Exam 2 pt3

Question 1

ncRNA carry out diverse functions because they can

Answer 1

bind to different type of molecules, like:
* DNA
* RNA
* proteins

Question 2

scaffold

Answer 2

when ncRNA binds to a group of proteins

Question 3

guide

Answer 3

ncRNA binds to a protein and guides it somewhere

Question 4

ncRNA functions

Answer 4

• scaffold
• guide
• alter protein
• blocker
• ribozyme
• decoy

Question 5

RNA in RNA world carried three key functions

Answer 5

1. info storage
2. self replication
3. catalytic activity

Question 6

information storage, how RNA did, why evolve, how evolve

Answer 6

• RNA store infor in base sequence
• DNA storage more stable though
• with DNA storage RNA can multitask
• RNA made DNA with reverse transcription

Question 7

Metabolism: how RNA did, why evolve, how evolve

Answer 7

• RNA did these
• proteins give benefit of more catalytic activity
• protein have many functions
• protein more advantageous

Question 8

HOTAIR

Answer 8

ncRNA that alters chromatin structure

Question 9

HOTAIR located on and transcribed by

Answer 9

HoxC genes, transcribed by the antisense strand of HoxC genes

Question 10

HOTAIR acts as a

Answer 10

scaffold that guides two histone modifying complexes to genes

Question 11

HOTAIR mechanism

Answer 11

• PRC2 binds HOTAIR at 5’ end
• LSD1 complex binds 3’ end
• HOTAIR binds GA rich region in target gene
• PRC and LSD1 methylate gene
• inhibit two genes

Question 12

_ is better at silencing that _ RNA

Answer 12

dsRNA than antisense RNA

Question 13

RNAi

Answer 13

dsRNA causes silencing of mRNA

Question 14

RNAi mediated by

Answer 14

miRNAs and siRNAs

Question 15

miRNA transcribed from _ genes while siRNA from _ genes

Answer 15

endogenous, exogenous

Question 16

mechanism of RNAi

2

Answer 16

Pri miRNA → pre miRNA → out of nucleus →
OR
pre siRNA enters cell
THEN
→ cut by dicer → form RIS complex → sense strand degraded → bind to target mRNA

• if miRNA, partial match, so translation is silenced
• if siRNA, perfect match so RNA is degraded

chap 17 page 30

Question 17

RISC composed of

Answer 17

it is a dsRNA produced from either pre-miRNA or pre-siRNA

Question 18

RNAi functions and benefits

Answer 18

• gene regulation with production of miRNA
• defense against virus
• transcription inhibition

Question 19

snoRNAs modify _ by _

Answer 19

rRNAs by methylation of ribose on 2’ OH and uracil to conversion

Question 20

snoRNA two types and what each does

Answer 20

• C/D box catlayze methylation of ribose
• H/ACA box catlyzes concertion of uracil to psedouracil

Question 21

adaptation phase of CRISPR

Answer 21

• spacer squisition
• Cas1 & 2 cleave bacteriophage DNA
• peice is inserted into Crispr gene
• spacer passed on to daughter cells

Question 22

expression phase of crispr

Answer 22

• Crispr, tracr and Cas9 genes are expressed
• trancrRNA is complementary to parts of pre-crRNA so it cleaves and makes crRNA
• crRNA-tracrRNA complex binds to Cas9

Question 23

interference phase of cripsr

Answer 23

• crRNA spacer complementary to bacteriophage DNA
• crRNA acts as a guide that causes trancrRNA-Cas9 complex to bind
• Cas9 protein endocuclease that makes ds break
• bacteriophage proliferation yeeted

Question 24

PIWI interacting RNAs silence _ in two ways:

Answer 24

silence TE in two ways
* prevent transcription
* directly inhibit RNA in cytosol

Question 25

how do PIWI RNAs silence transcription

Answer 25

pre-prRNA transcribed → cleaved to make piRNA → makes PRITS complex→ PRITS bind during transcription → modify TE gene → heterochromatin formation →silence transcription

Question 26

how do PIWI RNA directly inhibit

Answer 26

pre-prRNA transcribed → cleaved to make piRNA → makes PRISC complex→ PRISC binds to TE RNA → perfect match → dsRNA degraded

Question 27

A small effector molecule that enhances transcription binds to a regulatory protein and causes it to not bind to the DNA. The regulatory protein

Answer 27

is a repressor

Question 28

During diauxic growth involving glucose and lactose, bacterial cells

Answer 28

use up glucose first, then they metabolize lactose.

Question 29

For a riboswitch that controls transcription, what is the effect of a regulatory molecule such as TPP?

Answer 29

It binds to an RNA molecule and causes a change in its conformation.

Question 30

What is the role of mediator with regard to eukaryotic gene regulation?

Answer 30

Mediator controls the switch to the elongation phase of transcription.

Question 31

The following list describes events that are required for transcription of a eukaryotic gene. Put them in the correct order.

1. Chromatin remodeling and histone modification
2. Binding of activators
3. Elongation
4. Formation of the pre-initiation complex

Answer 31

2, 1, 4, 3

Question 32

The main role of the polycomb group complexes is to

Answer 32

cause gene repression in specific cell types.

Question 33

The Avy allele of the Agouti gene involves the insertion of a transposable element upstream from the normal Agouti promoter. Let’s suppose that pregnant female mice are fed a diet that contains chemicals that increase DNA methylation. With regard to offspring carrying the Avy allele, this diet would

Answer 33

cause their fur to be less yellow (more dark brown) because the Agouti gene would tend to be under expressed.

Question 34

Which genes of the CRISPR-Cas system are not needed for the expression and interference phases?

Answer 34

Cas1, Cas2

Question 35

A mutation in the operator site that prevents the lac repressor from binding would mean, would this be in merozygote

Answer 35

lac is always expressed

cis effect, yes

Question 36

would this be in merozygote, what would happen if there was a mutation so allolactose cannot bind

Answer 36

repressor stays bound

trans effect, other repressors will bind allolactose and overcome mutation

Question 37

_ motif promotes formation of dimer formation

Answer 37

zipper motif