100% satisfaction guarantee Immediately available after payment Both online and in PDF No strings attached
logo-home
GEN 7: Expressing the Genome $10.65   Add to cart

Class notes

GEN 7: Expressing the Genome

 3 views  0 purchase
  • Course
  • Institution

Lecture notes from Imperial College London, Medical Biosciences BSc, 2nd year, genetics and genomics (GEN) module. How is genomic DNA expressed, and how is it that different cell types with the same genome receive different instructions? In these notes, I delve deeper into transcription, and how...

[Show more]

Preview 2 out of 6  pages

  • October 4, 2023
  • 6
  • 2022/2023
  • Class notes
  • Andy porter
  • All classes
  • Unknown
avatar-seller
Expressing the Genome
REWATCH VIDEOS !

Anatomy of a gene & gene expression
- gene expression = gene info used to synthesise a functional gene product (protein/ functional RNA)
- protein-coding gene:



sproximal)




regulatory regian

- stages of transcription: initiation - elongation - termination
- basal transcription machinery assembles at promoter
- transcription start site (TSS) core



- TATA box
promoter


RNA pol II + 5 transcription factors - UASs, enhancers, URSs, silencers...
(TFIIB, TFIID, TFIIE, TFIIF, TFIIH)

binds TATA box first + comprises TATA-binding protein (TBP) &
TBP-associated factors (TAFs)
=> initiation complex factors (= the others) bind TFIID

- mRNA processing: 5’-capping, splicing (intron removal), 3’-polyadenylation (poly A tail)
- transcription factor = protein binding at or close to the core promoter => modulate transcription
- DNA helicase = subunit of TFIIH using E from hydrolysis of ATP to open up the DNA double helix
- transcriptome = all mRNA molecules produced


- quantitative PCR (qPCR): quantity (relative abundance) a specific transcript sequence (w/ cDNA)
- gene expression microarrays: detect & quantify transcripts >1,000 genes (w/ fluorescent probes)
- RNA-Seq: uses next gen sequencing to tell which genes are expressed w/ which expression levels
by comparing sequenced fragments to a reference genome

Chromatin environment & gene expression

, - differences in expression of the ~200 cell types are maintained by epigenetic mechanisms
- DNA methylation of the 5th carbon of the cytosine ring => 5-methylcytosine
=> distort double helix
=> inhibits transcription/ silence gene if at promoter sunmethylated (pGislands in
promote

=> occurs at CpG sites (5’ ... CG ... 3’) -> expressed

=> ~30,000 CpG islands (CGIs) in genome
(greater frequency of CpG dinucleotides)
=> many at gene promoters
- 1.5% DNA is 5-methylcytosine
-> silenced



-




- epigenetic inheritance can cause disease
=> genomic imprinting: DNA methylation ensures 1 parental allele is expressed and 1 silenced
=> ex: Prader-Willi Syndrome: silencing of maternal allele by imprinting AND deletion of
paternal allele in region of chr 15 with gene SNRPN
=> feeding problems: hyperphagia, insatiable appetite... + delayed motor skills
=> ex: Angelman Syndrome: silencing of paternal allele by imprinting AND deletion of maternal
allele in region of chr 15 with gene UBE3A
=> nervous system disorder: disabilities, seizures...


- histone tail modifications influence activity status of chromatin (euchromatin/ heterochromatin)
=> acetylation of histone H3 lysine 27: gene expression // tri-methylation: gene silencing
=> tri-methylation of histone H3 lysine 4: gene expression
=> di/ tri-methylation of histone H3 lysine 9: gene silencing


·

The benefits of buying summaries with Stuvia:

Guaranteed quality through customer reviews

Guaranteed quality through customer reviews

Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.

Quick and easy check-out

Quick and easy check-out

You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.

Focus on what matters

Focus on what matters

Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!

Frequently asked questions

What do I get when I buy this document?

You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.

Satisfaction guarantee: how does it work?

Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.

Who am I buying these notes from?

Stuvia is a marketplace, so you are not buying this document from us, but from seller lisaribau. Stuvia facilitates payment to the seller.

Will I be stuck with a subscription?

No, you only buy these notes for $10.65. You're not tied to anything after your purchase.

Can Stuvia be trusted?

4.6 stars on Google & Trustpilot (+1000 reviews)

82215 documents were sold in the last 30 days

Founded in 2010, the go-to place to buy study notes for 14 years now

Start selling
$10.65
  • (0)
  Add to cart