Week 5 Flashcards
Prokaryotic gene regulation:
What is the example of the inducible operon ?
Lac operon in bacteria
Prokaryotic gene regulation: (inducible operons)
In the absence of the inducer, a ______ is bound to the operator and no transcription occurs.
Repressor
Prokaryotic gene regulation: (Repressible operons)
The operon is transcribed in the absence of the ______. A co-repressor may also be needed to bind and activate the repressor before transcription will be ____.
repressor
inhibited
what 5 methods are present in Availability or amount of DNA level regulation (Eukaryotes) ?
- Chromatin remodeling
- DNA methylation
- Gene Deletion
- Gene amplificaiton
- Gene Rearrangement
What method is present for Transcriptional level of regulation in Eukaryotes ?
Gene specific transcription factors
What are the 5 levels of control in regulation of gene expression in eukaryotes ?
- Availiability or amount of DNA
- Transcriptional control
- Post-transcriptional control
- Translational control
- Post-translational control
What are the methods present for gene regulation in the Post-transcriptional level of control?
- Alternative splicing
2. mRNA editing
What are the methods present for gene regulation in the Translational level of control ?
- Translational initiation
2. mRNA stability or accessibility
What are the two main methods used for gene regulation in the Post-translational level of control?
- Phosphorlyation
2. Proteolytic cleavage
In DNA methylation under gene regulation, what bases can be methylated to reduce levels of gene transcription?
C and G
will make the DNA more Negative so that it binds tighter to Histones
What is the best example of Gene deletion level gene regulation in mammals?
- Development of Erythrocytes
- cells will destroy its nucleus and its entire DNA (during differentiation- cell continues to produce large amounts of globin from pre-sythesized mRNA but cannot produce other proteins
Gene amplification by the cell is used in _____ instances when proteins are needed more rapidly than the chromosomal number would permit.
rarely
What is the example of gene rearrangement used for gene regulation (DNA level)
Mammalian immune system is capable of generating diverse antibodies capable of recognizing any array of antigens
-Also, Transposons- migratory pieces of DNA that can insert themselves into DNA
At the transcriptional level of control, what are the examples of the gene specific transcription factors ?
- Nuclear hormone superfamily (steroid/thyroid hormones- common domain structure of central DNA binding domain and C-terminal hormone binding domain
- Super-family recognizes the hormone response element (HRE) to activate the expression of genes containing it
some pre-mRNA transcripts give rise to multiple mature mRNAs. They can be processed in more than one way, this is known as _____ ______.
alternative splicing
Use of alternative splice-sites in the same pre-mRNA allows the synthesis of different proteins from _______.
the same gene
Where is alternative splicing know to occur?
Tissue-specific or developmental fashions
mRNA editing is a ____ type of RNA processing event that alters the sequence of RNA ______.
rare
after it is formed
RNA editing refers to an alteration in the nucleotide sequence of RNA, the sequence of the mRNA differs from the ______ encoding it.
exons
What is the example of mRNA editing in mammals?
Apolipoprotein- in apoB transcripts in the small intestine, a cytidine in the coding region is converted to uridine generating a premature stop codon (otherwise in the liver it is normal and longer protein)
in the translational level of control, translation initiation has for an example of gene expression control ….?
Phosphorylation of translation initiator protein eIF2 results in decreased translation
Describe mRNA stability or accessibility at the translational control level of gene expression ?
- approach used by cell to quantitatively regulate output of a gene
- mRNAs vary greatly in their stability, with half-lives ranging from a few minutes to more than a day
- Example is Ferritin translation (accessibility)
The operon contains ?
Promotor and then all of the structural genes (can have multiple genes for one promoter region on Prokaryote DNA)
What happens when an operon is regulated on or off?
All of the genes within the operon are either turned on or off, can not seperate them