Regulation Of Genetic Expression Flashcards
(21 cards)
What is the reason people having the same cells, creating different types of proteins, and phenotypic appearance ?
Bcuz of the regulation of genetic expression. Even twins have the different phenotypes . According to which gene is being transcribed by which cell and how is it regulated
Gene expression site in prokaryotic and eukaryotic level
Pro- transcription only bcuz of the lack of compartmentalization , everything occurs spontaneously
Eu- different level different time eg, epigenetic gene transcription , post transcriptional modification , transition and translational modification
Eukaryotic DNA can be found in the cytoplasm
False. Only in the nucleus. Only prokaryotic DNA can be spotted in the cytoplasm
Is every gene being transcribed in the cell?
No. The DNA is a compact struture with histones. If every cell is being transcribed ——> messy asa histones need to be unwounded
The promoter sequence activity difference in pro and eu
In eukaryotes, each gene has their own promoter sequence.
What is an operon?
Genes that work together is known as an operon
In prokaryotes, if specific sequence of genes do not need to be transcribed , what will they do ?
There is an operator sequence on DNA where repressors bind to inhibit the transcription of that specific genes
What if the bacteria wants to enhance the gene transcription ?
The small macromolecules binds to activator site
Operons are present only in prokaryotes
False. Although very rare and uncommon, operons are present in some eukaryotic organisms
Lac operon’s structure
Lac Z- breakdown of lactose into small macromolecules
Lac Y - cellular transport of lactose into the cell
Lac A- transacetylase enzyme activity
Lac operon only operates when ———
Lactose is present . Otherwise, the func of LacZ, LacY and LacZ ka tone ma ya tot wuh
When the lactose in present, ———— can bind to ———
Allolactose is present and it can bind to repressor ——> so that repressor cannot bind to operator ===> lactose trancription (+)
When lactose is absent ——> vice versa——> allolactose (-) , repressor binds to the operator and lactose transcription is not
present
When glucose is absent, but lactose is present, how is the activity of lac operon?
Generally thinking, ——> glucose is absent so the cell needs energy and demand for glucose. Lac operon gene can transcribe lactose——> lactose is the dipolyssacharide of glucose and galactose. So lac operon must be activated. Since lactose is also present, the lac gene can operate.
Low level of glucose ——> increased cAMP molecule——> binds to CAP===> CAP binds to CAP binding site ——> activation of transcription
+
Lactose present - allolactose present - binds to repressor protein - repressor cannot bind to operator- the trancription (+)
Combing two, lactose trancription will be very active
How is the trancription of lac operon when both glucose and lactose are presnt
Lactose is present so transcription will be present
But glucose is present so camp conc will be low, camp cannot bind to CAP, CAP cannot bind to CAP binding site——> the lac gene will not be activated,
Summary, the transcription will be present but not be very active
Generally thinking, since glucose is present, the energy is sufficient, it does not need to transcribe more glucose for energy
Lac operon is ——— operon.
Indicible
Lactose shi mha transcribe ml ma shi yin ma transcribe boo
How is the operation of the TRP operon ?
Is it an inducible operon as well like lac-operon?
Tryp operon operates on negative feedback mechanism. Tryptophan present ——> try operon is repressed
Tryptophan absent ——> the tryp operon transcribe .
Tryp operon is the repressible operon . ( it represses when the tryptophan is present.
When tryptophan is present , it binds to repressor protein——> the repressor binds to operator sequence ——> the transcription is inhibited
When tryptophan is absent, the repressor protein is not bound with anything , cannot bind to operator, the transcription proceeds
How can we regulate the epigenetic gene expression of eukaryotes?
Methylation and acteylation of the DNA molecules
Methylation - chromosomes tightly packed together
Acetylation- causes nucleosomes in loose packaging
Temporary- does not chane the DNA base sequence
Epigenetic gene expression is before the ———
Transcription processes
Regulation of transcriptional modification
Eu transcription
- Transcriptional factors
- enhancer regions
- silencer region
- activator proteins
- repressor proteins
When TF 2B binds to the DNA——> DNA bends ——> enhancer regions far away from the promoter region get closer and associate with the TF and promoter regions
Regulation of post transcriptional gene expression
- Splicing ====> splicing introns to produce proteins encoded by specific genes. The alternative splicing ——> different proteins ===> regulation
- Capping and tailing are for stability and to prevent breakdown(stability)
The time RNA spend on cytoplasm is directly proportional to the protein synthesis
Decay rate fast——> less time in the cytoplasm ——> protein synthesis reduced
Decay rate slow——-> more time in cytoplasm——> protein synthesis more
- Micro RNAs and stability —> micro RNA breakdown the RNA and reduce their stability —> less pr-
- Binding of proteins to untranslated regions of the RNAs——> may increase or decrease stability
Addition of ubiquitin group leads to ———
Protein degradation
Addition of uniquitin indicates that protein lifespan is completed ——> those proteins move to proteosomes to be degraded
