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DNA Replication

DNA Replication. Structure of the DNA in the cell. Must pack between 1and 3 meters into each cell (except RBCs) Uses a “coiled-coiled strucure” DNA wound around histones Histones cluster into Nucleosomes. Mechanism of Replication. http://www.johnkyrk.com/DNAreplication.html. DNA  mRNA.

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DNA Replication

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  1. DNA Replication

  2. Structure of the DNA in the cell • Must pack between 1and 3 meters into each cell (except RBCs) • Uses a “coiled-coiled strucure” • DNA wound around histones • Histones cluster into Nucleosomes

  3. Mechanism of Replication • http://www.johnkyrk.com/DNAreplication.html

  4. DNA  mRNA Transcription

  5. RNA vs. DNA DNA RNA Ribose Single Stranded (Usually) G, C, A, U bases Fragile • Deoxyribose • Double Stranded • G, C, A, T bases • Durable

  6. Types of RNA • Ribosomal RNA (rRNA) • Transfer RNA (tRNA) • Messenger RNA (mRNA)

  7. Transcription • In the nucleus • RNA polymerase • ONLY ONE SIDE OF DNA IS USED AS A TEMPLATE • RNA is edited by removing introns • Transcription YouTube

  8. Differences in Prokaryotes and Eukaryotes Prokaryotes Eukaryotes DNA is found in chromosomes and large Some pieces of DNA have protein information (exons) Some pieces are used for regulation or have an unknown use (introns) • Genome is small and circular • mRNA is ready for immediate use

  9. 0 mRNA Translation RNAProtein

  10. RNA Splicing • mRNA is transcribed as a whole transcript • Introns = DNA or RNA that does not have information for protein • Exons = DNA or RNA DNA or RNA containing information for proteins • Must splice out introns for RNA to function mRNA Splicing

  11. 0 • mRNA BINDS TO A RIBOSOME • mRNA IS READ AND CONVERTED TO A SPECIFIC AMINO ACID SEQUENCE • mRNA CODES FOR AMINO ACID • tRNA BRINGS AMINO ACID TO RIBOSOME • ANTICODON PAIRS WITH CODON AND BINDS WHILE AA ARE BONDED BY ENZYMES--INTO A PROTEIN CHAIN. • RNA to Protein

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  13. 0 • INFINITE VARIETY OF PROTEINS CAN BE SYNTHESIZED FROM THE 20 AMINO ACIDS. (ANY ORDER & ANY NUMBER OF AA) • THE SEQUENCE OF AA IN A PROTEIN DETERMINES THE CHARACTERISTICS OF THAT PROTEIN.

  14. MUTATION!!! MUTATION!!!!

  15. Gene Mutations • Point Mutation: change of a single nucleotide 1. substitution 2. insertion 3. deletion

  16. Substitution Example

  17. Frameshifts: Insertions and Deletions -shift reading of three letter words (codons) THE CAT ATE THE RAT AND WAS FAT -Remove the first C of CAT (deletion) THE ATA TET HER ATA NDW ASF (ignore AT) -Add and E to THE THE ECA TAT ETH ERA TAN DWA SFA (ignore T)

  18. Chromosomal Mutations • Overall change in the number or structure of chromosomes • Changes in number of chromosomes - Aneuploidys : loss or gain of a whole chromosome e.g. Trisomy 21 Down’s Syndrome 47, X_,+21

  19. Rearrangement of Single Chromosomes

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