Chqpter 18 - Regulqrion Of Gene Expression Flashcards
What type of operon is the trp operon ? Why?
Repressible operon.
Because it’s transcription is usually on but can be inhibited (repressed) by a specific small molecule (tryptophan) that binds allosterically to a regulatory protein.
What type of operon is the lactose operon ? Why?
An indicible operon
Because the operon is usually off but can be stimulated (induced) when a specific small molecule interacts with a regulatory protein.
Which enzyme of the lac operon code for :
- beta-galactosidase
- permease
- transacetylase
- lac Z
- lac Y
- lac A
Which operon is common in catabolic pathways?
Indicible
Which operon is common in anabolic pathways?
Repressible
What are examples of negative gene regulation?
Repressible and inducible operons
If corepressor is bound to the repressor, are genes expressed?
No
What does acetylation of histone tails promote?
Loose chromatin structure that permits transcription, the DNA is accessible for transcription
What does histone methylation promote?
It increases or decreases transcription of genes, depending on which amino acids are methylated.
Usually reduces transcription
Whether or not genes are expressed depends on the concentration of ___
Activators
In liver cells, activators required for expression of ___ are present.
Albumin
In lens cells, activators required for expression of ___ are present.
Crystallin
What can block the translation of specific mRNAs?
miRNA and siRNA
Cancer causing genes are
Oncogenes
Process of going from protooncogene to oncogene
- Translocation
- Gene amplification
- Point mutation
