Question: How many chromosomes? Confused!

[sangria1986]

So I'm confused-how many chromosomes do somatic cells have exactly? I read that we have 46 chromosomes. This is fine, but in somatic cells prior to mitosis (ie G1 phase only) does that mean the cell has 46 chromosomes or 46 homologous chromosomes?

From what I understand, after synthesis (S1 phase) DNA replication occurs and the cell replicates its chromosomes (correct?). So does it mean that a cell has 46 homologous chromosomes after S1 or does it have 2X 46 HOMOLOGOUS chromosomes after S1?

Also, in S1, DNA replication occurs-is this what contributes to the creation of homologues? OR is DNA replication separate from the formation of Homologues? If so, what is DNA replication for?

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[RogueUnicorn]

you're overthinking and slightly misinformed.

replication doesn't give you homologous pairs, fertilization does. all somatic cells have 23 homologous pairs or 46 total chromosomes. that being said, replication will double the genetic material of the 46 chromosomes by creating identical sister chromatids. until you split the sister chromatids the two are considered parts of one chromosome.

 

[sangria1986]

you're overthinking and slightly misinformed.

replication doesn't give you homologous pairs, fertilization does. all somatic cells have 23 homologous pairs or 46 total chromosomes. that being said, replication will double the genetic material of the 46 chromosomes by creating identical sister chromatids. until you split the sister chromatids the two are considered parts of one chromosome.

So during si when DNA replication occurs a total of 92 chromosomes are in the cell and when mitosis takes place the two new cells have 46 total?

 

[PharMed2016]

So during si when DNA replication occurs a total of 92 chromosomes are in the cell and when mitosis takes place the two new cells have 46 total?

You got it.

 

[RogueUnicorn]

So during si when DNA replication occurs a total of 92 chromosomes are in the cell and when mitosis takes place the two new cells have 46 total?

you wouldn't really say they are 92 chromosomes since the chromatids are attached. but i suppose it isn't completely incorrect to say that either... the accounting can get a bit fuzzy.


also, i'm still totally right about bernoulli's principle

 

[MCAT guy]

you wouldn't really say they are 92 chromosomes since the chromatids are attached. but i suppose it isn't completely incorrect to say that either... the accounting can get a bit fuzzy.


also, i'm still totally right about bernoulli's principle

Bleargh is right. It is actually incorrect to say there are 92 chromosomes. There are 46 chromosomes that have duplicated portions.

I actually had a question that marked me wrong for making this semantic error (saying there were 92).

 

[sangria1986]

you wouldn't really say they are 92 chromosomes since the chromatids are attached. but i suppose it isn't completely incorrect to say that either... the accounting can get a bit fuzzy.


also, i'm still totally right about bernoulli's principle

lol do you really still want to argue about this? I've looked it up and you're wrong....sorry

 

[sangria1986]

Bleargh is right. It is actually incorrect to say there are 92 chromosomes. There are 46 chromosomes that have duplicated portions.

I actually had a question that marked me wrong for making this semantic error (saying there were 92).

Thanks folks, yea I figured it out...I did get confused, mainly because I didnt know if the homologue chromosome is attached (its not) or if it is separate (it is). After I figured that out I was good.