Compare and contrast the structures of DNA and RNA.

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trophyhunter1 | College Teacher | (Level 1) Educator Emeritus

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DNA stands for deoxyribonucleic acid. It is the chemical that makes up the chromosomes and genes and contains the hereditary information for the organism. It is composed of a double helix--two complementary strands, much like a spiral staircase or ladder. A single unit of DNA is called a nucleotide, consisting of a sugar--deoxyribose, a phosphate group and one of four nitrogenous bases. These are adenine, guanine, cytosine and thymine.  Since the molecule is a double helix, a nucleotide bonds to a complementary nucleotide. There are base--pairing rules: adenine bonds to thymine and cytosine to guanine. RNA, or ribonucleic acid, is a single--stranded nucleic acid. It contains a different sugar--ribose and four bases--adenine, guanine, cytosine and uracil. RNA can copy the DNA code in a process called transcription. However, since RNA does not contain the base thymine, you must substitute uracil. For instance, if the DNA code reads ATCG, the complementary RNA transcript would be--UAGC.  Once DNA is copied by messenger RNA, the transcript is translated into a protein at the ribosome in the cell's cytoplasm.

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trophyhunter1 | College Teacher | (Level 1) Educator Emeritus

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Deoxyribonucleic acid or DNA is the chemical compound that contains our blueprint or hereditary information. It is found inside the nucleus of eukaryotic cells. The molecule of DNA is a double helix. It resembles a spiral staircase. The subunits of DNA are called nucleotides. A nucleotide consists of a five carbon sugar called deoxyribose, a phosphate group and one of four nitrogenous bases. These are adenine, guanine, cytosine or thymine. Complementary nucleotides are held together by hydrogen bonds. Adenine can bond to thymine, guanine to cytosine. RNA is a single stranded molecule in contrast to the double stranded DNA. It has a sugar called ribose and it also contains nitrogenous bases however, there is adenine, guanine, cytosine but not thymine. A different base known as uracil is present in RNA. RNA is capable of copying the DNA genetic code in a process called transcription. It carries this message to a ribosome in the cytoplasm, where translation occurs and a polypeptide is manufactured. The end result is that it folds into a functional protein. 

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nancy167 | College Teacher | (Level 1) Salutatorian

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DNA is deoxyrionucleic acid and contains the 5 carbon sugar deoxyribose. RNA is ribonucleic acid and contains the 5 carbon sugar ribose. DNA is a double stranded molecule. RNA is single stranded.
DNA contains 4 bases Adenine (A) , Cytosine (C), Guanine (G) and Thymine (T). In RNA Thymine is replaced by Uracil(U) but also contains A, C and G. Both DNA are composed of sub units called nucleotides.

A Nucleotide has 3 sub units: 5 carbon sugar, phosphate group and nitrogen base. The nucleotides in both DNA and RNA are linked by chemical bonds between the sugar of one nucleotide and the Phosphate of the next to form a 'sugar- phosphate backbone. RNA has several types: Messenger RNA(mRNA), Transfer RNA (tRNA) and Ribosomal (rRNA) Proteins are coded for by sequences of three bases on the nucleic acid strands.

A series of three bases on DNA is called a Triplet. On mRNA a sequence of three bases is called a codon and on tRNA it is called an anticodon. DNA, is a double stranded is too large to pass out of the nuclear pores and so is confined to the nucleus. mRNA is a single stranded can pass out of the nucleus to carry the genetic code to the ribosomes on the rough endoplasmic retiticulum for translation into sequences of amino acids. (Called Translation) DNA can undergo self replication,

But there is no process of replication in RNA The base pairing rule in DNA is A with T and C with G. In RNA the base pairing rule is A with U and C with G.

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