Beginning of the cell

[biology_06er]

Hi there

I was just wondeirng if someone can make sure I have this right......

so the other day we learned about the "beginning of the cell" and about stem cells etc..so is this right..

we begin as a zygote (egg+sperm)=a "cell"--then from there it divides and then again making a 7-8 cell blastocyst (i think thats what its called) and then from there each of those 7-8 cells differentiate into a specific region-eg cell 1 liver cells cell 2 heart cells etc etc---I doubt this is right cos we have more then 7-8 types of cell..and then what about stem cells?, they form terminal cells like muscle and neurons aye sooo where do these stem cells arrive from...if this is ALL wrong just say so and I'll go read the textbook all again otherwise just give me the gist of what I have said wrong

Thanks
biology_06er

[imreally]

"then from there each of those 7-8 cells differentiate into a specific region"
I guess you have a misunderstanding here.
I recommend you to check a developmental biology textbook.

[biology_06er]

oook..so I read again and again and am soo confused..and i refuse to go on to lecture 2 stuff without getting this stuff sussed..

I don't understand (and I'm talking about any eukaryote)-we begin as a zygote right?..and then form there on in we keep dividing and dividing till what?...we get to a eight cell stage? (or does it keep on dividing till 70 or so cell stage-as I read that somewhere)...and then its called a blastocyst right?..and those cells within are the basis of all the cells we will form..eg: heart, muscle, neurons, liver etc etc...and those 70 or so cells are called stem cells right?..so now at this point these the majority of these cells are designated a particular path eg to the heart, liver etc etc..and this all occurs by mitosis???...I have looked on line to find good animations that will make me understand but have failed...I know I'm probably asking really stupid questions but I just wanna know so I can carry on the rest of the year in peace... ...but then my textbook goes on to talk about symmetric/asymmetics cell division..is this just basically talking about eg a heart stem cell forming other heart cell stems (to keep that stem cell population maintained) and it also forms a restrictied-potential stem cell which goes on to form the "real" heart cell-the termianlly differentiated stem cell--but then why even bother to make another heart stem cell-cos isn't it correct to say once some of the heart cells die then they cant be formed again?...eeeek is this right?...

please help me...
Thanks
biology_06er

[biology_06er]

anyone????????????