Protein Synthesis

• DNA molecule


  A type of nucleic acid made up of nucleotides, composed of phosphate group, sugar (deoxyribose), and nitrogenous bases (A, T, C, G), has two strands that run antiparallel, nitrogenous bases held together by hydrogen bonds, has a double-helix structure
• Chromosomes


  Compacted DNA, or DNA that is wrapped around protein structures
• Four Types of Bases in DNA


  • Adenine
  • Thymine
  • Cytosine
  • Guanine
• Four Types of Bases in RNA


  • Adenine
  • Uracil
  • Guanine
  • Cytosine
• DNA has double-strand

  RNA has single-strand
• DNA is located in the nucleus

  RNA is located in the cytoplasm
• DNA has deoxyribose sugar

  RNA has ribose sugar
• Base Pair of DNA is A - T & G - C

  Base Pair of RNA is A - U & G - C
• DNA Replication


  Process of making copies of DNA, happens in the nucleus for eukaryotic cells before division, occurs before mitosis in a phase called interphase
• Enzymes involved in DNA Replication


  • Helicase
  • DNA Polymerase
  • Primase
  • Ligase
• Process of DNA Replication

  Starts at a certain part called the origin, Helicase breaks the bond between nitrogenous bases, Single-Stranded Binding Proteins (SSB) prevent DNA strands from rejoining, Topoisomerase prevents supercoiling, DNA polymerase adds complementary nucleotides to form new strands, 2 new DNA molecules are formed
• Alternative Process of DNA Replication

  Primase makes RNA primers on both strands, DNA Polymerase replicates DNA molecules, Leading strand replicates smoothly, Lagging strand leaves fragments due to enzyme direction, Okazaki Fragments are left by the lagging strand
• Semi-conservative replication


  DNA replication where a new strand and an old strand are retained
• Types of RNA


  • mRNA
  • rRNA
  • tRNA
• mRNA


  Messenger RNA that brings information from DNA to the cytoplasm for protein synthesis
• rRNA


  Ribosomal RNA that assembles amino acids in the correct order during protein synthesis
• tRNA


  Transfer RNA that supplies amino acids to the ribosome for protein assembly
• Transcription


  Process by which the information in DNA is copied into messenger RNA (mRNA) for protein production, happens in the nucleus
• Process of Transcription


  RNA polymerase binds and opens the DNA to be transcribed, RNA polymerase links free RNA nucleotides to the DNA strand, copying the information into mRNA
• Transcription


  Happens in the nucleus
• Transcription


  1. RNA polymerase binds and opens the DNA that will be transcribed

  2. RNA polymerase slides along the DNA strand and links free RNA nucleotides that pair with the nitrogenous bases of the complementary DNA strand

  3. When the process of base-pairing is completed, the RNA molecule breaks away as the DNA strands rejoin

  4. The RNA leaves the nucleus and goes to the cytoplasm
• Translation


  Process of converting the information in mRNA into a sequence of amino acids that make a protein
• Codonor triplet code


  A sequence of three DNA or RNA nucleotides that corresponds with a specific amino acid or stop signal during protein synthesis
• Triplet code


  A sequence of three DNA or RNA nucleotides that corresponds with a specific amino acid or stop signal during protein synthesis
• Translation


  1. mRNA binds to a ribosome

  2. tRNA molecules, each carrying a specific amino acid, approach the ribosome

  3. tRNA anticodon pairs with the first mRNA (start) codon adenine-uracil-guanine (AUG), to form the initiation complex

  4. The ribosome slides along the mRNA to the next codon

  5. A new tRNA molecule carrying an amino acid pairs with the second mRNA codon

  6. When the first and second amino acids are in place, an enzyme joins them by forming a peptide bond between them

  7. A chain of amino acids is formed until the ribosome reaches a stop codon on the mRNA strand

  8. The polypeptide chain is released and protein synthesis is complete
• Protein Synthesis


  Synthesis – to make something
• Proteins


  • Such as enzymes are mostly amino acids chained together in a certain order
• Genes


  • Make up DNA that codes for proteins
• A human has 46 chromosomes (each cell has 46)
• Human sperm and egg each contain 23 chromosomes
• Chromosomes have genes
• Genes have portions of DNA
• DNA is made up of nucleotides
• The bases in nucleotides have a sequence that makes a difference in genetic coding
• Eukaryotes have multiple origins while prokaryotes have only one
• DNA polymerase can only build in the 5’ to 3’ direction
• The strand that is originally 3’ to 5’ is the leading strand (direction is smooth)
• The strand that is 5’ to 3’ is the lagging strand
• Cytoplasm is the protein manufacturing area
• Monomer are building blocks