tRNA is the smallest of all three types of RNA mentioned above, and
consequently much more soluble than mRNA and rRNA. This is why tRNA
is also sometimes called soluble RNA. tRNA transports amino acids,
building blocks of protein synthesis, to specific areas of the mRNA of the
polysome. tRNAs are composed of a small number of nucleotide units (70–
90 units) folded into several loops or arms through base pairing along the
chain.
Translation: RNA and protein biosynthesis
Translation is the process by which mRNA directs protein synthesis. In this
process, the message carried by mRNA is read by tRNA. Each mRNA is
divided into codons, ribonucleotide triplets that are recognized by small
amino-acid-carrying molecules of tRNA, which deliver the appropriate
amino acids needed for protein synthesis.
RNA directs biosynthesis of various peptides and proteins essential for
any living organisms. Protein biosynthesis seems to be catalysed by mRNA
rather than protein-based enzymes and occur on the ribosome. On the
ribosome, the mRNA acts as a template to pass on the genetic information
that it has transcribed from the DNA. The specific ribonucleotide sequence
in mRNA forms an ‘instruction’ or codon that determines the order in which
different amino acid residues are to be joined. Each ‘instruction’ or codon
along the mRNA chain comprises a sequence of three ribonucleotides that is
specific for a given amino acid. For example, the codon U–U–C on mRNA
directs incorporation of the amino acid phenylalanine into the growing
protein.
4.8.4 DNA fingerprinting
DNA fingerprinting, also known as DNA typing, is a method of identification that compares fragments of DNA. This technique was first developed in
1985, originally used to detect the presence of genetic diseases. With the
exception of identical twins, the complete DNA of each individual is unique.
In 1984, it was discovered that human genes contain short, repeating
sequence of noncoding DNA, called short tandem repeats (STRs). The STR
loci are slightly different for every individual except identical twins. By
sequencing these loci, a unique pattern for each individual can be obtained.
On the basis of this fundamental discovery, the technique of DNA fingerprinting was developed.
The DNA fingerprinting technique has now been applied almost routinely
in all modern forensic laboratories to solve various crimes. When a DNA
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CH4 ORGANIC FUNCTIONAL GROUPS
consequently much more soluble than mRNA and rRNA. This is why tRNA
is also sometimes called soluble RNA. tRNA transports amino acids,
building blocks of protein synthesis, to specific areas of the mRNA of the
polysome. tRNAs are composed of a small number of nucleotide units (70–
90 units) folded into several loops or arms through base pairing along the
chain.
Translation: RNA and protein biosynthesis
Translation is the process by which mRNA directs protein synthesis. In this
process, the message carried by mRNA is read by tRNA. Each mRNA is
divided into codons, ribonucleotide triplets that are recognized by small
amino-acid-carrying molecules of tRNA, which deliver the appropriate
amino acids needed for protein synthesis.
RNA directs biosynthesis of various peptides and proteins essential for
any living organisms. Protein biosynthesis seems to be catalysed by mRNA
rather than protein-based enzymes and occur on the ribosome. On the
ribosome, the mRNA acts as a template to pass on the genetic information
that it has transcribed from the DNA. The specific ribonucleotide sequence
in mRNA forms an ‘instruction’ or codon that determines the order in which
different amino acid residues are to be joined. Each ‘instruction’ or codon
along the mRNA chain comprises a sequence of three ribonucleotides that is
specific for a given amino acid. For example, the codon U–U–C on mRNA
directs incorporation of the amino acid phenylalanine into the growing
protein.
4.8.4 DNA fingerprinting
DNA fingerprinting, also known as DNA typing, is a method of identification that compares fragments of DNA. This technique was first developed in
1985, originally used to detect the presence of genetic diseases. With the
exception of identical twins, the complete DNA of each individual is unique.
In 1984, it was discovered that human genes contain short, repeating
sequence of noncoding DNA, called short tandem repeats (STRs). The STR
loci are slightly different for every individual except identical twins. By
sequencing these loci, a unique pattern for each individual can be obtained.
On the basis of this fundamental discovery, the technique of DNA fingerprinting was developed.
The DNA fingerprinting technique has now been applied almost routinely
in all modern forensic laboratories to solve various crimes. When a DNA
178
CH4 ORGANIC FUNCTIONAL GROUPS