Chapter 5 The Structure and Function of Large Biological Molecules Place the nitrogenous bases A T G C and U into groups Purines A T and G Pyrimadines C U and T remember that the top of a pyramid is sharp so it CUTs you Which of these bases form hydrogen bonds with each other They all do but G C and A T bond specifically to each other Be able to compare and contrast the structures of DNA and RNA DNA Deoxynucleic acid RNA RiboNucleic Acid Basically you should be able to draw a DNA molecule and identify the following parts Study Guide for Exam III Nov 10th Year Chapter 16 The Molecular Basis of Inheritance Be able to analyze the results of experiments described in the beginning of Chapter 16 Used the Semi conservative model The mode by which DNA replicates Each strand acts as a template for a new double helix The established model of DNA replication in which each double stranded molecule is composed of one parental strand and one newly polymerized strand Watson and Crick double helix model Chagraff Rules of base binding Blender experiment DNA can change genetic influence through viruses You should be able to describe label draw a replication bubble with respect to the following aspects Helicase Unwinds DNA to create two single strands Single Strand Binding Protein SSB Binds to and stabilizes the single stranded DNA Study Guide for Exam III Nov 10th Primase Topoisomerase the molecule Polymerase III Polymerase I Ligase Telomerase Provides an RNA primer to start new DNA strand synthesis Travels ahead of helicase nicking and swiveling the DNA to relieve torsional strain on Assembles new DNA strand in the 5 3 direction Can remove RNA nucleotides as it adds new DNA in a 5 3 direction Joins two DNA strands together at their ends Maintains telomere length in germline cells to protect the health of gametes Study Guide for Exam III Nov 10th Year Synthesis of leading strands is continuous in the 5 to 3 direction To elongate the other new strand called the lagging strand DNA polymerase must work in the direction away from the replication fork Study Guide for Exam III Nov 10th Why is an RNA primer needed to start replication of DNA RNA Primase unzips the genes but DNA polymerase 1 can remove the nucleotides and fill in the DNA gap What is an Okazaki fragment and how are they eventually joined together to form a continuous DNA strand Okazaki segments in the lagging strand and are united by polymerase III Understand the differences between the replication of circular and linear chromosomes Bacteria prokaryotic Circular genome Single DNA molecule 1 origin of replication Humans eukaryotic Linear genome Multiple linear chromosomes Multiple origins of replication on each chromosome What do telomeres do for Eukaryotic chromosomes and why are they necessary Postpone the erosion of genes near the end of DNA Think about a buffer zone to keep the Center DNA intact Chromatin a complex of DNA and protein is found in the nucleus of eukaryotic cells You should be able to describe chromatin Why does DNA need to be tightly packed To prevent damage to it What do histone proteins do in the process of packaging DNA into chromatin Study Guide for Exam III Nov 10th How does chromatin structure affect transcription They act as a coil winding up the DNA around it Year Depending on how loose or tight the chromatin is will determine how much is expressed Heterochromatin less expressed Euchromatin more expressed Chapter 17 From Gene to Protein Know the process of transcription RNA is the bridge between genes and the proteins for which they code Transcription is the synthesis of RNA using information in DNA Transcription produces messenger RNA mRNA Translation is the synthesis of a polypeptide using information in the mRNA Ribosomes are the sites of translation Basically transcription goes like this The point is to replicate the DNA in this strand to take to an RNA to then be TRANSLATED into the protein Study Guide for Exam III Nov 10th How does transcription differ in prokaryotic and eukaryotic cells Prokaryotes Translation can begin before transcription has finished Eukaryotes Translation is completely separate from transcription What is a promoter and what does it do for transcription Area where DNA Polymerase attaches itself to begin transcription usually in the TATA box area of high A and T bases How does RNA polymerase work Study Guide for Exam III Nov 10th Year Understand the processes of elongation and termination including the proteins responsible for elongation and the DNA sequences responsible for termination Study Guide for Exam III Nov 10th How are Eukaryotic RNA transcripts modified and for what purpose They are modified to shorten the sequence towards what is needed through splicing they shorten the non coding sequences called introns What effects can splicing have on potential mRNA molecules Some genes can encode more than one kind of polypeptide depending on which segments are treated as exons during splicing This is called alternative RNA splicing Consequently the number of different proteins an organism can produce is much greater than its number of genes What is a spliceosome and what role do snRNA molecules play in splicing RNA splicing removes introns and joins exons creating an mRNA molecule with a continuous coding sequence SnRNPs example of spliceosome or proteins that splice away introns Know the translation initiation complex mRNA small subunit of ribosome large subunit of ribosome What is the first codon that begins translation and how does it define the 5 UTR AUG What is the structure and function of tRNA and how exactly does it bridge the gap between mRNA codons and specific amino acids Non coding RNA Is not translated into protein snRNA tRNA rRNA Study Guide for Exam III Nov 10th Links mRNA to specific amino acids Two binding sites on the tRNA molecule Year Anti codon which base pairs with a codon forming hydrogen bonds 3 end binds to a specific amino acid When does translation end and why When it reaches a stop codon of UAA UGA and UAG Know the different types of DNA mutations that we discussed Study Guide for Exam III Nov 10th Silent Mutations Missense Mutations Nonsense Mutations Have no effect on the amino acid sequence of the protein produced Change a codon so that a different amino acid is inserted at that position in the protein Change a codon to a stop codon so that the growing polypeptide is truncated What effect do each of them have on the protein produced from that gene Be able
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