Exam #1 W 9/26 at 7-8:30pm in UTC 2.102A Review T 9/25 at 5pm in WRW 102 and in class 9/26

The relationship between DNA and genes Fig 8.3 The relationship between DNA and genes a gene promoter coding region terminator non-gene DNA

Promoter sequences in E. coli Fig 8.7

Transcription initiation in prokaryotes: sigma factor binds to the -35 and -10 regions and then the RNA polymerase subunits bind and begin transcription Fig 8.8

Transcription Elongation Fig 8.9 Transcription Elongation

Termination of Transcription Fig 8.9

Eukaryotic promoters are more diverse and more complex

Transcription initiation in eukaryotes Fig 8.12 Transcription initiation in eukaryotes

Some genes code for RNA (tRNA, rRNA, etc) mRNA is used to code for proteins RNA synthesis Protein

rRNA is transcribed by RNA polymerase I

tRNA is transcribed by RNA polymerase III

mRNA is transcribed by RNA polymerase II

mRNA is processed during transcription and before it leaves the nucleus. (transcribed from DNA)

Addition of the 5’ cap, a modified guanine Fig 8.13

Addition of the 3’ poly-A tail Fig 8.13 After the RNA sequence AAUAAA enzymes cut the mRNA and add 150 to 200 A’s

DNA Composition: In humans: Each cell contains ~6 billion base pairs of DNA. This DNA is ~2 meters long and 2 nm wide. ~3% directly codes for amino acids ~10% is genes In a single human cell only about 5-10% of genes are expressed at a time.

mRNA is processed during transcription and before it leaves the nucleus. (transcribed from DNA)

Splicing of introns Fig 8.13

Conserved sequences related to intron splicing

Splicing an intron: intron removal. Fig 8.16

Splicing an intron: reattach exons. Fig 8.16

Some introns are self-splicing. Fig 8.18

Alternate splicing of introns/exons can lead to different proteins produced from the same gene.

Complex patterns of eukaryotic mRNA splicing (-tropomyosin) Fig 8.14

Fruit fly DSCAM, a neuron guide, 115 exons over 60,000 bp of DNA 20 exons constitutively expressed 95 exons alternatively spliced For over 38,000 possible unique proteins

Size and Number of Genes for Some Sequenced Eukaryotic Genomes

Some mRNAs are changed after transcription by guide RNA RNA editing: Some mRNAs are changed after transcription by guide RNA http://www.cc.ndsu.nodak.edu/instruct/mcclean/plsc731/genome/genome9.htm http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/R/RNA_Editing.html