help with this question please

[Demps]

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I guess I used to know it but........with time approaching on the D-Day, I don't know if I am confusing the crap out of myself... ahhh whatever... I forgot this concept of chromosome number vs. chromatid number

So its Destroyer bio #270

If an organism has a diploid number of 18, how many chromatids are visible at the end of mitotic prophase?

Answer is 36.


Not limited to this question, if anyone could simply just clarify how to do chromosome/chromatid # at a given phase. I will appreciate it. Thanks for the help guys!

 

[Hope30]

I guess I used to know it but........with time approaching on the D-Day, I don't know if I am confusing the crap out of myself... ahhh whatever... I forgot this concept of chromosome number vs. chromatid number

So its Destroyer bio #270

If an organism has a diploid number of 18, how many chromatids are visible at the end of mitotic prophase?

Answer is 36.


Not limited to this question, if anyone could simply just clarify how to do chromosome/chromatid # at a given phase. I will appreciate it. Thanks for the help guys!

I am not sure whether I am good enough, but I will try my best. Some of the things I am pointing out you probably already know.
2n = diploid
n = haploid
A chromosome consists of two chromatids. Therefore, a chromosome of 18 (diploid) has 36 chromatids (twice as much).

Mitosis always states 2n -- like repairing your skin cells (unlike reproducing)
Meiosis--- Human as an example
Prophase I - 2n (chromosome but in tetrad) Ex: 46
Metaphase I - 2n (still a tetrad) Ex: 46
Anaphase I - n (now, your tetrad splitted to opposite pole leaving you with haploid # of chromosome) Ex: 23
Telophase I - 23 chromosomes
Prophase II - n (23 chromosomes)
Metaphase II - n (23 chromosomes)
Anaphase II - n (23 chromosomes have 46 chromatids. The 46 chromatids cutted in half to yield 23 chromatids, but n does not change. However, after it splits to opposite pole, you consider each individual chromatid as chromosome)
Telophase II - n (23 chromosomes)

If you think it is right or anyone here can clarify my response, it would be great. I have a little trouble myself when I type this one up.

 

[Demps]

wouldnt it be 4n by the prophase because chromosomes duplicated

 

[Demps]

can I just think chromosomes and chromatids are the same thing in terms of # in these type of problems?

 

[Hope30]

can I just think chromosomes and chromatids are the same thing in terms of # in these type of problems?

Just remember that 2n --> n. 4n does not exist. Depend on the step you are on. A chromosome always has two chromatids. Only after anaphase, then you can consider a chromatid as a chromosome.

You have 23 chromosomes from mother and 23 chromosomes from father, giving you 46 chromosomes. Each chromosome from mother is paired with each chromosome from father giving you 46 homologous (one from dad and one from mom--identical genes in the same loci) chromosomes. I am sure you heard of people refer to 23 pairs of homologous chromosomes instead of 46 homologous chromosomes. In Prophase I, your 23 pairs of homologous chromosomes paired again to make tetrads. Remember: no 4n. For meiosis, you always start with 2n and end with n. Which step did it form n? Anaphase I. After that, all are n. All are 23 homologous chromosomes now (no 23 pairs anymore). Until you get down to Anaphase II, your 23 homologous chromosomes (23 chromosomes = 46 chomatids) splitted to opposite pole to make 23 chromatids 👎. Eventually, they start another process of meiosis division. Those 23 chromatids synthesize and replicate to make another set of chromatids. They now have 23 chromosomes.

Do get confused.

 

[Hope30]

Just remember that 2n --> n. 4n does not exist. Depend on the step you are on. A chromosome always has two chromatids. Only after anaphase, then you can consider a chromatid as a chromosome.

You have 23 chromosomes from mother and 23 chromosomes from father, giving you 46 chromosomes. Each chromosome from mother is paired with each chromosome from father giving you 46 homologous (one from dad and one from mom--identical genes in the same loci) chromosomes. I am sure you heard of people refer to 23 pairs of homologous chromosomes instead of 46 homologous chromosomes. In Prophase I, your 23 pairs of homologous chromosomes paired again to make tetrads. Remember: no 4n. For meiosis, you always start with 2n and end with n. Which step did it form n? Anaphase I. After that, all are n. All are 23 homologous chromosomes now (no 23 pairs anymore). Until you get down to Anaphase II, your 23 homologous chromosomes (23 chromosomes = 46 chomatids) splitted to opposite pole to make 23 chromatids 👎. Eventually, they start another process of meiosis division. Those 23 chromatids synthesize and replicate to make another set of chromatids. They now have 23 chromosomes.

Do get confused.

I mean Dont get confused 🙂

 

[smthngintheway]

Nvm.

 

[smthngintheway]

Actually ****, you're talking about chromatids........... Uhm....

 

[Demps]

Thanks Hope30! I will just keep it simple. I think I over-analyzed the question.

 

[Vsno123]

I guess I used to know it but........with time approaching on the D-Day, I don't know if I am confusing the crap out of myself... ahhh whatever... I forgot this concept of chromosome number vs. chromatid number

So its Destroyer bio #270

If an organism has a diploid number of 18, how many chromatids are visible at the end of mitotic prophase?

Answer is 36.


Not limited to this question, if anyone could simply just clarify how to do chromosome/chromatid # at a given phase. I will appreciate it. Thanks for the help guys!

http://faculty.clintoncc.suny.edu/f...io 101/bio 101 laboratory/mitosis/mitosis.htm 🙂