What two terms characterize bacteria?

Answer 1

There are many more than two things that characterize bacteria. Perhaps tiny size and lack of a nucleus would be just a beginning.

As newborns, we encounter our first microbes as we pass through the birth canal. Until that moment, we are 100 percent human.

Thereafter, we are, numerically speaking, 10 percent human, and 90 percent bacteria. Our microbiome contains at least 150 times more genes, collectively, than our human genome.

Think of it as a hulking instruction manual compared to a single page to-do list.

As we mature, we pick up more microbes from breast milk, food, water, animals, soil, and other people. Sometime in childhood, the bustling community of between 500 and 1,000 species stabilizes.

Some species are native only to humans, and may have been passed down within the family like heirlooms.

Others are generalists - maybe they've hopped aboard from pets, livestock, and other animal sources. Most of our microbes inhabit the colon, the final loop of intestine, where they help us break down fibers, harvest calories, and protect us from micro-marauders.

But they also do much, much more. Animals raised without microbes essentially lack a functioning immune system.

Entire repertoires of white blood cells remain dormant; their intestines don't develop the proper creases and crypts; their hearts are shrunken; genes in the brain that should be in the "off" position remain stuck "on."

Without their microbes, animals aren't really "normal."

What do we do for our microbes in return? Some scientists argue that mammals are really just mobile digestion chambers for bacteria.

After all, your stool is roughly half living bacteria by weight. Every day, food goes in one end and

microbes come out the other. The human gut is roughly 26 feet in length. Hammered flat, it would have a surface area of a tennis court.