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Can someone explain to me why if there is 26 chromosomes at prophase of mitosis there is still 26 chromosomes at telophase?
I thought the cell split so there would be half the amount?
I thought the cell split so there would be half the amount?
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#2
Wouldn't there be 46 chromosomes at telophase? The x shaped chromosome is pulled apart to form two string-like chromosomes at anaphase.
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(Original post by thrifty_reviser)
Wouldn't there be 46 chromosomes at telophase? The x shaped chromosome is pulled apart to form two string-like chromosomes at anaphase.
Wouldn't there be 46 chromosomes at telophase? The x shaped chromosome is pulled apart to form two string-like chromosomes at anaphase.
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#4
(Original post by ligays99999)
Can someone explain to me why if there is 26 chromosomes at prophase of mitosis there is still 26 chromosomes at telophase?
I thought the cell split so there would be half the amount?
Can someone explain to me why if there is 26 chromosomes at prophase of mitosis there is still 26 chromosomes at telophase?
I thought the cell split so there would be half the amount?
At the start of prophase, the DNA of each chromosome replicates to form two identical lengths of DNA joined in the middle by the centromere. Each of these lengths is called a "chromatid", but the "X" shape is still called "a chromosome". So here are now 46 chromatids, but still only 23 chromosomes.The total amount of DNA in the dividing cell is double that of the interphase cell.
During mitosis, the centromere disintegrates and one chromatid goes to one pole and the other goes to the opposite pole. The daughter cells now contain just one chromatid each. But remember - the dividing cell contained double the amount of DNA of the interphase chromosome. So now the daughter cells have the normal amount of DNA and the "chromatids" are now called "chromosomes" again.
Does that make sense?
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(Original post by OxFossil)
During interphase, each chromosome is just a single length of DNA. When you stain the cell in this state, you cannot see them because they are unwound so that transcription/replication enzymes can access the DNA. All you see is a hazy mess of DNA, spread out in the nucleus.
At the start phase of prophase, the DNA of each chromosome replicates to form two identical lengths of DNA joined in the middle by the centromere. Each of these lengths is called a "chromatid", but the "X" shape is still called "a chromosome". So here are now 46 chromatids, but still only 23 chromosomes.The total amount of DNA in the dividing cell is double that of the interphase cell.
During mitosis, the centromere disintegrates and one chromatid goes to one pole and the other goes to the opposite pole. The daughter cells now contain just one chromatid each.
But remember - the dividing cell contained double the amount of DNA of the interphase chromosome. So now the daughter cells have the normal amount of DNA and the "chromatids" are now called "chromosomes" again.
Does that make sense?
During interphase, each chromosome is just a single length of DNA. When you stain the cell in this state, you cannot see them because they are unwound so that transcription/replication enzymes can access the DNA. All you see is a hazy mess of DNA, spread out in the nucleus.
At the start phase of prophase, the DNA of each chromosome replicates to form two identical lengths of DNA joined in the middle by the centromere. Each of these lengths is called a "chromatid", but the "X" shape is still called "a chromosome". So here are now 46 chromatids, but still only 23 chromosomes.The total amount of DNA in the dividing cell is double that of the interphase cell.
During mitosis, the centromere disintegrates and one chromatid goes to one pole and the other goes to the opposite pole. The daughter cells now contain just one chromatid each.
But remember - the dividing cell contained double the amount of DNA of the interphase chromosome. So now the daughter cells have the normal amount of DNA and the "chromatids" are now called "chromosomes" again.
Does that make sense?
In simple terms then, 1 chromosome = 2 chromatids?
And how can there be 26 chromosomes at telophase but the mass of DNA is 30? (which is the answer)
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#7
(Original post by ligays99999)
Thanks for the reply.
In simple terms then, 1 chromosome = 2 chromatids?
And how can there be 26 chromosomes at telophase but the mass of DNA is 30? (which is the answer)
Thanks for the reply.
In simple terms then, 1 chromosome = 2 chromatids?
And how can there be 26 chromosomes at telophase but the mass of DNA is 30? (which is the answer)
Prophase is often said to begin only *after* the DNA of a chromosome has replicated (but before the chromatids have separated). I guess this is because you still cannot see the chromosomes until after the doubled chromosome condenses into the familiar "X" shape. So at prophase, you have already got your doubled mass of DNA - the same as at telophase.
And yes, 1 chromosome = 2 chromatids.
The tricky thing with this question is that you need to be clear about how your exam board defines the terms. A common definition is that a chromatid becomes a "daughter chromosome" once the chromatids have separated at anaphase, but I have also seen them still referred to as chromatids at this stage.
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(Original post by OxFossil)
Prophase is often said to begin only *after* the DNA of a chromosome has replicated (but before the chromatids have separated). I guess this is because you still cannot see the chromosomes until after the doubled chromosome condenses into the familiar "X" shape. So at prophase, you have already got your doubled mass of DNA - the same as at telophase.
And yes, 1 chromosome = 2 chromatids.
The tricky thing with this question is that you need to be clear about how your exam board defines the terms. A common definition is that a chromatid becomes a "daughter chromosome" once the chromatids have separated at anaphase, but I have also seen them still referred to as chromatids at this stage.
Prophase is often said to begin only *after* the DNA of a chromosome has replicated (but before the chromatids have separated). I guess this is because you still cannot see the chromosomes until after the doubled chromosome condenses into the familiar "X" shape. So at prophase, you have already got your doubled mass of DNA - the same as at telophase.
And yes, 1 chromosome = 2 chromatids.
The tricky thing with this question is that you need to be clear about how your exam board defines the terms. A common definition is that a chromatid becomes a "daughter chromosome" once the chromatids have separated at anaphase, but I have also seen them still referred to as chromatids at this stage.
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