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Exam 4 Biology Sets > Chapter 19: Control of Gene Expression in Eukaryotes > Flashcards

Chapter 19: Control of Gene Expression in Eukaryotes Flashcards

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1
Q

What is differential gene expression?

A

cells with the same genome express different sets of genes

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2
Q

What does differential gene expression do?

A
  • creates different cell types
  • arranges cells into tissues
  • coordinates activity
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3
Q

What are the four additional levels of gene regulation in eukaryotes?

A
  1. chromatin remodeling
  2. RNA processing
  3. mRNA stability
  4. protein degradation
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4
Q

What is chromatin remodeling?

A

genes must be made accessible

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5
Q

What is RNA processing?

A

splicing can create different combos of exons

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6
Q

What is protein degradation?

A

proteins can be marked and destroyed

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7
Q

What is mRNA stability?

A

mRNAs can be blocked or degraded

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8
Q

Describe histones.

A

DNA wrapped around proteins called histones

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9
Q

What is a nucleosome?

A

DNA + histones

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10
Q

What are the 3 ways chromatin is altered during gene expression?

A
  1. DNA methylation
    2.Histone acetylation
  2. chromatin-remodeling complexes
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11
Q

What is DNA methylation?

A
  • methyl groups (CH3) added to C nucleotides
  • catalyzed by DNA methyltransferases
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12
Q

What does methylation do?

A
  • condenses chromatin
  • low methylation near promoter: increase transcription and vice versa
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13
Q

What is histone acetylation?

A
  • acetyl groups are added to lysine on histone tails
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14
Q

What are histone acetyltransferases?

A
  • HATs
  • add acetyl groups, open DNA
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15
Q

What are histone deacetylases?

A

-HDACs
- remove acetyl groups, close DNA

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16
Q

Acetylation leads to ________ chromatin.

A

decondensed

17
Q

What are chromatin remodeling complexes?

A
  • large enzyme complex that uses ATP to reshape chromatin
  • slide nucleosomes, or knock histones off the DNA
18
Q

What are epigenetics?

A

any mechanism of inheritance due to something other than changes in DNA sequence

19
Q

What are the 2 major implications of epigenetics?

A
  1. epigenetic patterns can be passed to offspring
  2. epigenetic patterns can be altered by environment
20
Q

What is the core promoter?

A

binding site for RNA polymerase

21
Q

Describe promoter proximal elements.

A

close to promoter, allow coordinated regulation of genes of the same type

22
Q

Describe enhancers.

A

far from the promoter, bound by an activator to begin and increase transcription

23
Q

Describe silencers.

A

far from the promoter, bound by repressors and shut down transcription

24
Q

Describe general transcription factors.

A
  1. bind to core promoter to initiate transcription in many genes
  2. not involved in much regulation
25
Q

Describe regulatory transcription factors.

A
  1. bind to enhancers, silencers, promoter-proximal elements
  2. specific for dif types of cells
26
Q

What are the 4 steps of transcription initiation?

A
  1. chromatin remodeling
  2. exposure of promoter and regulatory sequences
  3. assembly of proteins
  4. RNA polymerase binds to core promoter
27
Q

What is chromatin remodeling?

A
  • transcriptional activators bind to enhancers, recruit chromatin remodeling complexes or HATs
28
Q

What is exposure of promoter and regulatory sequences?

A
  • a region of DNA is exposed, including the promoter, promoter-proximal element, and other enhancers
29
Q

What are assembly of proteins?

A
  • other transcriptional activators bind to exposed DNA
  • DNA is looped and activators bind to mediator
30
Q

What is RNA polymerase binds to core promoter?

A
  • GTFs and RNAP assemble on mediator, RNAP binds to promoter and transcription begins
31
Q

What is alternative splicing?

A

the same primary transcript (pre-mRNA) can be spliced in different ways (same gene can yield more than one mature mRNA)

32
Q

What is RNA interference?

A

short single stranded RNAs work w/ a protein complex to bind to mRNAs to cause either…
1. degradation of the mRNA
2. block mRNAs from translation

33
Q

What are the 3 RNA interference molecules?

A
  • microRNAs
  • short interfering RNAs
  • PIWI-interacting RNAs
34
Q

What are the steps of miRNA production?

A
  1. transcription by RNA polymerase II (forms hairpin)
  2. processed and exported from nucleus by special protein complexes
  3. bound by RISC and unwound into single strand
  4. RISC + mRNA base pairs to mRNA (perfect match=mRNA destroyed, imperfect match=prevent translation)
35
Q

What does ubiquitin do?

A

small proteins that are added to a protein to degrade them

36
Q

What does the proteasome do?

A

large complexes that break down ubiquitinated proteins

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