1.3.2A segment of DNa that contains the information required for the synthesis of a functional protein or rNa is referred as a gene. 1.3.3 DNA is large biomacromolecule. In bacteria, all the genetic information is stored in a single dna molecule; in a eukaryotic cell each chromosome contains one single DNa molecule
1.3.2 A segment of DNA that contains the information required for the synthesis of a functional protein or RNA is referred as a gene. 1.3.3 DNA is large biomacromolecule. In bacteria, all the genetic information is stored in a single DNA molecule; in a eukaryotic cell each chromosome contains one single DNA molecule
3 Gene (a)Monocistronic 5 3′ Gene 1 Gene 2 Gene 3 (b) Polycistronic
1.4 RNA can be divided into several classes of different functions 1.4.1 Ribosomal RNAs(rRNA)are structural components of ribosomes(the protein synthesis machine in cells) 1.4.2 Messenger rna (mRNA) are copies of DNA(Synthesized by dna transcription), that carry the information of one or a few genes to the ribosomes, where the corresponding protein(s) is(are)synthesized
1.4 RNA can be divided into several classes of different functions. 1.4.1 Ribosomal RNAs (rRNA) are structural components of ribosomes (the protein synthesis machine in cells). 1.4.2 Messenger RNA (mRNA) are copies of DNA (synthesized by DNA transcription), that carry the information of one or a few genes to the ribosomes, where the corresponding protein(s) is(are) synthesized
1.4.3 Transfer rna (tRNA) are adapter molecules that faithfully translate the information in a mrNa molecule into the specific amino acid sequences in a polypeptide chain 1. 4. 4 Some rna molecules. named as Ribozymes, have catalytic activities functioning in the processing(cleavage)of precursor rNa molecules(Thomas Cech and sidney altman won the nobel prize in Chemistry in 1989 for discovering ribozymes)
1.4.3 Transfer RNA (tRNA) are adapter molecules that faithfully translate the information in a mRNA molecule into the specific amino acid sequences in a polypeptide chain. 1.4.4 Some RNA molecules, named as Ribozymes, have catalytic activities functioning in the processing (cleavage) of precursor RNA molecules (Thomas Cech and Sidney Altman won the Nobel Prize in Chemistry in 1989 for discovering ribozymes)
1.5 Some bases are modified in both dna and rna molecules 1.5.1 The most common modification found in DNA are methylation of some bases(catalyzed by specific DNa methylases or methyltransferase), including, e.g., No-Methyladenine, 5-methylcytosine, N2-methylguanine) 1.5.2 The higher level of 5-methylcytosine in certain eukaryotic DNA sequences(often at Cpg sequences)correspond to a lower level of gene activities
1.5 Some bases are modified in both DNA and RNA molecules. 1.5.1 The most common modification found in DNA are methylation of some bases (catalyzed by specific DNA methylases or methyltransferase), including, e.g., N6 -Methyladenine, 5-methylcytosine, N2 -methylguanine) 1.5.2 The higher level of 5-methylcytosine in certain eukaryotic DNA sequences (often at CpG sequences) correspond to a lower level of gene activities