The Central Dogma of BiologyProtein synthesis begins with a section of DNAcalled a gene which contains the informationfor the production of a single protein.
The Central Dogma of BiologyDNARNAProteinTranscriptionTranslation
There are three important differences between thestructure of DNA and the structure of RNA.1. The pentose sugar foundin RNA is ribose instead ofdeoxyribose.2. The nucleotide thyminefound in DNA is replacedwith uracil in RNA.3. DNA is a double-helix,and RNA is a single strand.
TranscriptionRNA Polymerase breaks the hydrogen bondsbetween the two strands of DNA.
TranscriptionOne of the DNA strands serves as a templatefor the construction of a new messenger RNA.
TranscriptionComplementary nucleotides align themselvesalong the exposed nitrogen bases of the DNA.
TranscriptionThe newly constructed mRNA molecule isreleased into the nucleus and the DNAreforms.mRNADNARNA Polymerase
TranscriptionThe transcription phase of protein synthesis isover when mRNA exits the nucleus through anuclear pore and enters the cytoplasm.http://www.youtube.com/watch?v=41_Ne5mS2ls
Protein Synthesis: Part TwoTranslationTranslation takes place in the cellular cytoplasm. Theprocess is mediated by large molecular machines calledRibosomes.
Vocabulary:Ribosomes: the molecular structure responsible fortranslating mRNA into protein.
TranslationMost ribosomes are found on the outside membraneof the rough endoplasmic reticulum.
Rough Endoplasmic Reticulum: A membranous structure inthe cytoplasm of a cell where proteins destined for export areassembled.Vocabulary:
Translation starts when a ribosome attaches to amessenger RNA molecule and begins to assembleamino acids based on the sequence of codons in themRNA molecule.Translation
DNA and RNA use only fourbases to create a code thatdetermines the sequence of20 different amino acids inthe final protein.In order to do this nucleicacids use three letter“words” called codons toindicate each of the aminoacids in the sequence.What are codons?
A third form of RNA called transfer RNA, tRNA, is found inthe cytoplasm.Translation
TranslationThe tRNA molecule has a sequence of three nucleotides calledan “anticodon” at one end and a corresponding amino acid atits opposite end.AnticodonAmino AcidTransfer RNA
TranslationDuring translation the anticodon on the tRNA aligns with thecodon on the mRNA
The ribosome provides a site where tRNA moleculesalign with the codons on the mRNA molecule.Translation
TranslationThe amino acid on the tRNA is then “transferred” to thegrowing protein chain and the tRNA is released back intothe cytoplasm to pick up another amino acid.http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120077/micro06.swf::Protein%20Synthesis
Eventually the ribosome reaches the end of the mRNA andprotein sequence is complete.Translationhttp://www.youtube.com/watch?v=41_Ne5mS2lshttp://www.youtube.com/watch?v=Jml8CFBWcDs&feature=related