葉緑体

• Reading: ようりょくたい
• Romaji: youryokutai
• Kanji breakdown: 葉 (you) — leaf; 緑 (ryoku) — green; 体 (tai) — body, substance, organelle
• Pronunciation: /joː.ɾʲo.kɯ.taɪ/

Meaning

Chloroplast. The membrane-bound organelle found in plant and algal cells responsible for converting light energy into chemical energy through photosynthesis.

葉緑体 contain chlorophyll (葉緑素) and other pigments that absorb sunlight, driving photosynthesis (光合成) to produce glucose. Modern cell biology regards them as derived from ancient cyanobacterial endosymbionts (endosymbiotic theory). Their structure includes the outer membrane, stroma, thylakoids, and grana — each playing distinct roles in the light and dark reactions of photosynthesis.

Examples

1. 植物細胞の葉緑体は光合成を行い、太陽エネルギーをブドウ糖に変換する。 Chloroplasts in plant cells carry out photosynthesis, converting solar energy into glucose.
2. 葉緑体が含む葉緑素は、赤と青の光を吸収し緑色の光を反射するため葉は緑に見える。 The chlorophyll contained in chloroplasts absorbs red and blue light and reflects green light, which is why leaves appear green.
3. 葉緑体はもともと独立した光合成細菌が植物細胞に取り込まれたものという説が有力だ。 The prevailing theory is that chloroplasts were originally independent photosynthetic bacteria that were incorporated into plant cells.

Usage Guide

Context: biology, botany, cell biology, biochemistry

Tone: descriptive

Origin & History

Compound of 葉 (leaf) + 緑 (green) + 体 (body, organelle). The name literally means 'leaf-green body', directly describing both the colour due to chlorophyll and the leaf-centred context of the organelle.

Cultural Context

Era: Meiji–Modern

Generation: Adults (with biology education)

Social background: Universal (educated)