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USC / Biology / BIOL 303 / What influences eukaryotic gene expression?

What influences eukaryotic gene expression?

What influences eukaryotic gene expression?

Description

School: University of South Carolina
Department: Biology
Course: Fundamental Genetics
Term: Fall 2016
Tags:
Cost: 25
Name: Genetics week 11 notes
Description: chapter 17; will be on exam 3 on 4/14
Uploaded: 04/02/2017
7 Pages 233 Views 1 Unlocks
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16.8 Ara operon exerts positive and negative control Don't forget about the age old question of What are the three origins of multicellularity?

~ regulator protein → can be positive or negative repressor or inducer

~ Arabinose present → operon is induced; positive regulation

~ Arabinose absent → operon is repression; negative regulation 

If you want to learn more check out What is activated by the parasympathetic nervous system?

Week 11Don't forget about the age old question of What is a social institution for?

Chapter 17: Regulation Of Gene Expression in Eukaryotes

We also discuss several other topics like What is a set of people who interact more or less regularly with one another and who are conscious of their identity as a group?

17.1 Eukaryotic Gene can occur at any of the Steps Leading from DNA to Protein Product Different from Prokaryotes;

  • lots of DNA
  • MRNA processing
  • many chromosomes
  • chromatin structure
  • MRNA with a variety of half-lives
  • Transitional and post translational regulation

If you want to learn more check out What is the relationship between stability & control and pilot workload/acceptance?

Figure 17.12

Chromatin →  DNA → transcription → pre-mRNA If you want to learn more check out When does Communication Start to happen?

                                              ↓

Protein ← Translation ← Ribosome ← MRNA

17.3 Eukaryotic etene Expression is influenced by chromatin Modifications

~ Chromosome territories  → designated areas in nucleus where certain chromosomes are located; can be connected with why certain chromosomes get mutated easier

~ interchromosomal domain  → areas between chromosome territories 

 

Histone Modifications and Nucleosomal Chromatin Remodeling

Repressor and HDAC complex bound: histones deacetylated

Activator binding recruitment of HAT complex:

histones acetylated

Transcription Activated

Repeat deacetylation 

☆ Reduction of positive charge on histone protein weakens interactions between histone and DNA ☆

☆ Figure 17.4 ☆

DNA methylation

~ some genes are very open to methylation because they have a CpG island near promoter

~ CpG indicates methylation site; C* gets methylated

→ Epigenetics; stress, nicotine, infection, carcinogens, UV radiation and inflammation

can all alter DNA and chromatin structure

→ Epigenetics and cancer: tumor suppressor genes can get turned off by CpG

hypermethylation and genetic mutation

~ genetic mutations turn on oncogenes

→ Genomic chromosomal instability can be caused by translocations and/or global hypomethylation;can also lead to cancer

Epigenetics and the Environment

  • environmental effects can cause DNA mutations and alter chromatin structure 
  • Folic acid can increase methylation

ex: agouti-colored mice

17.4 Eukaryotic Gene Transcription initiation is regulated at specific cis-acting sites

~ Focused promoter → promoter in one specific gene area; one major transcript

~ Dispersed promoter → promoters dispersed throughout gene, multiple transcripts

☆ Fig 17-6 and 17.7 ☆

~ many sequences in promoters that affect transcription

Enhancers and Silencers

⤷ stimulate                 ⤷ shuts down

transcription                 transcription

~ proteins that bind to the sites and influence promoter

~ TADS → topologically associating domains

⤷ “neighborhood" of genome; in one TAD, everything interacts, but do not interact with 

stuff in other TADS

17.5 Eukaryotic Transcription is regulated by Transcription Factors that Bind to CIS-Acting Sites

 ⟶ Human Metallothionein VIA Gene

 ⟶ Transcription Factors ⟶ have the ability to recognize and bind to a sequence; activation or repression domain

 ⟶ ex: leucine zipper, helix-turn-helix and zinc finger

17.6 Activators and Repressors interact with General Transcription Factors at the Promoter

 ⟶ Formation of the RNA Pol II Transcription

~ general transcription factors are needed at a promoter to initiate transcription

~ Figure 17.7 shows assembly of general transcription factors

 ⟶ interactions with Activators and repressors

 ~ formation Of DNA loop allow factors that bind to an enhancer or silencer at a distance from a

promoter to interact with general transcription factors in the pre-initiation complex and to regulate the level of transcription 

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