well, the life does not start. It’s there for several bilions of years since it originated, because even the singular cell is alive (see unicellular organisms). So, the egg is still alive and stays alive while dividing. If it wasn’t alive, it would not grow 😉

that’s the point. Life, as it is defined by modern biology, likely developed only once some 3-4 billion years ago. Thereafter, living cells did only arise from other living cells. But what distinguishes us from a bacterium, which is also a living organism but consists only of one single cell is that our genome. It possesses the all the information to built up a bunch of differentiated cells, making different tissues and organs. And that is what happens in a developing fetus. It’s the usage of different genes at different stages of development, giving each cell subset a defined identity, ultimately together bulding up a mature human being, which will be viable on its own.
Nice to see that someone from a different background is interested in things like this. I think this is it what makes biology so fascinating, the ability of a single cell to perform complex processes and of a whole lot of differentiated cells to act together building up organisms.

Hi josalsam

How life began is not a question science has been able to answer. There are different ideas on how it may have originated, in scientific terms these are referred to as hypotheses. However all that can be scientifically stated is that life exists and new life always comes from a pre-existing life. This if you like is the scientific fact of life. 🙂 There is no evidence that a new life originates from any other source.

Now in human terms a new living organism begins when a male sperm and a female egg interact. What we commonly refer to as conception. The biological information in the sperm joins up with the biological information in the female egg setting off an incredibly complex process. This egg cell begins to divide and multiply in a very controlled way that eventually results in the development and birth of a new child.

During this process of division different types of cells emerge that form the different organs and tissues in the growing foetus.( i.e.a skin cell is different from a kidney cell) In humans there are some 200 or so different cell types, all having originated from that initial division.

Clearly some kind of a blueprint or body plan controls this whole process. Where this blueprint resides or how it originated is unknown to science.

We do know that a lot of the information that is needed is contained in the genome of the cell. This genome resides in the nucleus of each cell. It is clear that other information exists outside the nucleus of the cell.

It is also clear that some form of communication exists between cells. This becomes self evident when we think of the development process. Not only do different cell types have to be created but also each type of cell has to find it’s way to different parts of the growing foetus as the build takes place.

Then there is also the question of timing of all of this activity. Different things happen at different stages in the growing foetus.

The study of this process is the subject of a particular branch in biology known as developmental biology.

Whether you have a religion or not is a matter of belief. If the evidence from science supports a particular belief then that belief becomes a fact and therefore no longer a belief. 🙂

Hope this gets you started.

Really? Which one?

Mitochondria have their own genome and reside outside the nucleus.

In plants Chloroplasts too have their own genome

OK, it sounded like something outside of the cell…

Are there developmental genes encoded in the mitocondrial DNA? I was under the impression that only metabolic genes (housekeeping genes) were on the mito DNA?

I am not too familiar with mtDNA but as I understand matters it does play a role in development as well.

Since mr. josalsam has mentioned religion in his question with "life" I presume he is talking about how cells go from clumps of machines to the point of obtaining consciousness, rather than the definition of "life" for just one cell, is that right mr. josalsam.

Since you are an engineer I hope you can appreciate the fact of information processing, receiving and distribution leading a sequence of binaries involving organization and management from center point to the periphery. Thats technically a very superficial idea of how consciousness began.

Biotechnology is not limited to medical/health applications (unlike Biomedical Engineering, which includes much biotechnology). Although not normally thought of as biotechnology, agriculture
Agriculture
Agriculture is the production of food and goods through farming. Agriculture was the key development that led to the rise of human civilization, with the husbandry of domesticated animals and plants creating food surpluses that enabled the development of more densely populated and stratified…

clearly fits the broad definition of "using a biotechnological system to make products

what does that have to do with the question? 🙄

For someone that belief in God like me, it shows that the God is EXIST. There are so many things happened around us that can’t be explain.

i have no knowledge about the mtDNA.can anyone tell me about the mtdna.

I believe what you are referring to as ‘life’ is a perception of the world around you, or a consciousness. It is hard to say that life ‘begins’ at any set point in fetal development, as stated above, all the cells which contribute to the fetus and resulting person spawned from an original set of living cells, as the cells multiply and go from stage to stage they are not merely pieces of flesh or a jumble of organic matter as some might assume, they are a defined as human from the beginning and develop slowly into something morphologically recognizable to the rest of us as a person. there is no point along the process where the fetus is endowed with life, it forms overtime, and develops a consciousness over time, to be technical, though, it was living from the beginning of the process.

I’m not sure if this is going to help you very much, it helps if you see life as a chemical process rather than a metaphysical happenstance, the latter being impossible to describe.

in endosymbiotic theory it is hypothesized mitochondria did not evolve inside eukaryotic cells but were consumed and incorporated into the cellular mechanics of the eukaryote, this is why they have their own DNA, because they were once individual organisms separate from other cells.

Refering back to the original post – the retired engineer said he didn’t believe in god but "believed" in evolution. Even scientists do not "believe " in evolution – as with all scientific theories, evolution is accepted as the best explanation for a phenomenon or condition and carries the caveat that future data may one day drive a competing theory.
As belief refers largely to acceptance without data – effectively on faith – the engineer has arguable chosen another god about which he knows little.

However, on this occasion, the phenomenon bears the same name as the body of theory. In short, evolution is the fact to be explained, and evolutionary theory, consisting of various theories of evolution, is the explanatory framework within which models are constructed by scientists.