上泽文百大学 2.A Pair of Nucleic Acid Chains with Complementary SHANGHAI JIAO TONG UNIVERSITY Sequences Can Form a Double-Helical Structure 3.4-A spacing 在确定DNA三维结构的过程中发现碱 基特异性配对。Maurice Wilkins和 Rosalind Franklin获得了DNA纤维的 x-光衍射图谱（图4.10)。 该衍射图谱说明DNA是两条链缠绕形 成规则的螺旋结构。 从这些数据及其他数据，James Watson和Francis Crick推测DNA具 有双螺旋结构，这种双螺旋结构与核酸 的功能相吻合。 Figure 4,10 X-ray diffraction photograph of a hydrated DNA fiber.The central cross is diagnostic of a helical structure.The strong arcs on the meridian arise from the stack of nucleotide bases,which are 3.4 A apart
2. A Pair of Nucleic Acid Chains with Complementary Sequences Can Form a Double-Helical Structure Figure 4,10 X-ray diffraction photograph of a hydrated DNA fiber. The central cross is diagnostic of a helical structure. The strong arcs on the meridian arise from the stack of nucleotide bases, which are 3.4 A apart, 在确定DNA三维结构的过程中发现碱 基特异性配对。Maurice Wilkins和 Rosalind Franklin获得了DNA纤维的 x-光衍射图谱（图4.10）。 该衍射图谱说明DNA是两条链缠绕形 成规则的螺旋结构。 从这些数据及其他数据，James Watson 和Francis Crick推测DNA具 有双螺旋结构，这种双螺旋结构与核酸 的功能相吻合
上游究更大学 2.A Pair of Nucleic Acid Chains with Complementary SHANGHAI JIAO TONG UNIVERSITY Sequences Can Form a Double-Helical Structure DNA的高级结构： DNA双螺旋 0000D0000+ Lear double-stranded DNA molecule Circular DNA molecule DNA a间 核小体 螺线管 我tufe或nn 超螺线管 00nm 向) 700nm W方A/w4mrW 染色体
2. A Pair of Nucleic Acid Chains with Complementary Sequences Can Form a Double-Helical Structure DNA的高级结构：
上游充通大兽 2.A Pair of Nucleic Acid Chains with Complementary SHANGHAI JIAO TONG UNIVERSITY Sequences Can Form a Double-Helical Structure o 大肠杆菌基因组只有一个 DNA双链，每条链的长度 是460万核苷酸 Figure 4.8 Electron micrograph of part of the E.coli genome
Figure 4.8 Electron micrograph of part of the E. coli genome. 2. A Pair of Nucleic Acid Chains with Complementary Sequences Can Form a Double-Helical Structure 大肠杆菌基因组只有一个 DNA双链，每条链的长度 是460万核苷酸
上游充通大兽 2.A Pair of Nucleic Acid Chains with Complementary SHANGHAI JIAO TONG UNIVERSITY Sequences Can Form a Double-Helical Structure 已知DNA最长的生物是印度亚洲鹿，其基因组长度与人基因组长度相当，但 只有3种染色体，其中最长的染色体长度含有10亿多个核苻酸。如果将这种 DNA分子完全伸展，其长度将超过1英尺。 Figure 4.9 The Indian muntjak and its chromosomes.Cells from a female Indian muntjak(right)contain three pairs of very large chromosomes(stained orange).The cell shown is a hybrid containing a pair of human chromosomes(stained green)for comparison
Figure 4.9 The Indian muntjak and its chromosomes. Cells from a female Indian muntjak (right) contain three pairs of very large chromosomes (stained orange). The cell shown is a hybrid containing a pair of human chromosomes (stained green) for comparison. 2. A Pair of Nucleic Acid Chains with Complementary Sequences Can Form a Double-Helical Structure 已知DNA最长的生物是印度亚洲鹿，其基因组长度与人基因组长度相当，但 只有3种染色体，其中最长的染色体长度含有10亿多个核苷酸。如果将这种 DNA分子完全伸展，其长度将超过1英尺
上游充通大兽 2.A Pair of Nucleic Acid Chains with Complementary SHANGHAI JIAO TONG UNIVERSITY Sequences Can Form a Double-Helical Structure 单链DNA或单链RNA能够形成茎环结构 G。C G● A。U T。A G。C TA G。C A。T 5-TAA AGG-3' 5'-UUGG U·A-UUGCA-3' DNA molecule RNA molecule Figure 4.19 Stem-loop structures.Stemloop structures may be formed from Single-stranded DNA and RNA molecules
单链DNA或单链RNA能够形成茎环结构 2. A Pair of Nucleic Acid Chains with Complementary Sequences Can Form a Double-Helical Structure Figure 4.19 Stem-loop structures. Stemloop structures may be formed from Single-stranded DNA and RNA molecules