How does a single cell organism know what to do?

Question

How does a single celled organism or anything smaller than that know how to behave? Doesn't it require a brain or thought process to make decisions about ones environment?

If you answer that its instinct, where does that come from? What teaches it instinct?

Answer 1

I'm not sure that there are any cases of single-celled organisms exhibiting any sort of "behavior". Even the ones with motion from the flagella don't have behavior as such.

All the growth, movements and actions are dictated by signalling mechanisms that take place usually with protein-protein interactions or protein-RNA, protein-DNa interactions. These interactions are dictated strictly be reaction to environment, certain chemicals, or extracellular proteins, viruses, etc come into contact with the cell and trigger these signaling cascades which cause the reaction of the single-celled organism.

Answer 2

This question is kinda retarded. You can't claim we evolved AND were created. You believe one or the other. God isn't a single cell organism. God is the creator of what you are lucky enough to live on, this planet, you are breathing the air God created. We didn't evolve from a single cell organism.

Answer 3

Single celled organisms dont make decisions. They behave as their DNA and its environment determines.

Cause-effect. They grow until a certain size, then they divide itself in two single cells, for example. It is written on their DNA.

Another example, they stay if temperature is perfect and doesnt change, if it rises they move to a colder place. It is written on their DNA.

DNA is not related to instinct. DNA is related to automated physical or chemical reactions, instinct is related to decisions, only brains can make decisions.

Answer 4

The brain of a single celled organism is its DNA. The DNA tells the cell what to do and how to do it. It causes the right proteins to develop and the right amino acids to be produced.