Humans, plants and animals are all made up of millions of tiny cells that perform different jobs to achieve different goals in the ultimate fight for survival. Without cells, life wouldn’t exist. There are such things as single cell organisms of which organelles are the sole components. Organelles include mitochondria, golgi apparatus, vesicles, nucleus, cytoplasm and lysosomes. cytoplasm However, we, much like many living things, are multi-cellular creatures and rely on all of the organelles and a myriad of cell types for survival. Cellular specialization is the process that determines what type of cell a zygote will become. In the course Biology 101, learn more about organelles, single celled organisms, multi-celled organisms and cellular development.
It’s important to understand the process of cellular development before understanding the depths of cellular specialization. When a sperm and egg meet during conception a zygote is born. The zygote will multiply itself enough times to create a blastocyte. A blastocyte is essentially a bundle of identical zygotes that will eventually go on to become an embryo, or the first stage in fetal development. Within the blastocyte are masses of pluripotent cells. These cells can become any of the cells that comprise our body, be it a nervous system cell, a cardiac cell or an immune system cell. Once the cells differentiate or specialize they become unipotent which means they can no longer become another type of cell. They have been programmed for a specific function and there is no going back (however in some amphibians unipotent cells can return to pluripotent cells for healing – but in humans this is generally not the case). Cellular specialization is the process by which cells are specialized to become a certain kind of cell with a designated function.
Gene Regulation and Cues
So how do these cells know what kind of job they should perform? Pluripotent cells respond to transcription factors, or cues, that initiate gene regulation. The kind of cues the cell receives depends on where it is located within the blastocyte. Gene regulation refers to the expression of specific genes on a chromosome that are determined by cues. These cues can come from inside the cell (internal cues) or from adjacent cells (external cues). These cues signal gene regulation which indicates to the cell, hey, you’re going to be a part of the nervous system, or, the digestive system, or the heart. During gene regulation, genes are selected on the chromosomes to be activated. A certain combination of genes will create a certain type of cell. The other genes will remain deactivated and be rendered useless. There are other external cues such as the environment that can also contribute to cell specialization. Some cells will develop proteins to help protect itself from heat, lack of oxygen and so on. Stem cell research is the process of taking pluripotent cells and implementing environmental cues to create desired types of cells for organ replacement and even organ and tissue regrowth. Studying for the GCSE? Even if you’re not, this GCSE Biology prep course will help you understand a lot of the concepts covered in this article.
After genes are turned on or off through these cues the cell becomes a unipotent cell, as discussed in cellular development. At this point the cell knows where it belongs and what its function is. Cells become tissues, tissues become organs and organs allow organisms to survive. For instance, a pluripotent cells takes internal cues from its location in the body that it is to become a cardiac cell. The chromosomes inside the cell’s nucleus respond by activating appropriate genes and deactivating unnecessary genes associated with all cardiac cells. These cells will eventually become a part of the cardiac tissue and later on they will become a part of the cardiac muscle, or the heart. The cardiac cell is considered specialized to perform a certain function, in this case, develop and operate the heart. It reminds me of the old school computer game Lemmings. You know, those troll-looking creatures that are each programmed to do a specific job, one is a digger, one is a climber, one is a blocker etc. and they work together to prevent precarious situations and to survive. Cells are kind of like this as they work as a network to create life and sustain life. The beginning of life and all of the implications associated with that is a hotly debated topic. Quantum physicists try their best to uncover truths hidden deep within the universe’s unknown. In the course Quantum Physics, get an elementary approach to the topic and see what atomic and subatomic particles have to do with the world around us.
A fundamental application of cell specialization is seen with fetal development and gender. Believe it or not, all embryos at 5 weeks of age are females. That’s right boys, until the sex-determining region of Y (also known as the SrY gene) is activated – both females and males are exactly alike. The sex-determining region of the Y originates in the testes and flows from adjacent cell to adjacent cell until all of the cells know to activate that gene. Once the gene is activated, male proteins start being produced and the embryo begins to take on male traits.
Every cell becomes specialized at some point in cellular development. Some can become further differentiated from external environmental transcription factors to perform specific functions under certain circumstances. Cells are pretty amazing and can adapt quickly when necessary. Under conditions like hypoxia or heat intolerance, cells transform slightly to protect themselves and then return to their natural state once the threat is no longer present. Read more about the importance of Biology. Our bodies are constantly reacting to internal and external cues and it’s all due to microscopic components that make up our organism. For more in-depth coverage about cell structure and function check out the course Biotech Basics.