Question

at what point does a cell or cells become a living thing

Answer 1

That's a quite interesting question. As we know, cells are the smallest unit of life. To say they are living things, they have to survive the questions for a living organism ( independet replication, metabolism, stimulus detection, etc.). On of the heaviest questions is the one for independent replication, which kicks out phages and viruses as living things. They need a host. So maybe independent replication (cell division) is the point it starts?

Answer 2

What structures and functions of a cell make it living?

Answer 3

Another interesting question. It's the whole thing. I would argue, that the cell division as process is most important, but then it starts with polymerase, primase etc. as "structures". The translation also is quite important, which makes the structure of the ribosomes as most important too.