-violet rays.

DNA to RNA Transcription
The DNA contains the master plan for the creation of the proteins and other molecules and systems of the cell, but the carrying out of the plan involves transfer of the relevant information to RNA in a process called transcription. The RNA to which the information is transcribed is messenger RNA (mRNA). The process associated with RNA polymerase is to unwind the DNA and build a strand of mRNA by placing on the growing mRNA molecule the base complementary to that on the template strand of the DNA. In the mRNA, Uracil is substituted for thymine as the base complementary to...
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