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Chapter 5

BIL 250 Chapter Notes - Chapter 5: Stem-Loop, Ribosomal Rna, Peptide


Department
Biology
Course Code
BIL 250
Professor
Kevin Mc Cracken
Chapter
5

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CHAPTER 5
Transcription
Synthesis of a ssRNA molecule using the DNA template (1 DNA strand transcribed)
In protein synthesis: protein coded gene is transcribed to give mRNA
Occurs in the nucleus
The transfer of genetic information in DNA to RNA base sequences
Important Types of RNA
mRNA: Messenger, encodes amino acid sequence of polypeptide
tRNA: Transfer, transports aminos to ribosomes during translation
rRNA: Ribosomal, ribosomes form with protein
snRNA: Small,nuclear, complex formed with proteins used in eukaryotic RNA processing
miRNA/siRNA: Micro, small interfering, result in gene silencing
Transcription Process (PROKARYOTES)
DNA unwinds next to gene
RNA Polymerase catalyzes synthesis
Transcried 5’-’ fro teplate ’-5’
Initiation
5’ Prooter interacts with RNA Polymerase
RNA coding sequence
’ Teriator deteries top poit
1. RNA Polymerase + sigma factor (a poly) = RNA Poly holoenzyme
Needed for bindind
Different sigma factors = different promotor sequences
2. RNA Poly Holoenzyme binds promoters and untwists DNA
Loose to -35 promoter
Tight to -10 promoter
Elongation
After 8-9 bp of RNA synthesis, sigma factor is released and recycled
RNA Poly completes transcription
DNA untwists and re-anneals
Part hybrid RNA-DNA, most RNA displaced
Termination
TWO TYPES of terminator sequences
Type I (p-INDEPENDENT): takes physical structure
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