If animal cells were to have cell walls...

If animal cells were to have cell walls, the cells, and the animal, would become rigid. There would be no need for a skeleton since the cell walls give support to the animal. The movements of the animal would become stiff and the cells may not be able to pass through blood vessels and other small spaces with the extra bulk of the cell wall.

Analogy of an Animal Cell

I am comparing the animal cell with a restaurant's kitchen. Nucleus: The chef in charge of the whole kitchen, just like the nucleus that gives commands to the other chefs. Nucleolus: A cookbook with the different recipes that are like DNA for the chef, or nucleus, to refer to. Ribosomes: Food created. It is a source of protein that is created by the cell, or kitchen. Rough endoplasmic reticulum: Pots, pans and utensils. They synthesise the production of ribosomes. Golgi apparatus: Ziplock bags which package and segregate the proteins. Lysosomes: Garbage disposal which cleans out waste from the kitchen. Plasma membrane: The walls and doors that let the information and proteins go in and out. Mitochondria: Stove, the main energy source in the kitchen. Taken from: eport2.cgc.maricopa.edu/published/h/lo/hlofgreen59/collection/2/2/upload.doc

Interesting Fact About Biology

A group of organisms shares a common descent if they share a common ancestor. All organisms on the Earth have been and are descended from a common ancestor or an ancestral gene pool. This last universal common ancestor of all organisms is believed to have appeared about 3.5 billion years ago. Taken from http://en.wikipedia.org/wiki/Biology#Continuity