Wednesday, August 21, 2013

Describe the process of Transcription & Translation in Eukaryotic Cells

During the process of transcription, transcription factors attach first to certain spots in the DNA. In eukaryotes, this spot usually the TATA box, segment of DNA with the code TATA. Then RNA polymerase comes down, pries apart the two DNA strands and binds as well. The complex formed by the DNA and the transcription factors are called the transcription initiation complex. Once the DNA has been transcribed, the resultant mRNA strand is called the primary transcript. Since eukaryotes have a nucleus, transcription is seperated from translation both temporally and spatially. Post-transcriptional modifications also must occur to protect the transcript from hydrolytic enzymes and help facilitate transport. A 5' cap is added to the 5' end and a long poly-A tail (long sequence of adenine bases) also added to the 3' end. Finally, introns are removed by a spliceosome complex. Introns are long uncoding sequences found between sequence that actually are translated into protein (exons). Two splieceosomes come in on either end of each intron and remove them. Then the mRNA exits the nucleus to be translated in the cyotosol.




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Translation, this is where the proteins are made using the codes of amino acids, the codes for these amino acids are found in the nucleus and needs to be translated into the ribosomes where proteins is made. A messenger called RNA is able to carry this information and transfers it to the ribosome. The RNA molecule then 'sticks' to the ribosome which then allows for all the amino acids which connect with the certain combinations of nucleotides to make proteings- which is just a chain of amino acids. RNA is simply one strand of the DNA which holds combinations of nucleotides. 

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