Chapter 29 Flashcards
mRNA
RNA that is involved in the directly involved in the synthesis of proteins
3 Major Classes of RNA
- mRNA
- rRNA
- tRNA
1st step of gene expression
Transcription
Housekeeping Genes
Genes that are always expressed for basic cellular functions
Promoter
Start sequence that RNA polymerase binds to begin transcription
RNA polymerases eukaryotes
- RNA pol I -> rRNA
- RNA pol II -> mRNA + miRNA
- RNA pol III -> tRNA
RNA polymerase synthesizes in what direction?
5’ - 3’
Operon
Several protein producing genes that are linked together and controlled by one promoter
Two types of regulation of transcription in prokaryotes
- Positive control
- Negative control
Structural genes
Genes that encode for proteins
Lac Operon
Used to create proteins that can break down lactose (catabolism).
Where does RNA polymerase bind to in gene.
Promoter region, -35 -10 region Pribnow box or TATA box
Trp Operon
Used to create enzymes responsible for synthesizing tryptophan (anabolism)
Can allolactose induce transcription in the presence of glucose?
No
CRP
Protein that binds to the regulatory region to indicate the lack of glucose. When glucose levels decrease cAMP levels increase, cAMP then binds to CRP which attaches to the regulatory region telling the RNA polymerase to bind.
Negative control induction
Repressor is bound to DNA, falls off when a co-inducer binds to repressor
Negative control repression
Repressor is not bound to DNA, corepressor binds to repressor and the complex binds to DNA
Positive control induction
Co-inducer binds to inducer activating it on the DNA
Positive control repression
Active inducer falls off DNA when corepressor binds.
Attenuation
Ribosome stalls at stop codon making allowing for regions 3 and 4 to bind and terminates transcription. When the ribosome is stopped at the trp codons regions 2 and 3 bond, but this does not inhibit transcription
Sigma Factor
Binds to RNA polymerase in E.Coli to stimulate its binding and transcription.
