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3.a&p i dna.2010
 

3.a&p i dna.2010

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Power Point I for Dr. Krasilovsky's Bio 110

Power Point I for Dr. Krasilovsky's Bio 110

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    3.a&p i dna.2010 3.a&p i dna.2010 Presentation Transcript

    • A&P I - DNA, RNA & PROTEIN SYNTHESIS
    • Readings for DNA and Protein Synthesis
      • Chap. 3: pages 93; 96; 100-107
      • Skim text - concentrate on lecture notes
      • Importance and structure of DNA: Deoxyribose Nucleic Acid
      • A. Historical Review
        • 1. 1900s - Morgan’s studies with fruit flies showed that genes were located on chromosomes, and chromosomes consisted of protein and DNA
        • 2. 1952 - Hershey-Chase demonstrated that DNA (not protein) was the genetic material of a viral phage
    • B. Structure of DNA
      • 1. Nucleotide monomers:
        • Phosphate
        • Pentose sugar(C 5 ) (Deoxyribose sugar)
        • Organic Nitrogen group: cytosine, adenine, guanine, thymine
    • B. Structure of DNA (continued)
      • 2. Polynucleotide chain with linkage via phosphates to next sugar, with nitrogen base away from backbone of Phos-Sugar-Phos-Sugar
      • 3. Dehydration synthesis
    •  
      • 4. 1954 - classical one page paper in Nature by Watson & Crick using Franklin’s and Wilkins’ data
      • A double helix - 2 polynucleotide strands
      • Sugar-phosphate chains of each strand are like the side ropes of a rope ladder
      • Pairs of nitrogen bases, one from each strand, form the rungs or steps
      • The ladder forms a twist every 10 bases (all from x-ray studies!)
    •  
      • 5. Later confirmation that:
      • # of adenine equal to # of thymine
      • # of guanine equal to # of cytosine
      • This dictates combinations of N-bases that form steps/rungs
      • Does not restrict the sequence of bases along each DNA strand
    • Fig. 3.32
    • C. Replication / Duplication of DNA
      • 1. Due to complimentary base pairing – one strand of DNA polynucleotide determines the sequence of the other polynucleotide strand
      • 2. Therefore, each strand of double stranded DNA acts as a template
      • 3. The double helix first unwinds – controlled by enzymes and uses new nucleotides that are free in the nucleus to copy a complimentary strand off the original DNA strand
    • Models of DNA Replication
      • View A&P Animation - Structure & Replication
      • View 16-07 L4 from BIO text
      • View animation 16-10 (3 and 2)
      • View 16-11
    • 4. Information storage in DNA
      • The 4 nitrogen bases are the “alphabet” or code for all the traits an organism possesses
      • Different genes or traits vary in the sequence and length of the bases
      • ATTTCGGAC vs..... ATTTAC
      • Every three bases = one amino acid in a protein/peptide
    • II. Ribonucleic Acid (RNA)
      • A. Structure of RNA
        • 1. Nucleotide monomer
          • Phosphate
          • Pentose sugar = ribose (extra oxygen)
          • Nitrogen base = A / G / C plus U = uracil instead of thymine
          • Single stranded - possibly
          • 3 types (messenger/transfer/ribosomal RNA)
    • B. Synthesis of RNA - Transcription
      • 1. DNA acts as template, but only one strand of DNA utilized at a given time
      • 2. This exposed strand is controlled by specific enzymes that pair the DNA nucleotides with free RNA nucleotides, which are also present in the nucleus
      • 3. These RNA nucleotides form a single stranded RNA nucleic acid
      • 4. DNA = ATTCGCAT
      • 5. RNA = UAAGCGUA
      • 6. Short segments of DNA transcribed at a time, with start and stop messages
    •  
      • View 17-02
      • View 17-06 movie
      • View 17-06 photos
    • C. Three types of RNA
      • 1. m-RNA: messenger RNA
        • Transcribed from a specific segment of DNA which represents a specific gene or genetic unit
      • 2. t-RNA: transfer RNA
        • Transcribed from different segments of DNA and their function is to find a specific amino acid in cytoplasm and bring it to the mRNA
      • 3. r-RNA: ribosomal RNA
        • Transcribed at the nucleolus -with proteins function as the site of protein synthesis ( in cytoplasm)
    • Three types of RNA
    • III. Protein synthesis = Translation
      • A. Ribosomes = sites of protein synthsis
        • 1. 30 to 40% protein
        • 2. 60 to 70% RNA (rRNA)
        • 3. Assembled in nucleus and exported via nuclear pores
        • 4. Antibiotics can paralyze bacterial ribosomes, but not eukaryotic ribosomes
        • 5. 2 ribosomal subunits - a large and a small
        • 6. There are three sites on the ribosome that are involved in protein synthesis
    • A. Ribosomes (continued) - bring mRNA together with amino acid bearing tRNAs
      • 8. Three ribosomal sites
        • P site - (peptidyl-tRNA) holds the tRNA carrying the growing peptide chain, after several amino acids have been added
        • A site - (aminoaccyl-tRNA) holds the next single amino acid to be added to the chain
        • E site - (exit site) site where discharged tRNA minus amino acids leave ribosome
    •  
    • C. Protein Synthesis
      • 1. One mRNA can bind to several ribosomes termed a polyribosome
      • 17-17 movie and stills
      • 17-18
      • 17-19
      • 17-20
      • 17-21
    • Fig. 3.37 modified
    •  
    • Fig. 3.37
    • Fig. 3.38 modified
    •  
    •