Genetics 2

Question 0

What type of RNA makes up the spliceosome machinary?

Answer 0

snRNA (small nuclear)

Question 1

What are introns? What are exons?

Answer 1

Introns are expressed DNA which are then removed from the mRNA. Exons are the bit that is left in the mRNA and coded into protein.

Question 2

At percent of the genome is protein coding?

Answer 2

<2%

Question 3

What are the house cleaning RNA?

Answer 3

1. rRNA (~80%)
2. transfer RNA (15%)- carries amino acid to machinary.
3. snRNA- small nuclear RNA is part of the spliceosome.
4. snoRNA- small nucleolar RNA is present in the nucleus of the cell and modifies rRNA, tRNA and snRNA.

Question 4

What do the housekeeping RNAs do?

Answer 4

Regulate steps needed to go from mRNA to protein.

Question 5

What is short and long ncRNA?

Answer 5

short = 200 nts

Question 6

What does miRNA do? (microRNA)

Answer 6

It binds to complementary strands of RNA, expedites degradation and suppress protein translation.

Question 7

Are miRNAs positive or negative regulators of protein translation?

Answer 7

Negative.

Question 8

What is piRNA?

Answer 8

PIWI RNA is small (~30nt), it is found in spermatogenic cells and silence some repeats.

Question 9

What are retrotransposons?

Answer 9

Reverse transcriptase went from RNA to DNA. They jump around the genome, make up >40% of the genome, are regulated by PIWIs, and can be deleterious (can cause cancer).

Question 10

How do you measure transcriptomes?

Answer 10

Micro arrays.

Use cDNA to make DNA, tag it with florescence, catch it with probes.

Question 11

What are the major parts of the transcriptome?

Answer 11

I. mRNA
II. ncRNA
A. House-Keeping (snRNA, snoRNA, rRNA, tRNA)
B. Regulatory
1. Small RNA (miRNA, piRNA)
2. long non-coding RNA (lncRNA)

Question 12

What’s the difference between Endo, Ecto, and Mesoderm?

Answer 12

Endo: Organs
Ecto: Skin and nerves
Meso: Muslces

Question 13

What are two types of epigenetic modification?

Answer 13

DNA methylation

Histone modification

Question 14

DNA methylation of a cytosine generally does what to expression?

Answer 14

It generally suppresses expression.

Question 15

What is the majority of RNA that is transcribed?

Answer 15

The vast majority is lncRNA, and the function is largely unkown.

Question 16

What are small interfering RNA?

Answer 16

siRNA is double stranded RNA that is usually introduced by a virus (or scientist) and they can “knockdown” an mRNA.

Question 17

How do piRNA and PIWI work?

Answer 17

piRNA and PIWI proteins for a complex and then silence retroansposons in germline cells.

Question 18

What is a nucleosome?

Answer 18

DNA wrapped 1.65x around a histone.

Question 19

How many proteins make up a histone?

Answer 19

8

Question 20

Are histones positively or negatively charged?

Answer 20

Positively.

Question 21

When do DNA and histone synthesis happen?

Answer 21

During S phase.

Question 22

Where does most of the cell repair happen?

Answer 22

G1 and G2

Question 23

What are histones made out of?

Answer 23

It’s an octomer. 2 x H2A, 2 x H2B, 2 x H3, 2 x H4.

H1 is a linker protein.

Question 24

What is a missense mutation?

Answer 24

When a single nucleotide is changed, resulting in a different AA.

Question 25

What is a nonsense mutation?

Answer 25

a SNP that results in a premature stop codon.

Question 26

What are some forms of histone modification?

Answer 26

methylation, acetylation, phosphorylation.

Question 27

Are histone modifications reversible?

Answer 27

Yes.

Question 28

What does a histone methylation do?

Answer 28

It represses transcription (heterochromatin).

Question 29

What are 4 roles of epigenetics in normal cells?

Answer 29

1. Control cell differentiation thru differential gene expression.
2. Control transposable elements
3. Imprinting- usually both genes are expressed, but sometimes one is turned off.
4. Assess environment to adjust genetic response accordingly

Question 30

What are lncRNA critical for in mammals?

Answer 30

X chromosome inactivation.