Students from the science stream would be well-versed with the term eukaryotic cells. The cells which make up complex living organisms like humans, animals, and plants, are examples of these. Now, why the name eukaryotic? Well, it actually means those cells which own true cell nucleus - apparently the brain of the cell. It is necessary to know that these cells contain certain cell organelles and contribute to the totality of the organism at large.
First of all, you need to understand that body cells are supposed to be the structural and functional units that control the body metabolism and help it maintain to optimum levels for the smooth functioning of all the organs. Initially, when life came into existence which is actually several years ago, the organisms were one-celled and thus lacked nucleus; they got the name prokaryotic cells meaning the primitive cells. The eukaryotic cells have been evolved from the former during the course of evolution, and thus have resulted in the body makeup of complex individuals. Though plant and animal cells come under the same generic term, eukaryotic cells, there is a marked line of difference between the two. Plants cells are characterized by cell wall and chloroplast pigment which are absent in animal cells completely. You will get to know easily when you observe the cells under the microscope.
As I said, eukaryotic cells are highly complex with a number of cell organelles inside each cell. All these organelles work in coordination, so that each organ is able to carry out the functions specific to it and that too with ease. The most important cell organelle is the nucleus. Just as the brain is for humans, same is the nucleus for cells. It controls the cell functions properly and is mainly composed of the hereditary materials; DNA (deoxyribonucleic acids) and RNA (ribonucleic acids), which basically control the phenotype and genotype of an organism or plant. Apart from the nucleus which is a distinct entity, the rest organelles are present in the cytoplasm which is a gel like matrix substance. These help in the metabolism of carbohydrates, protein manufacturing and transport. Along with this, a constant flow of nutrients and ions is going on, in and out of the cells. The 2 cell organelles I need to mention here are mitochondria and chloroplast. Mitochondria is considered the power house of the cells and provides the energy for all the life activities. Chloroplast, on the other hand, is unique to plant cells alone and essential in preparation of food (carbohydrates).
The characteristic feature of the eukaryotic cells is that, these divide by 2 processes; meiosis and mitosis, resulting in increase of the cell number, and thus a part of multicellular and complex organisms. Mitosis is continuously going on in the body, wherein one cell divides to form 2, 2 to form 4, and so on. Meiosis, on the other hand, is a reductional division occurring only during the reproduction phase. The eukaryotic individuals are thus diploid (containing 2 sets of chromosomes; one from the female and other from the male gamete).