Notes on Nucleic Acids 2 types of nucleic acids: DNA – deoxyribonucleic acid RNA – ribonucleic...
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Transcript of Notes on Nucleic Acids 2 types of nucleic acids: DNA – deoxyribonucleic acid RNA – ribonucleic...
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Notes on Nucleic Acids2 types of nucleic acids:DNA deoxyribonucleic acidRNA ribonucleic acidChapter 8
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organic compoundslarge, made of subunits called nucleotides Click image for interactive journey into human DNA
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Each DNA nucleotide is made up of 3 parts:1. Phosphate group2. Deoxyribose 5 carbon sugar3. Nitrogen base either adenine, thymine, cytosine, or guanine
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Nitrogen basesPurines adenine (A) and guanine (G)
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Pyrimidines thymine (T) and cytosine (C)
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The bases are held together by weak hydrogen bondsBase pairings in DNA:A T C G
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A model of DNA was constructed in 1953 at Cambridge University in England
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Scientist James Watson, (1951-1953)Field of study biologyCountry - America
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Scientist Francis Crick (1951-1953)Field of study biophysics Country - England
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Their model is described as a double twisted helix (looks like a twisted ladder)Watson and Crick published their proposed DNA double helical structure in a paper in the journal Nature in April 1953. In this paper Watson and Crick acknowledged that they had been "stimulated by.... the unpublished results and ideas" of Wilkins and Franklin.
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Scientist Maurice Wilkins, (1950-1953)Field of study biophysics Country - England
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Scientist Rosalind Franklin, (1951-1953)Field of study Molecular Biology (x-ray diffraction)Country - England Click image for interpret-ation of the X-ray
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The process by which DNA builds an exact copy of itself - replicationfirst the double helix must be unwound this is done by enzymes called helicasesthen DNA polymerases (enzymes which move along each DNA strand) add nucleotides to the exposed bases
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Replication occurs every time a cell divides, therefore passing the DNA code on into every cell
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Genes are the DNA-encoded information that specifies particular proteins;Each gene is made of a specific sequence of nucleotides
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The working structures of genes are made of RNA RNA structure:1. Consists of a single strand of nucleotides
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2. Ribose a 5 carbon sugar3. Uracil (U) instead of thymine (T) uracil is paired with adenine
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RNA base pairings:A U C G
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Three types of RNA mRNA messenger RNA2. tRNA transfer RNA 3. rRNA ribosomal RNA All are needed for processing the information from DNA into proteins (gene expression)
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Differences in DNA and RNA:DNARNA1. double stranded single stranded2. thymine uracil3. nucleus only cytoplasm4. deoxyribose sugar ribose sugar
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Gene expression occurs in two stages:1. Transcription information in DNA is transferred to mRNA2. Translation the information in mRNA is used to make a protein
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Roles of DNA & RNA in transmitting genetic informationStory time: the analogyComp Book Draw the Flow Map: DNA expression in the cellYou need your pencil plus three colors:Pencil will draw cell membrane/ cell parts/ labelsRED: DNA moleculesBLUE: any RNA moleculesPURPLE: protein
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DNA RNA
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RNA protein
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1. Transcription (DNA RNA) occurs in nucleusbegins with the enzyme RNA polymerase which binds to the promoter
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Promoter a specific sequence of DNA that acts as a start signal for transcriptionTerminator a sequence of bases that tells the RNA polymerase to stop adding nucleotides
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Transcription Video
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mRNA is an RNA copy of a gene used as a blueprint for a proteincarries hereditary information from DNA and delivers it to the site of translationacts as a template for the assembly of amino acids
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tRNA acts as an interpreter moleculetranslating mRNA sequences into amino acid sequences
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rRNA plays a structural role in ribosomes
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2. Translation (RNA proteins) occurs in cytoplasm @ a ribosomeboth free ribosomes & ribosomes attached to ERuses nucleic acids to synthesize proteins
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involves all three RNA types:rRNA in the ribosome
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mRNA containing the genetic message
message is made of codons
AUG-AAA-UAC-CCU-CCA-GCG-GGA
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Codon a series of three-nucleotide sequenceseach codon corresponds to an amino acid or signifies a start or stop signal
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tRNA carrying specific amino acids to be joined
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AUG-AAA-UAC-CCU-CCA-GCG-GGAmRNAtRNAUACtRNAtRNAtRNAGGAAUGGGUProtRNAUUUribosomeMetLysTyrSerTranslation (Example)Growing polypeptide
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Translation: mRNA, tRNA & rRNA in cooperative actionto make proteins!!!
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AUG-AAA-UAC-CCU-CCA-GCG-GGAmRNAtRNAUACtRNAtRNAtRNAGGAAUGGGUProtRNAUUUribosomeMetLysTyrSerTranslation (Repeated)Growing polypeptide
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Translation Video
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A PolysomeCan you ID the 3 RNAs?
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Awesome summary video from www.youtube.com Click here to view