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Published byAnnabel Roberts Modified over 9 years ago
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{ DNA Deoxyribonucleic Acid
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History What is passed on from parents to offspring? Protein or DNA? DNA! What is the structure, what does it look like?
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DNA Structure 1.Chargaff 1.Watson, Crick, Franklin and Wilkins
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Chargaff Rule
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Franklin and Wilkins
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Model of DNA Structure
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Hydrogen Bonds Complementary base pairing
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Nucleotide
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Backbone Rungs
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Replication Enzyme that unzips Helicase SSBP’s Single Stranded Binding Proteins Replication Video
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DNA had a 5’ and 3’ side Antiparallel
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Only add to 3’ side of the DNA molecule 5’ and 3’ ends
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Enzyme adds Nucleotide to the 3’ end
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How does so much DNA get copied? - Replication Bubbles - Replication fork
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Primer Short sequence of RNA that is needed to begin DNA synthesis
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DNA Polymerases DNA Polymerase III Only works by adding nucleotides to the 3’ end of the NEW strand Works in 5’ 3’ direction DNA Polymerase I Removes RNA from Primer and adds DNA
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Ligase- attaches Okazaki fragments of the lagging strand “Like Glue”
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DO NOW
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http://highered.mcgrawhill.com/sites/00724373 16/student_view0/chapter14/animations.html# http://highered.mcgrawhill.com/sites/00724373 16/student_view0/chapter14/animations.html# McGraw Hill Website
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Central Dogma DNA RNA Protein
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Transcription
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DO NOW 1. 3 ways DNA is different from RNA
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Transcription 3 Steps 1.Initiation 2.Elongation 3.Termination
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Initiation Promoter Region- beginning of a gene TATA Box - part of the promoter, upstream of the gene -sequence of T’s and A’s RNA Polymerase unwinds the DNA
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Elongation -RNA Polymerase – Only adds to the 3’ end of RNA -Antiparallel -Base pairing rules -U or Uracil instead of T -mRNA- messenger RNA
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Termination Terminator Sequence- sequence of T’s in the DNA Terminator Sequence- sequence of T’s in the DNA Primary RNA transcript is released (pre-mRNA) Primary RNA transcript is released (pre-mRNA)
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RNA Processing Primary RNA transcript( pre- mRNA), modified before it leaves the nucleus 5’ end G Cap- modified Guanine, tell its to go to the Ribosome 3’ end Poly A tail – inhibit degradation
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RNA Processing Introns- parts of DNA that are not expressed between exons Exons - genes are expressed mRNA splicing- remove the intros - exons exit as mature RNA transcript - expressed Splisosome- cuts the RNA and joins the exons
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Translation 3 nucleotides in the mRNA is called a codon.
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20 amino acids Genetic Code- information encoded in genetic material translated into amino acid sequences 4 x 4 x 4= 64 One start and 3 stop signals
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Universal
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shape
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Average Protein is 400 aa avg RNA ( exons) 1200
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Translation- mRNA to protein tRNA ( transfer RNA)- transfer amino acids to a growing polypeptide Anticodon- complementary to the mRNA codon
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3 steps of Translation 1.Initiation 2.Elongation 3.Termination
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- Bring together mRNA, tRNA, - ribosome ( small subunit) - Binds the 5’ cap - Start codon AUG – Met, Methionine - Then the large subunit - Antibiotics Translation- Initiation
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E site, P site, A site First one tRNA P site, A site afterwards Translation- Elongation
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Termination Translation ends when one of three stop codons, UAA, UAG, or UGA, enters the A site Ribosomes separate, polypeptide released
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Mutations
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Sickle Cell Anemia
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http://www.dnalc.org/resources/3d/17-sickle-cell.html
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438-base sequence.
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Can’t Carry Oxygen
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Tay Sachs Inherited genetic mutation Gene codes for an enzyme that breaks down fatty acids Build up of fatty acids in the brain http://www.pbs.org/wgbh/nova/body/cracking-the-code-of-life.html
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Mutation Change in the nucleotide Sequence ( letters/bases) of a gene 1. Base Substitution ( can be bad or silent) 2. Base Addition/ Deletion- worse - alter group of 3 Affects the PROTEIN
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Mutagens cause Mutations Errors in DNA replication Xray, UV light Sometimes GOOD? How so?
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