Chapter 11 Lecture Notes What is DNA made of? A pentose sugar (deoxyribose) A phosphate Purine and pyrimidine bases (nitrogenous bases) Adenine, guanine, cytosine, thymine Deoxyribose + base + phosphate= nucleotide Nucleotides can be mono, di, or trinucleotides DNA has an antiparallel orientation A pairs with T G pairs with C G and C have triple bonds A and T have double bonds Melting proteins destabilize hydrogen bonds How is DNA replicated? Semi conservative process Double stranded DNA splits apart and each strand is replicated into daughter strands How does information flow from genes to proteins? DNAtranscriptionRNAtranslationproteins Transcription Transcripted to: Ribosomal RNA Messenger RNA- carries genetic info to proteins Transfer RNA Small regulatory RNA How does RNA differ from DNA? Has an ?OH group at position 2 Uses uracil instead of thymine How is the info content in DNA transcribed to produce RNA? Initiation- RNA polymerase binds to DNA Elongation- RNA polymerase synthesizes RNA using DNA template Termination- RNA polymerase dissociates from DNA Promoter initiates transcription Many copies of mRNA come from a single gene How is RNA translated into protein? Initiation- small subunit of ribosome finds start codon then tRNA comes and forms hydrogen bonds to base pair with start codon forming the anticodon, then the large subunit comes and starts translation Elongation- small and large subunit move along strand and tRNA comes in every three bases to base pair with it Termination- subunits meet stop codon and a release factor comes in to release subunits How was the genetic code deciphered? Artificial polynucleotide instead of mRNA helped figure out genetic code Codon tables AUG is the start codon UAA, UAG, UGA are stop codons N terminus to the left, C terminus to the right Proteins either stay in cytoplasm, mitochondria, chloroplast, Peroxisomes, nucleus or the RER Posttranslational modifications or proteins Proteolysis- cleaved Glyocoslyation- sugar added Phosphorylation- phosphate added All mutations are alterations of the nucleotide sequence Point mutation- change in a single base pair Chromosomal mutation- change in segments of DNA Deletions Duplications Induced mutation- due to outside agent, a mutagen A mutagen for cancer is a carcinogen
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