Transcription

Question 1

RNA is transcribed in the _____ to ______ direction

Answer 1

5’ to 3’

Question 2

Prokaryotic initiation of transcription

Answer 2

• TATAAT sequence serves as part of promoter region
• requires the association of RNA polymerase and sigma factors to initiate transcription
• different sigma factors can be recruited
• initiation occurs when RNA polymerase binds to sigma subunit to create a holoenzyme which is able to unwind DNA

Question 3

Prokaryotic Elongation during transcription

Answer 3

RNA polymerase is able to unwind DNA revealing both strands
Can then begin to catalyze the production of RNA strand
elongates the strand by adding individual nucleotides
Can restore the DNA back to its double helix

Question 4

Prokaryotic Termination during transcription

Answer 4

1. Rho-independent sequences are transcribed and then fold back on themselves to create a loop which pauses the RNA polymerase and releases the mRNA
2. Rho-dependent terminators use a specific prokaryotic protein or rho- factor which moves along the RNA to destabilize the interaction between DNA and RNA leading to the release

Question 5

Eukaryotic initiation of transcription

Answer 5

General transcription factors are required to mediate the binding of RNA polymerase to a promoter

Question 6

Eukaryotic elongation during transcription

Answer 6

RNA polymerase reads a sequence of DNA and can produce the complementary strand of RNA

Question 7

Eukaryotic termination during transcription

Answer 7

RNA Polymerase 2: depends on poly (A) dependent mechanism of termination
RNA Polymerase 3: have transcription terminated after transcription of a termination sequence in a mechanism that resembles the rho-dependent sequence
RNA Polymerase 1: transcription is terminated using a specific eukaryotic termination factor

Question 8

RNA polymerase 1

Answer 8

transcribes genes for ribosomal RNA

Question 9

RNA polymerase 2

Answer 9

transcribes mRNA

Question 10

RNA polymerase 3

Answer 10

transcribes genes for tRNA

Question 11

5’ Cap

Answer 11

addition of a modified guanosine to the 5’ end to make a cap
ensures stability of mRNA molecule
ensures the export of mRNA from the nucleus
help with the attachment of the ribosome and initiation of translation

Question 12

Poly A tail

Answer 12

tail made up of adenines added to the 3’ end

help protect against ribonuclease enzymes that target phosphodiester bonds

Question 13

Spliceosome

Answer 13

composed of 5 small nuclear ribonucleoproteins which are able to recognize the splice site

Question 14

Chaperonins

Answer 14

assist in protein folding to ensure the protein is folded correctly

Question 15

Splicing

Answer 15

RNA and splice some form complementary base pairing

• catalyzes a reaction which allows specific hydroxyl group to attack the phosphodiester bond essentially cutting it
• intron forms a loop which allows the two exons to form back together

Question 16

Intron

Answer 16

non-coding region of RNA

Question 17

Exon

Answer 17

coding region of RNA

Question 18

mRNA is exported from _______ to the ___________

Answer 18

nuclear compartment

cytoplasm of the cell

Question 19

Prokaryotic transcription occurs in the _______________

Answer 19

cytoplasm of the cell

Question 20

Eukaryotic transcription occurs in the ______________

Answer 20

nucleus of the cell

Question 21

____________ must occur before the amino acid sequence is produced

Answer 21

RNA splicing

Question 22

Central Dogma

Answer 22

describes the relationship between DNA, RNA, and proteins