Biol 1543 1st Edition Lecture 8 Outline of Last Lecture I Enzyme Activity Can Mirror Drug Action II Enzyme inhibitors block enzyme action III Feedback inhibition regulates cell activity IV Many poisons pesticides and drugs are enzyme inhibitors V Your liver and the smooth ER VI Endplasmic Reticulum Complications VII Drug Abuse Basics Outline of Current Lecture I Nucleotide monomers II DNA and RNA are polymers of nucleotides III DNA is a double stranded helix IV REPLICATION V The flow of genetic information VI From DNA to protein VII TRANSCRIPTION VIII Eukaryotic RNA is processed before leaving the nucleus IX TRANSLATION X The genetic code XI REVIEW XII Mutations can change the meaning of genes Current Lecture I Nucleotide monomers a The monomers of nucleic acids are nucleotides composed of a sugar phosphate and nitrogenous base b The sugar and phosphate form the backbone for the nucleic acid or polynucleotide II DNA and RNA are polymers of nucleotides a DNA is a nucleic acid made of long chains of nucleotide monomers i the sugar is deoxyribose unique to DNA b DNA has four kinds of nitrogenous bases i A T C and G ii Two types add picture 1 Pyrimidine and Purine c RNA is also a nucleic acid but has a slightly different sugar i sugar in RNA is ribose d RNA uses U Uracil instead of T the other 3 bases are same Sugar phosphate backbone A Nucleotide III DNA is a double stranded helix a James Watson and Francis Crick worked out the three dimensional structure of DNA based on work by Rosalind Franklin b The structure of DNA consists of two polynucleotide strands wrapped around each other in a double helix c Hydrogen bonds between bases hold the strands together d Each base pairs with a complementary partner i A pairs with T and G pairs with C IV REPLICATION a DNA replication depends on specific base pairing i Replication starts with the separation of DNA strands ii Each strand becomes a template to assemble new nucleotides into complementary strands b Replication aka duplication is making an identical copy c DNA replication is a complex process due in part to the fact that some of the helical DNA molecule must untwist d happens quickly i 50 nucleotides added every second mammals ii 500 added every second in bacteria e with very few errors i Only about 1 of 1 000 000 000 nucleotides is mispaired ii DNA has a proofreading enzyme iii DNA also has a repair enzyme V The flow of genetic information a A genotype is an organism s genetic makeup b A phenotype is the characteristic we see i the manifestation of the genetic information what it becomes c The DNA genotype is expressed through proteins giving us the phenotypes we see d A particular gene is a long line of nucleotides i A unit of information e Genes specify how to build polypeptides proteins i Genes to proteins VI From DNA to protein a The DNA of the gene is transcribed into RNA which is translated into the polypeptide i two main stages of expressing information in DNA 1 Transcription in the nucleus DNA to RNA 2 Translation RNA into protein in the Cytosol VII TRANSCRIPTION a Transcription produces genetic messages in the form of RNA b The DNA helix unzips and RNA nucleotides line up along one strand of the DNA following base pairing rules A U C G c As the single stranded RNA peels away from the gene the DNA strands then rejoin d Three stages of transcription i Initiation the RNA polymerase hooks on to the DNA to start transcription at the promoter DNA section ii Elongation Moves along the DNA to copy the code iii Termination Stops at the terminator section on the DNA VIII Eukaryotic RNA is processed before leaving the nucleus a Transcription i RNA that is used to make proteins mRNA ii messenger RNA carries the genetic message from DNA out of the nucleus b Translation i a ribosome attaches to mRNA ii tRNA translates the message to a polypeptide IX TRANSLATION a Genetic information written in codons is translated into amino acid sequences i The words of the DNA language are triplets of bases called codons ii The codons in a gene specify the amino acid sequence of a polypeptide 1 Three codons will code for one amino acid iii Nearly all organisms use exactly the same genetic code X The genetic code a Each codon is translated into one amino acid XI REVIEW a The flow of genetic information in the cell DNA RNA protein i The sequence of codons in DNA spells out the structure of a polypeptide XII Mutations can change the meaning of genes a Mutations are changes in the DNA base sequence caused by some error in DNA or by mutagens i Mutagens are something capable of causing a genetic change Such as radiation b Substituting inserting or deleting nucleotides alters a gene with varying effects on the organism i Three primary ways genes are altered 1 substituting of a nucleotide 2 insert of an extra nucleotide 3 delete a nucleotide c Erythrocytes red blood cells d by concave disc is the shape of the normal red blood cell e in sickle cells they are sickle shaped like a quarter moon i the shape does not allow for very good oxygenation of the tissue f Symptomatic and supportive this is how they take care of sickle cell because there is no cure