Gene Expression

Question 1

What is the Central Dogma of Molecular Biology?

Answer 1

DNA Replication
Transcription
Translation

Question 2

Define: Constitutive Expression

Answer 2

Genes that are constantly transcribed (I.E. Housekeeping Genes)

Question 3

Define: Facultative Expression

Answer 3

Genes that are not always expressed (I.E. Heat Shock Proteins)

Question 4

Steps in Gene Expression

Answer 4

1. Activation of signal transduction by physical or chemical cues from the environment
2. Chromatin Remodelling
3. Transcription
4. mRNA Transport
5. Translation
6. Post-translational Modification
7. Protein Sorting/Targeting

Question 5

[Types of RNA Polymerase]

Type I
Location
Products
Effect of Alpha Amanitin

Answer 5

[I]

Nucleolus
rRNA
Insensitive

Question 6

[Types of RNA Polymerase]

Type II
Location
Products
Effect of Alpha Amanitin

Answer 6

Nucleoplasm

mRNA
miRNA
snRNA

HIgh sensitivity

Question 7

[Types of RNA Polymerase]

Type III
Location
Products
Effect of Alpha Amanitin

Answer 7

Nucleoplasm

tRNA
5S Subunit of rRNA

Intermediate Sensitivity

Question 8

What is Alpha-Amanitin?

Answer 8

Toxin used to determine type of RNA polymerase

Question 9

What genes are unique to prokaryotes?

Answer 9

Polycistronic Genes

Question 10

What steps in Gene Expression are not present in prokaryotes?

Answer 10

Chromatin Remodelling
mRNA Transport
Post-translational Modification

Question 11

TATA Box

Location

Answer 11

TATAAT

-10 Base Pair

Question 12

TTGACA Box Location

Answer 12

-35 Base Pair

Question 13

rRNA

Function
Abundance
Stability

Answer 13

Ribosomal basic structure component
80%
Very Stable

Question 14

mRNA

Function
Abundance
Stability

Answer 14

Codes for proteins
2-5%
Unstable-Very Stable

Question 15

tRNA

Function
Abundance
Stability

Answer 15

Adaptors between mRNA and Amino Acids
15%
Very Stable

Question 16

snRNA

Function
Abundance
Stability

Answer 16

Spicing of pre-mRNA
>/= 1%
Very Stable

Question 17

snoRNA

Function

Answer 17

Guide medical modifications of other RNAs

Question 18

miRNA

Function
Abundance
Stability

Answer 18

Participates in gene silencing and target degradation
<1%
Stable

Question 19

Differences Transcription vs DNA Replication (3)

Answer 19

 RNA strand does not remain H-bonded to the DNA template
 RNA molecules produced are released from DNA template as single strands
 RNA molecules are shorter than DNA molecules

Question 20

Differences RNA Polymerase vs DNA Polymerase (2)

Answer 20

 RNA polymerase catalyzes linkage of ribonucleotides, not deoxy-ribonucleotides
 RNA polymerase can initiate elongation without a primer

Question 21

Function: Guanylyltransferase

Answer 21

Catalyzes the addition of the guanosine triphosphate part of the cap

Question 22

Function: Guanine-7-methyltransferase

Answer 22

Catalyzes cytosolic methylation of the terminal guanine at the 7th nitrogen of the purine ring

Question 23

Function: S-adenosylmethionine

Answer 23

Source of the methyl group

Question 24

[Cleavage of Pre-mRNA]

Termination signal of mRNA

How many BP away from the sequence?

Answer 24

AAUAAA

30-35 BP

Question 25

[Addition of Poly-A Tail] Function Added by what? What is the signal?

Answer 25

Stabilizes the mRNA and facilitates its exit from nucleus to the cytosol Polyadenlyate Polymerase AAUAAA signal

Question 26

What is added during the synthesis of the 5' cap? How is it linked?

Answer 26

7-methyl-guanosine cap at the 5' terminal end of the pre-mRNA Tri-phosphate linkage

Question 27

[Transport of mRNA from Nucleus to Cytoplasm] Function: Mlp-1-2 Complex

Answer 27

Prohibits improperly transcribed mRNA strands from passing NPC

Question 28

[Transport of mRNA from Nucleus to Cytoplasm] Function: TREX

Answer 28

Plays a role in mRNA packaging and nuclear export

Question 29

Site of Amino Acid attachment on tRNA

Answer 29

3'-end

Question 30

Number of rRNA in Eukaryotes Prokaryotes

Answer 30

E: 4 P: 3

Question 31

[Ribosomes] Prokaryotic Subunits? Eurkaryotic Subunits?

Answer 31

P: 50S + 30S = 70S E: 60S + 40S = 80S

Question 32

[Three Binding Sites for tRNA] A Site P Site E Site

Answer 32

A: Acceptor site P: Carries chain of AA already synthesized E: Exit Site

Question 33

[tRNA Post Processing] Removal of?

Answer 33

Leader sequence at 5' End

Question 34

[tRNA Post Processing] Replacement of?

Answer 34

Two nucleotides at the 3' end by the sequence CCA (Which all mature tRNA molecules terminate)

Question 35

[tRNA Post Processing] Chemical Modification of?

Answer 35

Bases

Question 36

[tRNA Post Processing] Excision of?

Answer 36

Introns

Question 37

Function: Streptomycin

Answer 37

Changes shape of 30S portion | Causes mRNA code to be read incorrectly

Question 38

Function: Tetracyclines

Answer 38

Interfere with attachment of tRNA to mRNA-Ribosome Complex

Question 39

Function: Erythromycin

Answer 39

Binds to 50S portion, prevents translocation-movement of ribosome along mRNA

Question 40

Function: Chloramphenicol

Answer 40

Binds to 50S Portion | Inhibits Peptide Bond Formation