Lecture 8

Question 1

Small ncRNAs are about ____bases in length. There are multiple types, and they are located in the _____ of protein coding genes and act as ________ complexes (RNPs).

Answer 1

200 bases

Introns

Ribonucleoprotein complexes (RNPs)

Question 2

snRNA are ncRNAs that function in ________ complexes. Remember that U1 acts to direct the action of these complexes via complementary binding to the intron/exon junction at the ___’ end of the intron, while U2 does the same at the ___’ end of the intron. It’s a ______ reaction that joins the two ends together, allowing for removal of the intron. Keep in mind different U1s and U2s recognize variants of the consensus splice sites.

Answer 2

Spliceosome

5’

3’

Transesterification

Question 3

snoRNAs (small nucleolar RNA) are responsible for modification and maturation of __RNA. They convert ____ to pseudo____ and add an O-____ group to the 2’ hydroxyl group of other riboses

Answer 3

rRNA

Uridine

Pseudo Uridine

O-methyl group

Question 4

miRNAs are very small _____ RNA processed from a larger dsRNA precursor. They bind via complementarity to the 3’___ of mRNA, blocking their translation or inducing their degradation. Similarly, long ncRNAs associate with _____/_____ regions of protein coding GENES, interfering with their _______. Expression of most coding genes is regulated via BOTH of these mechanisms.

Answer 4

Antisense RNA

3’ UTR

Promoter/Enhancer

Transcription

Question 5

miRNA processing is as follows: ___ processing of primary transcript (pri-miRNA) into individual pre-mRNAs. Then, ____ cleavage into double stranded stems containing the final miRNA sequence. This is followed by binding to the ______ complex, where the miRNA matures into single stranded mature miRNA.

Answer 5

Drosha

Dicer

RISC

Question 6

XIST (X-Inactivation Specific Transcript) –> single copy gene on the Xchromosome that mediates gene ______ compensation process of X-inactivation in females via it’s long ncRNA product. IC (imprinting center) genes are single copy genes whose expression regulates _______ of protein coding gene clusters via genomic imprinting.

Answer 6

Dosage compensation

Transcription

Question 7

X-inactivation is perpetual via hyper______. The X chromosome that is inactivated is the one in which the XIST gene is transcribed. The XIST gene on the other X chromosome is silenced via an ______ blocking protein.

Answer 7

hypermethylation

Autosomal blocking protein

Question 8

Prader Willi syndrome arises from the same LARGE deletion on the q arm of chromosome ____ as Angelman syndrome. The difference is in which parent the deletion is inherited from. If it’s from the father —> ______ syndrome. If it’s from the mother –> ______ syndrome. The reason for this is because the _____ gene is silenced in males, while the ______ gene is silenced in females such that when their gametes combine, there’s one active copy of each gene. If the gene is silenced in the gamete from one parent, and is totally absent due to deletion in the other parent’s gamete, the offspring will have the syndrome that corresponds to that gene (no gene product = syndrome.) NOTE: PWS can also be caused by a SMALL deletion of the _____ copy of the PWS gene., while the AS gene on the same chromosome is intact. Similarly, a _____ mutation in ____3A of the _____ copy of the AS gene can cause AS.

Answer 8

Chromosome 15

Prader Willi

Angelman

Angelman

Prader Willi

Paternal

Point mutation

UBE3A

Maternal