For over many years, bacteria have lived with humans. The first person to study bacteria under microscope was Anthony van Leeuwenhoek. Bacteria’s structure of cell has supported them to survive. Bacteria has their own ways of metabolizing. They can be classified by their source of carbon, as well as by where they gain their energy. Bacteria reproduce by a process named “binary fission”. They grow in 4 phases: Lag phase, log phase, stationary phase, and death phase. DNA is inside an molecule. Bacteria also has plasmids, a small and round DNA molecule. There are bacteria that cause harm, or bacteria that benefit the world. Bacteria that harms are called pathogenic bacteria. Many pathogenic bacteria roam this Earth. Examples of pathogenic bacteria are Bacillus anthracis, Clostridium botulinum, Francisella tularensis subsp, and Yersinia pestis. The good bacteria are named as bioremediators. They cure the hazardous waste through bioremediation. There are also bacteria that benefit humans. They can create food that we eat every day, or make antibiotics for our sickness, and many more. As we live our days here on Earth, bacteria both cause havoc and advantage for us. Frankly, bacteria are very important organism in our lives.Bacterial Growth: All About BacteriaThe bacteria surround us in this world. The humankind has basically lived with bacteria throughout the whole history. The bacteria are microscopic, single-celled prokaryotes. Anthony van Leeuwenhoek discovered bacteria. Anthony was the first one to study bacteria under microscope during the late 1600’s. (Davidson, 2017).Cellular StructureThere are structures that benefit the bacteria. This covering is preservative covering made of carbohydrates. Then there is the cell envelop. It is made of approximately three layers, which are the inside of cell wall, plasma membrane, and sometimes the outer capsule. Cell wall holds and attaches pili and flagella, and also shape the cytoplasmic membrane. Cytoplasm is where the functions for cell growth, metabolism and replications happens. Cytoplasm stabilizes organelles. Cytoplasmic membrane, also known as the Plasma membrane, is a layer of phospholipids and proteins. It surrounds the inside of the bacterium. Flagella is hair-like structures that helps the bacteria move around. Pili is small hair-like structure sticking out from the outside cell surface to support the bacteria to attach to other cells and surfaces. Ribosome creates protein. (Davidson, 2017).MetabolismMetabolism is the word used to describe all the chemical reactions inside a cell. Organisms are able to be grouped according to the source of carbon they use for metabolism as well as their energy source. Organisms that exchange inorganic carbon dioxide into organic carbon compounds are called autotrophs. Organisms that obtain fixed carbon from organic compounds created by other organisms are named heterotrophs. Furthermore, we can categorize organisms by where they obtain their energy. Organisms that use light as the source of energy are named phototrophs. Organisms that use chemicals as the source of energy are called chemotrophs. There are prokaryotes that demand oxygen for them to metabolize. They are called obligate aerobes. However, the ones who cannot permit oxygen are called obligate anaerobes. Facultative anaerobes are able to use aerobic metabolism when oxygen is nearby, but if oxygen is not around, it shifts to anaerobic metabolism. (Khan Academy, n.d).Growth and ReproductionBacteria reproduce asexually in a process named “Binary Fission”. Binary fission is when single celled organism divides into two identical single celled organisms. The binary fission steps start as the cell grows. Then the DNA is copied and attaches to the cell membrane. Next, the DNA and its copy separate, and the cell grows larger. Finally, the cell splits into two. Now the both cell has identical DNA. The growth of bacterial population happens in exponential growth. With each division cycle, they are being doubled. There are the phases of bacterial growth. Lag phase, log (exponential) phase, stationary phase, and the death phase. During the lag phase, the bacteria are getting used to their surroundings. They synthesize enzymes, proteins, RNA and many more. They increase in metabolic activity. During the log (exponential) phase pattern of growth has rapidly increased. If the bacteria are pathogenic, this would be the time that disease symptoms occur. Next is the stationary phase. During this phase, the number of workable bacteria cells remains the same and the rate of bacterial growth is equal with bacterial cell death rate. After the tiring rapid cell division, nutrients would be consumed, and toxic products will be set free. The cell division cannot continue at the same pace if it is more difficult to find nutrients and deal the toxins. The final phase is the death phase. During this phase, the decline in population occurs. The number of viable cells reduces exponentially. (Todar, 2012).DNADNA of bacteria is held in a circular molecule named the bacterial chromosome. The chromosome with protein and RNA molecules creates a structure named nucleoid in cytoplasm of the bacterial cell. The bacteria contain plasmids. Plasmid is round and small DNA molecules. Plasmids can duplicate independently because each plasmid holds a stretch of DNA that makes sure it gets copied by the host bacterium. The bacteria can gain new plasmids from other bacterial cells or from environment but they can also lose plasmids when a bacterium divides into two. (University of Waikato, 2018).Pathogens/BioremediatesPathogenic bacteria are the bacteria that cause diseases to mankind. Pathogenic bacteria enter a host organism and retrieves nutrients from the host’s cells, causing to harm the host. There are many different pathogenic bacteria in this world. However, there are commons ones such as Staphylococcus, Streptococcus, The Gram-Negative Bacilli, and Neisseria. (Herriman, 2017). Bioremediation is the biological treatment of perilous waste by microorganisms. Bioremediators are the organisms used in bioremediation. Some of the bioremediators are bacteria, archaea, and fungi. (Study.com, n.d).ConclusionHelpful bacteria benefit us in many ways in this world. They produce some foods we consume every day, help manufacture antibiotics, help people with insulins, and help with genetic engineering and many more reasons.