Unicellular organisms die


What does it mean to die or what is death in biology?

If we ask the question about life (what does life mean?), Then it should also be necessary to ask the question about death. So what does death mean?

We said flatly, life ...

I) be cellular
II) have metabolism
III) wax
IV) is irritable
V) pass the stimuli on
VI) show movement
VII) adapt
VIII) reproduce and keep re-forming

Life was invented through nature in the history of the earth. But what about death?

Death also had to be invented first

The simplest living things, the successful bacteria, appear first in the natural history of living things. They reproduce by simple cell division or by exchanging DNA, i.e. genetic recombination. Basically, however, bacteria cannot die if they have food and a habitat.

The same applies to higher unicellular organisms (vegetable or animal). When cells divide, the parent cell changes into the daughter cells.

So dying, death, first had to be invented, with single-celled living beings death does not yet exist.

Volvox was one of the first organisms to show natural death

The Volvox lattice sphere is one of the first living things to show natural death. Consisting of thousands of individual cells, Volvox forms a grid sphere in which all cells are connected to one another via a plasma network. So there is an exchange of information, the ball is a colony that already shows features of an “organism”.

In the life cycle of Volvox, multiplication cells form, which grow into daughter colonies inside the mother sphere. If the daughter colonies are sufficiently large, the mother bulb tears open and the daughter colonies are released. She dies in the process.

Dying and death in plants

Death and dying appear to us mostly as a sudden event. But especially with the plants, we see how slowly dying can happen here.

If a plant lacks water, the turgor (water pressure) in the tissues drops and leaves and stems hang down. But that doesn't mean that the plant has already died. A bunch of flowers has only a limited time left to feed water into the leaves through the cut stem. As long as the leaves, stems and flowers are still fresh.

Salad or vegetables such as potatoes are also cut off or separated from their living environment. But metabolism still takes place in the tissues, the green leaves carry out photosynthesis or the meristems (germinal tissue) are still alive.

In cormophytes (shoot plants) a mark of death is given when the vascular bundles no longer function and meristems can no longer form new shoots. But this can only happen in places and then only one branch dies. If the vascular bundles of the whole plant are destroyed, the dying process is irreversible.

A potato is alive as long as it is not completely dried out or has not been cooked.

Dying and death in animals and humans

When a person dies, the time of death is recorded. "A person is dead when the functions of his brain, including the brain stem, have failed irreversibly." This definition of death is entered in the Swiss Transplantation Act. This means that a person is dead when their brain and brain stem no longer function.

Anyone who has held a wake or who has taken care of the dead knows that it is not that easy. Why else would a dead person have to be shaved before the funeral?

The body of the brain dead can regulate blood pressure and body temperature, pass urine, produce hormones, heal wounds and fight infections. Brain-dead children can grow and pregnant women can mature a fetus. In addition, the body can react to pain stimuli with a rise in blood pressure or hormone release.