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DNA Replication and Protein Synthesis

DNA Replication and Protein Synthesis. DNA Replication. DNA must make an exact copy of itself. The main players a) DNA helicase 1) DNA helicase unzips DNA strands b) DNA polymerase 1) DNA polymerase does 3 jobs a) make nucleotides

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DNA Replication and Protein Synthesis

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  1. DNA Replication and Protein Synthesis

  2. DNA Replication • DNA must make an exact copy of itself. • The main players a) DNA helicase 1) DNA helicase unzips DNA strands b) DNA polymerase 1) DNA polymerase does 3 jobs a) make nucleotides b) forms the bonds between sugar phosphate molecules and nucleotides c) proofreads the new DNA strand

  3. Overview of Replication 3) Overview of DNA Replication a) DNA unwinds, each strand is used as a template. b) An old strand is paired with a new strand. 1) Pairing old with new guarantees that an exact copy is made because of the base pairing rule

  4. Protein Synthesis 1) There are three steps in protein synthesis: a) DNA Replication DNA makes a copy of itself b) Transcription  DNA is copied into mRNA c) Translation  mRNA code is used to make a protein 2) RNA is “decoded” DNA that makes proteins a) There are three types of RNA 1) messenger RNA (mRNA)  carries the copies of DNA to the rest of the cell 2) ribosomal RNA (rRNA)  makes up most the ribosome where proteins are made 3) transfer RNA (tRNA)  transfers amino acids to ribosomes during translation

  5. 3) Three differences between DNA and RNA Notice that in RNA, the base Thymine is replaced with Uracil. Uracil on RNA will bond with Adenine on DNA.

  6. Protein Review • Proteins are made of one or more polypeptides, each of which consists of a specific sequence of amino acids linked together by peptide bonds. • 20 different amino acids make up proteins. • The sequence of amino acids determines how the polypeptide will twist and fold into the three-dimensional structure of the protein • The function of a protein depends on its three-dimensional shape, which is determined by its amino acid sequence

  7. New Protein Info • DNA provides the genetic code. mRNA is a copy of the code. The code is read 3 bases at a time • Three bases on mRNA is called a codon • Each codon codes for a specific amino acid. • The sequence of bases (and therefore codons) determine the type of protein that is produced. • Some special codons a) The start codon is AUG (also codes for methionine) b) The stop codons UAA, UAG, and UGA cause the ribosome to stop translating a mRNA

  8. Example of Codons Given: Sequence of bases on mRNA Sequence broken into codons Codons translated into amino acids UCGCACGGU UCG – CAC – GGU serine – histidine - glycine

  9. Mutations • Mutations are changes in the DNA sequence that affect genetic information.

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