Genetic Exam 1 - Bacterial Transcription

Central Dogma

DNA -> transcribed into RNA -> translated into protein

Template Strand/ non-coding

The DNA strand that provides the template for ordering the sequence of nucleotides in an mRNA transcript.

3' - 5'

non-template strand (coding strand)

The strand of DNA that is not transcribed during synthesis of RNA. Its sequence corresponds to that of the mRNA produced from the other strand.

5' - 3'

3 stages of transcription

initiation, elongation, termination

Initiation

- occurs in the promoter region

- Consensus Sequences

- (-35 sequence) TTGACA

- (-10 sequence) TATAATA

Transcriptional Start Site

+1

Transcription Factors

proteins that control the rate of transcription

Elongation

RNA nucleotides are added to the chain

RNA Polymerase Structure

6 subunits, 4 unique

- alpha (2x): aid in assembly

- beta (2x): aid in binding and synthesis of RNA

- omega - aids in assembly of core

- sigma: recognizes promoter

Termination

2 types, RHO dependant and RHO independent

Rho Dependent Termination

- Rho utilization site (RUT): region before terminator sequence that signals the P protein

- P protein binds to rut site

- RNA polymerase stops due to hairpin and p protein shoots it off the DNA

Termination Sequence

GC rich region which ends up forming a hairpin structure to pause transcription

Rho Independent Termination

- GC rich region forms hairpin

- second T rich sequence results in a U rich sequence in RNA

- T - U bonds are weak and it dissociatess

Prokaryotic Transcription vs Eukaryotic Transcription

Bacteria:

- RNA polymerase made of 6 subunits

- Promoter Region

- TTGACA -35 from +1

- TATAATA - 10 from +1

- Elongation

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