Bacteria can also acquire new genetic material from other bacteria, viruses, plants, and even yeasts. When mistakes are made during replication and a mutation occurs, it creates variety within the population that could-under the right circumstances-lead to an enhanced ability to adapt to a changing environment. Their offspring are identical, essentially clones with the exact same genetic material. They reproduce by dividing into two cells, a process called binary fission. Unlike more complex forms of life, bacteria carry only one set of chromosomes instead of two. Sometimes they carry accessory small rings of DNA, known as plasmids, that encode for specialized functions like antibiotic resistance. Most bacteria carry a single circular molecule of DNA, which encodes (or programs) the essential genes for reproduction and other cellular functions. These single-celled organisms, generally visible under a low-powered microscope, come in three shapes: spherical (coccus), rodlike (bacillus), and curved (vibrio, spirillum, or spirochete). This gives microbes a huge advantage over humans when it comes to adapting for survival.īacteria are 10 to 100 times larger than viruses and are more self-sufficient. If their environment suddenly changes, the community’s genetic variations make it more likely that some will survive. Because they reproduce so quickly, microorganisms can assemble in enormous numbers with great variety in their communities. Humans produce a new generation every 20 years or so bacteria do it every 20 to 30 minutes, and viruses even faster. This process operates far more efficiently in the microbial world than in people. Through natural selection, organisms that are genetically better suited to their surroundings have more offspring and transmit their desirable traits to future generations. The success of microorganisms is due to their remarkable adaptability. For these tiny invaders, a dead host is a dead end. Lactobacillus bacteria, which produce lactic acid to help with digestion.Īnd though some microbes make us sick and even kill us, in the long run they have a shared interest in our survival. In many cases, the microbes derive benefits without harming us in other cases, both host and microbe benefit. The vast majority of microbes establish themselves as persistent “colonists,” thriving in complex communities within and on our bodies. Among their other beneficial roles, microbes synthesize vitamins, break down food into absorbable nutrients, and stimulate our immune systems. Microbes in the human gastrointestinal tract alone comprise at least 10 trillion organisms, representing more than 1,000 species, which are thought to prevent the gut from being colonized by disease-causing organisms. In fact, our bodies contain at least 10 times more bacterial cells than human ones, blurring the line between where microbes end and humans begin. Microbes occupy all of our body surfaces, including the skin, gut, and mucous membranes. Experts believe about half of all human DNA originated from viruses that infected and embedded their nucleic acid in our ancestors’ egg and sperm cells. There is a close connection between microbes and humans.
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