Under the right conditions, you might be able to see an amoeba proteus, a human egg, and a paramecium without using magnification. A magnifying glass can help you to see them more clearly, but they will still look tiny.
In multicellular organisms, cells work together in teams. Multiple cell types, each specialized for a certain function, team up to form tissues. And multiple tissue types are organized into organs.
At any one time, a dozen different types of materials may be passing through the membrane of a cell. The job of the membrane is to regulate this movement in order to maintain the proper balance of ions, water, oxygen, carbon dioxide, nutrients, and other molecules.
ATP is the main energy currency not only in our cells, but in all forms of life on the planet. All cells make it (it doesn't travel from cell to cell), and they use it to power nearly all of their processes.
The cell is the basic building block of life. In its 3.5 billion years on the planet, it has proven to be a powerhouse, spreading life first throughout the seas, then across land, developing the rich and complex diversity of life that populates the planet today.
In the follow up to Darwin's Lost World, Martin Brasier introduces the quest for the missing history of life and the cell. Through a series of journeys it emerges that the modern plant cell is one of the most deeply puzzling and unlikely steps in the whole history of life. Weaving together several threads, Brasier emphasizes the importance of single-celled forms to marine ecosystems; symbiosis and coral reefs; and the architecture and beauty of single-celled Foraminifera and what they tell us about evolution.