Deoxyribonucleic Acid: DNA

To qualify as the genetic material, DNA has to fulfil two key requirements:
1) Genotype function or Replication: The genetic material must have the capability to store genetic information, and transmit this information faithfully from parents to offspring, generation after generation. This indicates that the genetic material should have the ability to replicate itself and make [...]

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Nucleic acids: DNA vs RNA

I know this is very elementary and any high school student must be knowing the differences between RNA and DNA. But I feel a blog which deals with diverse aspects of molecular biology and biotechnology deserves a mention of basic differences between the two molecules.
DNA is double helical; RNA is single helical.
DNA contains deoxyribose pentose [...]

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Nucleic Acids: An introduction contd…

The base of a nucleotide is joined covalently in an N-β-glycosyl bond to the 1′ carbon of the pentose sugar, and the phosphate is esterified to 5′ carbon. The N-β-glycosyl bond is formed by removal of water, as in O-glycosidic bond formation. The nitrogenous bases present in nucleic acids are:
1) Purines: Adenine and [...]

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Nucleic Acids: An introduction

Nucleic acids (DNA and RNA) are the polymers of nucleotides. Each nucleotide is made up of 3 components: 1) a pentose sugar, 2) a phosphate, and 3) a nitrogenous (nitrogen-containing) base. A nucleotide without the phosphate group is called a nucleoside. The nitrogenous bases are derivatives of two compounds: pyrimidine and purine. The bases and [...]

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rRNA

Ribosomal RNAs (rRNAs) constitute ribosomes where protein synthesis occurs. rRNA and ribosomal proteins combine to form ribosomes. Both prokaryotic and eukaryotic rRNA are made from longer precursors called preribosomal RNAs, or pre-rRNA .
In bacteria, a single 30S, 6500 nucleotides long, RNA precursor, after processing, makes 16S, 23S and 5S rRNAs. RNA at both ends of [...]

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Poly(A) tail

At the 3′ end, most eukaryotic mRNAs have a string of 80-250 adenylate residues called the poly(A) tail. The poly(A) tail is added in a multistep process after the mRNA transcript has been synthesized. Two sequences are required for cleavage and polyadenylation (addition of ploy(A) tail) of the mRNA: 1) A highly conserved polyadenylation signal [...]

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Eukaryotic mRNA: 5′ cap and 3′ poly(A) tail

The 5′ end of eukaryotic mRNA is capped with a guanine nucleotide (which is methylated forming 7-methyguanosine). The cap (5′-G) is added to the mRNA after transcription. The addition of 5′ G is catalyzed by a nuclear enzyme, guanylyl transferase. The cap is linked to the 5′ terminus of the mRNA through an unusual 5′,5′-triphospahe [...]

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mRNA: Leader and trailer sequences

All mRNAs contains two regions. A coding region which consists of a series of triplet codons representing the amino acid sequence of the coded protein, starting with and AUG (initiation codon) and ending with a termination codon. This is referred to as the open reading frame (ORF). Extra regions are present at both the 5′ [...]

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mRNA

mRNA encodes the amino acid sequence of the polypeptide specified by a gene. The function of mRNA is the same in all cells, but there are some differences in the synthesis and structure of prokaryotic and eukaryotic mRNA.
1) In bacteria, mRNA is transcribed and translated in the single cellular compartment, i.e, there is no spatial [...]

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tRNA contd…

 
The so-called extra arm is the most variable part of tRNA molecule, and on the basis of nature of the extra arm, tRNAs have been divided into two classes:
1) Class 1 tRNAs: They have a smaller extra arm, which is 3-5 bases long. They represent approximately 75% of all tRNAs.
2) Class 2 tRNAs: [...]

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