Q1. Prokaryotic cell E. coli consists of a single closed-circular DNA molecule of 4.6 x 106 bp long. This DNA molecule would be 1.6 mm if the double helix is relaxed. Please describe what strategies does E. coli use to pack such a long molecules into its nucleoid less than a micrometer (mm) in diameter. (20 points)

Molecular biologists routinely use restriction enzymes as key reagents for a variety of applications including genomic mapping, restriction fragment length polymorphism (RFLP) analysis, DNA sequencing, and a host of recombinant DNA methodologies. Few

Chapter 5 Macromolecules and Molecular Genetics The key informational macromolecules in prokaryotic and eukaryotic cells are DNA, RNA, and protein. Molecular Genetics deals with the mechanisms by which the information in DNA is replicated, and by which it can be transcribed into rNa and translated into specific proteins

DNA转录RNA前体加工成熟RNA的过程 RNA合成的两种方式: 1、DNA指导的RNA合成。 2、RNA指导的RNA合成

一、反（无）意义链（antisense strand）：作为RNA合成模板的DNA链，方向3'→5' 二、有意义链（sense strand）：与反意义链互补、与转录产物如mRNA的序列相同的DNA链叫有意义链，方向5'→3

一、物理性质 1、形态DNA为白色纤维状固体;RNA为白色粉末状固体? 2、溶解性微溶于水,不溶于乙醇、乙醚和氯仿等一般的有机溶剂;DNA在溶液中粘度大,RNA粘度小

一、顺式作用元件和反式作用因子 Cis-acting element：不编码任何产物的 DNA片段，能影响与之相联系的同一条 DNA链上的基因表达 :启动子。 Trans-acting factor （转录因子TF） 由调节基因编码，调节基因是一种特殊 的结构基因，其编码产物（RNA或蛋白质） 可以扩散，控制其他基因的表达

Chapter 5 Macromolecules and Molecular Genetics DNA Replication Complementary base pairing Semiconservative Template and primer From 5'-phosphate to the 3'-hydroxyl end DNA polymerase and ligase A short stretch of RNA serves as primer Primase: a specific RNA-polymerizing enzyme

一、病毒： 是一种非细胞型微生物，最小的生命单位，其核心是脱氧核糖核酸（DNA）或核糖核酸(RNA)，外壳是蛋白质。 二、病毒自身不能进行代谢，但能在宿主细胞内增殖，并将遗传信息传递给子代。 三、病毒分成DNA病毒和RNA病毒两大类

Arrangement of DNA in Prokaryotes Vertebrates Algae Fungi Free-living prokaryotes Obligately parasitic Bacteria Chloroplasts Nudleod Mitochondria Viruses