Student Assessment of Learning Gains (SALG) website

DNA molecule Gene 1 Gene 2 Gene 3 DNA template strand TRANSCRIPTION TRANSLATION mRNA Protein Codon Amino acid

DNA Signal Gene NUCLEUS Chromatin modification Chromatin Gene available for transcription Exon Intron Tail RNA Cap RNA processing Primary transcript mRNA in nucleus Transport to cytoplasm CYTOPLASM Transcription Gene Expression

mRNA in cytoplasm Translation CYTOPLASM Degradation of mRNA Protein processing Polypeptide Active protein Cellular function Transport to cellular destination Degradation of protein

Transcription

33 Promoter TATA box DNA strand 55 33 55 Transcription factors 55 55 33 33 RNA polymerase 55 55 55 33 33 RNA transcript Transcription initiation complex INITIATION

Promoter Transcription unit DNA Start point RNA polymerase 55 55 33 33

Promoter Transcription unit DNA Start point RNA polymerase 55 55 33 33 Initiation 33 33 1 RNA transcript 55 55 Unwound DNA Template strand of DNA

Promoter Transcription unit DNA Start point RNA polymerase 55 55 33 33 Initiation 33 33 1 RNA transcript 55 55 Unwound DNA Template strand of DNA 2 Elongation Rewound DNA 55 55 55 33 33 33 RNA transcript

Promoter Transcription unit DNA Start point RNA polymerase 55 55 33 33 Initiation 33 33 1 RNA transcript 55 55 Unwound DNA Template strand of DNA 2 Elongation Rewound DNA 55 55 55 33 33 33 RNA transcript 3 Termination 55 55 55 33 33 33 Completed RNA transcript

Elongation RNA polymerase Nontemplate strand of DNA RNA nucleotides 3  end Direction of transcription (“downstream”) Template strand of DNA Newly made RNA 33 55 55

Protein-coding segment Polyadenylation signal 33 3  UTR5  UTR 55 5  Cap Start codon Stop codon Poly-A tail G PPPAAUAAA AAA … NEXT: Add the Poly-AAAAAA tail and GTP Cap (UTR = untranslated region)

hn-RNA mRNA Coding segment Introns cut out and exons spliced together 5  Cap Exon1 Intron 55 Exon2 Intron 120 Exon 3 Poly-A tail 5  Cap 5  UTR3  UTR NEXT: (Eukaryotes) Remove Introns Also Alternative Splicing & Trans-splicing occurs SPLICING

RNA transcript (pre-mRNA) Exon 1Exon 2Intron Protein snRNA snRNPs Other proteins 55

RNA transcript (pre-mRNA) Exon 1Exon 2Intron Protein snRNA snRNPs Other proteins 55 55 Spliceosome

RNA transcript (pre-mRNA) Exon 1Exon 2Intron Protein snRNA snRNPs Other proteins 55 55 Spliceosome components Cut-out Intron (lariat) mRNA Exon 1 Exon 2 55

The RNA Tie Club was right!

RNA transcript (pre-mRNA) Exon 1Exon 2Intron Protein snRNA snRNPs Other proteins 55 55 Spliceosome snRNA ->

Amino acid attachment site (a) Two-dimensional structure Hydrogen bonds Anticodon 33 55 tRNA ->

Ribosome mRNA Signal peptide Signal- recognition particle (SRP) CYTOSOL Translocation complex SRP receptor protein ER LUMEN Signal peptide removed ER membrane Protein Insulin! SRP-RNA rRNA in ribosomes

GFP = Green Florescent Protein (from Jelly fish)

Enhancer TATA box Promoter Activators DNA Gene Distal control element Studying Promoters GFP

Enhancer TATA box Promoter Activators DNA Gene Distal control element Group of mediator proteins DNA-bending protein General transcription factors Studying Promoters GFP

Enhancer TATA box Promoter Activators DNA Gene Distal control element Group of mediator proteins DNA-bending protein General transcription factors RNA polymerase II RNA polymerase II Transcription initiation complex RNA synthesis GFP Studying Promoters

Control elements Enhancer Available activators Albumin gene (b) Lens cell Crystallin gene expressed Available activators LENS CELL NUCLEUS LIVER CELL NUCLEUS Crystallin gene Promoter (a) Liver cell Crystallin gene not expressed Albumin gene expressed Albumin gene not expressed GFP (blue) GFP (red) blue! red!

“Brainbow” GFP= Nobel Prize 2008 Martin Chalfie, Roger Tsien and Osamu Shimomura

TRANSCRIPTION RNA PROCESSING DNA RNA transcript 33 55 RNA polymerase Poly-A RNA transcript (pre-mRNA) Intron Exon NUCLEUS Aminoacyl-tRNA synthetase AMINO ACID ACTIVATION Amino acid tRNA CYTOPLASM Poly-A Growing polypeptide 33 Activated amino acid mRNA TRANSLATION Cap Ribosomal subunits Cap 55 E P A A Anticodon Ribosome Codon E