Final answer:
Prokaryote symbiosis refers to the mutually beneficial relationship between prokaryotic cells and hosts, including humans. In this interaction, prokaryotes live in or on larger organisms, contributing to health and ecological balance. The endosymbiotic theory is based on the concept of symbiosis between prokaryotic cells leading to the evolution of eukaryotic cells.
Step-by-step explanation:
Prokaryote symbiosis refers to the close and often long-term interaction between prokaryotic organisms, which are single-celled organisms without a nucleus. When two different kinds of organisms live together in a close relationship, it is called symbiosis. This relationship can be classified in different ways, such as mutualism, commensalism, or parasitism. In mutualism, both organisms benefit, while in commensalism, one benefits without harming the other, and in parasitism, one benefits to the detriment of the other. Prokaryotes can form symbiotic relationships with a vast array of organisms, including humans, where they are part of the human microbiome.
Humans are walking ecosystems, meaning we have numerous prokaryotic cells living on and inside our bodies, outnumbering our own cells by about ten to one. Some of these prokaryotic microbes are essential for human health, such as those producing vitamin K in our gut. The prokaryotic cells that are part of our microbiome can be involved in mutually beneficial relationships or commensal relationships with their host.
The endosymbiotic theory explains the evolution of eukaryotic cells as a result of a symbiotic relationship between two or more prokaryotic cells, where smaller prokaryotic cells took up residence inside larger ones. This relationship gave rise to complex cells with organelles such as mitochondria and chloroplasts, which are found in contemporary eukaryotic cells.