DNA

Question 1

What charge is DNA backbone

Answer 1

Negative, oxygen on phosphate faces outward.

Question 2

What are histones

Answer 2

Protein complexes rich in Lysine and Arginine (+ charge), forms DNA-protein complex called chromatin.

Question 3

What is a nucleosome

Answer 3

Unit of DNA packaging including 8 histone complexes

Question 4

Another name for linker DNA complex in a nucleosome

Answer 4

H1 class histone

Question 5

What is a solenoid

Answer 5

Further complexing of nucleosome - H bonds, hydrophobic, and salt interactions hold together.

Question 6

Explain HATs versus HDACs

Answer 6

Histone acetyltransferase are associated with euchromatin by acetylation of lysine. Deacetyltransferase removes acetyl group and is associated with heterochromatin. HDACs are often unregulated in cancer and inhibitors are therapeutic target.

Question 7

How can DNA be activated or silenced

Answer 7

tails are modified by acetylation of lysines, methylation of lysines, and phosphorylation of serines ( all of which change charges). *Methylation silences (heterochromatin) *Acetylation activates

Question 8

Order of mRNA procession

Answer 8

5’ guanosine cap> poly A tail> splicing (large molecules order changes)

Question 9

Prokaryotic ribosome subunits?

Answer 9

(50S and 30 S) 5S, 23S, and 16S

Question 10

Eukaryotic ribosome subunits?

Answer 10

(60S and 40 S) 5S, 5.8S, 18S, and 28S

Question 11

What is microRNA

Answer 11

non-coding RNA that functions in development, cell differentiation, and regulation of cell cycle/apoptosis. Coded in the intron.

Question 12

What energetically drives formation of phosphodiester bonds?

Answer 12

pyrophosphate is released from triphosphate.

Question 13

Steps of prokaryotic DNA replications

Answer 13

initiator protein (DNA A) binds to replication origin (OriC) > Helicase (DNA B) associates with initiator complex > Opening of DNA allows Ligase (DNA G) to bind > DNA polymerase > Single stranded binding proteins keep DNA unwound and topoisomerase releases supercoiling .tension

Question 14

Differences of Eukaryotic DNA replications

Answer 14

1. Multiple replication origins
2. Prokaryotes have 3 polymerase ( Pol III is main one) and Eukaryotes have 15, (Pol delta is main one).
3. Proofreading is efficient

Question 15

Differences between Topo I and II

Answer 15

Topo I makes a single stranded nick and seals back together to release tension from winding

Topo II makes a double stranded break of tangled DNA and seals back together. *In proliferating cells

Question 16

How to solve DNA overhand problem?

Answer 16

Telomerase uses RNA sequences to lengthen 3’ end, RNA primes then has room to bind, and then reverse transcriptase fills in overhang
*Disease is Werner Syndrome