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chromosome - (Mar/10/2007 )

I just learned about 'chromosome' recently, so I had some questions
As you can see in the picture, let's see the normal chromosome first, I really don't know what is chromatid in that normal chromosome, does it have two chromatids? the upper one and the lower one? Then let's see the left, replicating chromosome. My teacher said the chromosome replicated and then became two chromosomeS, for an example, 46 chromomes in the nuclear, then they replicate, so now become 92? but in the picture, i think it is still one, you need to think it is as a whole though it consists of two? Are there four chromatids there? upper two and lower two? In the example i gave, so though they replicate, still 46? BTW, how the chromosome replicates? Is that like this ')(' , two put together, so ')' is a chromosome, '(' is another chromosome Or two cross to each other, like this 'X', so '\' is a chromosome, '/' is another chromosome?
Truly hope you can help me out, I am so confused.


hi MIA6, are a high school student?!
anyway, each chromosome has one chromatid in its single form (not replicated), and after replication it's the same chromosome but with two chromatids now..
somatic cells for example have 46 chromosomes (single form) , but to start a mitotic division these chromosomes have to become )( so the new divided cells can have the same number of chromosomes (46)..
hope this help



it would really help to look into a basic biology school book - that can answer all of your question!