The second was that the melanosomes in her feathers were always embedded in the keratin of which the feather is made .

第二点是，羽毛中的黑素体总是镶嵌在组成羽毛的角蛋白中。

Composed of keratin , lipids and the pigments that give them their beautiful brilliant colors , feathers are particularly fascinating given the amazing work that they do .

羽毛中包含有角质，油脂以及为它们带来斑斓色彩的色素，羽毛所起到的作用让人惊叹。

Your eyes need to be transparent , however ; they can 't be covered by a layer of dead cells and keratin .

然而，眼睛却需要透明的保护层；在眼睛表面不能覆盖有死细胞或者角蛋白。

Nails , on both the fingers and the toes , are made of keratin , the same stuff our hair contains , only denser and harder .

手指甲与脚指甲，都是由角蛋白组成，这也是我们头发的主要组成部分，只不过较之更密实更坚硬。

Most of your body is protected by skin of course , and your outer layer of skin is made of dead cells and keratin , an opaque , protective substance .

当然你身体的大部分是由皮肤来保护，皮肤外层是由死细胞和角蛋白（即一种不透明的防护物质）组成。