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    • Thread Starter

    I am extremely stuck on these question

    and explain why glycine has two codons , GGG AND GGU?

    thank you so much in advance!
    • Community Assistant

    Community Assistant
    Let's see what I can remember from my A-Levels...

    I can't see the photo but here is how we remembered the stages:

    Prophase is the one where they're bunched up
    Metaphase is where they're in a line in the middle
    Anaphase is where they pull away from each other
    Telophase is when they separate

    As for the 2 codons, isn't it because a codon is the set of 3 letters? 1 codon is GGG and the other is GGU

    I can't see the image either. During prophase they nucleus membrane will dissolve and the DNA will be tighly wound to form chromosomes. During metaphase the chromosomes align across the middle of the cell and the spindle fibres form and attach to the chromosomes. During anaphase the spindle fibres shorten pulling the chromatids to opposite ends of the cell (the chromosome is pulled apart into two single pieces called chromatids). During telophase the chromatids unravel into loose strands of DNA, a nucleus membrane forms around the DNA and there will be a nucleus at either pole of the cell. The cell cytoplasm may begin to pinch as cytokenisis begins.

    I'm sorry but I don't know the answer to your other questions as I haven't covered that yet, still at GCSE level.

    (Original post by saffsmith97)
    I am extremely stuck on these questions, would anybody be able to help me with the answer and help me understand it?

    what stage of mitosis is cell A?
    what is the evidence that cell B is in anaphase>?

    Explain the following statement in terms of your knowledge of the structure and
    function of DNA: The DNA which codes for the human protein, -globin, has 850
    base pairs but there are only 141 amino acids in this protein.

    and explain why glycine has two codons , GGG AND GGU?

    thank you so much in advance!
    So coding-DNA is degenerate, which means that each amino acid can be coded for by more than 1 codon. The reason for this is relatively simple, codons contain 3 "letters" out of a selection of 4, which means there is 4x4x4 combinations of 3 letters = 64 combinations, however there are only 20 amino acids, which means for every 1 amino acid, there are 3 codons (in reality it's not as simple as 3 codons per amino acid, some are coded for by more than 3, some by less than 3). So that explains your final 2 questions, there will be more than one codon coding for the same amino acid, hence why there are more base pairs than amino acids, and it also explains the glycine Q (although glycine has 4 codons not 2 ... lol)
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