3 Structure of genome Definition:the distribution and arrangement of various functional DNA regions along the DNA molecules The genetic material of most organisms is DNA,however,a few contains RNA genome (mainly virus 11
11 3 Structure of genome • Definition: the distribution and arrangement of various functional DNA regions along the DNA molecules • The genetic material of most organisms is DNA, however, a few contains RNA genome (mainly virus）
4 Transcriptional unit of prokaryotes and eukaryotes Operon of bacteria produce polycistron mRNA Operon In a bacterial chromosome,a group of contiguous genes that have related functions are transcribed into a single mRNA molecule在细菌中，一些功能上相关的酶的基因常一个 紧接着一个地串联排列，受同一操纵区控制，这种由多个结构 基因及其共同的转录操纵区组成的单一转录单位称为操纵子。 cistron The mRNA that encoding a specific peptide. polycistron A piece of mRNA that encoding more than one specific peptide. Most eukaryotic genes produce monocistrons 12
12 4 Transcriptional unit of prokaryotes and eukaryotes Operon of bacteria produce polycistron mRNA Operon：In a bacterial chromosome, a group of contiguous genes that have related functions are transcribed into a single mRNA molecule在细菌中，一些功能上相关的酶的基因常一个 紧接着一个地串联排列，受同一操纵区控制，这种由多个结构 基因及其共同的转录操纵区组成的单一转录单位称为操纵子。 cistron：The mRNA that encoding a specific peptide. polycistron： A piece of mRNA that encoding more than one specific peptide. Most eukaryotic genes produce monocistrons
trp operon Promoter Promoter Genes of operon DNA trpR , tpE■trpD trpc trpB trpA Operator Regulatory RNA/ Start codon Stop codon gene polymerase mRNA mRNA 5 E D C B Protein Inactive repressor Polypeptides that make up enzymes for tryptophan synthesis (a)Tryptophan absent,repressor inactive,operon on.RNA polymerase attaches to the DNA at the promoter and transcribes the operon's genes. 13
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Part 2 Structural features of viral genome 1 Introduction .Each viral particle,or virion,consists of genetic material,DNA or RNA,within a protective protein coat called capsid; Grouped by nucleic acid DNA RNA viruses; By host types plant virus,animal virus and bacteria virus (phage). 14
14 Part 2 Structural features of viral genome 1 Introduction • Each viral particle, or virion, consists of genetic material, DNA or RNA, within a protective protein coat called capsid; • By host types：plant virus, animal virus and bacteria virus (phage). • Grouped by nucleic acid：DNA & RNA viruses;
2 Features of Viral Genome (1)Genome size of different viruses vary greatly. i.e.the DNA size of HBV is 3.2kb and encoding only 4 proteins;while the genome of vaccinia virus is as large as 300kb,encoding hundreds of proteins7不同病毒基因组差异很大 (2)A virus may employ either DNA or RNA as the genetic material,but rarely do they contain both.The genome DNA or RNA might be single stranded or double stranded.The shape might be circular or linear.i.e.X174 contains scDNA, while adenoviruses employ linear,dsDNA. 15
15 2 Features of Viral Genome ▶(1) Genome size of different viruses vary greatly. i.e. the DNA size of HBV is 3.2kb and encoding only 4 proteins; while the genome of vaccinia virus is as large as 300kb, encoding hundreds of proteins不同病毒基因组差异很大 ▶(2) A virus may employ either DNA or RNA as the genetic material, but rarely do they contain both. The genome DNA or RNA might be single stranded or double stranded. The shape might be circular or linear. i.e. фX174 contains scDNA， while adenoviruses employ linear, dsDNA