Ch. 29 Transcription and Regulation of Gene Expression

All cells contain what three major classes of RNA that participate in protein synthesis ?

MRNA, rRNA, and tRNA

All RNA’s are synthesized from DNA templates by …

DNA dependent RNA polymerases (transcription)

Only …..direct the synthesis of proteins

MRNAs

RNA polymerases link NTP’s what are they ?

ATP, GTP, CTP, and UTP

In DNA dependent RNA polymerase where does the polymerase move and where does the RNA chain grow ?

The polymerase moves along the DNA strand in the 3’-5’ direction

The RNA chain grows 5’-3’during transcription

Nucleotide sequences that identify the location of transcription start sites where transcription begins

Promoters

Without a sigma bond, the core polymerase can transcribe DNA into RNA but cannot…

Intimate transcription at specific sites

Template vs Nontemplate stand

Template- strand of duplex DNA that is read by RNA polymerase

Nontemplate- the strand not read by RNA polymerase

The four stages of Transcription

1. Binding of RNA polymerase holoenzyme to template DNA at promoter sites

2. Initiation of polymerization

3. Chain elongation

4. Chain termination when in contact with stop codons

RNA polymerase binding sites

1. Initiation site- bind ATP and GTP (most RNA’s begin with a purine at 5’ end)

2. Elongation site- binds second incoming NTP

The core polymerase without sigma is..

The elongation enzyme

An ATP dependent helicase that moves along the RNA transcript, unwinds the hybrid and releases RNA chain

Rho

Induction vs Repression

Induction- increased synthesis of enzymes in response to the presence of a metabolite

Repression- decreased synthesis in response to a metabolite

An accessory protein used to activate transcription

Catabolism activator protein