Chapter 4Chapter 4Chapter 4Chapter 4 Messenger RNAMessenger RNAMessenger RNAMessenger RNA b4.1 Introduction4.1 Introduction4.1 Introduction4.1 Introduction b4.2 4.2 4.2 4.2 mRNA is produced by transcription and is translated mRNA is produced by transcription and is translated mRNA is produced by transcription and is translated mRNA is produced by transcription and is translated b4.34.34.34.3 Transfer RNA forms a cloverleaf Transfer RNA forms a cloverleaf Transfer RNA forms a cloverleaf Transfer RNA forms a cloverleaf b4.44.44.44.4 The acceptor stem and The acceptor stem and The acceptor stem and The acceptor stem and anticodonanticodonanticodonanticodon are at ends of the are at ends of the are at ends of the are at ends of the tertiary structure tertiary structure tertiary structure tertiary structure b4.54.54.54.5 Messenger RNA is translated by Messenger RNA is translated by Messenger RNA is translated by Messenger RNA is translated by ribosomesribosomesribosomesribosomes b4.64.64.64.6 Many Many Many Many ribosomesribosomesribosomesribosomes bind to one mRNA bind to one mRNA bind to one mRNA bind to one mRNA b4.74.74.74.7 The life cycle of bacterial messenger RNA The life cycle of bacterial messenger RNA The life cycle of bacterial messenger RNA The life cycle of bacterial messenger RNA b4.84.84.84.8 Eukaryotic mRNA is modified during or after its Eukaryotic mRNA is modified during or after its Eukaryotic mRNA is modified during or after its Eukaryotic mRNA is modified during or after its transcriptiontranscriptiontranscriptiontranscription b4.94.94.94.9 The 5 end of eukaryotic mRNA is capped The 5 end of eukaryotic mRNA is capped The 5 end of eukaryotic mRNA is capped The 5 end of eukaryotic mRNA is capped b4.104.104.104.10 The 3 terminus is The 3 terminus is The 3 terminus is The 3 terminus is polyadenylatedpolyadenylatedpolyadenylatedpolyadenylated b5.115.115.115.11 SummarySummarySummarySummary 4.1 Introduction4.1 Introduction4.1 Introduction4.1 Introduction bMessenger RNA (mRNA)Messenger RNA (mRNA)Messenger RNA (mRNA)Messenger RNA (mRNA) provides an intermediate that provides an intermediate that provides an intermediate that provides an intermediate that carries the copy of a DNA sequence that represents protein. carries the copy of a DNA sequence that represents protein. carries the copy of a DNA sequence that represents protein. carries the copy of a DNA sequence that represents protein. bThe feature of mRNAThe feature of mRNAThe feature of mRNAThe feature of mRNA Its sequence is the important : each nucleotide triplet Its sequence is the important : each nucleotide triplet Its sequence is the important : each nucleotide triplet Its sequence is the important : each nucleotide triplet within the coding region of the mRNA represents an amino within the coding region of the mRNA represents an amino within the coding region of the mRNA represents an amino within the coding region of the mRNA represents an amino acid in the corresponding protein. However, the structure acid in the corresponding protein. However, the structure acid in the corresponding protein. However, the structure acid in the corresponding protein. However, the structure of the mRNA, in particular the sequences on either side of of the mRNA, in particular the sequences on either side of of the mRNA, in particular the sequences on either side of of the mRNA, in particular the sequences on either side of the coding region, can play an important role in controlling the coding region, can play an important role in controlling the coding region, can play an important role in controlling the coding region, can play an important role in controlling its activity, and therefore the amount of protein that is its activity, and therefore the amount of protein that is its activity, and therefore the amount of protein that is its activity, and therefore the amount of protein that is produced from it.produced from it.produced from it.produced from it. 4.1 Introduction4.1 Introduction4.1 Introduction4.1 Introduction bTransfer Transfer Transfer Transfer RNAsRNAsRNAsRNAs ( ( ( (tRNAtRNAtRNAtRNA) ) ) ) are small are small are small are small RNAsRNAsRNAsRNAs that are used to provide that are used to provide that are used to provide that are used to provide amino acids corresponding to each particular amino acids corresponding to each particular amino acids corresponding to each particular amino acids corresponding to each particular codoncodoncodoncodon in mRNA. in mRNA. in mRNA. in mRNA. bThe feature of The feature of The feature of The feature of tRNAtRNAtRNAtRNA Its three dimensional structure is important; and it has the Its three dimensional structure is important; and it has the Its three dimensional structure is important; and it has the Its three dimensional structure is important; and it has the ability to base pair with mRNA. ability to base pair with mRNA. ability to base pair with mRNA. ability to ba