sept 14, 2011 new
TRANSCRIPT
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BT-202Netaji Subhas Institute of Technology,
Dwarka, New Delhi.Dr. Amita Pandey
Sept 14, 2011
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• Nucleotide• Nucleoside
• 2’-deoxy-D-ribose• D-ribose
• Pyrimidines• Purines
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Deoxyribonucleotide:-dAMP-dGMP-dTMP-dCMP
Ribonucleotide:-AMP-GMP-UMP-CMP
Nucleoside:-Deoxyadenosine-Deoxyguanosine-Deoxythymidine-Deoxycytidine
Nucleoside:-Adenosine-Guanosine-Uridine-Cytidine
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• Minor bases -methylated-hydroxymethylated-glycosylated
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Phosphodiester bond
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Hydrolysis of RNA molecules
Mixture of 2’- and 3’-monophoaphate
derivatives
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• Oligonucleotide-50 nucleotides polymer
• Polynucleotide-longer polymers
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DNA structure by Watson and Crick1953
-hydrophobic interactions-van der Waals interactions-dipole-dipole interactions
-hydrogen bonds
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• Primary structure: -nucleotide sequence
• Secondary structure:-stable structure taken up by nucleotides
• Tertiary structure:-folding of chromosomes
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Frederich Miescher (1868): isolated and characterized DNA from leukocytes and called it “nuclein”. He found that it was rich in phosphorus and nitrogen.
O. T. Avery, C. MacLeod, and M. McCarty (1940s): first time said DNA was the genetic material.
A.D. Hershey and M. Chase (1952): confirmed that DNA not protein is the genetic material.
E. Chargaff (1940s): “Chargaff’s rules” he said that A = T and G = C.
R. Franklin and M. Wilkins (1950s): DNA molecules are helical with two periodicities along their long axis.
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Watson and Crick (1953):
-hydrophillic phosphate and deoxyribose on outside -hydrophobic bases on inside-two grooves-hydrogen bonding between base pair-antiparallel-10.5 bp in each turn-complementary
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Complementarity laid the foundation for DNA replication
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B-form is the most stable
A form B-form Z-form
-A-form arises dehydration
-Z-form is detectable in both bacteria and eukaryotes
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• Palindrome• Mirror repeats• Hairpins• Cruciforms
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• Triplex DNA• G tetraplex
Hoogstein pairing
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• F. Jacob and J. Monod (1961): proposed the name messenger RNA.
• Transcription: process of forming mRNA on DNA template.
• Monocistronic: mRNA encoding a single polypeptide.
• Polycistronic: mRNA encoding for more than one polypeptide.
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mRNA
G pairs with C and A pairs with U
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• A-form of RNA is predominant form• Hairpins are most common secondary structures
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• rRNA: provides peptidyl transferase activity during translation– Large subunit (LSU): 18S rRNA– Small subunit (SSU): 5S, 5.8S, and 28S rRNAs
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Reversible denaturation and annealing of DNA
-viscosity of DNA-pH-temperature
-absorption of UV light-hypochromic effect-hyperchromic effect
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• Melting point tm
-higher GC content higher
melting temp
Partially denatured DNA
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Hybridization
• Hybrid duplexes-temperature-evolutionary relationship
• Southern hybridization
• Northern hybridization
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Mutations
Alteration in DNA structure that produce permanent changes in the genetic information
-deamination cytosine undergoes deamination spontaneously
Adenine deaminates to HypoxanthineGuanine deaminates to Xanthine
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-depurination-apurinic or apyrimidinic
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• Radiation-cyclobutane pyrimidine dimers-6-4 photoproduct
• Ionizing radiation-ring opening-fragmentation of bases
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• Chemicals-deaminating agents eg. Nitrous acid-alkylating agents
• Oxidative damage-hydrogen peroxide, hydroxyl radicals, and superoxide radicals
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Learning check!
• Phosphatidylethanolamine has a net charge of at pH 7.0.zero
• Lipids molecules are the only essential components of biological membranes.TrueFalse
• Lipids in bilayer have high ratio of diffusion.lateral
• Palmitic acid is a acid.fatty
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• Match Glycerophospholipids CholesterolSphingolipids PhosphatidylcholineSteroid Spingomyelin
• Lipids containing hydrocarbon chain serve as energy stores.TrueFalse
• Ergosterol is a glucorticoid.TrueFalse
• Polyunsaturated Fas contain multiple bonds.double
• Phospholipases are enzymes that catalyze of glycophospholipids.hydrolysis
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• Which of the following is not a complex lipidTriacylglycerolGlycolipidsSphingolipidsPhospholipids
• Sphingolipids are significant components of biological membranes.TrueFalse
• Which FA would have a melting temperaturehigher than palmitic acid (16:0)?Myristic acid (14:0)Palmitic acid (16:1)Oleic acid (18:1)Stearic acid (18:0)
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Assignment # 4
Lehninger:Question 2, 5, 6, 8, and 9.