1. The white of an egg is known as the albumen, which comes from albus, the Latin word for “white.” Four alternating layers of thick and thin albumen contain approximately 40 different proteins, the main components of the egg white in addition to water. Opaque ropes of egg white called chalazae hold the yolk in the center of the egg. Like little anchors, they attach the egg yolk’s casing to the inner membrane lining the eggshell. The more prominent they are, the fresher the egg.

2. The shell of an egg is covered with as many as 17,000 tiny pores. Eggshell is made almost entirely of calcium carbonate (CaCO3) crystals. It is a semi-permeable membrane (air and moisture can pass through its pores). The shell also has a thin outermost coating called the bloom or cuticle that helps keep out bacteria and dust.

3. Lying between the eggshell and egg white are two membranes, the outer and inner membranes. These two transparent protein membranes provide efficient defense against bacterial invasion. They are incredibly strong, made partly of keratin, a protein that’s also in human hair. The clear casing that encloses the yolk is called the vitelline membrane. The yolk contains less water and more protein than the white, some fat, and most of the vitamins and minerals of the egg. These include iron, vitamin A, vitamin D, phosphorus, calcium, thiamine, and riboflavin. The yolk is also a source of lecithin, an effective emulsifier. Yolk color ranges from just a hint of yellow to a magnificent deep orange, according to the feed and breed of the hen.

4. An air space forms when the contents of the egg cool and contract after the egg is laid. The air cell usually rests between the outer and inner membranes at the egg’s larger end, and it accounts for the crater you often see at the end of a hard-boiled egg. The air cell grows larger as an egg ages.

Can you highlight the signal words that describe the physical characteristics of the components.