The building blocks of all organisms. They are

 The three parts of the cell theory are all living things are made up of cells, cells are the most fundamental unit of life, and all cells come from preexisting cells through the process of cell division (Editors, n.d.). Cells are the basic building blocks of all organisms. They are the smallest unit of life and contain the organism’s hereditary information. Some microorganisms are made up of only one cell, while other bigger organisms such as human beings are made up of millions of different cells. The human body has many different kinds of cells; each specialized for a specific purpose (Editors, n.d.). For example, blood cells only specialize in the blood production. When cells combine, it forms a tissue; several tissues combine can make up an organ; several organs can make up a system, and the system can make up the organism. A process of growing new cells is called mitosis. All living organism begins life as a single cell. As a living organism grows, cells begin to reproduce as well.            The nucleus is an organelle made up of a double membrane nuclear envelops that keeps the entire organelle encased. The nucleus is found in eukaryotic cells and contains the majority of the cell’s genetic material. The nucleus maintains the genes and controls the functions of the entire cell. Nucleus is also known as the brain of the cell. Cells with a nucleus are called eukaryotic and those without a nucleus are prokaryotic (Davidson, 2015).            The nuclear envelop is a membrane around the entire nucleus. There are pores and spaces for RNA and proteins to pass through while the nuclear envelop keeps all of the chromatin and nucleous inside. Chromatin is made of DNA, RNA, and nuclear protein; chromosomes are made up of DNA. The function of chromatin is to package the DNA into the nucleus of a cell. DNA is the nucleic acid inside of the cell that contains the genetic instructions for the development. Chromosomes are responsible for carrying all of the information to help a cell grow and reproduce (Davidson, 2015). The nucleolus is a round body located in the nucleus. It is the largest structure in the cell nucleus and responsible for rewriting ribosomal RNA and combine it with proteins (NCBI,n.d.).            Mitochondria is found in most of the eukaryotic cells. It is a small structure that made up of double membranes and a matrix. The functions of mitochondria depend on the cell type in which they are present. The most important function of the mitochondria is to produce energy, then the energy will be used by the cell to carry out various function. The mitochondria generate the energy of the cell in the form of adenosine triphosphate (ATP). The mitochondria other functions are controlling the cell cycle, which is signaling, differentiation, growth and death (Bright Hub, n.d.). Chloroplasts are usually found in plants cells, but absent in animal cells. Because the chloroplasts take part in the process of photosynthesis; all plant cells take part in the process of photosynthesis which converts energy into sugars (Bailey, 20170.            Scientists believe that these organelles arose from prokaryotic cells, because mitochondria have their own cells membranes, just like a prokaryotic cell does and the chloroplasts have many similarities to mitochondria. Mitochondria and chloroplasts retain small genomes with some resemblance to those found in prokaryotes. Mitochondria are found in fungi, plants, and animals; they used oxygen to produce energy in form of ATP. In comparison, chloroplasts are found in plants cells and they convert energy into sugars, which could prove that they are evolved from photosynthetic prokaryotes (NCBI, 2000).            A ribosome is a cell organelle and it’s responsible for making proteins. A ribosome, formed from two subunits locking together, functions to translate encoded information from the cell nucleus provided by messenger ribonucleic acid (mRNA) and link together amino acids selected and collected from the cytoplasm by transfer ribonucleic acid (tRNA) (British Society for Cell Biology, n.d.). Ribosomes can be found floating within the cytoplasm or attached to the endoplasmic reticulum. Ribosomes make different proteins based on where they located in a cell. If it is floating, it will make proteins that will be utilized within the cell. When ribosomes are attached to the endoplasmic reticulum, the proteins will be used for inside and outside of the cell (British Society for Cell Biology, n.d.). Ribosomes are also found in prokariyotes. Proteins play a critical part, all cells require protein to functions and carry out daily activities.            Endoplasmic reticulum is an important organelle in eukaryotic cells. It is responsible for production, processing and transport proteins and lipids. Endoplasmic reticulum produces protein and lipids for many other cells (NCBI, 2015). There are two regions of the endoplasmic reticulum that differ in both structure and function. One region is called rough endoplasmic reticulum and the other is smooth endoplasmic reticulum. The rough endoplasmic reticulum has ribosomes attached and the ribosomes are absent in the smooth endoplasmic reticulum. The rough endoplasmic reticulum is responsible for manufactures membranes and secretory proteins. The soft endoplasmic reticulum is responsible for carbohydrate and lipid synthesis (NCBI, 2015).            The Golgi apparatus can be found in most eukaryotic cells and it is also known as Golgi body or Golgi complex. The Golgi apparatus is made up of membrane-bound sacs called cisternae and its major function is to modify, sort, and package proteins to be secreted. The Golgi apparatus other function is to transport lipids throughout the cell (Molecular Expressions, 2015). The Golgi apparatus works closely with the endoplasmic reticulum. When the endoplasmic reticulum makes a protein, a transition vesicle is also made. It drifts through the cytoplasm to the Golgi apparatus where it gets absorbed. After the Golgi works on the molecules inside, it secretes a vesicle into the cytoplasm which releases the protein molecule out of the cell (Molecular Expressions, 2015).             Lysosome enzymes are made by proteins from the endoplasmic reticulum and enclosed within vesicles by the Golgi apparatus. Lysosomes are formed from the fusion of vesicles from the Golgi complex with endosomes. Lysosomes are spherical membranous sacs that hold enzymes. The enzyme proteins are first created in the rough endoplasmic reticulum. Those proteins are packaged in a vesicle and sent to the Golgi apparatus. The Golgi then creates the digestive enzymes and pinches off a small, very specific vesicle. That vesicle is a lysosome. Lysosomes functions are digesting and recycling the cell’s material (National Center for Biotechnology Information, 2000). ReferencesEditors. (n.d.). Cell theory. Retrieved from Center for Biotechnology Information. (2000). Lysosomes. Retrieved from          Expressions. (2015, November 13). The golgi apparatus. Retrieved from    Society for Cell Biology. (n.d.). Ribosome. Retrieved from          resources/softcell-e-learning/ribosome/National Center for Biotechnology Information. (2000). The origin and evolution of cells. Retrieved from   (n.d.). Cell theory. Retrieved from Center for Biotechnology Information. (n.d.). The nucleolus. Retrieved from   , M. (2015, November 13th). The nucleus. Retrieved from    Hub. (n.d.). Mitochondria function and structure. Retrieved from  , M. (2015, November 13th). Mitochondria. Retrieved from  , R. (2017, October 17th). Chloroplast function in plant cell structure. Retrieved from    Center for Biotechnology Information. (2015, October 3rd). The endoplasmic reticulum:            structure, function and response to cellular signaling. Retrieved from