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Thylakoid
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<p>Thylakoids are membrane-bound compartments inside <a href="/facts/Chloroplast/fo8U3yTx">chloroplasts</a> and <a href="/facts/Cyanobacterium/S8bKxIU9">cyanobacteria</a>. They are the site of the <a href="/facts/Light-dependent_reactions/kBnR8Lcp">light-dependent reactions</a> of <a href="/facts/Photosynthesis/TMV7w693">photosynthesis</a>. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen. Chloroplast thylakoids frequently form stacks of disks referred to as grana (singular: <i>granum</i>). Grana are connected by intergranal or <a href="/facts/Stroma_(fluid)/AYwQHKSm">stromal</a> thylakoids, which join granum stacks together as a single functional compartment. </p><p>In thylakoid membranes, chlorophyll pigments are found in packets called <a href="/facts/Quantasome/hdE8bqEK">quantasomes</a>. Each quantasome contains 230 to 250 chlorophyll molecules. </p>