文档介绍：六、、细菌细胞结构
一般构造：如细胞壁、细胞膜、细胞质、核质体、核糖体等，是所有细菌都有的构造
特殊构造：主要有鞭毛、菌毛、性菌毛、荚膜和芽孢等，并非所有细菌都有的构造
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Figure 1. Schematic di六、、细菌细胞结构
一般构造：如细胞壁、细胞膜、细胞质、核质体、核糖体等，是所有细菌都有的构造
特殊构造：主要有鞭毛、菌毛、性菌毛、荚膜和芽孢等，并非所有细菌都有的构造
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Figure 1. Schematic diagram of a typical procaryotic cell. Minimally, a procaryote is composed of a cell wall and plasma membrane that surrounds its cytoplasm containing a chromosome, ribosomes, enzymes, several classes of RNA, and small molecules (precursors).
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（一）细胞壁cell wall:
细胞壁的观察方法：
① 质壁分离＋染色
② 电镜观察
G＋与Gˉ细菌cw的模式结构
★共有组分— 肽聚糖
★特有组分— G＋ 磷壁酸
Gˉ 脂多糖
细胞壁是位于菌体的外层，内侧紧贴细胞膜的一层无色透明，坚韧而有弹性的结构。细胞壁约占细胞干重的10%—25%。
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Figure 3 - Electron micrograph of a G+ cell wall.
Figure 4 - Electron micrograph of a G- cell wall.
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细胞壁cell wall:
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Gram Positive
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Gram Negative
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革兰氏阳性菌肽聚糖单体
概念： 肽聚糖是由 N—乙酰胞壁酸（NAM）和N—乙酰葡糖***（NAG）以及短肽链（主要是四肽）组成的亚单位聚合而成的大分子聚合物。
（1）细胞壁的基本骨架——肽聚糖（共有成分）
肽聚糖网格状结构
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Figure 5 - A comparison of L and D amino acids. Note that while the structure is identical, it is impossible to superimpose them.
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NAG 与 NAM 残基以ß-1,4糖苷键交替连接，形成聚糖的骨架（主链）； 一组相同的短肽侧链接于NAM上； 相连主链上的短肽侧链通过一条肽桥、或直接相连，从而形成网状分子结构。
肽聚糖单体→网状结构
G+菌肽聚糖单体
Gˉ菌肽聚糖单体
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Figure 8. Schematic diagram of the peptidoglycan sheet of Staphylococcus aureus. G = N-acetyl-glucosamine; M = N-acetyl-muramic acid; L-ala = L-alanine; D-ala = D-alanine; D-glu = D-glutamic acid; L-lys = L-lysine. This is one type of murein found in Gram-positive bacteria. Compared to the E. coli peptidoglycan (Figure 7) there is L-lys in place of DAP (diaminopimelic acid) in the tetrapeptide. The free amino group of L-lys is substituted with a glycine pentapeptide (gly-gly-gly-gly-gly-) which then becomes an interpeptide bridge forming a link with a carboxy group from D-ala in an adjacent tetrapeptide side chain. Gram-positive peptidoglycans differ from species to s