https://padlet.com/shamsalzaiide/emecgpox85kkzaxa -Transcription -RNA splicing -RNA processing en-us 2021-03-09 09:05:34 UTC 2026-02-10 05:53:27 UTC hello@padlet.com https://padlet.net/icons/png/1f9ec.png https://padlet.com/shamsalzaiide/emecgpox85kkzaxa/wish/1286532398 Translation is the process of turning mRNA into a protein. The order of mRNA will be read in the ribosome in groups of three(also known as a codon). The genetic code is redundant, meaning that certain amino acids are specific by more than one codon.]]> 2021-03-09 09:14:58 UTC https://padlet.com/shamsalzaiide/emecgpox85kkzaxa/wish/1286532398 https://padlet.com/shamsalzaiide/emecgpox85kkzaxa/wish/1286543957 Transcription consists of three stages: initiation, elongation, and termination. Initiation begins when an enzyme, RNA polymerase, recognizes and binds to DNA at the promoter region. The promoter “tells” RNA polymerase where to begin transcription and which of the two strands to transcribe. A collection of proteins called transcription factors recognize a key area within the promoter, the TATA box (because of its many repeating thymine and adenine nucleotides), and mediate the binding of RNA polymerase to the DNA. The completed assembly of transcription factors and RNA polymerase bound to the promoter is called a transcription initiation complex. Once RNA polymerase is attached to the promoter, DNA transcription of the DNA template begins. Elongation of the strand continues as RNA polymerase adds nucleotides to the 3′ end of a growing chain. RNA polymerase pries the two strands of DNA apart and attaches RNA nucleotides according to the base pairing rules: C with G and A with U. The stretch of DNA that is transcribed into an mRNA molecule is called a transcription unit. Each unit consists of triplets of bases called codons (for example, AAU, CGA) that code for specific amino acids. A single gene can be transcribed into mRNA simultaneously by several molecules of RNA polymerase following each other in a caravan fashion. Like DNA polymerases, RNA polymerase has mechanisms for proofreading during transcription. Because mRNA is usually short-lived, any errors in mRNA are not as potentially harmful as errors in the DNA sequence. Termination is the final stage in transcription. Elongation continues for a short distance after the RNA polymerase transcribes the termination sequence (AAUAAA). At this point, mRNA is cut free from the DNA template. ]]> 2021-03-09 09:18:50 UTC https://padlet.com/shamsalzaiide/emecgpox85kkzaxa/wish/1286543957 https://padlet.com/shamsalzaiide/emecgpox85kkzaxa/wish/1286559524 Alternative RNA splicing is a process through which different RNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons, and which are treated as introns- exons are expressed sequences, while introns are intervening, noncoding sequences. Regulatory proteins specific to a cell type control intron-exon choices by binfing to regulatory sequences within the primary transcript. Alternative splicing takes place during RNA processing.]]> 2021-03-09 09:23:56 UTC https://padlet.com/shamsalzaiide/emecgpox85kkzaxa/wish/1286559524 https://padlet.com/shamsalzaiide/emecgpox85kkzaxa/wish/1286559582 Before the newly formed pre-RNA strand is shipped out of the nucleus to the ribosome in the cytoplasm, it is altered or processed by a series of enzymes. Here are the details. A 5′ cap consisting of a modified guanine nucleotide is added to the 5′ end. This cap helps the RNA strand bind to the ribosome in the cytoplasm during translation. A poly (A) tail, consisting of a string of adenine nucleotides, is added to the 3′ end. This tail protects the RNA strand from degradation by hydrolytic enzymes, and facilitates the release of mRNA from the nucleus into the cytoplasm. Noncoding regions of the mRNA called introns or intervening sequences are removed or spliced out by snRNPs, small nuclear ribonucleoproteins, within spliceosomes. This removal allows only exons, which are expressed sequences, to leave the nucleus. As a result of this processing, the mRNA that leaves the nucleus is a great deal shorter than the original transcription unit. If the average length of a human DNA molecule that is transcribed is about 27,000 nucleotides long, the primary transcript is also the same length. However, an average-size protein of 200 amino acids requires only 1,200 nucleotides of RNA to code for it. Therefore, out of the original 27,000 nucleotides, 15,800 noncoding nucleotides must be removed or spliced out during RNA processing.

]]> 2021-03-09 09:23:57 UTC https://padlet.com/shamsalzaiide/emecgpox85kkzaxa/wish/1286559582 shamsalzaiide https://padlet.com/shamsalzaiide/emecgpox85kkzaxa/wish/1286580582 Translation involves three phases: initiation, elongation, and termination. 
Before the newly formed pre-RNA strand is shipped out of the nucleus to the ribosome in the cytoplasm, it is altered or processed by a series of enzymes. A 5′ cap consisting of a modified guanine nucleotide is added to the 5′ end. This cap helps the RNA strand bind to the ribosome in the cytoplasm during translation. A poly (A) tail, consisting of a string of adenine nucleotides, is added to the 3′ end. This tail protects the RNA strand from degradation by hydrolytic enzymes, and facilitates the release of mRNA from the nucleus into the cytoplasm. Noncoding regions of the mRNA called introns or intervening sequences are removed or spliced out by snRNPs, small nuclear ribonucleoproteins, within spliceosomes. This removal allows only exons, which are expressed sequences, to leave the nucleus. As a result of this processing, the mRNA that leaves the nucleus is a great deal shorter than the original transcription unit. If the average length of a human DNA molecule that is transcribed is about 27,000 nucleotides long, the primary transcript is also the same length. However, an average-size protein of 200 amino acids requires only 1,200 nucleotides of RNA to code for it. Therefore, out of the original 27,000 nucleotides, 15,800 noncoding nucleotides must be removed or spliced out during RNA processing.]]> 2021-03-09 09:30:31 UTC https://padlet.com/shamsalzaiide/emecgpox85kkzaxa/wish/1286580582