9.6 Chromatin, Transcription, RNA Processing

Question 1

the “poly-A addition signal” is integral for the 3’ processing. What other sequence is?

Answer 1

a string of U or GU nucleotides

Question 2

what disease is associated with incorrect splicing? (bood cells - incorrect expression of globin genes)

Answer 2

thalassemias

Question 3

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 _______.

Answer 3

8, DNA, histone H1

Question 4

The exposed 5’ end of the new RNA is modified by a methylated nucleotide (5’ 7-methyl guanosine). What is this called?

Answer 4

the mRNA cap

Question 5

how does a single gene generate multiple different proteins?

Answer 5

differential/alternative splicing

Question 6

at the extreme 5’ end of an intron, there is usually a “___-___” (nucleotide sequence)

Answer 6

G-U

Question 7

what are the three functions of the mRNA cap?

Answer 7

1. binds to a protein complex which is important for translation
2. allows for recognition of mRNAs vs. other RNAs without caps
3. helps to protect the 5’ end of the RNA from degradation

Question 8

what is the “poly-A addition signal”

Answer 8

5’ - AAUAAA - 3’

Question 9

on the intron sequence, there is always an “_____” that signifies the branch point

Answer 9

A

Question 10

a small family of basic proteins. They have a positive charge and thus interact strongly with the negative outside of DNA

Answer 10

histones

Question 11

at the extreme 3’ end of the intron, there is always a “__-__” (nucleotide sequence)

Answer 11

A-G

Question 12

proteins that help facilitate splicing are called: _______

Answer 12

snRNPs

Question 13

nucleosomes themselves are wrapped into a more elaborate structure/sprial called a _________

Answer 13

solenoid

Question 14

the solenoid structure decreases DNA length by ____ fold

Answer 14

8

Question 15

a _________ is added at the 3’ end of a transcript

Answer 15

poly-A tail

Question 16

describe the two main steps in the splicing of introns from transcripts

Answer 16

1. the branch point nucleotide attacks the 5’ splice junction and cleaves the backbone at this point
2. The 3’ OH of the first exon sequence then reacts with the 5’ end of the next exon, to precisely excise the intron

Question 17

the nucleosome decreases DNA length by ____ fold

Answer 17

5

Question 18

the process of transcription starts with DNA and makes ____

Answer 18

RNA

Question 19

in a gene, the __________ are expressed and the ________ are intervening regions, not expressed.

Answer 19

exons, introns

Question 20

what protein lies outside the histone and is thought to hold the DNA in place?

Answer 20

histone H1

Question 21

_____ 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.

Answer 21

thalassemia
GU
incorrect