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Central Dogma

Central Dogma. Big Idea 3: Living systems store, retrieve, transmit, and respond to info essential to life processes. Essential Knowledge. 3A1: DNA, and in some cases RNA, is the primary source of heritable information. Central Dogma! Protein Synthesis.

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Central Dogma

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  1. Central Dogma Big Idea 3: Living systems store, retrieve, transmit, and respond to info essential to life processes.

  2. Essential Knowledge • 3A1: DNA, and in some cases RNA, is the primary source of heritable information.

  3. Central Dogma! Protein Synthesis • Genetic info flows from nucleotide sequence in a gene to amino acid sequence in a protein

  4. Fig. 5-26-1 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM

  5. Fig. 5-26-2 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2 Movement of mRNA into cytoplasm via nuclear pore

  6. Fig. 5-26-3 DNA 1 Synthesis of mRNA in the nucleus mRNA NUCLEUS CYTOPLASM mRNA 2 Movement of mRNA into cytoplasm via nuclear pore Ribosome 3 Synthesis of protein Amino acids Polypeptide

  7. Types of RNA Involved • mRNA: Carries info from DNA to ribosome

  8. Types of RNA Involved • tRNA: Bind specific amino acids and allow info in the mRNA to be translated into a linear peptide sequence.

  9. Types of RNA Involved • rRNA: functional building blocks of ribosomes (site of translation)

  10. Types of RNA Involved • RNAi:  RNA interference molecules that inhibit gene expression; sometimes destroy mRNA. • 2 molecules involved: microRNA and siRNA (small interfering RNA) that regulate gene expression.

  11. Transcription Occurs Here! Translation Occurs Here!

  12. Transcription • DNA  mRNA, made by RNA polymerase II • RNA polymerase binds on promoter (nucleotide), reads DNA from 3’ to 5’ • 3 stages: Initiation,Elongation, Termination

  13. RULE! • A on DNA complements U on RNA • RNA has no T base!

  14. Initiation • Promoters: start RNA synthesis, TATA box is one in eukaryotes • Transcription factors: help binding of RNA polymerase • Completed assembly called a transcription initiation complex

  15. Fig. 17-8 A eukaryotic promoter includes a TATA box 1 Promoter Template 5 3 3 5 TATA box Template DNA strand Start point Several transcription factors must bind to the DNA before RNA polymerase II can do so. 2 Transcription factors 5 3 3 5 Additional transcription factors bind to the DNA along with RNA polymerase II, forming the transcription initiation complex. 3 RNA polymerase II Transcription factors 3 5 5 5 3 RNA transcript Transcription initiation complex

  16. Elongation • Transcription progresses at a rate of 40 nucleotides per second in eukaryotes

  17. Termination • In bacteria: polymerase stops transcription at end of terminator (nucleotide sequence) • In eukaryotes: polymerase continues transcription after pre-mRNA is cut  polymerase eventually falls off DNA

  18. RNA Processing • Enzymes modify mRNA • Ex: Addition of poly-A tail on 3’ end and a GTP 5’ Cap • Helps export mRNA and protect from degrading hydrolytic enzymes

  19. RNA Processing • RNA splicing: removes introns (noncoding), joins exons (coding)

  20. Translation • mRNA message gets translated into a protein w/ help of transfer RNA (tRNA)

  21. Occurs at Ribosomes • 2 ribosomal subunits (large and small) are made of proteins and ribosomal RNA (rRNA)

  22. Ribosomes • Either free floating in cytoplasm

  23. Ribosomes • Or Attached to Rough Endoplasmic Reticulum

  24. P Site: holds tRNA that carries growing polypeptide chain A Site: holds next tRNA that will add a. acid to chain E Site: holds exit tRNA that doesn’t have an a. acid Ribosomes

  25. Initiation of Translation • mRNA interacts w/ rRNA of ribosome at start codon AUG • mRNA is read in triplets called codons, which encodes a specific amino acid. • tRNA carries the amino acid to the mRNA and ribosome

  26. Termination of Translation • Amino acids join to make a peptide chain • Stop codon stops process, release of new peptide chain.

  27. Amino Acid Sequences

  28. mRNA and Transcription Big green thing = RNA polymerase

  29. Protein Synthesis Videos • NOVA: DNA Secret of Life

  30. Prokaryotic Protein Synthesis

  31. Phenotypes are determined through protein synthesis!

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