Biology Chapter 10 Notes!
Biology Chapter 10 Notes! Bio 240
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This 0 page Class Notes was uploaded by Izabella Nill Gomez on Thursday November 5, 2015. The Class Notes belongs to Bio 240 at University of Tennessee - Knoxville taught by Dr. Hughes in Summer 2015. Since its upload, it has received 12 views. For similar materials see General Genetics (Bio 240) in Biology at University of Tennessee - Knoxville.
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Date Created: 11/05/15
Biology 240 Chapter 10 Notes Genetic material information contained in genes that when passed onto a new generation in uences the form and characteristics of each individual Also a source of variability through mutation For a molecule to serve as genetic material must have 4 characteristics replication storage of information expression of information variation by mutation Replication is fundamental for all living organisms Once doubled must be partitioned equally to all cells Also occurs in formation of gametes Storage of information requires the molecules to act as repositories of genetic information that maymay not be expressed The need to have vast information is needed to produce varying gene products Expression is a complex process that is the underlying basis for the concept of information ow within the cell The initial event is transcription of DNA where mRNA tRNA and rRNA are synthesized mRNA is translated to protein by mediation of tRNA and rRNA Each mRNA is speci c to the gene it39s a product of Translation converts mRNA to protein from amino acid chains Transcription translation DNA to RNA to proteincentra dogma of molecular genetics DNA rst studied in 1869 by Swiss chemist Miescher lsolated nuclei and derived acidic substance with DNAnucein 1910 Levene learned DNA contained nucleotides Started basis for tetranucleotide hypothesis for DNA structure In the 1940s Chargaff elaborated on this demonstrating the variation of nucleotides in different organisms 1944 Avery McLeod and McCarty published quottransforming principlequot in bacteria Based of Grif th39s 1927 experiment on pneumonia Smooth strains are infectious and have a polysaccharide capsule to protect themselves from phagocytic bacteria rough strains do not HR and IS used in experiment Heat killed smooth strain did not result in in death of mice but the combination of rough plus heatkilled smooth strain resulted in death because of some interaction transformation A transforming principle might be part of the polysaccharide capsule or compound required for capsule synthesis The smooth cells served as a nutrient source for rough strains Dawson in 1931 took one step further and showed that smooth could incubate in rough to regain infectious ability Avery McLeod and McCarty isolated smooth pneumonia strains and centrifuged collected and heatkilled them They then obtained a ltrate that retained the ability to transform rough strains The protein was removed and polysaccharides then digested The transforming principle was found to be DNA because a phosphorous ratio was found After eliminating all proteins with digesting enzyme ribonuclease RNase the transforming ability was still retained When DNase was injected the transforming ability was lost The study of E coli and bacteriophage T2 revealed that DNA is carried in the phage head to replicate and infect host cells Experiment by Hershey and Chase labeled DNA with phosphorous and protein with sulfur After being centrifuged bacteriophages were checked to see that DNA was transferred to bacterial cells after adsorption This demonstrated that genetic material phage T2 was DNA not protein found outside cell Spizizer and Fraser independently reported that by using protoplasts enzymatically naked cells they could initiate phage reproduction with disrupted T2 particles Virus did not have to be intact for infection Transfection infection process by only viral nucleic acid proves conclusively that OX174 phages39 DNA alone contains all the necessary information for production of mature viruses Indirect evidence that supports DNA as the Genetic material in Eukarva Found in nucleus along with protein Mitochondria and chloroplasts have DNA with genetic roles Protein is found everywhere The amount of DNA in haploid sperm to the diploid number in blood cells and the number of chromosomes correlates UV light is capable of inducing mutations Action spectrum of UV light measures the wavelength by the number of mutations it induces The absorption spectrum is compared with this to tell what could be the genetic material The molecule serving as the genetic material is expected to absorb at the wavelengths found to be mutagenic DNA and RNA at 260 um protein at 280 The strongest evidence of DNA as the genetic material is with recombinant DNA technology Segments of eukaryotic DNA are spliced into bacterial DNA the complex is inserted in the bacterial cell and the gene expression is monitored If a eukaryotic gene is introduced the subsequent protein is produced Some viruses contain RNA and not a DNA core RNA is the genetic material When puri ed RNA from tobacco mosaic virus TMV is spread on tobacco leaves characteristic lesions caused by viral infection subsequently appear RNA is the genetic material SpiegelmanPace demonstrated that RNA can be isolated and replicated in vitro depending on the enzyme RNA replicase which is isolated from host E coli cells following infection When replicated RNA is added to E coli transfection occurs RNA directs viral reproduction Retroviruses use RNa as a templateto synthesize DNA via reverse transcription under direction of reverse transcriptase Nucleotides building blocks of nucleic acids Consist of a nitrogenous base pentose sugar and a phosphate group 2 type of nitrogenous bases purines A G and pyrimidines CT Pentose sugars can be ribose for RNA or deoxyribose for DNA The data available to Watson and Crick allowed them to propose the double helix and came from 1base decomposition analysis of hydrolyzed samples of DNA from Chargaff and 2 Xray diffraction studies of DNA from Rosalind Franklin 1953 Chargaff39s rules 1 Amount of A is proportional to T amount of G is proportional to C 2 The sum of purines AG equals the sum of pyrimidines CT 3 The percentage of GC doesn39t necessarily equal AT DNA Model by Watson and Crick semiconservative 2 long polynucleotide chains coiled around a central axis double helix Both chains antiparallel 339539 and 539339 Bases of both chains at stacked Paired nitrogenous bases AT GC Complimentary with hydrogen bonding Each turn is 10 base pairs long Major groove alternating with a minor groove Hydrophobic interior of double helix hydrophilic phosphate backbone NP P PP N Structure of RNA chemically similar to DNA but single stranded Complimentary copies of DNA Teomerase RNA and RNA primer is involved in DAN replication at end of the chromosome Possible Exam Questions 1 If protein had been the hereditary material what would have Hershey and Chase39s experiment resulted in P inside the cell and not S 2 Sample DNA is 27 guanine so what percent thymine is in the sample 23 27 is cytosine loo5446 462 23 adenine 23 thymine