BIMM 100 quiz 1 notes

BIMM 100 quiz 1 notes - Macromolecules DNA Replication...

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Macromolecules DNA Replication Transcription Pro v Euk Proteins Macromolecules: 1. DNA- made of a sugar, nitrogenous base and phosphate. DNA is made of monomers called nucleotides and nucleotides are organic bases linked to a 5 carbon sugar that has a phosphate attached to 5’ carbon - sugar in DNA is deoxyribose and in RNA it is ribose Bases Adenine and Guanine are purines and Thiamine, Cytosine and uricil are pyrimidines ribose and deoxyribose differ at the 2’ carbon where ribose has an OH instead of an H—b/c DNA lacks a hydroxyl group at the 2’ carbon there cannot be phosphodiester bond hyrdolysis like there is in RNA DNA and RNA have directionality that goes from 5’ 3’ The chemical linkage between adjacent nucleotides is called a phosphodiester bond (links adjacent nucleotides) DNA and RNA have different 3D conformations One DNA molecule includes many genes Bending of DNA is critical to the dense packing of DNA in chromatin, the protein-DNA complex in which nuclear DNA occurs in eukaryotic cells. RNA nucleotides are different than DNA nucleotides b/c of the sugar
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2. Nucleotide Polymers- adjacent nucleotides are joined by covalent bonds that form between the –OH group on the 3C on one nucleotide and the phosphate on the 5C on the next nucleotide these links create the backbone of sugar-phosphates Adenine base pairs with Thiamine via 2 hydrogen bonds and C with G via 3 Hbonds (purine binds to pyimidine) Hydrophobic and van der waals interactions b/w the stacked adjacent base pairs further stabilize the double-helical structure 3. DNA Strand Separation- During replication and transcription on DNA, the strands of the double helix must separate to allow the internal edges of the bases to pair with bases of the nucleotides being polymerized into new polynucleotide chains. Denaturing of DNA done by increasing temperature to increase thermal energy needed to break hydrogen bonds and other forces that stabilize the double helix Stacked base pairs in duplex DNA absorb less UV-light than unstacked bases in single stranded DNA so single stranded DNA absorbs light better Melting temp of DNA depends on several factors: molecules with more GC pairs will melt at a higher temp than DNA that is AT rich. Also ion conc. Influences Tm b/c low conc. of positively charged increases electrostatic repulsion b/w the two neg charged strands of DNA keeping them further apart and also pH affects the Tm denatured single stranded DNA forms random coils w/o organization in structure renaturing DNA is dependent on time, ion conc and DNA conc
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Torsinal Stress in DNA Unwinding DNA for DNA replication of cicular DNAcauses torsinol stess to relieve torsinal stress, bacteria and eukaryotes have enzyme topoisomerase I which binds to DNA at random sites and breaks phosphodiester bonds in one strand to relieve supercoils that form in DNA Topoisomerase I makes nicks in one strand of DNA and
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This note was uploaded on 02/07/2009 for the course BIMM bimm 100 taught by Professor Dr.sato during the Fall '08 term at UCSD.

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BIMM 100 quiz 1 notes - Macromolecules DNA Replication...

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