Danyaaaaaal
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I have a couple of questions about this topic because I really cant get my head around it :P

In transcription, is mRNA copied or is the gene halved to create mRNA, my textbook says the latter so im quite confused
Where do the carrier molecules (and amino acids on them) come from?
What happens to the mRNA after the stages are complete?

Thanks in advance
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Bookworm-278
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Hi,

I'm taking A Level biology and I'm not sure how much of this is useful at GCSE, but my textbook says this:
- Transcription uses the DNA as a template to make pre-mRNA, which is then spliced to produce mRNA. Splicing is the process of removing parts of the DNA that don't code for proteins (these are called introns).This basically means that mRNA is a copy of the DNA's base sequence.
- I think the carrier proteins you are referring to are called tRNA (transfer RNA) molecules at A Level. These are specific to an amino acid and carry the amino acids in protein synthesis. tRNA molecules are another type of RNA and are made in the nucleus. I think my A Level tutor said that the amino acids they carry are collected from an amino acid pool in the cell.
- Once protein synthesis is complete, mRNA, the ribosome and tRNA molecule involved will all separate from the protein chain. I'm not completely certain what would happen to the mRNA next, but I would guess that it is left free in the cell's cytoplasm. There are organelles in the cytoplasm called lysosomes, which basically act as the 'dustbin' of the cell, so they might ingest the mRNA and break it down into its useful components to be re-used in some way, but this is only a guess.

Hope this helps .
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Danyaaaaaal
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(Original post by Bookworm-278)
Hi,

I'm taking A Level biology and I'm not sure how much of this is useful at GCSE, but my textbook says this:
- Transcription uses the DNA as a template to make pre-mRNA, which is then spliced to produce mRNA. Splicing is the process of removing parts of the DNA that don't code for proteins (these are called introns).This basically means that mRNA is a copy of the DNA's base sequence.
- I think the carrier proteins you are referring to are called tRNA (transfer RNA) molecules at A Level. These are specific to an amino acid and carry the amino acids in protein synthesis. tRNA molecules are another type of RNA and are made in the nucleus. I think my A Level tutor said that the amino acids they carry are collected from an amino acid pool in the cell.
- Once protein synthesis is complete, mRNA, the ribosome and tRNA molecule involved will all separate from the protein chain. I'm not completely certain what would happen to the mRNA next, but I would guess that it is left free in the cell's cytoplasm. There are organelles in the cytoplasm called lysosomes, which basically act as the 'dustbin' of the cell, so they might ingest the mRNA and break it down into its useful components to be re-used in some way, but this is only a guess.

Hope this helps .
I think you may have confused me a bit more Thanks nonetheless
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