Prokaryotes are microscopic organisms that were most likely the first life forms on Earth and are the most abundant on Earth. Prokaryotes are single-celled, organisms that can cause serious disease. Prokaryotes can be found in air, ater, soil, and even in extreme environments such as volcanoes.
Bacterial Cell Wall
The bacterial cell wall is a layered structure surrounding the membrane that protects the prokaryotic cell from damage. Bacteria are classified based on their cell wall. A gram positive bacteria can be stained because its cell wall is made of mostly peptidoglycan, whereas a gram negative bacteria cannot be stained because it has very little peptidoglycan.
Prokaryotes don't have organelles, except for ribosomes. Prokaryotes have a single chromosome rather than multiple chromosomes as eukaryotes do. Prokaryotic DNA is circular, rather than a linear double-helix structure like that of Eukaryotes.
The single-celled organisms can move using flagella or pilli. Flagella is like a rotating motor that moves the organism whereas pilli allows the prokaryote to stick and grab onto other moving organisms, piggyback movement.
Prokaryotes are often classified based on their metabolic pathways or their oxygen requirements. On metabolic classifications, prokaryotes can be autotrophs, heterotrophs, chmosynthetic, or photosynthetic. On oxygen classifications, prokaryotes can be obligate anaerobes, facultative anaerobes, and aerobic.
Prokaryotes can reproduce via binary fission. They can change their DNA via conjugation, transformation, transduction, and mutation. Conjugation is exchanging DNA via a sex pilus with another prokaryote. Transformation is uptake of foreign DNA from a dead cell. Transduction occurs when a virus accidentally takes in another bacteria's DNA and injects it into another prokaryote. Mutation is when DNA changes for natural reasons or damage.
Viruses infect other cells in order to reproduce. Viruses are made mainly of capsids and DNA/RNA. Viruses can either have a harmful lytic cycle where they burst the host cell to release more viruses or follow the lysogenic cycle, where they incorporate themselves into the host DNA to get replicated for free.