Animal and Plant Cells Have Features in Common | 动物与植物细胞的共同特征

📚 Animal and Plant Cells Have Features in Common | 动物与植物细胞的共同特征

All living organisms are composed of cells, which are the basic structural and functional units of life. Both animal and plant cells are eukaryotic, meaning they possess a true nucleus and membrane-bound organelles. Despite their obvious differences, these two cell types share a remarkable number of fundamental features essential for maintaining life. Exploring these commonalities not only reinforces the concept of a shared evolutionary origin but also helps us understand the core processes that sustain all eukaryotic organisms.

所有生物体都由细胞组成，细胞是生命的基本结构和功能单位。动物细胞和植物细胞都属于真核细胞，意味着它们拥有真正的细胞核和膜结合的细胞器。尽管它们存在明显的差异，这两种细胞类型共享了大量对维持生命至关重要的基本特征。探索这些共同点不仅可以强化它们拥有共同进化起源的概念，也有助于我们理解维持所有真核生物体生存的核心过程。

1. Introduction to Cell Theory and Eukaryotic Cells | 细胞学说与真核细胞简介

The cell theory states that all living things are composed of cells, that the cell is the basic unit of structure and function, and that all new cells arise from pre-existing cells. Both animal and plant cells are eukaryotic, characterised by the presence of a membrane-bound nucleus and compartmentalised internal structures called organelles. Having evolved from a common ancestral eukaryote, these two cell types exhibit a conserved set of features that will be examined in detail.

细胞学说指出，所有生物体都由细胞组成，细胞是结构和功能的基本单位，且所有新细胞都来源于已有的细胞。动物细胞和植物细胞均为真核生物，其特征在于拥有由膜包被的细胞核以及被分隔开来的内部结构——细胞器。由于它们源自一个共同的真核祖先，这两种细胞类型展现出一系列保守的特征，下文将进行详细讨论。

2. The Plasma Membrane: A Universal Barrier | 质膜：通用的屏障

Every living cell is enclosed by a plasma membrane, a thin, flexible boundary that separates the internal environment from the exterior. In both animal and plant cells, the plasma membrane is composed primarily of a phospholipid bilayer with embedded proteins, described by the fluid mosaic model. The phospholipids provide a stable but fluid barrier, while membrane proteins serve as channels, carriers, receptors and enzymes. This common structure is fundamental for selective permeability, allowing the cell to control the passage of ions, nutrients and waste products.

每一个活细胞都由质膜包裹，质膜是一层薄而柔韧的边界，将内部环境与外部隔离开来。在动物细胞和植物细胞中，质膜主要由嵌入蛋白质的磷脂双分子层组成，这一结构可以用流动镶嵌模型来描述。磷脂分子提供了一个稳定但具有流动性的屏障，而膜蛋白则充当通道、载体、受体和酶。这种共同的结构是实现选择透过性的基础，使细胞能够控制离子、营养物质和废物的进出。

In addition, the outer surface of the plasma membrane carries glycoproteins and glycolipids that form the glycocalyx, which is crucial for cell–cell recognition, adhesion and communication. Both animal and plant cells utilise these molecular signatures to interact with their surroundings. Receptor proteins embedded in the membrane allow the cell to detect and respond to hormonal signals and environmental changes, a feature conserved across the two kingdoms.

此外，质膜的外表面带有糖蛋白和糖脂，它们形成糖衣，对细胞识别、细胞粘附和通讯至关重要。动物细胞和植物细胞都利用这些分子特征与周围环境相互作用。嵌入质膜中的受体蛋白使细胞能够检测和响应激素信号以及环境变化，这是两个界中保守的特征。

3. Cytoplasm and Cytosol: The Internal Environment | 细胞质与胞质溶胶：内部环境

The cytoplasm comprises all the material enclosed by the plasma membrane except the nucleus. It consists of the cytosol — a viscous, aqueous fluid — and a variety of organelles suspended within it. Both animal and plant cells maintain this internal medium, which serves as the site for numerous metabolic reactions, including the early steps of glucose breakdown in glycolysis. The cytosol also contains dissolved ions, amino acids, nucleotides and enzymes necessary for cellular metabolism.

细胞质包括质膜以内、细胞核以外的所有物质，由胞质溶胶（一种粘稠的水样液体）和悬浮其中的各种细胞器组成。动物细胞和植物细胞都维持着这种内部介质，它是无数代谢反应发生的场所，包括糖酵解中葡萄糖分解的早期步骤。胞质溶胶中还含有溶解的离子、氨基酸、核苷酸以及细胞代谢所必需的酶。

A filamentous protein network known as the cytoskeleton extends throughout the cytoplasm, providing structural support and enabling intracellular movement. This network is present in both cell types, highlighting another shared component of the eukaryotic cytosol. The ability to compartmentalise reactions within membrane-bound organelles while maintaining a common metabolic pool in the cytosol is a key evolutionary achievement of eukaryotes.

一种称为细胞骨架的蛋白质纤维网络贯穿整个细胞质，提供结构支撑并实现细胞内运动。这个网络在两种细胞类型中均存在，突显了真核生物胞质溶胶中的另一个共享组件。能够在膜结合的细胞器内分隔反应，同时在胞质溶胶中维持共有的代谢池，是真核生物进化中的一项关键成就。

4. Nucleus: The Control Centre | 细胞核：控制中心

The nucleus is the most conspicuous organelle in almost all eukaryotic cells. It is bounded by a double membrane called the nuclear envelope, which is perforated by nuclear pores that mediate the selective transport of macromolecules such as RNA and proteins. Both animal and plant cells contain a nucleus (with the exception of a few highly specialised cells such as mature red blood cells and phloem sieve tube elements), underscoring its central role in hereditary information storage and gene regulation.

细胞核是几乎所有真核细胞中最显著的细胞器。它被一层称为核被膜的双层膜所包裹，核被膜上分布着核孔，介导RNA和蛋白质等大分子的选择性运输。动物细胞和植物细胞都含有细胞核（少数高度特化的细胞除外，如成熟的红细胞和韧皮部筛管分子），这强调了它在遗传信息存储和基因调控中的核心作用。

Inside the nucleus, DNA is organised along with proteins into chromatin, which condenses into visible chromosomes during cell division. A prominent substructure, the nucleolus, is responsible for synthesising ribosomal RNA (rRNA) and assembling ribosomal subunits. This nuclear architecture and its functions in transcription and ribosome biogenesis are essentially identical in animal and plant cells, reflecting a deeply conserved eukaryotic blueprint.

在细胞核内部，DNA与蛋白质一起被组织成为染色质，染色质在细胞分裂期间凝聚成可见的染色体。一个显著的亚结构——核仁——负责合成核糖体RNA（rRNA）并组装核糖体亚基。这种核的结构及其在转录和核糖体生物发生中的功能，在动物细胞和植物细胞中基本一致，反映了一种深度保守的真核生物蓝图。

5. Mitochondria: Powerhouses of the Cell | 线粒体：细胞的动力工厂

Mitochondria are double-membrane-bound organelles found in the cytoplasm of virtually every animal and plant cell. They are often described as the powerhouses of the cell because they host the reactions of aerobic respiration, producing adenosine triphosphate (ATP) from the breakdown of organic substrates. The inner mitochondrial membrane is extensively folded into cristae, which provide a large surface area for the electron transport chain and ATP synthase, key components of oxidative phosphorylation.

线粒体是存在于几乎所有动物和植物细胞细胞质中的双层膜包被的细胞器。它们常被称为细胞的动力工厂，因为它们承载着有氧呼吸的反应，通过分解有机底物产生三磷酸腺苷（ATP）。线粒体内膜高度折叠形成嵴，这为电子传递链和ATP合酶提供了巨大的表面积，它们是氧化磷酸化的关键组成部分。

Supporting the endosymbiotic theory, mitochondria contain their own circular DNA, 70S ribosomes, and can replicate independently within the cell. This semi-autonomous nature is conserved in both animal and plant cells. The universal requirement for ATP as an energy carrier links all eukaryotic life, and the presence of mitochondria in these two cell types is one of the strongest pieces of evidence for their common ancestry.

支持内共生学说的是，线粒体含有自身的环状DNA、70S核糖体，并能在细胞内独立复制。这种半自主的性质在动物细胞和植物细胞中都是保守的。ATP作为能量载体的普遍需求将所有的真核生物联系在一起，而线粒体在两种细胞类型中的存在，是它们拥有共同祖先最有力的证据之一。

6. Ribosomes: Protein Synthesis Machinery | 核糖体：蛋白质合成机器

Ribosomes are the molecular machines that translate genetic information into proteins. In both animal and plant cells, cytoplasmic ribosomes are of the 80S type, composed of a large 60S subunit and a small 40S subunit. These ribosomes are assembled in the nucleolus and then exported to the cytosol, where they can either float freely or attach to the rough endoplasmic reticulum. The universal process of translation relies on ribosomes reading the sequence of codons in messenger RNA (mRNA) and catalysing the formation of peptide bonds between amino acids.

核糖体是将遗传信息翻译成蛋白质的分子机器。在动物细胞和植物细胞中，细胞质核糖体均为80S型，由一个60S大亚基和一个40S小亚基组成。这些核糖体在核仁中组装后被运出到胞质溶胶中，它们可以自由漂浮，也可以附着在粗面内质网上。翻译这一通用过程依赖于核糖体读取信使RNA（mRNA）中的密码子序列，并催化氨基酸之间肽键的形成。

The fact that the core ribosomal RNA and protein components are highly conserved across animals and plants further underscores their common evolutionary origin. While mitochondrial and chloroplast ribosomes are of the 70S type (similar to prokaryotes), the universally present 80S cytoplasmic ribosomes represent a key unifying feature of all eukaryotic cells.

事实上，核心的核糖体RNA和蛋白质组分在动物和植物中都是高度保守的，这进一步强调了它们共同的进化起源。虽然线粒体和叶绿体中的核糖体属于70S型（与原核生物相似），但普遍存在的80

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