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Unformatted text preview: DNA Structure & Replication- Pyrimidines Cytosine & Thymine -Purines Adenine & Guanine -Nucleotide chains= chemical bonds between sugars and & phosphate backbone-Hydrogen bonds connect bases-Antiparallelism-A&T= 2 bonds-C&G= 3 bonds-Negative phosphate groups attract to positive + histones-Chromatin coiled up DNA 30% DNA, histones, binding proteins & 10% RNA DNA Replication-semiconservative 2 double helices from one -DNA unwinds, builds new nucleotide chain and anneals-Helicase- unwind and hold apart replicating DNA, also repairs errors in replicated DNA-primerase builds RNA primer at the start of each segment-DNA polymerase enzyme adds bases can only add to existing strand attaches to RNA primer-DNAp adds DNA to 3 end replication only from 5 to 3 direction -2 nd strand replicates 3 to 5 DNA loops out and replication is discontinuous Okazaki fragments- 150 nucleotides sealed by ligase From DNA to Protein-Translation DNA Protein folds and functions - Replication Occurs only in S phase G1-S-G2-M Transcription/ Translation Occurs all the time except during M RNA vs. DNA-differences-RNA= single stranded-RNA has Uracil for Thymine -Ribose not Deoxyribose-DNA stores/ RNA controls mRNA- messanger- carries info that specifies a protein-specifies particular codon-cell type specific muscle cell for actin & myosin/ skin for keratin -500- 4500 bases long-Start AUG Methionine -Stop UAG/ UGA/ UAA rRNA- ribosomal- associate with certain proteins to form a ribosome, which structurally support and catalyze protein synthesis.-2 subunits separate in cytoplasm, join at site of init iation of protein synthesis-catalyze formation of peptide bonds (AAs)-100-3,000 bases long t RNA- transfer- binds an m RNA anti- codon at one end and a specific am ino acid at the other and basically transports AAs to a ribosome for protein synthesis. DNA Polymerase DNA Replication requires primer RNA Polymerase Transcription No primer attaches to template DNA Replication Transcription Translation Transcription Factors- proteins which bind DNA at certain sequences, int iating t ranscription at specific sites...
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