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Nucleic Acids and Protein Synthesis How we make the proteins that our body is made of
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I.DNA: Deoxyribonucleic Acid A. Nucleotides are subunits of DNA; Consist of sugar, phosphate, and nitrogenous base
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B. Structure of DNA has 2 parts 1. Backbone of DNA is made of Sugar (Deoxyribose) and Phosphate groups
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2. Rungs of DNA are made up of Nitrogen Containing Bases a. Purines: Two rings i. Adenine (A) ii. Guanine (G)
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b. Pyrimidines: One Ring i. Thymine (T) ii. Cytosine (C)
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C. The Double Helix 1. First proposed by James Watson and Francis Crick in 1953
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D. Complimentary Base Pairing 1. Base Pairs connect to each other with Hydrogen Bonds 2. Cytosine bonds with Guanine and vice versaG-C (Base Pair) C-G (Base Pair) 3. Adenine bonds with Thymine and vice versaT-A (Base Pair) A-T (Base Pair)
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E. DNA replication: making copies of DNA 1. DNA double helix is unzipped using the enzyme Helicase
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2. DNA polymerase moves along the exposed chains and adds nucleotides by using base pairing rules
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II.RNA: Ribonucleic Acid A. Differences from DNA 1. Sugar is ribose not Deoxyribose
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2. RNA is single stranded (DNA is double stranded)
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3. Nitrogenous Base: RNA uses the pyrimidine Uracil (U) instead of Thymine (T) 4. So in RNA Uracil pairs with Adenine U-A A-U
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B. Types of RNA: 1. Messenger RNA (mRNA): a copy of DNA; carries genetic info from the nucleus to the cytoplasm so it can be “read”
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2. Transfer RNA (tRNA): Brings amino acids to mRNA strand so they can be used to make a protein
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3. Ribosomal RNA (rRNA): makes up the ribosomes (where proteins are made)
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III. Transcription: Process in which the genetic information for an organism is copied from DNA to RNA.
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A. RNA is made from DNA by the enzyme RNA polymerase
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B. As RNA polymerase moves along DNA strand, it uses base pairing to add the correct nucleotides C. Promoter: Region of DNA where transcription will begin D. Termination Signal: Region of DNA where transcription stops
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Transcription
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IV.Genetic Code: The exact same code that is used by most organisms to translate mRNA into proteins A. Codons: A 3 letter sequence that codes for a specific amino acid (22 different AA). 1. Codons are read from the mRNA
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V.Translation: the making of polypeptides (proteins) by using the information from the mRNA strand
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A.Steps of translation: 1. mRNA leaves nucleus through pore and goes to cytoplasm
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2. tRNA molecules float in cytoplasm. tRNA contains an anticodon i. Anticodon: corresponding sequence of letters to codon ex. Codon = UCA Anticodon= AGU
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3.Ribosome reads the codons on the mRNA strand and signals for the corresponding tRNA which is carrying an Amino Acid a. Start Codon: Codon that tells the ribosome to begin translation b. Stop Codon: Codon that tells the ribosome to stop translating
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