📚 IGCSE Edexcel Biology: Cell Structure Key Points | IGCSE Edexcel 生物：细胞结构 考点精讲
Welcome to this focused revision guide covering the cell structure topic for the Edexcel IGCSE Biology specification. We will review the essential structures, compare different cell types, master microscopy calculations, and highlight common examination pitfalls. Let's dive into the world of cells.
欢迎阅读这篇针对 Edexcel IGCSE 生物学细胞结构专题的考点精讲。我们将回顾基本结构，比较不同细胞类型，掌握显微镜计算，并强调常见考试易错点。让我们一起进入细胞的世界。
1. Eukaryotic Cells: The Basics | 真核细胞：基础知识
Eukaryotic cells have a true nucleus enclosed by a nuclear membrane. This sets them apart from prokaryotes.
真核细胞拥有由核膜包围的真正细胞核，这与原核生物不同。
Both animal and plant cells are eukaryotic and share many common organelles such as mitochondria, ribosomes, and endoplasmic reticulum.
动物细胞和植物细胞都属于真核细胞，共有许多细胞器，如线粒体、核糖体和内质网。
In contrast, prokaryotic cells (e.g., bacteria) lack a nucleus and membrane-bound organelles.
相反，原核细胞（如细菌）没有细胞核和膜结合的细胞器。
2. Animal Cell Structure | 动物细胞结构
An animal cell typically contains a nucleus, cytoplasm, cell membrane, mitochondria, ribosomes, and vesicles.
动物细胞通常包含细胞核、细胞质、细胞膜、线粒体、核糖体和小泡。
The cell membrane is selectively permeable, allowing some substances to pass while restricting others.
细胞膜具有选择透过性，允许某些物质通过，而限制其他物质。
Mitochondria are the site of aerobic respiration, releasing energy in the form of ATP.
线粒体是有氧呼吸的场所，以ATP的形式释放能量。
Ribosomes are tiny organelles that synthesise proteins by linking amino acids together.
核糖体是微小的细胞器，通过连接氨基酸合成蛋白质。
3. Plant Cell Structure | 植物细胞结构
Plant cells have all the structures found in animal cells plus a rigid cell wall, a large permanent vacuole, and chloroplasts.
植物细胞拥有动物细胞中的所有结构，另外还有刚性的细胞壁、大液泡和叶绿体。
The cell wall is made of cellulose and provides support and protection, preventing the cell from bursting when turgid.
细胞壁由纤维素构成，提供支持和保护，防止细胞在膨胀时破裂。
Chloroplasts contain chlorophyll, which absorbs light energy for photosynthesis to produce glucose.
叶绿体含有叶绿素，吸收光能用于光合作用，产生葡萄糖。
The large central vacuole stores cell sap and helps maintain turgor pressure, which keeps the plant upright.
中央大液泡储存细胞液，有助于维持膨压，保持植物挺立。
4. Key Organelles and Their Functions | 关键细胞器及其功能
Here we summarise the main organelles and their roles as required by the specification.
这里我们总结大纲要求的主要细胞器及其作用。
Nucleus: Contains genetic material (DNA) and controls cell activities such as growth and division.
细胞核：包含遗传物质（DNA），控制细胞活动如生长和分裂。
Mitochondria: Carry out respiration, releasing energy for the cell's metabolic processes.
线粒体：进行呼吸作用，为细胞代谢过程释放能量。
Ribosomes: Sites of protein synthesis; can be free in the cytoplasm or attached to the rough endoplasmic reticulum.
核糖体：蛋白质合成的场所；可游离在细胞质中或附着在粗面内质网上。
Chloroplasts: Found only in plant cells and some protists; conduct photosynthesis.
叶绿体：仅存在于植物细胞和某些原生生物中；进行光合作用。
Cell wall: In plants, provides structural strength; in fungi, made of chitin; in bacteria, made of peptidoglycan.
细胞壁：在植物中，提供结构强度；在真菌中，由几丁质构成；在细菌中，由肽聚糖构成。
Vacuole: In plants, a large permanent vacuole helps with storage and turgidity; in animal cells, vacuoles are small and temporary.
液泡：在植物中，大液泡有助于储存和维持膨压；在动物细胞中，液泡小而临时。
5. Prokaryotic Cells: Bacteria | 原核细胞：细菌
Bacteria are single-celled prokaryotes, which are much smaller than eukaryotic cells (typically 0.5–5 μm).
细菌是单细胞原核生物，比真核细胞小得多（通常0.5–5微米）。
They lack a nucleus; instead, their genetic material is a single circular chromosome floating in the cytoplasm.
它们没有细胞核；相反，它们的遗传物质是一条在细胞质中漂浮的环状染色体。
Bacterial cells may also contain small rings of DNA called plasmids, which can carry genes for antibiotic resistance.
细菌细胞还可能含有称为质粒的DNA小环，这些质粒可能携带抗生素抗性基因。
Most bacteria have a cell wall for protection, but it is not made of cellulose. Some have a slime capsule and flagella for movement.
大多数细菌有用于保护的细胞壁，但不是由纤维素构成。有些细菌有荚膜和用于运动的鞭毛。
6. Fungi and Yeast Cells | 真菌与酵母菌细胞
Fungi, such as yeast (a single-celled fungus) and Mucor (a multicellular fungus), have eukaryotic cells with a cell wall made of chitin.
真菌，如酵母菌（一种单细胞真菌）和毛霉（一种多细胞真菌），具有真核细胞，细胞壁由几丁质构成。
Yeast cells contain a nucleus, cytoplasm, cell membrane, mitochondria, ribosomes, and a vacuole; they do not contain chloroplasts.
酵母菌细胞含有细胞核、细胞质、细胞膜、线粒体、核糖体和液泡；它们不含叶绿体。
Many fungi store carbohydrates as glycogen and can reproduce by budding (yeast) or by producing spores.
许多真菌以糖原形式储存碳水化合物，可以通过出芽（酵母菌）或产生孢子进行繁殖。
7. Using a Microscope | 显微镜的使用
In the IGCSE practical, you must be able to use a light microscope to observe cells and calculate magnification.
在IGCSE实验中，你必须能够使用光学显微镜观察细胞并计算放大率。
ication × objective lens magnification. Always start with the lowest power objective lens.
总放大率 = 目镜放大率 × 物镜放大率。总是从低倍物镜开始观察。
Learn to prepare a temporary slide: place the specimen on a slide, add a drop of water or stain, cover with a coverslip at an angle to avoid air bubbles.
学会制作临时装片：将标本放在载玻片上，加一滴水或染液，倾斜盖上盖玻片以避免气泡。
When drawing cells, use a sharp pencil, draw clear continuous lines, no shading, and label with straight ruled lines.
绘制细胞图时，用尖铅笔，画清晰连续的线条，不加阴影，用
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