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Bio 101 Exam 5 > Gene Regulation in Eukaryotes > Flashcards

Gene Regulation in Eukaryotes Flashcards

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1
Q

Do Eukaryotes have operons?

A

No- usually one gene per one promoter

  • genes with similar functions often have similar promoters
  • this allows a particular transcription factor to regulate a set of genes with similar functions
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2
Q

Different types of RNA polymerases

A

RNAP 1: rRNA
RNAP 2: mRNA
RNAP 3: tRNA

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3
Q

What binds to promoter DNA?

A

RNAP and 30+ transcription factors

Bacteria only have 1-2

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4
Q

Chromatin Remodeling

A

DNA must be accessible for transcription to occur

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5
Q

Heterochromatin

A

DNA tightly wrapped up by proteins

Inaccessible by RNAP

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6
Q

Euchromatin

A

DNA loosely wrapped, accessible by RNAP

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7
Q

Histones

A

DNA packaging proteins in eukaryotic cells: 4 proteins
The histone octamer is the basic unit of DNA compaction
From here, DNA can be assembled into compact chromatin

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8
Q

Compaction of DNA regulation

A
  • Chemical modification of histones
  • histone tails are POSITIVELY charged due to amino acid side chains
  • DNA is NEGATIVELY charged
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9
Q

Histone acetylaton

A

Acetylating (+) charges on histones neutralizes thecharge:charge interactions between DNA and histones
THIS TENDS TO LOOSEN COMPACTION

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10
Q

Histone Acetyltransferases

A

tend to ACTIVATE transcription

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11
Q

Histone Deacetylases

A

remove acytly groups from histones
INCREASES compaction
DECREASES transcription

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12
Q

DNA methylation

A 
occurs especially at cytosene
CG repreats (CpG DNA)
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13
Q

DNA methyltransferases

A

ADD methylation to DNA

tends to REPRESS transcription

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14
Q

DNA demethylases

A

remove methylation from DNA

tend to ACTIVATE transcription

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15
Q

Transcription Factors

A

-bind first to the promoter of the eukaryotic gene

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16
Q

TFIID (TATA-binding protein)

A
  • binds to TATA sequence (or similar) upstream from the transcription start site
  • other transcription factors pile on
  • together these factors recruit RNA polymerase to the promoter
17
Q

The gene LacI(s) codes for a “super repressor” mutant. The protein product of this gene cannot bind lactose but can still bind DNA. How would the Lac Operon behave in a strain encoding this gene?

A

The strain would not transcribe the Lac operon in any situation

18
Q

THe gene lacI(HTH) codes for a DNA binding domain mutant. THe protein product of this gene can bind lactose but cannot bind DNA. How would the Lac operon behave in a strain encoding this gene?

A

This strain would transcribe the Lac operon only in the absence of glucose but regardless of whether lactose is present or not

19
Q

Imagine that you delete the gene for the catabolite activator protein (CAP). How would this CAP mutant behave?

A

This strain would not transcribe the Lac operon in any situation

20
Q

Imagine that you delete the gene for adenylate cyclase, the enzyme in E. Coli that synthesizes cyclic AMP. How would this mutant behave?

A

This strain would not transcribe the Lac operon in any situation

21
Q

Imagine that you delete the gene for adenylate cyclase, the enzyme in E. Coli that synthesizes cyclic AMP so that it constitutively synthesizes cyclic AMP regardless of glucose availability. How would this mutant behave?

A

This strain would transcribe the Lac operon only in the presence of lactose but regardless of whether glucose was present or absent

22
Q

Imagine that you delete the gene encoding the repressor of the Trp operon. How would this mutant behave?

A

This strain would constitutively express teh Trp operon regardless of the presence of tryptophran

23
Q

Imagine that you mutate the gene encoding the repressor of the Trp operon so that this repressor no longer binds tryptophan. How would this mutant behave?

A

This strain would not be able to express the Trp operon

24
Q

Dehydration response element (DRE)

A

sequence of DNA in the promoters for a set of genes involved in for a set of genes involved in drought response in plants

25
Q

Alternative splicing

A

Allows more than one protein to come from a single gene

26
Q

Regulatory Transcription Factors

A
  • binding of gene regulatory proteins to sites far away from the promoters in the rule in eukaryotes
  • gene regulatory proteins can even bind downstream from the promoters they control
  • extensive looping of DNA allows gene regulatory proteins to contact RNAP
  • combination of negative and positive signals from gene regulatory proteins controls the probability of transcription

Bio 101 Exam 5 (6 decks)

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