Week 3: Gene Expression

University:
The Pennsylvania State University
Course:
BIOL 230W | Cellular Biology
Academic year:

2023
Views:

107

Pages:

1
Author:

Sarah Landeck

BIOL 230W - Week 3 Gene Expression — Prokaryotes have circular DNA and plasmids (assist in organism function) —> almost all DNA in prokaryotes code for proteins, cant regulate expression — Genome size increases with multicellularity (mammals > yeast) —> increases regulatory DNA, regulates gene expression in a genome — Regulatory genes are non-coding, structural genes are coding genes —> reg. genes include promoters, silencers, enhancers, introns, and UTRs —> the only type of structural genes are exons (expressed) — Transcription Factors: proteins that bind to DNA and regulate transcription —> interact with regulatory DNA to turn transcription on and o — TATA box tells transcription factors where to position RNA polymerase — Transcription rate is determined by how fast mRNA synthesis occurs —> depends on number of times transcription initiation complex occurs (made of transcription factors and RNA polymerase) Gene Expression pt 2 — Once DNA is separated, it is 2 strands —> non-coding (template, antisense) and coding (non-template, sense) - coding strand makes mRNA —> the coding strand is the same as the mRNA strand except T sub. U — Incoming nucleotides are always added to the 3’ end of existing nucleotide —> 5’ end is attached to phosphate group — In eukaryotes, pre-mRNA must be processed (3 steps) to become mature ff —> steps = 5’ cap addition, splicesome removes introns, 3’ poly-A tail added