9.6 Chromatin, Transcription, RNA Processing Flashcards
the “poly-A addition signal” is integral for the 3’ processing. What other sequence is?
a string of U or GU nucleotides
what disease is associated with incorrect splicing? (bood cells - incorrect expression of globin genes)
thalassemias
a nucleosome has _______ histone proteins, which forms a disk-like structure. The _____ is wrapped around the outside of this histone core and is held in place by histone _______.
8, DNA, histone H1
The exposed 5’ end of the new RNA is modified by a methylated nucleotide (5’ 7-methyl guanosine). What is this called?
the mRNA cap
how does a single gene generate multiple different proteins?
differential/alternative splicing
at the extreme 5’ end of an intron, there is usually a “___-___” (nucleotide sequence)
G-U
what are the three functions of the mRNA cap?
- binds to a protein complex which is important for translation
- allows for recognition of mRNAs vs. other RNAs without caps
- helps to protect the 5’ end of the RNA from degradation
what is the “poly-A addition signal”
5’ - AAUAAA - 3’
on the intron sequence, there is always an “_____” that signifies the branch point
A
a small family of basic proteins. They have a positive charge and thus interact strongly with the negative outside of DNA
histones
at the extreme 3’ end of the intron, there is always a “__-__” (nucleotide sequence)
A-G
proteins that help facilitate splicing are called: _______
snRNPs
nucleosomes themselves are wrapped into a more elaborate structure/sprial called a _________
solenoid
the solenoid structure decreases DNA length by ____ fold
8
a _________ is added at the 3’ end of a transcript
poly-A tail
describe the two main steps in the splicing of introns from transcripts
- the branch point nucleotide attacks the 5’ splice junction and cleaves the backbone at this point
- The 3’ OH of the first exon sequence then reacts with the 5’ end of the next exon, to precisely excise the intron
the nucleosome decreases DNA length by ____ fold
5
the process of transcription starts with DNA and makes ____
RNA
in a gene, the __________ are expressed and the ________ are intervening regions, not expressed.
exons, introns
what protein lies outside the histone and is thought to hold the DNA in place?
histone H1
_____ is a disease resulting from incorrect expression of globin genes in blood cells. One mutation changed a ____ at the start of an intron into a GC, causing _____ splicing.
thalassemia
GU
incorrect
