Bio 121: General Biology - Study Guide
Bio 121: General Biology - Study Guide Bio 121
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This 6 page Study Guide was uploaded by Holden Hershey on Friday October 17, 2014. The Study Guide belongs to Bio 121 at Syracuse University taught by Wiles in Fall. Since its upload, it has received 159 views. For similar materials see General Biology in Biology at Syracuse University.
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Date Created: 10/17/14
Overview of Transcription Translation also MutationsGenetics DNA is the genetic material Experiments with bacteria and with phages provided the first strong evidence WatsonCrick deduced that DNA is a double helix and they built a structural model Rosalind Franklin produced the image that showed DNA in double helix formation Two anti parallel sugarphosphate chains wind around the outside of the molecule The nitrogenous bases project in to the interior where they hydrogen bond in specific pairs 040 00 Chargaff s Rules 1 Base composition of DNA arises between species 2 For each species the percentages of AT GC roughb Protein Required in DNA ReplicationRepair The MeselsonStahl experiment showed that DNA Replication is Semiconservative The parental molecule unwinds and each strand then serves as a template for the synthesis of a new strand according to these basepairing rules DNA Pobmerases proofread new DNA replacing incorrect nucleotides Mismatch Repair enzymes correct errors that persist Nucleotide Excision Repair process by which DNA gets shorter with each round of replication The presence of telomeres repetitive sequences at the ends of linear DNA molecules postpones the erosion of genes Telomerase catalyzes the lengthening of telomeres in germ cells Chromosomes consist of a DNA molecule packed together with proteins histone Nucleoid of a bacterial cell is circular DNA compacted with proteins Chromatin DNAHistonesOther Proteins Eukaryotic Cells Histones bind to each other to form nucleosomes most basic unit of DNA packaging Chromosomes occupy restricted areas in the In terphase nucleus In In terphase most chromatin is less compacted euchromatin but some remains highly condensed heterochromatin DNA polymer of nucleotide Nitrogenous basePen tose S ugarPhosphate Group Backbone alternating sugar and phosphate groups joined by covalent bonds Phosphate groups attach to 5 carbon of one deoxyribose and the 3 of the next deoxyribose 5 F ive Prim e 3 T hreePrime Double Helixantiparallelchain runs in opposite directions 5 end phosphate attached to 5 deoxyribose carbon 3 end Hydroxyl attached to 3 deoxyribose carbon Order of its building blocks stores genetic information Hydrogen Bondingbetvveen specific base pairs Binds two chains of helix Semiconservative Replication Each daughter double helix consists of 1 original strand and 1 new complementary strand Zstrands unwind DNA helicase Replication is initiated DNA Primase synthesizes RNA Primer DNA Polymerase adds nucleotide subunits Topoisomerasesprevent tangling and knotting Bidirectional start at origin of replicationBuild in both ways DNA S yn thesis Always proceeds in the 5 3 direction Leading Strand synthesized continually Lagging Strand Synthesized discontinuousb have to wait for it to be unzipped more Forms short Okazaki Fragments Short Fragmen ts DNA Primase synthesizes RNA Primers DNA Polym erases Proofread each new nucleotide Against template nucleotide Finds Errors in base pairing Removes incorrect nucleotides Inserts correct nucleotides DNA to Protein Information encoded in DNA Codes sequences of amino acids in proteins T W0 STEP PROCESS Transcription Translation Transcription Syn thesis of mRNA complementary to a template strand of DNA Specifies amino acid sequences of pobpeptide chains RNA Syn thesis is catalyzed by RNA Polymerase RNA Polymerase links together RNA nucleotides complementary to the DNA template strand Translation Translating the language of nucleic acids into amino acids Syn thesizes polypeptide chain Specified by mRNA Also acquires tRNA and ribosomes Three Steps InitiationElongationTermination Translation In more depth Cell translates an mRNA message using tRNA AminocytltRNA Synthetasebinds tRNA to a specific amino acid tRNA then lines up to its anticodon at the complementary codon on the mRNA Ribosomes coordinate the 3 stages of translation mRNA and tRNA move through theA and P sites o a ribosomal subunit to for peptide bonds and amino acids they eventually exit through the E site After Translation modifications to proteins can ajfect their shape Free ribosomes in the cytosol initiate the syn thesis of all proteins but proteins with a signal peptide are synthesized in the Rough endoplasmic reticulum a gene can be transcribed by multiple RNA polymerase simultaneously A single mRNA molecule can be translated simultaneously by a number of ribosomes forming a polvribosome Promoter often a TA TABox establishes where RNA syn thesis is initiated Transcription factors help E ukaryotic RNA Polymerase recognize promoter sequences forming a Transcription Initiation Complex E ukaryotic Cells modify RNA after Transcription Eukaryotic mRNA undergoes RNA processing which includes RNA Splicing the addition of a modified nucleotide 5 cap to the 5 end and the addition of a PobA tail to the 3 end RNA Splicing Introns are removed and exons are spliced together Sgliceosomes Carry out RNA splicing Sometimes RNA can catalyze its own splicing Ribozymes How RNA can splice itself Elongation building longer chains of amino acids Eventualb have a whole protein Termination mRNAPobpeptideRibosome disassociate Because of a Release Factor CodonGenetic information is encoded here Sequence of 3 mRNA nucleotides Specifies 1 amino acid or a Start or Stop code A UGStartAdenineUracilGuanine Information in DNA is translated by RNA RNA Structure Uracil instead of Thymine Pyrimidine Transfer RNA tRNA Decoding molecule in translation Anticodoncomplementary to mRNA codon Specific for one amino acid Ribosomes Read the information from mRNA helps build amino acids Large subunit small subunit Genetic Code Redundant some amino acids have more than one codon quotA UG Start UAAUAGUGA Stop Virtualb Universal All organism use this Suggests that all organisms have a common ancestor Few minor exception to standard code found in all organisms Intronsnoncoding regions interrupt eXons Removed from original premRNA Extrons coding regions in eukaryotic genes Spliced to produce continuous polypeptide coding sequence Mutations Frame shift Mutations Insertion or deletion of one or two base pairs in a gene Destroys protein function Changes codon sequences downstream from mutation Transposons Movable DNA sequences jump into the middle ofa gene Discovered by Barbara McClintock Retrotransposons Replicate by forming RNA intermediate Reverse transcriptase converts to original DNA sequence before jumping into gene Genes specify Proteins via Transcription and Translation Beadle and Tatum s studies of mutant strains of Neurospora led to the One gene one polypeptide Hypothesis During Gene Expression information encoded in genes is used to make polypeptide chains enzymes or RNA molecules In bacteria these processes are coupled but in eukaryotes they are separated in space and time by the nuclear membrane Small scale mutations include pint mutations changes in DNA nucleotide pair which may lead to production of nonfunctional proteins Nucleotide pair substitutions can cause missense or nonsense mutations Nucleotide pair insertions or deletions may produce frames shift mutations Spontaneous mutations can occur during DNA replication recombination or repair Chemical and physical mutagens cause DNA damage that can alter genes Transcription happens in the NucleusNucleolus speci cally Translation happens in the Cytoplasm of the cell on afree or attached Ribosome
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