Cells — The Building Blocks of Life
細胞 — 生命的基石
Every living thing — from a tiny ant to a giant blue whale — is made of cells. Learn what a cell is, what is inside it, and how plant and animal cells differ.
每一種生物——由微小的螞蟻到巨大的藍鯨——都是由細胞組成的。一起學習細胞是甚麼、細胞裏面有甚麼，以及植物細胞和動物細胞的分別。
1 · What is a cell?
細胞是甚麼？
A cell is the basic unit of life — the smallest part of a living thing that can do everything needed to stay alive. Most cells are so small that you need a microscope to see them. Your body alone contains about 37 trillion cells!
細胞是生命的基本單位——是生物裏能執行所有生命活動的最小部分。大多數細胞細小得需要顯微鏡才看得見。單是人體就有大約 37 萬億個細胞！
All living things are made of cells. Some organisms, such as bacteria and amoeba, are just a single cell.
所有生物都由細胞組成。有些生物（如細菌、變形蟲）只是一個單細胞。
2 · Animal cells vs plant cells
動物細胞 對 植物細胞
Animal cells and plant cells share many parts, but plant cells have two extra features:
動物細胞和植物細胞有很多相同的部分，但植物細胞有兩個額外結構：
- Cell wall — a stiff outer layer that gives the plant shape and support. Animals do not have this.細胞壁——給植物提供形狀和支撐的堅硬外層。動物沒有這個結構。
- Chloroplasts — the green parts that capture sunlight to make food through photosynthesis.葉綠體——捕捉陽光、透過光合作用製造食物的綠色部分。
3 · Meet the parts of a cell
認識細胞的各部分
- Nucleus — the control centre; it holds the DNA.細胞核——控制中心，內含 DNA。
- Mitochondria — the powerhouse; they release energy.線粒體——發電廠，釋放能量。
- Cell membrane — the gate; it controls what enters and leaves.細胞膜——閘門，控制物質進出。
- Cytoplasm — the jelly-like liquid that fills the cell.細胞質——充滿細胞的果凍狀液體。
- Ribosomes — the protein factories.核糖體——製造蛋白質的工廠。
4 · Quick check
小測驗