Exam #1 is T 9/23 in class (bring cheat sheet) Available M 9/22: 10am-noon, 1:30-2:30pm, and after 3:30pm. T 9/23 after 10am

How do cells express genes?

Tbl 12.3

A processed mRNA ready for translation 5’ untranslated region 3’ untranslated region

Sometimes RNA is the final product.

The ATM repair pathway inhibits RNA polymerase I transcription in response to chromosome breaks Michael Kruhlak, Elizabeth E. Crouch, Marika Orlov, Carolina Montano, Stanislaw A. Gorski, Andre Nussenzweig, Tom Misteli, Robert D. Phair & Rafael Casellas Nature Vol 447 pg 730-734 7 June 2007

How does DNA damage affect transcription? The ATM repair pathway inhibits RNA polymerase I transcription in response to chromosome breaks Michael Kruhlak, Elizabeth E. Crouch, Marika Orlov, Carolina Montano, Stanislaw A. Gorski, Andre Nussenzweig, Tom Misteli, Robert D. Phair & Rafael Casellas Nature Vol 447 pg 730-734 7 June 2007

rRNA is transcribed by RNA polymerase I

comprised of rRNA

rDNA and transcription of rRNA

rDNA is arranged in repeated transcription units Fig 12.16

Fig 12.16 One transcript is then processed into the three major components of ribosomes

How can you measure transcription? Fig 1a

DNA damage inhibits rRNA transciption 0 Gy 10 Gy Fig 1a

More irradiation leads to less transcription Fig 1a

Transcription arrest is transitory Fig 1b

DNA damage by laser. Only damaged nucleoli show decreased transcription. Fig 1c

What cellular components are involved? Ku has been shown in vitro to inhibit RNA pol I after DNA damage. Atm kinase is part of signal transduction following DNA breaks. Fig 2a

Atm must be phosphorylated to mediate the decrease in transcription Fig 2b

Brca1, H2ax, Ku80, and 53bp1 are involved in DNA repair Brca1, H2ax, Ku80, and 53bp1 are involved in DNA repair. Transcription arrest occurs, but resumption is delayed. Fig 2c

DNA damage arrests rRNA transcription via ATM

Combinations of 3 nucleotides code for each 1 amino acid in a protein. Fig 13.2 Combinations of 3 nucleotides code for each 1 amino acid in a protein.

The Genetic Code: 64 codons 20 amino acids 1 start codon 3 stop codons Tbl 13.2 The Genetic Code: 64 codons 20 amino acids 1 start codon 3 stop codons

Translation involves different RNA’s Fig 12.1 Translation involves different RNA’s Protein

rRNA folds up by intramolecular base pairing Fig 13.16

Ribosomes are made of both RNA and protein Fig 13.15

On the ribosome, the mRNA, tRNA’s, and growing polypeptide come together Fig 13.16

The structure of transfer RNA Fig 13.12 The structure of transfer RNA

Fig 13.19 Translation initiation sequences along with the start codon signals the start of translation

Translation initiation in eukaryotes Fig 13.18

The poly-A tail and 5’ cap are involved in translation initiation

The Genetic Code: 64 codons 20 amino acids 1 start codon 3 stop codons Tbl 13.2 The Genetic Code: 64 codons 20 amino acids 1 start codon 3 stop codons

Fig 13.14 Redundancy in codons means that some tRNAs bind to the codon via wobble

mRNAs are usually translated by multiple ribosomes simultaneously

In bacteria, transcription and translation occur simultaneously Fig 13.22

Termination of translation by binding of release factor (a protein) to the stop codon Fig 13.21

All protein interactions in an organism (C All protein interactions in an organism (C. elegans) compose the interactome

post-translational modifications: activation, inactivation, destruction, and translocation RNA synthesis Protein

How do cells express genes?

Exam #1 is T 9/23 in class (bring cheat sheet) Available M 9/22: 10am-noon, 1:30-2:30pm, and after 3:30pm. T 9/23 after 10am