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[OS 201] 3rd Lecture Exam > Gene Expression > Flashcards

Flashcards in Gene Expression Deck (40)
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1

What is the Central Dogma of Molecular Biology?

DNA Replication
Transcription
Translation

2

Define: Constitutive Expression

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

3

Define: Facultative Expression

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

4

Steps in Gene Expression

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

5

[Types of RNA Polymerase]

Type I
Location
Products
Effect of Alpha Amanitin

[I]

Nucleolus
rRNA
Insensitive

6

[Types of RNA Polymerase]

Type II
Location
Products
Effect of Alpha Amanitin

Nucleoplasm

mRNA
miRNA
snRNA

HIgh sensitivity

7

[Types of RNA Polymerase]

Type III
Location
Products
Effect of Alpha Amanitin

Nucleoplasm

tRNA
5S Subunit of rRNA

Intermediate Sensitivity

8

What is Alpha-Amanitin?

Toxin used to determine type of RNA polymerase

9

What genes are unique to prokaryotes?

Polycistronic Genes

10

What steps in Gene Expression are not present in prokaryotes?

Chromatin Remodelling
mRNA Transport
Post-translational Modification

11

TATA Box

Location

TATAAT

-10 Base Pair

12

TTGACA Box Location

-35 Base Pair

13

rRNA

Function
Abundance
Stability

Ribosomal basic structure component
80%
Very Stable

14

mRNA

Function
Abundance
Stability

Codes for proteins
2-5%
Unstable-Very Stable

15

tRNA

Function
Abundance
Stability

Adaptors between mRNA and Amino Acids
15%
Very Stable

16

snRNA

Function
Abundance
Stability

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

17

snoRNA

Function

Guide medical modifications of other RNAs

18

miRNA

Function
Abundance
Stability

Participates in gene silencing and target degradation
<1%
Stable

19

Differences Transcription vs DNA Replication (3)

 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

20

Differences RNA Polymerase vs DNA Polymerase (2)

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

21

Function: Guanylyltransferase

Catalyzes the addition of the guanosine triphosphate part of the cap

22

Function: Guanine-7-methyltransferase

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

23

Function: S-adenosylmethionine

Source of the methyl group

24

[Cleavage of Pre-mRNA]

Termination signal of mRNA

How many BP away from the sequence?

AAUAAA

30-35 BP

25

[Addition of Poly-A Tail]

Function

Added by what?

What is the signal?

Stabilizes the mRNA and facilitates its exit from nucleus to the cytosol

Polyadenlyate Polymerase

AAUAAA signal

26

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

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

Tri-phosphate linkage

27

[Transport of mRNA from Nucleus to Cytoplasm]

Function: Mlp-1-2 Complex

Prohibits improperly transcribed mRNA strands from passing NPC

28

[Transport of mRNA from Nucleus to Cytoplasm]

Function: TREX

Plays a role in mRNA packaging and nuclear export

29

Site of Amino Acid attachment on tRNA

3'-end

30

Number of rRNA in

Eukaryotes
Prokaryotes

E: 4
P: 3