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Ch. 12
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DNA: the genetic material Griffith - 1928, used a bacteria that causes pneumonia to figure out that there are smooth (S) strains and rough (R) strains, the S cells killed mice, while the R cells did not, a mixture of R and S Cells did however kill the mouse, he conclude that there was a transformation from R to S Avery - 1944, identified molecule that transferred R into S Hershey and Chase - 1952, discovered that DNA is the transforming factor by using Radioactive Labeling
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Griffith’s Experiment
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Hershey and Chase Experiment
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DNA Structure Nucleotides - subunits of nucleic acids, contain a 5-carbon sugar, a phosphate, and a nitrogenous base. DNA adenine (A), guanine (G), cytosine (C), and thymine (T) RNA adenine, guanine, cytosine, and uracil (U) A and G are double rings so they are called Purine Bases C, T and U are single rings called Pyrimidine Bases
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Chargaff Chargaff - found that the amount of G is equal to the amount of C, and A is equal to T Chargaff's Rule - G=C, and A=T
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Structure and Bases
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DNA History Con’t X-ray diffraction - used to figure out the shape of DNA (double helix) Watson and Crick - Double Helix structure 1. two outside strands consist of alternating deoxyribose and phospate 2. cytosine and guanine bases pair to each other by three hydrogen bonds 3. thymine and adenine bases pair to each other by two hydrogen bonds A purine always bonds to a pyrimidine base, so A=T and C=G Therefore, C+T = G+A
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DNA Structure Top rail goes from the 5' carbon on the left to the 3' carbon on the right ( 5'-3') Bottom rail goes from the 3' carbon on the left to the 5' carbon on the right (3'-5') Chromosome Structure Human chromosomes have anywhere from 51 million to 245 million base pairs
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DNA Replication Semiconservative Replication - parental strands of DNA separate, serve as templates and produce DNA molecules that have one strand of parental DNA and one strand of new DNA DNA Helicase - enzyme responsible for unwinding the DNA, breaks the Hydrogen bonds between the bases When unzipped RNA primase adds a primer or starting point on each DNA strand DNA Polymerase - enzyme that adds the nucleotides to the new DNA strand starting at the 3' end and then zips the strands back up
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DNA Replication
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DNA Replication Con’t Chargaff's rule is demonstrated therefore there are exact copies of each other Leading strand - strand that is copied as the DNA unwinds, built continuously Lagging strand - replicates in the opposite direction as the DNA unwinds Okazaki fragments - chunks 100-200 nucleotides long on the lagging strand where replication takes place
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DNA Replication
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Nerdy Scientist Pick-Up Line
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RNA RNA - contains ribose (sugar), uracil (replaces thymine), and is usually single stranded mRNA - messenger RNA, formed from one strand of a DNA molecule, they direct the synthesis of specific proteins rRNA - ribosomal RNA, forms ribosomes in the cytoplasm tRNA - transport RNA, smaller segments of RNA that transport amino acids to the ribosome
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RNA introns - sequences that are not coded for on the DNA molecule exons - the sequences that are used in the code DNA ultimately makes proteins, there are also 20 different amino acids that make up proteins DNA sequences (codes) make up these amino acids Codon - three base codes in DNA and mRNA that make up amino acids
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Transcription Transcription - DNA code is transferred to mRNA in the nucleus, then uses the code to synthesize proteins Template strand - the strand of DNA that is copied by the RNA Nontemplate strand - the strand of DNA that is not used by the RNA
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Translation Translation - once the mRNA is synthesized and processed, it moves to the ribosome, it attaches to the ribosome and the code is read and translated into proteins tRNA - is basically an interpreter for the mRNA codon sequence anticodon - three base coding sequence that is complimentary to the codon sequence
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Amino Acids
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What is the Sequence? Start - Serine - Histidine - Tryptophan - Glycine - Stop Start - Proline - Asparagine - Isoluecine - Valine - Glutamate - Stop mRNA~ AUG - CCG - UUU - GGA - UGG - UGU - GGG - UAA
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What is the Sequence Con’t Amino Acids tRNA DNA
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Terms Gene regulation - ability of an organism to control which genes are transcribed in response to the environment Operon - section of DNA that acts as an on/off switch for transcription Mutation - permanent change occur in a cells DNA point mutation - one base is exchanged for another (substitution) Frame shift mutation - when a gain or a loss of a base Duplication - when bases are duplicated Expanding mutation - repetitive bases Mutagen - Certain chemicals and radiation that can damage DNA sequences
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Genetic Mutations
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Test Info TEST - 10 questions Vocabulary with its definition DNA Helicase, tRNA, DNA polymerase, Codon, rRNA, mRNA, genetic code, ribose, deoxyribose, RNA polymerase, anticodon, replication, transcription, translation, ribosomes, x-ray diffraction, and Hydrogen bond Historical Contributions Match the scientist with his/her contributions Griffith, Avery, Hershey Chase, Franklin, Watson Crick, Chargaff Comparing Molecules Compare molecules of DNA, mRNA, and tRNA know the structure!!!!!!! Matching Codons Fill in a table like we did in class know the DNA, mRNA, tRNA, and the amino acid Processes Exactly from our notes The process of DNA replication, transcription, and translation
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Book Review Review Page 353 #’s: 3-5, 8-11, Pg.354 #’s: 17, 18, 26-28, 30, 34 Pg.356-357 #’s: 1-5, 9, 10, 12, 13, 16-18
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