Chapter 12.3  dna,rna and protein
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Chapter 12.3 dna,rna and protein






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Chapter 12.3  dna,rna and protein Chapter 12.3 dna,rna and protein Presentation Transcript

  • 12.3 DNA, RNA, & Protein
    • Chain of events:
    • DNA -> RNA-> Synthesis of Protein
    • Occurs in ALL living things – from bacteria to humans
  • RNA – Ribonucleic Acid
    • Single stranded helix
    • Contains ribose sugar (not deoxyribose)
    • Uracil replaces thymine
    • 3 types of RNA
    • 1. mRNA (messenger RNA)
    • 2. rRNA (ribosomal RNA)
    • 3. tRNA (transfer RNA)
    View slide
  • Messenger RNA (mRNA)
    • Carries genetic information from DNA
    • Travel from nucleus to the ribosome
    • Direct protein synthesis
    • Ribosomal RNA (rRNA)
    • Helps join the mRNA codons to the tRNA anticodons in the ribosome s. It produce enzymes needed to bond amino acids together during protein synthesis
    • Transfer RNA (tRNA)
    • Transport amino acids to the ribosome
    View slide
    • Transcription- The process of transferring genetic information from DNA to RNA
    • forms one single-stranded RNA molecule
  • Steps of Transcription
    • Step 1: DNA molecule unzips. RNA polymerase binds where mRNA will be synthesized.
    • Step 2: Free RNA nucleotides attach to DNA nucleotides by base pairing
    • Step 3: mRNA strand breaks from DNA
    • Step 4: mRNA leaves nucleus and goes to cytoplasm to the ribosomes
  • Transcription Clip
    • Codon- 3 base code in DNA or mRNA. Each base of a codon in DNA is transcribed in to the mRNA code.
    • The order of nitrogen bases in mRNA will determine the type and order of amino acids in a protein
    • The code is universal - the codons represent the same amino acids in all organisms
    • Three nucleotides code for one amino acid
    • Example – UUU codes for phenylalanine
  • Codons
    • 64 possible codons
    • 20 different amino acids
  • Codons
    • Start Codon
    • AUG
    • Stop Codons
    • UGA
    • UAA
    • UAG
    • Translation- the process of converting the information in mRNA into amino
    • acid chains (proteins)
    • It occurs at the ribosome in the cytoplasm
    • tRNA - brings amino acids to the ribosomes
    • Each mRNA codon joins to the correct tRNA anticodon (complement to the mRNA codon)
    • the end result of translation is the formation of an amino acid chain (protein)
  • Steps of Translation
    • Step 1: tRNA picks up amino acids in cytoplasm and takes to mRNA attached to the ribosome
    • Step 2: The anticodon on the tRNA connects to the complementary codon on the mRNA strand
    • Step 3: The amino acids attach to one another by peptide bonds forming long chains
    • Step 4: When stop codon is reached, translation ends and amino acid strand released
  • Nitrogen Base Sequence
  • Quick Molecular Genetic Terminology
    • Replication = DNA  DNA
    • Transcription = DNA  RNA
    • Translation = RNA  Amino Acids
    • Polypeptide = Chain of amino acids
    • Adenine, cytosine, & guanine = DNA & RNA
    • Thymine = DNA Only
    • Uracil = RNA Only
  • Transcription/Translation Clip