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Genetic code Central Dogma: DNA - RNA - protein. DNA: resides in the nucleus. It codes information in genes. Transcription: Inside the nucleus, the DNA genes get transcribed into RNA (messenger RNAs or mRNAs). Alpha factors: these are how phages control transcription inside their bacterial host. By making different factors at different times, the phage can control the correct transcription sequence of early, middle, and late genes. Sometimes you come across the term co-repressors and co-inducers. When a co-repressor binds to its target, the resulting complex becomes either an active repressor or an inactive inducer. When a co-inducer binds to its target, the resulting complex becomes either an active inducer or an inactive repressor. The mRNA gets dragged along also - the codon that was in the A site is now in the P site after translocation. The A site is now empty and ready for the binding of a new aminoacyl-tRNA to a new codon. The initiation complex forms around the initiation codon (AUG which is just down stream of the Shine-Dalgarno sequence. The Shine-Dalgarno sequence is the "promoter" equivalent of translation for prokaryotes (Kozak sequence for eukaryotes).
Both subunits are needed for translation to occur and they come together in a hamburger fashion that sandwiches the mRNA and tRNAs in between. Mechanism of translation: Chain Initiation: To begin translation, you need to form the initiation complex.
Regulation of transcription in eukaryotes is described under the topic: Molecular Biology: Eukaryotes Translation Roles of mRNA, tRNA, rRNA mRNA (messenger RNA contains codons that code for the peptide sequence. tRNA (transfer RNA contains the anticodon on the "tip" and the corresponding amino acid on the "tail". They are the end product of what's encoded in the genes and they perform all the functions in the cell. Codon-anticodon relationship Codon: The mRNA is a sequence of nucleotides, but it codes for a sequence of amino acids. Lies just downstream of the Shine Dalgarno sequence (Kozak sequence for eukaryotes). Termination codon (UAG, UGA,UAA signals the end of translation. Unlike other codons, tRNA are not involved. Instead a protein called "release factor" comes along and terminates translation. Ribosome has 2 subunits - the large and the small. The large subunit is responsible for the peptidyl transfer reaction. The small subunit is responsible for the recognizing mRNA and binds to the Shine-Dalgarno sequence on the mRNA (Kozak sequence for eukaryotes). This protects the 5' end from exonuclease degradation. The poly-A tail protects the 3' end of the mRNA from exonuclease degradation. Eukaryotic mRNA: 5' cap - nucleotides - 3' polyA. Prokaryotic mRNAs don't have the 5' cap or polyA tail. Enhancers increase transcription when bound by transcription factor, silencers decrease transcription when bound. Enhancers and silencers in prokaryotes are close to the core promoter, and is part of the extended promoter. Chain Elongation: protein is made from the N terminus to the C terminus. mRNA codons are read from the 5' to the 3' end. Elongation consists of: Binding: new tRNA with its amino acid (tRNAamino acid is called aminoacyl-tRNA) enters the A site. Rho dependent termination: a protein called the factor travels along the synthesized RNA and bumps off the polymerase. Regulation of transcription in prokaryotes: Transcription factors (proteins) binds to enhancers or silencers (DNA) to affect transcription. Information for school personnel and those who work in our children s schools to be able to identify signs of suspected cases of child abuse. Previous annual reports can be downloaded in PDF format from the Downloads section. Find out how we are working with our members to improve European payments. He was then transferred to Buchenwald concentration camp and finally Flossenburg. Even during the privations of the concentration camp, Bonhoeffer retained a deep spirituality which was evident to other prisoners. He continued to minister to his fellow prisoners. After a hiatus from the music scene, Maroon 5 released their second studio album, It Wont Be Soon Before Long in May 2007, five years after Songs About Jane. The second set debuted at #1 on the Billboard 200 with first week sales of nearly half a million. Chain elongation: nucleoside triphosphates (AUGC s) adds corresponding to the DNA template. No primer is required. RNA elongates as the RNA polymerase moves down the DNA template. RNA is made from the 5' to 3' direction.
TRNA structure: clover leaf structure with anticodon at the tip, and the amino acid at the 3' tail. rRNA is made of nucleotides, many of which is modified for structural and functional reasons.