This article is available at 5 reading levels at .The facts about cellsAn illustration of cells. Photo from Pixabay.Cells are the basic building blocks of life. Some life forms, or organisms, are made out of a singlecell, whereas others are made of millions.Scientists estimate that our bodies contain anywhere from 75 to 100 trillion cells, which come inhundreds of different types. Cells do everything from providing energy to allowing animals toreproduce.Below are 10 facts about cells, some of which are well-known while others may surprise you.1. Cells are too small to be seen without magnification.Cells come in a variety of sizes, ranging from 1 to 100 micrometers across. A micrometer is amillionth of a meter, and there are more than 25,000 micrometers in a single inch.The study of cells is called cell biology. Because cells are so small, it would have been impossible tostudy them without the invention of the microscope. Thanks to this technology, cell biologists canstudy detailed images of even the smallest of cells.By ThoughtCo.com, adapted by Newsela staff on 10.18.17Word Count917Level930L
This article is available at 5 reading levels at .2. There are two main types of cells.Cells are divided into eukaryotic and prokaryoticcells. Eukaryotic cells have nuclei that are surroundedby membranes. A nucleus is a structure that storesgenetic information such as DNA. Animals, plants andfungi are called eukaryotes because they areorganisms that are made of eukaryotic cells.Prokaryotes are creatures that are made of a singleprokaryotic cell. Examples include bacteria and archaeans. Unlike a eukaryotic cell, the nucleus ofa prokaryotic cell is not surrounded by a membrane. This region in the cell is called nucleoid.3. Prokaryotic single-celled organisms were the earliest and most basic forms of life on Earth.Prokaryotes can live in environments that would be deadly to most other organisms. Somearchaeans are even able to live inside animal intestines. Others live in extreme environments suchas hot springs, swamps and wetlands.