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DNA G T S P C A C A S P G T
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DNA DEOXYRIBONUCLEIC ACID
PRIMARY FUNCTIONS TO STORE AND USE INFORMATION TO DIRECT THE ACTIVITIES OF THE CELL THE PRODUCTION OF PROTEINS IN THE CELL PROTEINS ARE THE STRUCTURAL UNITS OF THE CELL CPROTEINS ALSO CONTROL ALL CHEMICAL PROCESSES WITHIN THE CELL MUST BE SELF-REPLICATING MAKING EXACT COPIES OF ITSELF EACH NEW CELL CREATED MUST HAVE AN EXACT COPY
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DNA STRANDS Nucleic acids are complex molecules produced by living cells and are essential to all living organisms. These acids govern the body’s development and specific characteristics by providing hereditary information and triggering the production of proteins within the body. This computer-generated model shows 2 strands of deoxyribonucleic acid (DNA) and the double-helical structure typical of this class of nucleic acids. Ken Eward, Photo Researchers, Inc.
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STRUCTURE OF DNA NITROGEN BASES
H C N O H PURINES ADENINE GUANINE PYRIMIDINES O H C N O C H N C C H H O C C N H CYTOSINE THYMINE
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NUCLEOTIDE PHOSPHATE PO4 GROUP ADENINE THYMINE CYTOSINE GUANINE
PENTOSE SUGAR NITROGEN BASE RIBOSE OR DEOXYRIBOSE
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DISCOVERY James Dewey Watson and Francis Harry Compton Crick
The DNA (deoxyribonucleic acid) molecule is the genetic blueprint for each cell and ultimately the blueprint that determines every aspect of a living organism. The DNA molecule was discovered in 1951 by James Watson, Francis Crick, and Maurice Wilkins using X-ray diffraction. In 1953 Watson (left) and Crick (right) described the structure of the DNA molecule as a double helix, somewhat like a spiral staircase with many individual steps. In 1962 Watson and Crick received the Nobel Prize in Medicine for their pioneering work on the structure of the DNA molecule. Photo Researchers, Inc.
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DNA - THE DOUBLE HELIX DNA IS MADE UP OF TWO LONG CHAINS OF NUCLEOTIDES COMPLIMENTRY NITROGEN BASES ARE JOINED LIKE RUNGS IN A LADDER DOUBLE STRANDED - TWISTS AROUND A CENTRAL AXIS TO FORM A STRUCTURE CALLED A DOUBLE HELIX STRUCTURE DISCRIBED BY WATSON AND CRICK IN 1953 PURINE AND A PYRIMIDINE ALWAYS BOND SO RUNGS ARE ALWAYS THE SAME LENGTH HAS A RIGHT HAND TWIST WITH A FULL TURN CONSISTING OF TEN BASE PAIRS STRANDS OF NUCLEOTIDES HELD TOGETHER BY HYDROGEN BONDS ADENINE ONLY BONDS TOTHYMINE(2 HYDROGEN BONDS) CYTOSINE ONLY BONDS TO GUANINE (3 HYDROGEN BONDS)
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COMPLIMENTARITY OF NUCLEOTIDES
ADEINE ONLY BONDS TO THYMINE P A T S S P P S C G S P CYTOSINE ONLY BONDS TO GUANINE
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DNA HELICASE STEP 1: TWO STRANDS UNCOIL AND SEPERATE, THE
DECOILING PROCESS IS ACCOMPLISHED BY DNA HELICASE C G T A S P G T S P C A C A S P G T DNA HELICASE
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T A C G G A C T A T C T G A T C STEP 2: EACH STRAND IS MATCHED WITH A
COMPLIMENTARY NUCLEOTIDE FROM THE NUCLEOPLASM G S P C A S P G T C S P A S P T S P A S P T S P T S P C S P G S P A S P T S P DNA POLYMERASE C S P STEP 3: DNA POLYMERASE FORMS THE SUGAR TO PHOSPHATE BONDS TO CONNECT NUCLEOTIDES
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FINAL STEP: TWO IDENTICAL DNA MOLECULES ARE
G T A S P C G T A S P FINAL STEP: TWO IDENTICAL DNA MOLECULES ARE PRODUCED EACH MOLECULE IS COMPOSED OF ONE NEW AND ONE OLD STRAND SEMI-CONSERVATIVE
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DNA REPLICATION DNA HELICASE UNZIPS THE DNA MOLECULE BY BREAKING HYDROGEN BONDS UNPAIRED BASES ON EACH STRAND REACT AND BOND TO COMPLIMENTARY BASES IN THE NUCLEOPLASM HYDROGEN BONDS ARE RE-ESTABLISHED BETWEEN NITROGEN BASES DNA POLYMERASE - CATALYZES THE FORMATION OF THE SUGAR TO PHOSHATE BONDS TWO MOLECULES ARE FORMED EACH WITH ONE OLD AND ONE NEW STRAND - SAID TO BE SEMI-CONSERVATIVE EACH NEW MOLECULE CONTAINS THE EXACT SAME SEQUENCE OF NITROGEN BASES DUE TO THE COMPLIMENTARY NATURE OF NUCLEITIDE BONDING REPLICATION DOE NOT BEGIN AT ONE END AND PROCEED TO THE OTHER - INSTEAD IT STARTS AT MANY POINTS SIMULTANEOUSLY (OTHERWISE IT WOULD TAKE 16 DAYS)
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ACCURACY AND REPAIR PROCESS MUST OCCUR WITH GREAT ACCURACY
BUILT IN PROOFREADING FUNCTION PERFORMED BY ENZYMES OR PROTEINS DAMAGE TO DNA CAN ALSO OCCUR BODY HEAT RADIATION CHEMICALS A GROUP OF 20 OR MORE REPAIR ENZYMES RECOGNIZE AND REMOVE DAMAGED NUCLEOTIDES NUCLEOTIDES ARE THEN REPLACED
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RNA RIBONUCLEIC ACID LIKE DNA ALSO COMPOSED OF NUCLEOTIDES
3 MAJOR DIFFERENCES SINGLE STRANDED RATHER THAN DOUBLE SUGAR IS RIBOSE INSTEAD OF DEOXYRIBOSE URICIL REPLACES THYMINE AS A NITROGEN BASE THREE TYPES OF RNA MESSENGER RNA (mRNA) CARRIES INFORMATION CONTAINED WITHIN THE DNA MOLECULE TO THECYTOPLASM TRANSFER RNA (tRNA) BRINGS SPECIFIC AMINO ACIDS TO THE SITE OF PROTEIN SYNTHESIS RIBOSOMAL RNA (rRNA) A MAJOR COMPONENT OF THE RIBOSOME
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TRANSCRIPTION DNA SEPERATES DNA MASTER STRAND mRNA STRAND RNA
U C S P G A C A S P G T G T S P C A DNA SEPERATES C A S P G T G T S P C A DNA MASTER STRAND mRNA STRAND U C S P G A C A S P G T P C G T A S RNA POLYMERASE
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STEPS IN TRANSCRIPTION
DNA MASTER STRAND STEPS IN TRANSCRIPTION MESSENGER RNA 1. RNA POLYMERASE BINDS TO DNA AND SEPERATES STRANDS 2. ENZYME DIRECTS FORMATION OF HYDROGEN BONDS BETWEEN DNA MASTER STRAND AND RNA NUCLEOTIDES 3. SUGAR TO PHOSPHATE BONDS AR ESTABLISHED BETWEEN RNA NUCLEOTIDES 4. RNA POLYMERASE CONTINUES TO READ DNA SEQUENCE UNTIL TERMINATION SEQUENCE IS REACHED 5. NEWLY FORMED mRNA IS RELEASED TO CYTOPLASM 6. DUE TO COMPLIMENTARY NATURE OF NUCLEOTIDES BASE SEQUENCE IS PRESERVED FROM DNA TO mRNA U C S P G A T
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The End
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