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Genetics (Bio 332) > 14.2 Slides > Flashcards

14.2 Slides Flashcards

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1
Q

Positive regulation

A

when the binding of a regulatory protein to the DNA causes a gene to be expressed

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2
Q

negative regulation

A

when the binding of a regulatory protein to the DNA prevents a gene from being expressed

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3
Q

What is an activator?

A

a regulatoryprotein that promotes gene expression

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4
Q

What is a repressor?

A

A regulatory protein that prevents gene expression

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5
Q

What is an inducer?

A

a small molecule that promotes gene expression

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6
Q

What is a co-repressor?

A

A small molecule that prevents gene expression (typically works with a repressor)

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7
Q

What is a signling molecule?

A

A small molecule that transmits signals to regulatory systems (cell communication)

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8
Q

What is a regulatory sequence?

A

sequences on DNA/RNA that control gene expression (promoters, operators, CAP binding site, etc)

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9
Q

What is a positive feedback loop?

A

when the product promotes the expression of genes, creating more of the product

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10
Q

What is a negative feedback loop?

A

When the product blocks the expression of genes, creating more of the product

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11
Q

In eukaryotes, are different genes required in different cell types?

A

yes

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12
Q

When does eukarotic gene regulation occur?

A
  • at each stage
  • Nucleus: chromatin packaging/unpackaging, transcription, intron processing
  • Cytoplasm: translation, RNA stability, post-translational modifications
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13
Q

When does eukaryotic gene regulation involve multiple layers?

A

eukaryotic gene regulation always involves multiple layers of regulation

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14
Q

Where does gene expression (transcription) occur in eukaryotes?

A

in uncondensed regions of the DNA (eucromatin)

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15
Q

What is chromatin remodeling the result of?

A
  • histone and DNA modifications
  • histone tail acetylation tends to relax chromatin (high expression)
  • DNA methylation tends to lead to tighter compaction (low expression)
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16
Q

What are writers?

A
  • writers introduce modifications on DNA and histone tails
  • Ex. histone acetylases, histone methyltransferases, histone kinases, etc.
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17
Q

What are readers?

A

Readers recognize these modifications and recruit chromatin remodeling enzymes, or recruit transcription factors

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18
Q

What do erasers do?

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A
  • erasers remove the modifications introduced by the writers
  • ex. histone deacetylases, histone demethylases
19
Q

Activators in eukaryotic gene regulatory systems

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A
  • multiple activators are used in eukaryotic gene regulatory systems
  • some activators can bind to enhancer sequences (DNA sequences that can boost the transcription of a gene) that are near (cis) or far (trans) from the promoter
20
Q

What are trans enhancer elements called?

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A

Upstream activating sequences (UAS)

22
Q

What are insulators?

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A
  • cis (near the promoter) regulatory elements
  • recruit proteins that block the action of enhancer elements
23
Q

What is eukaryotic gene regulation through mRNA processing?

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A
  • the control of gene expression that occurs after transcription, but before translation, by modifying pre-mRNA into mature mRNA
  • This includes processes like splicing, capping, and polyadenylation, which can influence mRNA stability and translation efficiency
24
Q

Ex. of eukaryotic gene regulation through mRNA processing: sex determination in flies

Study These Flashcards
A
  • XX:AA female, 1:1
  • XY:AA male 0.5:1
  • It is the ratio of X to A chromosomes that controls sex determination
25
Sex determination in flies: protein products explained
* X creates a protein, and A produces a protein * females (XX) create double the amount of X protein than males (XY) * So, when X and A dimerize, females have some X protein left over * The X homodimer is a transcription factor which leads to Sxl expression
26
What are transcription factors?
* proteins that control gene expression by binding to specific DNA sequences, thereby influencing the process of transcription * They act as regulators, either promoting or repressing gene activity, which ultimately determines which proteins are produced in a cell
27
What does the XX homodimer in flies do? What does this lead to?
* the XX homodimer is a transcription factor thaat leads to expression of Sxl * When sxl is expressed, female sex development is promoted * males do not create enough X protein to form the X homodimer. So, there is no transcription of sxl, and the gene is not expressed... leading to male sex development
28
What is tra? in flies
a protein required for female sex development
29
What is sxl? in flies
sxl is a splicing factor that is required to produce the mRNA that can synthesize the tra protein
30
What is the general structure of euk mRNAs? like, what do they contain
* 1 ORF (sometimes w introns that need to be removed) * 5' CAP (added after transcription) * polyA tail (added after transcription by polyA polymerase) * regulatory information in the 5' and 3' UTRs (untranslated regions)
31
What does the 5' CAP do to euk mRNAs?
* added after transcription * acts as a recognition signal for the ribosome and ensures proper translation * protects mRNA from degradation
32
What does the polyA tail do?
* added after transcription by polyA polymerase * protects mRNA from degredation and enhances translation
33
# eukaryotic gene regulation through mRNA translation/stability What do polyA binding proteins do?
* promote translation * terminate translation * trigger mRNA degradation
34
# gene regulation through RNA switches what is a riboswitch
* a secondary structure in RNAs that occur when a ligand binds that result in a change in protein synthesis * typically in a 5' UTR domain
35
# gene regulation through RNA switches: riboswitch What does thiamine (vitamin B12) do?
* thiamine binds to the mRNA preventing translation of an enzyme needed to synthesize thiamine (thiamine diphosphokinase) * with riboswitches, the ligand that binds is often the product of the gene expression
36
# gene regulation through RNA switches: thermoswitch What is a thermoswitch?
A regulatory segment of an mRNA that forms under certain temperatures
37
What can riboswitches do?
* block transcription by creating transcription termination sequences * recruit factors that cleave RNA * recruit splicing factors to alter intron processing * block the RBS, preventing translation
38
RNAinterference(RNAi): gene regulation through ncRNAs
* In cells, dsRNAs are targeted for degradation * short, non-coding RNAs that are complementary to specific mRNAs can lead to the degradation mRNA targets (and therefore lower protein expression)
39
What are siRNAs and miRNAs?
* small interfering RNA and microRNA * small, noncoding RNA molcules
40
What do researchers use RNAi for?
to lower the gene expression by lowering mRNA levels
41
What is tissue specific promoter?
* ex of RNAi * regulatory sequence of DNA that drives the expression of a gene only in specific tissues/cell types, activates upstream activating sequence
42
What happens when siRNA binds to a target sequence?
* siRNA is complementary to gene of interest * then mRNA for the gene is targeted for degradation, leading to less of that protein
43
What do lncRNAs do?
* regulate gene expression * through transcription regulation, chromatin modifications, and translational regulation * scaffolds (provide a platform for protein-protein or RNA-protein interactions) and decoys (sequester proteins or RNA molecules)
44
gene regulation through post-translational modifications
* modifications to proteins can affect their activity * ex. phosphorylation of an initiation factor blocks translation in the ribosome * ex. ubiquitination targets modified proteins for degradation * ex. acetylation

Genetics (Bio 332) (18 decks)

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