Transcription happens in the NUCLEUS
This is where the useless confusing parts parts of the mRNA are cut out so we are left with the parts that code for amino acids.
DNA
In the nucleus the bases of DNA are copied onto a strand of RNA called mRNA (messenger RNA). This is done by RNA polymerase (an enzyme).
These bases are copied onto the mRNA
This transparent shape is RNA polymerase, and it is unzipping the DNA and matching the bases, copying them onto a strand of mRNA
The bases it uses are available, just floating around in the nucleus.
A T C G C G T A T C G A T C G C G T
mRNA
T A G C G C A T A G C T A G C G C A
A U C G C G U A U C G A U C G C G U
There is a small difference in the mRNA. RNA does not have the base Thymine so it is replaced with Uracil (U)
You might be wondering where RNA polymerase begins copying from. The polymerase detects a section of the DNA called the promoter and begins from there.
Protein Production
Transcription & Translation
Promoter
RNA coding sequence
As we can see, there is also a terminator.
Terminator
Not that terminator!
The terminator is the area of DNA that tells the polymerase to stop copying.
Now we have our beautiful mRNA strand
BUT before we can go onto the next stage of protein production, the mRNA has to be spliced
It's like editing a video and taking out all the parts in between that you don't want.
So then what splices it and how does this thing know which parts to splice?
These snurps combine with other proteins to make spliceosomes which do the actual splicing
Something called a snurp knows which parts to splice out. Introns (base sequences that don't code for anything) are spliced out and exons (sequences with the code) are joined together
This means more efficient protein production because the useless bits which don't code for amino acids are taken out, and only the useful parts are left behind.
After the splicing, transcription is done and the mRNA strand moves out of the nucleus and into an organelle called a ribosome
And after all this, you have your protein! The body really is amazing
Translation can be divided into THREE stages. The first, initiation consists of theses three steps:
The next stage is elongation
This is where translation begins.
FIRST: mRNA attaches to a ribosome
SECOND: The ribosome reads the codons (sequence of three bases) on the mRNA
THIRD: tRNA with complementary codons called anticodons come and match up to the mRNA. The tRNA has an amino acid attached
SO... codons on the mRNA match up to a specific tRNA which is attached to an amino acid
Therefore
mRNA tRNA Amino acids
Codons
Elongation continues until the final stage, termination. Like before, this is where it stops.
It is an amazingly complex and complicated structure and it is just one of the countless proteins in your body
It is the same as initiation with a difference, a second tRNA brings a second anticodon and a second amino acid.
The first amino acid attaches to the second, creating a polypeptide.
The first tRNA deattaches and leave the ribosome, leaving behind its amino acid and it goes in search of another ribosome with mRNA attached. As the polypeptide gets longer, it folds, taking the shape of the protein it will become
During termination, the polypeptide (which is now a long chain of amino acids) is released when a stop codon is reached.
tRNA attached to amino acid
Here in this diagram we can see these things
Polypeptide (protein)
mRNA attached to ribosome
After the polypeptide is released it forms a protein and leaves the ribosome.
Complementary pairing
The mRNA has served it function and leaves the ribosome, and it is replaced by another mRNA strand.