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Genetics > Chapter 17: The Beginning of the End > Flashcards

Chapter 17: The Beginning of the End Flashcards

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Biology 101 flashcards
1
Q

Activates or Inactivates: Histone methylation occurs at different amino acids

A

Both

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2
Q

Activates or Inactivates: Histone deacetylases remove acetyl groups from N-terminus of histones

A

Inactivates

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3
Q

Activates or Inactivates: Transcriptional activator binds an enhancer sequence

A

No effect

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4
Q

Activates or Inactivates: Histone acetyltransferases attach acetyl groups to the N-terminus of histones

A

Activates

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5
Q

ChIP: What is it?

A

Technique that determines specific locations within genome where proteins interact with DNA

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6
Q

DNase 1 hypersensitive sites

A

Sites approximately 1 kilobase upstream of a transcriptionally active gene where chromatin is cleaved to relax its structures and make DNA accessible

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7
Q

Drosophilia: If male-specific splicing of tra yields male traits in females, what was deleted?

A

Sxl deletion

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8
Q

Drosophilia: If male-specific splicing of dsx yields male traits in females, what was deleted?

A

tra deletion

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9
Q

Drosophilia: If the absence of sex-determining regulatory proteins yields opposite sex traits, what was deleted

A

dsx deletion

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10
Q

How do response elements work to regulate transcription?

A

They are binding sites for transcriptional activators in response to stimuli

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11
Q

RNAi steps

A
  1. dsRNA introduced into cell
  2. Long dsRNA cleaved into short dsRNA
  3. RISC binds to short dsRNA
  4. Sense strand is separated from the antisense strand and degraded
  5. Antisense RNA pairs with target RNA
  6. Target RNA degraded
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12
Q

How do cells have different morphologies and functions if they contain same genetic info?

A

Different cells express particular genes at different levels

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13
Q

Sequence of DNA located upstream of gene that signals the start of transcription

A

Promoter

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14
Q

Regulatory protein that blocks transcription by binding to operator site

A

Repressor

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15
Q

Transcriptional element that blocks the signal between enhancers and promoters

A

Insulator

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16
Q

Gene that controls the expression of 1+ genes by promoting or inhibiting transcription

A

Regulatory gene

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17
Q

Molecule that activates mRNA synthesis by disabling the protein that prevents transcription

A

inducer

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18
Q

Short sequence of DNA located near promoter region that is recognized by repressor protein

A

Operator

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19
Q

What binds directly to DNA sites and repositions nucleosomes/ alters chromatin structure without altering chemical structure of histones directly?

A

Chromatin-remodeling complexes.

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20
Q

What do chromatin-remodeling complexes do

A

Expose promoters, put DNA in more exposed configuration

21
Q

Histone modifications either alter chromatin structure or

A

provide recognition sites

22
Q

HISTONE methylation

A

Repress or activate

23
Q

HISTONE acetylation

A

stimulates transcription, destabilized chromatin.

24
Q

Steps of ChIP

A
  1. Covalent bonds between proteins/DNA
  2. Cell lysed
  3. Antibodies added
  4. DNA fragments without protein destroyed
  5. proteins and antibodies dissociate and destroyed, thus only protein binding regions of DNA remain
25
Q

DNA methylation: Where does it happen? Methylation is associated with what?

A

CpG

Repression of transcription.
Deacetylation of histones

26
Q

The basal transcription apparatus alone does

A

minimal transcription, activators and coactivators help increase this

27
Q

What stimulates and stabilizes the basal transcription apparatus

A

Transcriptional activator protein

28
Q

In the absence of galactose, ___ bocks ___ from activating transcription.

A

GAL80

GAL4

29
Q

What is galactose enhancer?

A

UAS(G)- regulatory sequence.

30
Q

GAL4

A

Stimulates transcription by enhancing assembly of basal transcription apparatus.

31
Q

When galactose present…

A

GAL80 binds to GAL3. Transcription happens, genes that break down galactose transcribed

32
Q

What is insulator? (NOT Silencer)

A

Blocks or insulates effect of enhancers NOT transcription as a whole.

33
Q

How do enhancers affect initiation of promoters so far away?

A

DNA loops out bring promoter and enhancer close together.

34
Q

What is and what is the point of stalled transcription Ex: heat-shock

A

To have genes ready to go. Ex: heat shock.
No stress= stalled transcription
Stress= fast and efficient transcription

35
Q

What allows eukaryotic genes to respond to the same stimulus? What are they called?

A

Response elements: common regulatory elements upstream of the start sites of a collective group of genes in response to a common environmental stimulus/transcription factor.

Found in both promoters and enhancers

36
Q

What are the additional sequences that help promote or repress the use of particular spice sites during RNA splicing?

A

exonic/intronic splicing enhancers and splicing silencers

37
Q

Alternative Splicing: T-antigene

A

SF2: enhances second splice site, resulting in all 3 genes and small t antigen. The T-antigen is needed for replication of the mammalian virus.

38
Q

Alternative Splicing in Drosophila Sex development

A

Females: Sxl, tra pre-mRNA spliced at 3’ site, to produce Tra-2 & Tra. Which have female sprcific splicing of dsx pre mRNA to create the protein.

Males: No sxl protein, nonfunctional tra protein, dsx pre-mRNA (premature stop codon)

39
Q

Which RNA inhibits translation and has imperfect base pair?

A

miRNAs

40
Q

Which RNA pairs perfectly and results in degradation?

A

siRNA

41
Q

What cleaves and processes double stranded RNA into single stranded siRNAs or miRNAs?

A

Dicer

42
Q

4 mechanisms of gene regulation by RNA interference

A
  1. Cleavage
  2. Inhibition of translation (miRNA)
  3. Transcriptional silencing (altering chromatin structure)
  4. Degradation of mRNA (silencer-independent)
43
Q

Sometimes transcription relies on

A

Increase in increase in initiation factor

44
Q

What IS part of basal transcription apparatus?

A

Transcription factors, TAP, RNA polymerase, protein coactivators

45
Q

In mRNA degradation, what must happen before 5’ cap is removed?

A

Shortening of poly(A) tail

46
Q

Name 4 ways most repressors can inhibit eukaryotic transcription

A
  1. Interfere directly with assembly of BTA.
  2. Compete with activators for DNA binding sites
  3. Bind to sites of DNA near activator and prevent it from contacting the BTA.
  4. Repressor bind to response elements that allow genes to stop being transcribed.
47
Q

Mechanisms of mRNA degradation

A
  1. 5’ cap is removed followed by 5’ –> 3’ removal of nucleotides
  2. Nucleotides are removed starting at 3’ end and moving 5’.
  3. mRNA is cleaved at internal sites
  4. mRNA is randomly cleaved and degraded regardless of directionality
48
Q

What does the RITS (RNA transcriptional silencing) complex do? What proteins are found in there?

A

Methylates histone tails, causing them to bind DNA more tightly and restricting transcription of genes.

Methyltransferases.

49
Q

If I want to see evidence of active regions of DNA transcription, I should look at the ability of….

A

DNase 1 to cleave specific sites within the DNA

Genetics (15 decks)

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