{"id":193,"date":"2015-07-13T20:24:26","date_gmt":"2015-07-13T20:24:26","guid":{"rendered":"https:\/\/courses.candelalearning.com\/biolabsxmaster\/?post_type=chapter&p=193"},"modified":"2017-11-01T15:39:00","modified_gmt":"2017-11-01T15:39:00","slug":"dna-structure-and-function","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/biolabs1\/chapter\/dna-structure-and-function\/","title":{"raw":"DNA Structure and Function","rendered":"DNA Structure and Function"},"content":{"raw":"Our genetic information is coded within the macromolecule known as deoxyribonucleic acid (DNA). DNA\u00a0belongs to a class of organic molecules called nucleic acids<\/strong>. The building block, or monomer, of all nucleic\u00a0acids is a structure called a nucleotide. A nucleotide has three parts: phosphate<\/strong>, deoxyribose sugar<\/strong>, and a\u00a0nitrogen base<\/strong>.\r\n\r\n\"The\r\n\r\nThere are four different nucleotides that make up a DNA molecule, each differing only in the type of\u00a0nitrogenous base. These include adenine<\/strong> (A), thymine<\/strong> (T), cytosine<\/strong> (C), and guanine<\/strong> (G), often indicated by\u00a0their first letters only.\r\n\r\nJames Watson and Francis Crick discovered the three dimensional shape of DNA in the early 1950s. The\u00a0shape, which they described as a double helix, has the shape of a twisted ladder.\r\n\r\n\"This\r\n

The Genetic Code<\/h2>\r\nThink of the four nucleotides that make up DNA as the letters of an alphabet. To spell out a word (in this case\u00a0an amino acid) three \"letters\" from our alphabet are required. Since only about 20 amino acids make up all the\u00a0proteins, having a four-letter alphabet is more than sufficient to spell out the 20 \"words\" (see the calculations\u00a0that follow). The genetic code is universal (almost) for all living things. What this means is that the triplet code\u00a0spells the same amino acid in different organisms, from dolphins to plants to bacteria!\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
Sequence of Nucleotides<\/th>\r\n# Amino Acids Coded<\/th>\r\n<\/tr>\r\n<\/thead>\r\n
one<\/td>\r\n41<\/sup> = 4 (not enough)<\/td>\r\n<\/tr>\r\n
two<\/td>\r\n42<\/sup> =16 (not enough)<\/td>\r\n<\/tr>\r\n
three<\/strong><\/td>\r\n43<\/sup> =64<\/strong> (more than enough)<\/strong><\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n

The Gene Concept<\/h2>\r\nThink of a gene as a segment of DNA on a chromosome that codes for a series of amino acids that when linked\u00a0together makes up what is known as a polypeptide<\/strong>. Polypeptides are then folded into complex three-dimensional shapes that become functional proteins.\r\n

The Central Dogma<\/h2>\r\n\"An<\/a>All organisms use the same fundamental\u00a0mechanism for gene expression.\r\n\r\nDNA \u2192\u00a0RNA \u2192\u00a0Polypeptide \u2192\u00a0Protein\r\n

Protein Synthesis<\/h2>\r\nProtein synthesis is a two step process.\r\n\r\nDNA \u2014(transcription)\u2192 RNA \u2014(translation)\u2192 Polypeptide\r\n\r\nTranscription<\/strong> happens when the information from the DNA template is transcribed onto another form of\u00a0nucleic acid known as ribonucleic acid or RNA (actually messenger RNA).\r\n\r\nTranslation<\/strong> happens when the information from the language of nucleic acid is translated into the language of\u00a0proteins.\r\n

Part 1: DNA to Protein Exercise <\/strong><\/h2>\r\nThe following DNA sequence is part of the gene that controls dimples. Decode the DNA message into mRNA,\u00a0tRNA and finally amino acids. Use the genetic code chart to fill in the table below.\r\n\r\nNote: The genetic code is\u00a0based on mRNA (not DNA or tRNA). When you have finished this, you will be able to determine the\u00a0phenotype of the person the DNA came from. (If arginine is the 3rd amino acid, the person will have dimples.)<\/em>\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
DNA<\/th>\r\nmRNA codon<\/th>\r\ntRNA anticodon<\/th>\r\nAmino Acid<\/th>\r\n<\/tr>\r\n<\/thead>\r\n
C\r\nG\r\nA<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
G\r\nT\r\nC<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
G\r\nC\r\nA<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
T\r\nA\r\nA<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n
    \r\n \t
  1. \"06_chart_pu3\"<\/a>Does the person with the\u00a0sequence above have dimples?<\/li>\r\n \t
  2. What two great tasks are\u00a0carried out by our genetic\u00a0machinery?<\/li>\r\n \t
  3. What name do we call a three-nucleotide sequences of mRNA?<\/li>\r\n \t
  4. How many DNA bases does it\u00a0take to code for an RNA codon?<\/li>\r\n \t
  5. How many amino acids does an\u00a0RNA codon code for?<\/li>\r\n \t
  6. What brings amino acids to the\u00a0ribosome<\/li>\r\n \t
  7. What is the difference between transcription and translation?<\/li>\r\n \t
  8. True or false: Most of the DNA in the human genome codes for proteins.<\/li>\r\n<\/ol>\r\n

    Part 2: Protein Synthesis Exercise <\/strong><\/h2>\r\nDNA: 3\u2032 AG C C G T A GAA T T 5\u2032 <\/strong>\r\n
      \r\n \t
    1. Using this strand of DNA as a template, draw a picture<\/strong>\u00a0of the complete DNA molecule. Include all<\/strong>\u00a0parts of the DNA molecule. You do not need to draw your molecule with atomic accuracy.<\/li>\r\n \t
    2. Now draw a complete picture of the mRNA strand that will be made from this DNA. Label<\/em>\u00a0the\u00a05\u2032 and 3\u2032 ends of your mRNA strand. (Use the given DNA strand at the top of this page as your\u00a0template . . .)<\/li>\r\n \t
    3. Carefully indicate the codons present in the mRNA strand from question 2.<\/li>\r\n \t
    4. Draw a complete<\/strong>\u00a0picture of all the tRNA molecules that will match up with the codons from the\u00a0previous question. Include\u00a0all appropriate<\/strong>\u00a0amino acids in your picture, and do not mix up\u00a0their order!<\/li>\r\n \t
    5. Draw a picture of the completed protein coded for by this strand of DNA (abbreviations are fine).\u00a0Show the amino acids in the same order they would be observed in the finished protein.<\/li>\r\n<\/ol>\r\n

      Part 3: Protein Synthesis Bingo<\/h2>\r\nFill in the boxes with 16 of the 20 amino acids. Every bingo square will be unique. Then listen as random\u00a0nucleotide sequences are pulled from the hat. Listen carefully to what kind of sequence is called! Use the\u00a0mRNA codon chart on the previous page to determine the amino acid associated with each sequence.\u00a0(Printable version here.<\/a>)\r\n\r\n\r\n\r\n\r\n\r\n\r\n
      alanine\u2014ala\u2014A<\/td>\r\ncysteine\u2014cys\u2014C<\/td>\r\nhistidine\u2014his\u2014H<\/td>\r\nmethionine\u2014met\u2014M<\/td>\r\nthreonine\u2014thr\u2014T<\/td>\r\n<\/tr>\r\n
      arginine\u2014arg\u2014R<\/td>\r\nglutamine\u2014gln\u2014Q<\/td>\r\nisoleucine\u2014ile\u2014I<\/td>\r\nphenylalanine\u2014phe\u2014F<\/td>\r\ntryptophan\u2014trp\u2014W<\/td>\r\n<\/tr>\r\n
      asparagine\u2014asn\u2014N<\/td>\r\nglutamic acid\u2014glu\u2014E<\/td>\r\nleucine\u2014leu\u2014L<\/td>\r\nproline\u2014pro\u2014P<\/td>\r\ntyrosine\u2014tyr\u2014Y<\/td>\r\n<\/tr>\r\n
      aspartic acid\u2014asp\u2014D<\/td>\r\nglycine\u2014gly\u2014G<\/td>\r\nlysine\u2014lys\u2014K<\/td>\r\nserine\u2014ser\u2014S<\/td>\r\nvaline\u2014val\u2014V<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n\"Empty<\/a>\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
      <\/td>\r\nSequence Called<\/td>\r\nDNA? mRNA? tRNA?<\/td>\r\nCodon<\/td>\r\nAA<\/td>\r\n<\/tr>\r\n
      1<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      2<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      3<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      4<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      5<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      6<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      7<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      8<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      9<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      10<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      11<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      12<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      13<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      14<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      15<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      16<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      17<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
      18<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n

      Part 4: Wheat Germ Extraction<\/h2>\r\nWheat germ is the sprouting embryo contained within a wheat kernel (the wheat seed). The remainder of the\u00a0wheat kernel is called the endosperm, and is the food storage site for the developing embryo. Our task today is\u00a0to break down the cells within the wheat germ and remove the DNA.\r\n

      Materials<\/h3>\r\n