Cell Structure: Core Knowledge Review | 细胞结构：核心知识梳理

📚 Cell Structure: Core Knowledge Review | 细胞结构：核心知识梳理

The cell is the fundamental unit of life. A clear understanding of cell structure is essential for success in any biology examination, as it underpins topics ranging from biochemistry to physiology.

细胞是生命的基本单位。清晰掌握细胞结构，是任何生物考试取得好成绩的基础，因为它是从生物化学到生理学等众多专题的基石。

1. Cell Theory and Basic Cell Types | 细胞学说与基本细胞类型

The classical cell theory states that all living organisms are composed of one or more cells, that the cell is the basic unit of structure and organization in organisms, and that all cells arise from pre-existing cells by cell division.

经典细胞学说指出：所有生物体由一个或多个细胞构成；细胞是生物体结构和组织的基本单位；所有细胞都通过细胞分裂来自已有细胞。

Modern extensions of the theory include the ideas that energy flow occurs within cells, that hereditary information is passed from cell to cell, and that all cells have the same basic chemical composition.

现代细胞学说的补充观点包括：细胞内发生能量流动；遗传信息在细胞间传递；所有细胞具有相同的基本化学组成。

At the most basic level, cells are classified into two major categories: prokaryotic cells, which lack a membrane-bound nucleus, and eukaryotic cells, which possess a distinct nucleus and membrane-enclosed organelles.

在最基本的分类层面，细胞可分为两大类：原核细胞没有以膜包被的细胞核；真核细胞具有明显的细胞核和膜包围的细胞器。

2. Prokaryotic vs Eukaryotic Cells | 原核细胞与真核细胞的比较

Prokaryotic cells are typically smaller, ranging from 0.5 to 5 μm, and their genetic material is concentrated in a nucleoid region rather than enclosed within a nuclear membrane.

原核细胞通常较小，直径约0.5至5 μm，其遗传物质集中在拟核区域，而非被核膜包裹。

Prokaryotes lack membrane-bound organelles such as mitochondria, chloroplasts, the Golgi apparatus and the endoplasmic reticulum. Their ribosomes are 70S type, and their cell walls (when present) contain peptidoglycan in bacteria.

原核细胞没有线粒体、叶绿体、高尔基体和内质网等膜包被细胞器。它们的核糖体为70S型，细菌的细胞壁（如果存在）含有肽聚糖。

Eukaryotic cells are larger, typically 10–100 μm, and contain a true nucleus, membrane-bound organelles, and 80S ribosomes. Plant and fungal cells have cell walls made of cellulose and chitin respectively, while animal cells have no cell wall.

真核细胞较大，通常为10–100 μm，含有真正的细胞核、膜包被细胞器以及80S核糖体。植物细胞和真菌细胞的细胞壁分别由纤维素和几丁质组成，而动物细胞没有细胞壁。

Prokaryote vs Eukaryote | 原核与真核