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Regulation of Genes (eukaryotes)

Not all genes in your body are always activated because sometimes you might not be doing something that the gene codes for. Regulation is crucial becomes it tells genes to turn on or off depending on what is happening. If all genes were to be on at all times, a large amount of energy would be used.

Differential Gene Expression: The expression of different genes by cells with the same genome.

Levels of regulation:
DNA replication level: 
  • Helicase unzips the H-bonds.
  • DNA polymerase catalizes the formation of new dna
  • Ligase joins short sections together to make the Dna.
Methylation Level:  Silencing DNA through the process of adding Methyl groups(CH3) this turns genes off. By removing the Methyl groups you turn the genes back on.

Nucleosome level(CHROMATIN STRUCTURE LEVEL):

Nucleosome form when eight separate histones sub units attach to the DNA  molecule.

Nucleosome is the tight loop of DNA and proteins , these nucleosomes coil each other up and stack on top of each other.The end result is a fiber of packed nucleosomes a.k.a a chromatin. After this this fiber is codensed to a thickness of 30 nanometers . Further coiling takes place until it takes the shape of a chromosome.

  • struc1) Promoter is a section in the dna , one promoter belongs to one gene, each gene has its own promoter unlike in a prokaryote. In a prokaryote one promoter can control multiple genes.   
  • struc 2) Multiple proteins work together in protein complexes to activate transciption of one particular gene

TRANSCRIPTION FACTORS can be: both known as transcription factors 

  • activators
  • Inhibitors 

The enhancer and activator interact , fold DNA back as a loop and this loop-atrracts RNA polymerase to start transcribing the gene that is under the control of the promoter. 


  • DNA is wrapped around protein called histone . 
  • Histone Acetylation Level: 


  • Once mRNA (serves as temporary copies of the information found in DNA) is produced through Transcription
  • There are sections called Exons and Introns (structural differences that code for proteins)
  • Exons are sections that code for proteins
  • Introns do not code for any protein they just sit there

(Transcription level)

Splicing level: Goal is to keep all axons inside to cell which code for proteins, and to keep out as many Introns so production of protein is not stropped.

Idea is to gather all Exons first and leave behind all the Introns out a.k.a splicing

Eukaryotic genes, diff sec of DNA.


Transcription is the process of making RNA from DNA template.

DNA is divided into regions, one region is the transcription unit in which RNA will be made, transcription factors are used to turn DNA into RNA such as the RNA Polymerase which synthesizes RNA. 

  • First transcription promoter is TFIID which is also the largest.
  • TBP( part of TFIID) binds to DNA in the transcription unit. 
  • Then TFIIA and TFIIB  also attach. 
  • Then RNA polymerase is attached to the transcription unit 
  • Other transcription factors come along 
  • ATP makes its way into the the transcription level and level of ATP is reduced to turn ATP into ADP and Pi.
  • Methylated cap is added to the 5’ of RNA polymerase as it synthesizes the RNA.
  • RNA makes its way out of nucleus
  • Then through the Cytoplasm 


Post Translational level: 

When proteins still need a few amino acids to be active. For example a protein may be sent to the Golgi Aparatus to be modified. 

Enzymes (kinases ) which add Phosphate to a protein and enzymes that can remove them. A.k.a (phosphatase.) 





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