Bacteria: these are single cellular organisms and have simple structures. Bacteria are small organisms that are everywhere, in plants, animals, and humans. They are on the inside and the outside of other organisms. They are also found in the air, soil, water and inside your body and o your skin. Bacteria can multiply rapidly in certain temperatures and in specific conditions. Bacteria cells are prokaryotic cells, which mean they have no nucleus or membrane bound organelles. Bacteria has an outer layer known as a capsule, this produces a thick jelly like material on the surface of the cell wall. The bacteria cell also has a flagellum which is attached to the outside of the cell which helps the cell to move around by waving it back and forth. They also have a cell wall which protects the cell and supports the cell. The cell doesn’t have a nucleus but instead has a nucleoid which is an irregular shaped region that holds nuclear information and where the genetic information is stored. It also has a plasmid which is small circular loops of DNA which carry genes.
Bacteria can be harmful and helpful. Harmful bacteria cause infectious diseases. This is when they attack tissues and cells in the body by releasing chemicals that are poisonous to cells. An example of a poison is toxins. For example, the bacteria can release a toxin called Clostridium tetani which causes the disease tetanus. Tetanus is a condition where a person’s muscles are paralyzed. Bacteria can also be helpful for example, bacteria allows the digestion of food in many animals. Also some bacteria help in the decay and decomposition of waste materials these are known as decomposers. Some bacteria are also involved in food production which is eaten by humans, for example, some bacteria cause milk to become sour and then cheese and yogurt is formed. The bacteria life cycle consists of four stages,. The first stage is called the lag phase. This is when the bacteria don’t grow but instead they adjust to their environment and metabolize which is that they produce vitamins and amino acids which is needed for division. They start to make copies of their DNA if the environment is suitable and provides enough nutrients. The second stage is the log phase. This is when the bacteria multiplies rapidly if the environment is right and the bacteria is receiving the correct nutrients. The third step is the stationary phase. This is when the bacteria growth dwindles. In this stage the growth and death rates equal because of lack of space. The fourth stage is the death phase. During this phase the bacteria loses all ability to reproduce which causes them to die. Bacteria death is as rapid as their growth.