2.4 Control of gene expression Flashcards
What is critical for all organisms?
Regulation of gene expression
What are three important things for the regulation of gene expression?
Genes and regulatory elements. Levels of gene regulation. DNA-Binding Proteins
What are operons?
In bacteria, groups of genes that are transcribed as a unit
What are structural genes?
Enconding proteins that are not regulatory
What are two examples of strucutural genes?
Tubulin and enzymes
What are regulatory genes?
Encoding products that interact with other sequences and affect the transcription and translation of these sequences
What is an example of regulatory genes?
Transcription Factors
What are regulatory elements?
DNA sequences that are not transcribed but play a role in regulating other nucleotide sequences.
What is an ex of regulatory elements?
Promoter sequence
What is constitutive expression?*
Genes is always on.
What is positive control?
Turn on gene expression
What is negative control?
Turn off gene expression
Where does transcription begin?
the initial transcription binding site, not the start codon
Why does the splicesome have to be nearly perfect?
Because the message will be trash if its not
What are domains?
group of AA responsible for binding to DNA forming hydrogen bonds with DNA
What is a motif?
Within the binding domain, simple structure that fits into the major groove of the DNA
What are three types of DNA binding proteins?
Helix-turn-helix, zinc fingers, leucine zipper
How are DNA-binding proteins grouped?
On structures or motifs
What is the structure of an operon?
promoter+operator+structural genes
What is a promoter?
region of DNA that initiated transcription of a particular gene
What helped produce the large phenotypic differences between humans and chimps?
Changes in small number of regulatory sequences
How do euk and bac differ pertaining to gene regulation? 3 ways
In euk: 1. Each structural gene has its own promoter and is transcribed separately. 2. DNA must unwind from the histone proteins before transcription. 3. Transcription and translation are separated in time and space.
What is the significance of DNase I hypersensitivity?
These sites have a more open chromatin configuration site. Include promoters, enhancers, insulators, silencers and locus control regions.
What are two ways for histone modification?
Addition of methyl groups to histone tails and addition of acetyl groups to histone proteins
What do chromatin remodeling complexes do?
reposition the nucleosomes, bind to DNA sites and unwind.
What happens when histone proteins are acetylated?
Their charge is altered, allowing transcription factors to bind to DNA. Activating genes.
Where does DNA methylation occur?
In the CpG islands.
whats the difference between active genes and unactive genes?
The Active genes will have the Cs unmethylated. The unactive genes will have the Cs methylated.
What is ChlP?
Tool used to study DNA binding proteins or events. By using antibodies that bind to specific proteins.
What is the initiation of transcription regulated by?
Transcription factors and regulator proteins
What do transcriptional activators and coactivators do?
Stimulate and stabilize basal transcription apparatus at core promoter
What is the main function of mediator complexes?
Transmit signals from the transcription factors to the polymerase
What do enhancers do?
Improve efficiency of transcription
How do euk’s solve the problem of activating different genes that need to work together?
Take transcription recognition sites and swap them out around the genes that need to work together.
What do insulators do?
Blocks the effect of enhancers
What do transcriptional repressors do?
Bind to silencers
How are genes able to respond to multiple inducers (multiple response elements)?
By having complicated promoters.
What are heat shock proteins?
produced by cells in response to exposure to stressful conditions.
What happens if there is no environmental stress?
Transcription stalls near start codon
What is an example of coordinated gene regulation?
Steroid response elements
What are response elements?
Common regulatory elements upstream of the start sites of a collective group of genes in response to a common environmental stimulus.
What are two examples of gene regulation through RNA splicing?
splicing in the T-antigen gene and splicing in the Drosophila sexual development.
What occurs in every category of cancer hallmarks?
Alternative splicing
What are two RNAs used in RNA interference?
siRNAs and microRNAs
What are the components to siRNAs and microRNAs?
Dicer and RISC (RNA-induced silencing complex).
What does microRNAs do?
Turn off genes.
What does MiR-1 do?
Plays a role in shutting down genes in proliferation
What does RNA silencing lead to?
Degradation of mRNA or to the inhibition of translation or transcription
Where do MiRNAs bind to?
3’ end of genes
How can some genes be regulated by processes that affect translation or by modification of proteins?
Proteins bind 5’ UTR. Affect availability of translation machinery.
What is the levels of regulation for bacterial gene control?
Primary transcription
What is the levels of regulation for euk gene control?
Many levels
Is there cascades of gene regulation in bacterial gene control?
Yes
Is there cascades of gene regulation in euk gene control?
Yes
Is DNA-binding proteins important for bac gene control?
Important
Is DNA-binding proteins important for euk gene control?
Important
Is the role of chromatin structure important for bac gene control?
No, Absent.
Is the role of chromatin structure important for euk gene control?
Important
Is negative and positve control present in either bac or euk gene control?
Both present
How is the initiation of transcription in bac and euk gene control?
Bac-Simple. Euk-Complex
Are enhancer common in bac and euk gene control?
Bac-Less common. Euk-common
How does transcription and translation occur in bacterial gene control?
Simultaneously.
How does transcription and translation occur in euk gene control?
separately
How common is regulation by small RNAs in bac and euk gene control?
bac- rare. Euk- common.
