Week of 11/9 Notes
Week of 11/9 Notes BIOL 1124
Popular in Intro Biol: Molecule/Cell/Phys
Popular in Biology
This 0 page Class Notes was uploaded by Bailey Brimfield on Monday November 16, 2015. The Class Notes belongs to BIOL 1124 at University of Oklahoma taught by Broughton in Fall 2015. Since its upload, it has received 27 views. For similar materials see Intro Biol: Molecule/Cell/Phys in Biology at University of Oklahoma.
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Date Created: 11/16/15
Week 1 19 Notes Translation 0 O O O O tRNA links info in codons with corresponding amino acids for each amino acid there is a speci c species of tRNA Holley identi ed the structure of tRNAs tRNAs read mRNA codons and deliver the corresponding amino acid to each codon Ribosomes proteinRNA complexes allow peptide bonds to form Ribosomes are formed during transcription An anticodon region of tRNA that is complementary to a codon on mRNA binds to the mRNA Aminoacyl tRNA synthetases charge the tRNA with the correct amino acid Each enzyme is highly speci c for one amino acid The enzyme uses an ATP to covalently bond the amino acid and tRNA Benzer determined that the synthetases recognize the shape of the tRNA not just the anticodon Ribosomes have large and small subunits They can make any protein Ribosomes have three sites involved in translation P peptidyltRNA binding site growing polypeptide chain is held here A aminoacyltRNA binding site the charged tRNA carrying the next amino acid enters here 0 The ribosome allows the amino acid to form a peptide bond with the polypeptide chain 0 If ribosomes did not exist the weak hydrogen bonds that would otherwise be formed would not be strong enough to hold the polypeptide chain together E exit site as the chain continues to grow and new bonds are formed by new tRNAs and their amino acids tRNAs that have already contributed their amino acids are moved through this site and out of the ribosome tRNA is not quotused upquot they continuously go back and forth in the translation cycle Posttranslational modi cations Prepare proteins for their functions Proteolysis cuts a polyprotein into multiple smaller nished products Glycosylation adds a carbohydrate to form a glycoprotein Phosphorylation adds phosphate groups catalyzed by protein kinases OO 0 Signal protein short sequence a signal peptide generally in the rst part of the protein Acts as an address to direct the protein to different locations In 1968 Holley Khorana and Nirenburg won Nobel Prizes Expression Production of a functional gene product Tightly regulated so genes are only expressed when their products are needed Spatial regulation for speci c tissues or places Temporal regulation developmental seasonal etc Can be regulated at many different levels but regulation of transcription is the primary control mechanism Constitutive genes actively expressed all the time ex Genes for glycolysis Facultative genes only expressed under conditions when needed Genes can be repressible or inducible Regulation begins at the promoter where transcription is initiated Primarily controlled by regulatory proteins called transcription factors inducers or repressors which bind to speci c regulatory sequences in the promoter region In prokaryotes this are called operators ln eukaryotes these are called enhancers Negative regulation binding of transcription factor blocks transcription turning the gene off Positive regulation binding of transcription factor permits transcription turning the gene on Bacteria have operons which are clusters of genes with a single promoter that are coordinately expressed They usually involve the same metabolic pathway E Coli lac operon E Coli prefers glucose will use lactose Needs a carrier protein a cleaving enzyme and a converter enzyme which are coded for by three genes all transcribed by the same promoter three genes the operon Negative inducible repressor protein usually binds to the operon blocking transcription In the presence of lactose the repressor protein detaches Jacob and Monod show gene expression is primarily regulated at the transcription level described the lac operon Won the 1965 Nobel Prize Genomics Study of an organism s genome all its genes OO O OO 00 O O O O Annotation identi cation of genes and gene sequences Function genomics determines gene function Model organism easy to breed short generation times ex Mice fruit ies C value is the total amount of DNA in a haploid genome Amount of DNA is not directly correlated to complexity of organism C value paradox Much of DNA is quotjunk DNAquot has no apparent purpose Some universal genes are found in all organisms Pseudogenes genetic fossils that are no longer needed and therefore not expressed Often accumulate mutations Only expressed by mistake Most mammals can synthesize ascorbic acid Vitamin C but primates cannot must be obtained Primates have an inactive partially deleted form of the gene pseudogene Birds have teeth genes not expressed Pseudogenes Only a small percentage of the genome is pseudogenes 60 or so of the genome is repetitive New genes often come from duplications of existing genes Important for diversi cation of genes Function constraint original gene function is necessary and must be preserved Transposable elements can move from place to place in the genome Can be cut and pasted or copied and pasted lf inserted in the middle of an existing gene renders it non func onal Discovered by Barbara McClintock is 19405 awarded Nobel prize in 1983 lnclude transposase which facilities excision and insertion Dead copies tend to accumulate over time Endogenous retroviruses viruses that have mutated and lost ability to function quotdeadquot in host s genome These accumulate 42 of genome is endogenous retroviral genetic material Only 15 of the human genome codes for protein tRNAs etc Most mutations are not subject to natural selection they don t affect organismal tness lf most of the human genome was essential we would quickly die out from mutations Ohno s original argument for junk DNA has yet to be falsi ed LINES long interspersed repeats SINES short interspersed repeats STRs short tandem repeats P 21 BacterialArchaealGenomes 0 Small with single circular chromosomes O 0 Mostly protein coding no introns Plasmids small chromosomes often present 0 Human Genome Project 0 O O O Began in 1986 nished in 2003 One of the rst eukaryotes sequenced Sanger shotgun sequencing sequences small parts and reassembles them based on overlapping parts Contig assembly involves millions of separate reads requires supercomputers