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2012-04-20 00:44:57
section 13

chapter 13 section 13.1 & 13.2
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  1. RNA: Ribonucleic acid
  2. consists of a single long chain of nucleotides.
  3. RNA's nucleotides consist of a:

    *sugar called ribose ribose c5 h10 05

    *phosphate group deoxyribose c5 h10 04

    *nitrogenous base
  4. RNA's bases are:




    *Uracil (not thymine but uracil has the same bonding shape as thymine)
  5. types of RNA:
    *messenger RNA (mRNA)

    *carries the DNA message from the nucleus to the ribosome in the cytoplasm

    *is a single straight strand of RNA nucleotides
    *ribisomal RNA (rRNA)
    *makes up part of a ribosome
    *transfer RNA (tRNA)
    *carries an amino acid to the correct site on the mRNA strand
    *has a cloverleaf shape
    *the 3 bases found at one end of the tRNA ase called "anticodon" these will bond with 3 complementary bases on the mRNA strand called "codon"
  6. protein synthesis

    *the process of making proteins
    *the DNA molecule contains all the "directions" for making all the proteins your body needs
    *each strand of DNA codes for many different proteins
    *there are 2 main steps: transcription & translation.
  7. step 1:
    making a copy (transcribing) of the DNA code for the needed protein

    *occurs in the nucleus of the cell
    *the section of DNA that codes for the needed protein unzips
    *RNA polymerase is the enzyme that binds to regions on the DNA called "promoters" (specific DNA base sequences)
    *it then begins to unzip the DNA section
    *only one of the unzipped strands is used as a template/pattern
    *this one strand contains the code for making the needed protein
    *RNA nucleotides bond to the DNA strand that codes for the needed protein
    *G bonds with C
    *U bonds with A
    *'T' on DNA will bond with 'A' on RNA
    *once the RNA strand is completley made it moves away from the DNA strand
    *the RNA strand is "edited" befor tit leaves the nucleus
    *introns are the peices that are removed from the RNA strand
    *exons are the pieces the are needed and are spliced together once the introns have been removed
    *the edited RNA is now called "messenger RNA" and moved out of the nucleus into the cytoplasm

    DNA strand: GCTATGC

    RNA strand: CGAUACG
  8. every 3 bases in a row on the RNA strand make up a "coden" each codon codes for a certain amino acids
    *there are over 20 different amino acids
    *proteins are made of many amino acids bonded together

    • RNA codons: UCG CAG GGU
    • amino acid it codes for: serine histidine glycine

    the codon AUG is the code for where the protein synthesis will start
  9. step 2: translation
    the code that mRNA transcribed from DNA now needs to be translated so that the amino acids are arranged in the correct sequence

    *occurs in the cytoplasm
    *a ribosome attaches to the mRNA strand and moves down the strand until it finds the start codon "AUG"
    *as the ribosome moves down the mRNA strand from the start codon tRNA anticodons (bases) bond to the mRNA codons (bases)
    *the amino acids that the tRNA's carry bond together
    *the bonded amino acid chain (polypeptide chain) breaks away from their tRNA's
    *the polypeptide chain will fold into its final shape or bond with other chains to form the protein