Lecture 20 Flashcards Preview

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Flashcards in Lecture 20 Deck (26)
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1
Q

What is a spliceosome?

A

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

2
Q

What is the usual beginning sequence of an intron?

A

G U

3
Q

What is the usual ending sequence of an exon?

A

A G

4
Q

What is the usual first sequence of an exons?

A

G (just G)

5
Q

What is the responsibility of snoRNAs?

A

(small nucleolar RNA)

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

6
Q

What is the responsibility of macroRNA?

A
  • they are the largest class of regulatory RNA and they regulate the transcription of genes that produce mRNA
7
Q

What is XIST RNA and what is its purpose?

A
  • X inactivation specific transcript RNA

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

8
Q

What is the role of the Autosomal Blocking protein?

A
  • it binds to the XIST gene and turns it off, making that chromosome active.
9
Q

What is always present in the male X chromosome?

A

Autosomal blocking protein

10
Q

What is icRNA responsible for?

A

DNA Imprinting (silencing certain genes)

11
Q

What is the genetic cause of Prayer Willi Syndrome?

A
  • 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.
12
Q

What is the genetic cause of Angelman Syndrome?

A
  • 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.
13
Q

How does imprinting work?

A

It hypermethylates specific genes, causing them to become inactive.

14
Q

What is the purpose of snRNA?

A

Assembly and function of spliceosome

15
Q

What is the purpose of miRNA

A

Regulate translation

16
Q

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

A

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

17
Q

What is the common size of a micro RNA?

A

19-25 nucleotides

18
Q

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

A

Less.

19
Q

Where is the location of hypermethylation in imprinting?

A

cpg islands

20
Q

What percent of genes does the XIST RNA imprint?

A

85%

21
Q

What is the role of the imprinting center?

A

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

22
Q

What is a contiguous gene syndrome?

A

More than one gene must be eliminated to have the disease

23
Q

What is uniparental disomy?

A

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

24
Q

What is the most common reason for PWS or AS?

A

Deletions are responsible for 70%

25
Q

What mutation is never responsible for PWS?

A

Point mutations

26
Q

How is x-inactivation decided?

A

Completely random