BIOL 2050 1st Edition Lecture 24 Outline of Last Lecture I. DNA Replication TerminologyOutline of Current Lecture II. Genetic InformationIII. From Gene to Proteina. Genetic Codeb. Transcription c. TranslationCurrent LectureGenetic Information- Gene Expression: the process by which DNA directs protein synthesis including two phases: transcription and translation- Proteins are links between genotype and phenotypeHistoryo 1902: Archibald Garrod first suggested that genes dictate phenotypes through enzymes that catalyze specific chemical reactionso Beadle and Tatum developed a one-gene one-enzyme hypothesis, which stated that each gene dictated the production of a specific enzyme.o Later discoveries found that not all proteins are enzymes and many proteins are composed of several polypeptides. Led to one-gene one-polypeptide hypothesisFrom Gene to Protein- RNA is the bridge between genes and the proteins for which they code- Transcription: synthesis of RNA using information in DNAo Produces mRNA- Translation: synthesis of a polypeptide using the information from mRNAo Ribosomes are the site of translation- In Eukaryotic cells the nuclear envelope separates transcription from translationo Central Dogma: DNA -> RNA -> Proteino Primary transcript: the initial RNA transcript from any gene prior to processingThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Genetic Codeo There are 20 amino acids but there are only four nucleotide bases in DNA Triplet Code: a series of nonoverlapping, three-nucleotide words- Responsible for the flow of information from gene to protein- Words of a gene are transcribed into three-nucleotide words of mRNAo These words are then translated into a chain of amino acids, forming a polypeptideo Template Strand: provides a template for ordering the sequence of complementary nucleotides in an RNA transcripto Codons: the mRNA base triplets that are read in a 5’ to 3’ direction during translation Each codon specifies an amino acido The genetic code is nearly universal Genes can be transcribed and translated after being transplanted from one species to anotherTranscription: first stage of gene expressiono RNA Polymerase: catalyzes RNA synthesis by prying the DNA strands apart and hooking RNA nucleotides together. Promoter: start point Terminator: stop sequence present in bacteria Transcription Unit: the stretch of DNA that is transcribedo The three stages of transcription: Initiation- Transcription Factors: mediate the binding of RNA Polymerase and the initiation of transcription. Elongation: RNA Polymerase moves along DNA - 40 nucleotides/sec Termination- Different in Bacteria and Eukaryotes- Eukaryotes: o Poly-A tailo 5’ cap Protect mRNA in the cytoplasm Help ribosomes attach by 5’ capo RNA Splicing: removes introns and joins exons creating an mRNA molecule with a continuous coding sequence Intron: noncoding region Exon: coding region Spliceosomes: recognize the splice sites (snRNPs) Ribozymes: catalytic RNA molecules that function as enzymes and cansplice RNA Alternative Splicing: allows for one gene to be synthesized into different proteins through different splicing combinationsTranslation: genetic information flows from mRNA to proteino Transfer RNA (tRNA): helps translate mRNA into a protein Transfer amino acids to the growing
View Full Document
Unlocking...