Regulation of Gene Expression (exam 3) Flashcards
(33 cards)
What are housekeeping proteins?
Structural proteins of chromosomes, RNA polymerases, DNA repair enzymes, etc
What are the 7 points of Gene Expression Regulation?
- Transcription initiation
- Posttranscriptional processing
- RNA stability
- Translation
- Protein modification
- Protein transport
- Protein degradation
Housekeeping genes are ______ expressed
constitutively
What is the purpose of long-range looping?
It is used to bring the transcription factors to the promoter region
DNA looping is more common in prokaryotes or eukaryotes?
eukaryotes
What is an operon?
A cluster of genes that share a promoter and regulatory sequences
Most bacterial repressors are
dimers containing alpha helices that insert into adjacent major grooves of operator DNA
What is the recurring structural element in repressors?
HTH motif
What is an advantage to using EMSA over footprinting assays?
binding can be detected when only a small fraction of the labeled DNA fragment is bound
Strong induction of the lac operon requires
lactose and lowered concentration of glucose
What occurs at the trp operon in the presence of trp?
trp binds to the repressor and activates it, resulting in the repressor binding to the operator region and reducing gene expression
What is a riboswitch?
domain of mRNA that can bind a small molecule ligand
Where are riboswitches found?
5’ UTR of bacterial mRNA
What do riboswitches do?
They directly interact with metabolites to regulate expression of the coding region
What impact does ligand binding have on a riboswitch?
ligand binding impacts conformation and activity
DNA changes that contribute to gene expression regulation
Primarily methylation, which is common in the immune system (ex. gene rearrangement of immunoglobulin genes in B cells and T cells)
Transcription changes that contribute to gene expression regulation
histone modifications to enable remodeling of chromatin and attraction of RNA polymerase, use of alternative promoters
Gene loss in eukaryotes
this does not normally occur, the only regular exception is the complete loss of the nucleus to form the mature RBC
Gene amplification in eukaryotes
does not normally occur in mammals, the exception is cancer cells in which normal cellular controls to prevent abnormal DNA replication are often disrupted. amplification of genes that promote resistance to chemotherapy can occur.
Pathological gene amplification is an important mechanism for
drug resistance in cancer cells
Methotrexate
an example of an antitumor drug that acts vi inhibition of dihydrofolate reductase
What is one method that tumor cells can accomplish pathological gene amplification?
generating multiple copies of the DHFR gene region, likely through errors during DNA replication
Posttranscriptional regulation: alternative splicing
Use of specific splice donor and acceptor sites is very dependent on the presence of proteins that bind to the pre-mRNA and act as splicing enhancers or silencers
mRNA stability
long half life for proteins such as albumin
short half life for proteins that regulate the cell cycle
Binding sites of microRNAs influence stability and translation
