BIOL 2013 Exam 3 Slides GENETICS FIGURE 8 2 PAGE 210 flow of genetic information DNA is the blueprint for a cell s proteins including enzymes DNA is obtained either from another cell in the same generation or from a parent cell during cell division DNA can be expressed within a cell or transferred to another cell through recombination and replication Expression genetic info is used within a cell to produce the proteins needed for the cell to function Transcription and translation Recombination Genetic info can be transferred between cells of the same generation Recombinant cell Replication genetic info can be transferred between generations of cells Daughter cells DNA REPLICATION REPLICATING DNA REPLICATION AND TRANSCRIPTION ARE THE TWO THINGS THAT DNA DOES DIRECTLY FIGURE 8 3 PAGE 211 DNA replication In DNA replication one parental double stranded DNA molecule is converted to two identical daughter molecules One strand acts as a template for the production of the other strand Uses DNA polymerase enzyme to join the newly added nucleotide to the growing DNA strand The two strands of DNA are antiparallel FIGURE 8 6 PAGE 213 replication of bacterial DNA FIGURE 8 1A PAGE 209 a prokaryotic chromosome DNA TRANSCRIPTION TRANSCRIBING DNA TO RNA DNA IS INVOLVED DIRECTLY FIGURE 8 7 PAGE 214 The process of transcription 1 2 3 4 5 RNA polymerase binds to the promoter and DNA unwinds at the beginning of a gene RNA is synthesized by complementary base pairing of free nucleotides with the nucleotide bases on the template strand of DNA The site of synthesis moves along DNA DNA that has been transcribed rewinds Transcription reaches the terminator RNA and RNA polymerase are released and the DNA helix reforms TRANSCRIPTION DNA RNA TYPES OF RNA rRNA ribosomal RNA Involved in protein synthesis tRNA transfer RNA Involved in protein synthesis mRNA messenger RNA Carries the coded info for making specific proteins from DNA to ribosomes where proteins are synthesized TRANSLATION PROTEIN SYNTHESIS DECODES THE LANGUAGE OF NUCLEIC ACIDS AND CONVERTS IT TO THE LANGUAGE OF PROTEINS Protein Synthesis DNA is necessary but does not participate directly in translation All of the details don t need to be covered INTERNET TRANSLATION PROCESS SLIDE Basic Principle 1 DNA has a message in it The message is in its sequence of bases AGTC That message is rewritten transcribed into RNA So now RNA has the message that was in DNA but in a slightly different form 2 What happens to the message in RNA If it happens to be messenger RNA that message is now translated into an amino acid sequence if it is long enough may be a polypeptide and is a protein The amino acids make up a protein Know the basics 1 2 Messenger RNA attaches to the ribosome and the sequence of bases in the RNA codes for amino acids How Discovered in the 1960 s and led to Nobel Prize shared by many Every three bases in messenger RNA called codon has a complimentary series of three bases in transfer RNA called anti codon G binds to C A binds to U Transfer RNA is specific to an amino acid Transfer and messenger RNA bind and deliver the specific amino acid FIGURE 8 9 PAGES 216 AND 217 Might be too confusing Know the basic concepts on the last slide The overall goal of translation is to produce proteins using mRNAs as the source of biological information The complex cycle of events illustrated here shows the primary role of tRNA and ribosomes in the decoding of this information The ribosome acts as a site where the mRNA encoded info is decoded as well as the site where individual amino acids are connected into polypeptide chains The tRNA molecules act as the actual translators one end of each tRNA recognizes a specific mRNA codon while the other end carries the amino acid coded for by that codon FIGURE 8 10 PAGE 218 Simultaneous transcription and translation in bacteria Unique to prokaryotes have their DNA free in the cytoplasm eukaryotes have their DNA in the nucleus We do transcription in our nuclei and translation in our cytoplasm Prokaryotes do translation and transcription As RNA is being made before it is even finished it is being translated Why is this They are both in the same place so they can happen at the same time Test Question Where does simultaneous transcription and translation occur Prokaryotes are far more efficient than eukaryotes FIGURE 8 8 PAGE 215 Genetic Code Code of life Explains how proteins are made amino acids match each codon code for the same amino acids Every 3 bases in MESSENGER RNA is called a codon and they have determined which Only 20 amino acids found in proteins which is why some have multiple codons that The discovery of this earned a lot of people nobel prizes Very difficult research There are 3 stop codons UGA UAA UAG When translation comes to one of these three codons it tells the translation to stop because it is the end of the protein DON T HAVE TO MEMORIZE MUTATIONS Change in the DNA base sequence Genotype genetic composition of an organism Phenotype expressed characteristics MUTATIONS Spontaneous Mutation occurs naturally Induced Mutation induced by a chemical or physical agent Silent Mutation change in genotype but not phenotype FIGURE 8 18 PAGE 225 Types of mutations and their effects on the amino acid sequences of proteins Missense mutation when the mRNA is translated into protein the incorrect base may cause the insertion of an incorrect amino acid in the protein if the base substitution results in an amino acid substitution in the synthesized protein nonsense mutation by creating a nonsense stop codon in the middle of an mRNA molecule some base substitutions effectively prevent the synthesis of a complete functional protein only a fragment is synthesized A base substitution resulting in a nonsense codon is called a nonsense mutation frameshift mutation one or a few nucleotide pairs are deleted or inserted in the DNA This mutation can shift the translational reading frame the three by three grouping of nucelotides recognized as codons by the tRNAs during translation PHYSICAL MUTAGENIC AGENT FIGURE 8 21 PAGE 228 the creation of a thymine dimer caused by ultraviolet light after exposure to UV light adjacent thymines can become cross linked forming a thymine dimer In the absence of visible light the nucleotide excision repair mechanism is used in a cell to repair the damage CHEMICAL MUTAGENIC AGENT SMOKING Tobacco Marijuana Etc SMOKING What is the greatest fear that teenage girls have about smoking wrinkles SMOKING