Do you ever wonder what makes up the human body? It's cells! From the smallest ant to the largest elephant, all living things—organisms are made up of cells.
Single-celled organisms like bacteria are the smallest functioning living things. Cells have many organelles, or parts, such as the nucleus and the mitochondria. These help cells function. The nucleus acts as the cell's control center, while the mitochondria's job is to gather energy from nutrients. Both actions are essential to the cell's function.
Animal and plant cells are very similar with a couple of main differences. One of these differences is the shape of the cells; while plant cells are box-like, animal cells are more rounded. Animal cells are rounded because they have a membrane that gives the cell its shape and helps waste and chemicals travel in and out of the cell.
Another of the main differences is that plant cells have a vacuole and animals do not. The vacuole is a pouch filled with sugary water. This helps with the cell's digestion and gets rid of cellular waste. Plant cells also have chloroplasts that are full of chlorophyll, which gives plants their green color.
Despite these differences, cells are very similar. Cells are constantly dividing into two, and all cells play important roles. For example, nerve cells tell the brain what the body needs and sperm cells are helpful in the reproductive process.
Even though they are microscopic, cells are a crucial part of all living things.
[Sources: Simpson Street Free Press Archives; The Kingfisher Children's Encyclopedia]