Lecture 20

Question 1

What is a spliceosome?

Answer 1

It is a bunch of RNA and DNA put together that cuts out introns to make mature mRNA

Question 2

What is the usual beginning sequence of an intron?

Answer 2

G U

Question 3

What is the usual ending sequence of an exon?

Answer 3

A G

Question 4

What is the usual first sequence of an exons?

Answer 4

G (just G)

Question 5

What is the responsibility of snoRNAs?

Answer 5

(small nucleolar RNA)

- they function in the nucleolus and are responsible for modification and maturation of rRNA

Question 6

What is the responsibility of macroRNA?

Answer 6

• they are the largest class of regulatory RNA and they regulate the transcription of genes that produce mRNA

Question 7

What is XIST RNA and what is its purpose?

Answer 7

• X inactivation specific transcript RNA

- purpose is to bind to the genes within a chromosome and inactivate them as seen in Barr bodies.

Question 8

What is the role of the Autosomal Blocking protein?

Answer 8

• it binds to the XIST gene and turns it off, making that chromosome active.

Question 9

What is always present in the male X chromosome?

Answer 9

Autosomal blocking protein

Question 10

What is icRNA responsible for?

Answer 10

DNA Imprinting (silencing certain genes)

Question 11

What is the genetic cause of Prayer Willi Syndrome?

Answer 11

• a very large deletion in the parental PWS gene within chromosome 15 of the sperm. This results in the offspring having no active PWS gene since the maternal PWS gene is always imprinted.

Question 12

What is the genetic cause of Angelman Syndrome?

Answer 12

• a very large deletion in the maternal AW gene within the egg. This results in the offspring having no active AW gene since the paternal AW gene is always imprinted.

Question 13

How does imprinting work?

Answer 13

It hypermethylates specific genes, causing them to become inactive.

Question 14

What is the purpose of snRNA?

Answer 14

Assembly and function of spliceosome

Question 15

What is the purpose of miRNA

Answer 15

Regulate translation

Question 16

What is the point of having so many proteins in between the U1 and U2 of the splicesome?`

Answer 16

To help navigate the nucleophilic attack of the 3’ exon to the correct 5’ exons.

Question 17

What is the common size of a micro RNA?

Answer 17

19-25 nucleotides

Question 18

The more miRNA of a particular type you produce, the _____ translation of the complementary mRNA.

Answer 18

Less.

Question 19

Where is the location of hypermethylation in imprinting?

Answer 19

cpg islands

Question 20

What percent of genes does the XIST RNA imprint?

Answer 20

85%

Question 21

What is the role of the imprinting center?

Answer 21

encodes the proteins that hypermethylates the appropriate genes (male or female)

Question 22

What is a contiguous gene syndrome?

Answer 22

More than one gene must be eliminated to have the disease

Question 23

What is uniparental disomy?

Answer 23

Getting two normal chromosomes from one parent as opposed to one normal chromosome from each parent

Question 24

What is the most common reason for PWS or AS?

Answer 24

Deletions are responsible for 70%

Question 25

What mutation is never responsible for PWS?

Answer 25

Point mutations

Question 26

How is x-inactivation decided?

Answer 26

Completely random