Chromosomes/chromatids Watch

hollahollaholla
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Whats the relationship between a chromosome and a chromatid?
Whats the function of a chromosome?( I understand that DNA makes up genes and genes code for amino acids, so how do chromosomes come into this)
Does a chromosome code for more than one characteristic?
If so, how can you have half the number in a haploid cell without loosing coding for specific characteristics?
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Mutmit287
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(Original post by hollahollaholla)
Whats the relationship between a chromosome and a chromatid?
Whats the function of a chromosome?( I understand that DNA makes up genes and genes code for amino acids, so how do chromosomes come into this)
Does a chromosome code for more than one characteristic?
If so, how can you have half the number in a haploid cell without loosing coding for specific characteristics?
ok so a chromosome (only ever present during cell division) is made up of two chromatids, each chromatid has the same genes in the same location. so in essence a chromosome is the combined name for the two sister chromatids.
a chromosome is just a condensed form of DNA present during division (chromatin is present during the rest of the cell cycle, this is DNA bound to histone proteins), each chromosome contains specific genes. so the gene on the chromosome is a section of DNA which codes for amino acids. this means that yes a chromosome could code for the lipase enzyme as well as a protease enzyme, they code for many different things.
during mitosis and meiosis the chromatin condenses to form the chromosomes, they then replicate to form the two sister chromatids. the sister chromatids seperate, as they are identical this is how in haploid cells you still have ever single gene, because duplication occurs before division.

this is incredibly complex and my best advice is for you to go and get a good textbook or video and watch this.
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hollahollaholla
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(Original post by Natalierm2707)
ok so a chromosome (only ever present during cell division) is made up of two chromatids, each chromatid has the same genes in the same location. so in essence a chromosome is the combined name for the two sister chromatids.
a chromosome is just a condensed form of DNA present during division (chromatin is present during the rest of the cell cycle, this is DNA bound to histone proteins), each chromosome contains specific genes. so the gene on the chromosome is a section of DNA which codes for amino acids. this means that yes a chromosome could code for the lipase enzyme as well as a protease enzyme, they code for many different things.
during mitosis and meiosis the chromatin condenses to form the chromosomes, they then replicate to form the two sister chromatids. the sister chromatids seperate, as they are identical this is how in haploid cells you still have ever single gene, because duplication occurs before division.

this is incredibly complex and my best advice is for you to go and get a good textbook or video and watch this.

Thank you so much!!
(Sorry to be a pain) but would it be right to say that a chromosome that has gone through nuclear division will have 4 chromatids then?
And for the haploid cells, how can that be so if duplication only occurs once, but halving occurs twice? If the homologous pairs separate, and then their chromatids seperate, wont you be missing the chromoatids from the homologous pairs that went to the other cell?
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Dinasaurus
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(Original post by hollahollaholla)
Thank you so much!!
(Sorry to be a pain) but would it be right to say that a chromosome that has gone through nuclear division will have 4 chromatids then?
And for the haploid cells, how can that be so if duplication only occurs once, but halving occurs twice? If the homologous pairs separate, and then their chromatids seperate, wont you be missing the chromoatids from the homologous pairs that went to the other cell?
You begin with a diploid cell, during interphase its chromosomes will replicate so there are two of each. (So 2 pairs of chromsomes)

When they halve you have 1 pair
Then they halve again so you have 1 chromosome per gamete.
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Mutmit287
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(Original post by hollahollaholla)
Thank you so much!!
(Sorry to be a pain) but would it be right to say that a chromosome that has gone through nuclear division will have 4 chromatids then?
And for the haploid cells, how can that be so if duplication only occurs once, but halving occurs twice? If the homologous pairs separate, and then their chromatids seperate, wont you be missing the chromoatids from the homologous pairs that went to the other cell?
no no, heres why... (sorry if this is to complex) but I will use meiosis as an example.
meiosis:
1) stage 1 of meiosis, so the cell enters the division phase and the chromosomes condense and duplicate to form 2 sister chromatids for every chromosome (so you have 2 of each chromosome in every cell, that means you will have 2 seperate pairs of sister chromatids (these are your two homologous chromosomes)).
2) still in stage 1 the spindle fibres seperate homologous chromsomes, so you get 1 chromosome from mum, and one from dad. these are taken to seperate cells (so 2 sister chromatids are in each cell).
3) stage 2 of meiosis occurs and the spindles fibres now seperate the sister chromatids (imagine like they go around hugging but now they have been forced apart) and they are taken to seperate cells.
this means that in each of the 4 haploid cells you will have 1 chromatid, this is haploid.

for mitosis the chromosomes seperate so 1 chromatid ends up in each of the daughter cells, as you have 2 of each chromosome (one from mum one from dad) in every cell that means you will have 2 chromatids of each numbered chromosome in every cell, this is diploid.

check out this image of meiosis to clear things up, remember there are 2 stages of meiois and division occurs twice, once in each of the stages.
http://ejdio.weebly.com/uploads/3/0/...96282_orig.jpg
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SANTR
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(Original post by hollahollaholla)
Whats the relationship between a chromosome and a chromatid?
Whats the function of a chromosome?( I understand that DNA makes up genes and genes code for amino acids, so how do chromosomes come into this)
Does a chromosome code for more than one characteristic?
If so, how can you have half the number in a haploid cell without loosing coding for specific characteristics?
DNA in eukaryotic cells (Cells which have a nucleus and distinct membrane bound organelles) is usually appears as thinly dispersed chromatin. It isn't visible the start of cell division. At the start of cell division the long thread like DNA appears short and condensed. The DNA has been tightly coiled into an X like structure. The long DNA strand has has been wrapped around proteins molecules called Histones.
During cell division, the DNA is replicated, so that there are two identical 'chromosomes'. The sister chromatids are identical, they are just copies of eachother.
A chromosome doesn't code for anything, it the gene which codes for proteins. A gene is a section of DNA, it is a section of the long stranded DNA, it consists of a particular sequence of bases. Codons, which are 3 bases, they code for one amino acid. A chromosome is just a long strand of DNA, it has 'many' genes i.e. section of DNA, sections of base sequences which code for polypeptides. Polypeptides such as enzymes, which in turn control the development of an organism and the reactions which take place.
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