B 5B Cellular Complexity on-level – 02
Jinny placed the slide with a drop of pond water under the microscope lens and looked. “OHHH!! they are moving as if they are alive.” She heard Mrs. Jackson’s gentle laughter as she came close to her bench and said “But they are alive, just like us.” That was one of the best days in Jinny’s biology class. She was curious to know more. Over the next few classes Mrs. Jackson explained that some of the earliest forms of life were microbes. They left their chemical signals on rocks consisting of a type of carbon that is essential for life.
Today, we divide cells into two separate groups – prokaryotes and eukaryotes. Prokaryotes lack a nucleus and contain circular DNA in their cytoplasm. Eukaryotes have a membrane-bound nucleus that contains its genetic material. Although there are differences, all cells are surrounded by plasma membrane, have genetic material, and have methods to produce energy.
The next day Mrs. Jackson asked the class about the functions their bodies were doing right then. Paul said, “My heart is pumping blood, and since I just had lunch my body probably is also digesting food.” “Correct,” said the teacher. She also said that the body can do all these functions because it is made up of the basic unit of life – the cell. A cell is a complex, superbly designed, highly adaptable structure.A living cell has ways to interact, communicate, modify, create and maintain the organism of which it is a part. A cell functions by constantly exchanging information with the environment.
The cell is like a well-designed, highly functional factory. The semipermeable membrane separates the internal environment from the outside. Membrane proteins stand as guards, sensing and communicating through chemical and electrical signals. The mitochondria are the power stations for the cell that manufacture energy to run this extremely complex factory. The DNA acts as a data bank that contains the blueprint of the organism all determined through a sequence of four bases. Elaborate transportation system carries raw materials where vesicles act like trucks carrying essential packages. There are also organelles that repair and recycle damaged parts.
A cell is a part of a more complex system, the lesson continued, but it serves as the basis of life due to its capability of growth, differentiation, adaptation, and cell death. The cell cycle is a complex process that involves several stages. As the cell grows and divides, it goes through checkpoints at every stage to detect damage and make necessary repairs to prevent uncontrolled growth or unwanted changes.