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DNA, Replication and Protein Synthesis

DNA, Replication and Protein Synthesis. We wish to suggest a structure for the salt of deoxyribose nucleic acid (D.N.A.). This structure has novel features which are of considerable biological interest… J. D. Watson F. H. C. Crick Nature (magazine) April 25, 1953.

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DNA, Replication and Protein Synthesis

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  1. DNA, Replication and Protein Synthesis We wish to suggest a structure for the salt of deoxyribose nucleic acid (D.N.A.). This structure has novel features which are of considerable biological interest… J. D. Watson F. H. C. Crick Nature (magazine) April 25, 1953 1953 - Watson and Crick Propose the structure of DNA. 1951 - Pauling’s research on proteins gives insight into the structure of DNA. 1952 – Franklin’s work with X-ray diffraction gives further clues as to the structure of DNA.

  2. All the activities of the cell are controlled by DNA. DNA is located in the nucleus of the cell. Just before cell division DNA coils to form chromosomes. A Chromosome is tightly coiled DNA. When a chromosome is unraveled, it reveals DNA’s double helix shape.

  3. What Is The Structure of DNA? S S S S Purines Pyrimidines Adenine Guanine Cytosine Thymine Structure of Nucleotide: BASE SUGAR (deoxyribose) PHOSPHATE P P P P

  4. What Is The Structure of DNA? C G P A T P P G C P P T S S P S S S S S S A P P Sides of Ladder Sides of Ladder Rung Cytosine Guanine Rung AdenineThymine Complimentary Pairs Are: Rung C – G A – T Rung DNA Forms a Ladder Shape called a “Double Helix.”

  5. The Life Cycle of the Cell DNA DNA RNA T T T T T T A A A A A A A A A A A A T T T T T T MET THR LEU ARG G G G G G G G G G C C C C C C C C C C C C C C C G G G G G G Nucleus Transcription Cell Growth and “Everyday Activity” ~ Protein Synthesis ~Transcription  Translation Interphase Translation RNA Nucleus Cytokinesis Cytoplasm is divided up into each cell. ReplicationDNA is doubled so each cell will have an exact copy of DNA. “Replicated DNA” is given to each cell. Replication Mitosis

  6. A T C G 26 letter Alphabet…A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Which is meaningless… t e s a l R b h l a T d c a o g b g e l l n m s r o k o I c h d . Unless… Richard dog black The belongs to small. The letters are put together in a meaningful way: The small black dog belongs to Richard. DNA works the same way. DNA uses a four letter alphabet to direct all of the cell’s activities.

  7. The most important characteristic of DNA is the code which occurs in complementary pairs A, T, C and G. They are the 4 letter alphabet of the genetic code which controls the activities of the cell. T T T T A A A A A A A A T T T T G G G G C C C C C C C C G G G G

  8. This “double helix structure” makes it possible for DNA to make an exact copy of itself. T T T T T T T T A A A A A A A A A A A A A A A A T T T T T T T T G G G G G G G G G G C C C C C C C C C C C C C C C C C C G G G G G G G G 1 DNA “unzips itself.” 2 Free-floating nucleotides attach themselves to each side. DNAPolymerase This is known as replication.

  9. Mitosis:Dividing the DNA When cells divide, they must make a copy of the DNA so the two resulting cells each have the exact same copy of genetic code. Cytokinesis:Dividing of the cell

  10. T T T T T T A A A A A A A A A A A A T T T T T T G G G G G G G G G C C C C C C C C C C C C C C C G G G G G G Cell DivisionThe newly formed cell receives the replicated copy of DNA. The free-floating nucleotides in the nucleus attach themselves to each side of the ladder. Once replicationhas occurred, the cell can now divide into two. Plant cell division: Animal cell division:

  11. Here is a practice website if you are connected to the internet: http://www.pbs.org/wgbh/aso/tryit/dna/shockwave.html

  12. Cells must make a copy of DNA (replication) before the cell divides so that each cell has a copy of the genetic code. Question: What is the genetic code used for? Answer: making proteins Why are proteins important? Blood cell with the correct DNA sequence for shape. Proteins are what make us different. Blood cell with an incorrect DNA sequence for shape. But proteins also make sure that some things stay the same.

  13. DNA carries the genetic code, but it never leaves the nucleus of the cell. So how does DNA direct the activities from the nucleus? The Answer Is… RNA.

  14. MET ARG THR LEU rRNA What is RNA? I take the message from DNA to the ribosome. 1 Messenger RNA(mRNA) 2 Transfer RNA(tRNA) mRNA tells us the order of the amino acids in making proteins. 3 Ribosomal RNA(rRNA) We stay in the ribosome and help with the bonding of amino acids. Ribosome

  15. What Is The Structure of RNA? S S S S Purines Pyrimidines Adenine Guanine Cytosine Uracil Structure of Nucleotide: BASE SUGAR (ribose) PHOSPHATE P P P P

  16. How does RNA differ from DNA? DNA RNA 1 Sugar Ribose Dexoyribose • Sugar in RNA is ribose instead of deoxyribose. Base 2 • The nitrogen base in RNA uracil replaces thymine. Strands 3 • RNA is generally single stranded rather than double stranded.

  17. Interphase Cell GrowthProtein Synthesis:Transcription  Translation Replication Cell Division Mitosis Protein Synthesis 1 Transcription DNA makes messenger RNA (mRNA), and then it is sent to the ribosome. 2 3 Translation Protein Synthesis mRNA serves as the code sotransfer RNA (tRNA) can placethe amino acids in sequence. The protein is made from the coded message. ARG LEU LEU ARG MET THR THR MET

  18. DNA RNA RNA T T T T T T T T T T T T T T DNA Cytoplasm TranscriptionDNA writes its code to make mRNA. Nucleus Next is translation DNA mRNA message sent to Ribosome

  19. The genetic code is built into triplets of nucleotides. (i.e. UGC) • These sequences code for specific amino acids. (i.e. UGC codes for serine) • mRNA triplet code is called a codon. (i.e. UGC on mRNA) • tRNA triplet code is called an anti-codon. (i.e. ACG on mRNA) • The circle chart refers to the codon to identify the amino acid. (i.e. UGC codes for serine) • In this next activity you will learn this “secret code” and make proteins.

  20. VAL LEU tRNA anticodon mRNA Codon mRNA Codon mRNA Codon MET PRO tRNA tRNA tRNA anticodon anticodon anticodon mRNA Codon Phenylal-anine Glycine GlutamicAcid AsparticAcid Leucine U C G A A C G U U G G U A C C A A U C Serine G Alanine G U A C A C A C G U U G Tyrosine G U G U Valine A C Stop A C G U Typtophan G U A C G U Arginine A A C C A Leucine C U G Serine G U A C A C C A Lysine U G G U Proline U G C A Asparagine A C G U U G C A Histdine A G C U Threonine Glutamine Methionine Arginine Isoleucine This Is the “start” codon and begins the amino acid chain.

  21. Interphase Cell GrowthProtein Synthesis:Transcription  Translation Replication Cell Division Mitosis TranslationThe ribosome and tRNA helps assemble the protein chain of amino acids. The amino acids are bonded together to start the protein chain. THR LEU MET ARG

  22. Mutations – Mistakes In DNA Correct Sequence: DNA TAC GCA TGG ATA mRNA AUG CGU ACC UAU MET ARG THR TYR THE FAT CAT ATE Point Mutation Substitution DNA TAC GTA TGG ATA mRNA AUG CAU ACC UAU MET HIS THR TYR THE FTT CAT ATE

  23. Mutations – Mistakes In DNA Correct Sequence: DNA TAC GCA TGG ATA mRNA AUG CGU ACC UAU MET ARG THR TYR THE FAT CAT ATE Frameshift Mutations Insertion Deletion Insertion of another “G” Deletion of “G” DNA TAC GGC ATG GAT A DNA TAC CAT GGA TA mRNA AUG GUA CCU AU mRNA AUG CCG UAC CUAU MET VAL PRO MET PRO TYR TYR THE FFA TCA TAT E THE ATC ATA TE

  24. The Life Cycle of the Cell DNA DNA RNA T T T T T T A A A A A A A A A A A A T T T T T T MET THR LEU ARG G G G G G G G G G C C C C C C C C C C C C C C C G G G G G G Nucleus Transcription Cell Growth and “Everyday Activity” ~ Protein Synthesis ~Transcription  Translation Interphase Translation RNA Nucleus Cytokinesis Cytoplasm is divided up into each cell. ReplicationDNA is doubled so each cell will have an exact copy of DNA. “Replicated DNA” is given to each cell. Replication Mitosis

  25. DNA Strand – DNA Strand – DNA Strand Protein-a Genes  Proteins  Traits TATA Box Helps position RNA Polymerase close to gene Introns Does not code for protein 1 3 5 RNAPolymerase 2 4 6 EnhancerAttracts RNA polymerase to this section of DNA PromoterSequences ExonsCode for Protein 1 3 5 2 4 6 pre-mRNA 1 3 5 mRNA (after splice) This allows millions of different possibilities for proteins.

  26. Protein-b Genes  Proteins  Traits DNA Strand TATA Box Helps position RNA Polymerase close to gene Introns 1 5 15 RNAPolymerase 2 4 6 Exons 1 5 15 2 4 6 pre-mRNA 1 5 15 mRNA (after splice) Exons 1 & 5 in this gene are used to make a different protein. Think of the variety of proteins that can be coded using different combinations of exons!!!

  27. Remember: It is our proteins that make us… Unique (different) Similar. (same) and Blood cell with the correct DNA sequence for shape. Proteins are what make us different. Blood cell with an incorrect DNA sequence for shape. But, proteins also make sure that some things stay the same.

  28. DNA  Proteins  What We Are We wish to suggest a structure for the salt of deoxyribose nucleic acid (D.N.A.). This structure has novel features which are of considerable biological interest… J. D. Watson F. H. C. Crick Nature (magazine) April 25, 1953

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