Functions and Dysfunctions of Genomic Regulation

Question 1

Why do cells condense their chromosomes?

Answer 1

To prevent damage to the DNA as chromosomes are separated and passed to the daughter cells

Question 2

Central Dogma

Answer 2

DNA –> RNA –> Protein

Question 3

Heterochromatin vs Euchromatin

Answer 3

Heterochromatin is tightly condensed and inactive in gene expression; euchromatin is lightly packed and extremely active

Question 4

Who determined the genetic code?

Answer 4

Nirenberg, Khorana, and Holly in 1966

Question 5

What sequences are common to most introns?

Answer 5

Start with GT and end with AG

Question 6

Histone Deacetylase (HDAC)

Answer 6

compacts chromatin, repressing gene transcription

Question 7

Histone Acetyl Transferase (HAT)

Answer 7

unwinds chromatin which enhances gene transcription

Question 8

PXR (receptor)

Answer 8

Nuclear receptor for xenobiotics

Question 9

DNA methylation

Answer 9

methyl groups added to cytosine and adenine; represses transcription when at a promoter

Question 10

CpG islands

Answer 10

abnormal hypermethylation can lead to transcriptional silencing; can be passed to offspring

Question 11

What does DNA polymerase require to start replication?

Answer 11

primer with a free 3’ OH end

Question 12

Topoisomerase Inhibitor Functions (4)

Answer 12

blocks cell cycle; generates single and double stranded breaks; harms the genome integrity; and apoptosis in the cell

Question 13

Deamination products of cytosine, adenine, and guanine

Answer 13

uracil, hypoxanthine, and xanthine respectively (CU-AH-GX)

Question 14

Target residues in histones for PTM

Answer 14

Lysine

Question 15

Why are histones positively charged?

Answer 15

attracted to the negatively charged DNA

Question 16

What factor can cause the formation of pyrimidine dimers (T-T or C-T) in DNA

Answer 16

UV exposure

Question 17

20% histone protein amino acid residues

Answer 17

lysine and arginine (+++++++)