Gene Regulation

Question 1

Purpose of Gene Regulation

Answer 1

• Give cell specialized role
• Gene product dosage
• Nuclear Envelope
• Respond to changing environmental stimuli
• Different developmental stages

Question 2

Always transcribed/expressed

• Gene product continuously needed to run the cell
  ex. GAPDH in glycolysis, rRNA genes, Actin

Answer 2

Housekeeping Genes (Constitutively expressed)

Question 3

Transcription and expression is more regulated.

• Transcribed and translated in response to the needs of the cell.
  ex. immune response, development, vasodialators/constrictors, HOX

Answer 3

Conditionally expressed genes (Facultatively expressed)

Question 4

Where does transcription occur?

Answer 4

• Chromosome territory
• Interchromosomal domain
• Transcription factory

Question 5

Each chromosome exists in a defined area of the nucleus.

Answer 5

Chromosome territory

Question 6

Areas of nucleoplasm between chromosomes

-Space

Answer 6

Interchromosomal domain

Question 7

Clusters of transcriptional machinery

Answer 7

Transcription factory

Question 8

• Is essential for transcription
• When bound by GTFs, recruits polymerase and causes basal transcription.
• Other elements fine tune transcription

Answer 8

Core Promoter

Question 9

“next to gene”

consensus sequence

Answer 9

Cis-acting sequence

Question 10

“from someplace else” (away from gene)

Answer 10

Trans-acting sequence

Question 11

Regulatory segments of the eukaryotic gene

Answer 11

-Set of cis acting elements are bound by trans acting factors

Question 12

Regulatory segments of the eukaryotic gene contain:

-Combination of coordinates strength of expression of that gene (can turn up or down gene expression)

Answer 12

• Core promoter
• Proximal elements—close
• Distal elements—far
  
  1. Enhancers
  2. Silencers

Question 13

Regulatory Elements

Answer 13

Enhancers

Silencers

Question 14

Bound by activators
Cis regulating element
-When bound, increase transcription of the gene

Answer 14

Enhancers

Question 15

Bound by repressors

-When bound, transcription is decreased and gene expression is repressed.

Answer 15

Silencers

Question 16

Regulation at the transcriptional level is upstream or downstream from the +1 site?

Answer 16

Upstream

Question 17

Have 2 major domains:

1. DNA binding domain
2. Transcription activation domain
   - Changing shape

Answer 17

Activators

Question 18

Subset of enhancers

• binding allows for the cell to respond to enviornmental changes by expressing genes involved in that response
  ex. ARE (antioxidant response element)

Answer 18

Response Elements

Question 19

Have opposite role of activators

-Decrease transcription

Answer 19

Repressors

Question 20

In response to injunctions from activators, these factors position RNA pol. at the start of transcription and initiate the transcription process

Answer 20

GTFs (General transcription Factors)

Question 21

Each gene has a specific set of regulatory elements that are bound by specific regulatory proteins
-More efficient because no need for more activators

Answer 21

Combinatorial gene regulation

Question 22

To measure expression

Answer 22

Measure amount of products:
1. RNA
2. Protein
Reporter System–located downstream from promoter of interest

Question 23

Histone core is moved so that the gene is accessible to transcription.
-Sliding exposes DNA

Answer 23

Chromatin Remodeling

Question 24

One gene can encode more than one protien because different combinations of exons are spliced together

Answer 24

Alternative Splicing

Question 25

mRNA turnover

Answer 25

• mRNA is degraded in a controlled manner
• Half-life
• Depends on structure of RNA and proteins bound to it and on poly A tail length
• Way to regulate translation of the mRNA transcript

Question 26

mRNA can be stored in such a way that they’re not translated right away.

• Speedy
• Good for immediate response, cell can regulate translation

Answer 26

Differential translation

Question 27

-Protein degradation in response to signals

Answer 27

Proteolysis