In Biology Almost all cells are very small An exception to t

In Biology, Almost all cells are very small. An exception to this \"rule\" is that most eggs are significantly larger cells (an unfertilized ostrich has a volume of about 1.3 liters and the yolk is the largest single cell). Yet as soon as an egg becomes fertilized, it begins to divide, eventually resulting in a mass of tiny cells.

What is different about an unfertilized egg from any other type of cell that might account for why it can be so much larger?

Solution

When we talk about the two reproductive gametes, the sperm and the egg, both of them are responsible for formation of the zygote which develops into an offspring. An unfertilized egg is much larger than a sperm because it contains all the organelles that would later assist in metabolism and growth inside the egg, where as the sperm contains majorly the genetic material only.

The egg cytoplasm has multiple nutritional component reserves present in the yolk which includes lipids, proteins, and polysaccharides. This is not the case with a normal cell which has just limited nutrients or takes up nutrients from its surrounding environment. An egg after getting laid cannot do so, for eg. bird eggs. Where as human eggs can take up nutrients from the placenta but even then they have additional organelles which results in a size larger than normal cells.