Control of gene expression in eukaryotes part 3 Flashcards Preview

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What five properties define active chromatin

i) decondensed structure, absence of histone H1
ii) reduced content in methylated cytosine (5meC)
iii) high proportion of acetylated histones.
iv) Presence of regulatory proteins (mainly activators) bound to their target sites on
the DNA.
v) Increased sensitivity to nucleases


What the four different types of alternative splicing

1. optional exon
2. optional intron
3. Mutually exclusive exons
4. Internal splice site (in an intron)


Define constitutive splicing

Two different splice variants occur from the same strand


Define regulated splicing

Proteins bind that either facilitate or prevent splicing


What is the main factor that causes either a long or short transcript to be generated in the B lymphocyte example?

Conecentration of CstF: if lots of it, short transcript is made


Define nonsense mRNA degradtion

Mechanism that allows the cell to degrade mRNA with a premature stop codon. Makes use of EJCs and UpF proteins to mediate degradation


Define upF proteins

attracted by ribosome and EJC in context of premature stop codon.


Define ADAR

- Adenosine Deaminase Acting on RNA
- often works near splice sites, changing adenosine to inosine.
- inosine has similar properties to guanine


What are the four types of polarizing distribution?

Posterior, anterior, terminal, or dorsoventral


What role does the 3" UTR play?

This is where transport proteins bind the mRNA


What exonuclease shortens Poly-A tails?



What role does the 3'UTR play in degradation

It has target sequences of endonucleases