Week 10 - Transcription

Question 1

Initiation

Answer 1

The beginning of transcription, where RNA polymerase binds to DNA at the promoter region (often near the TATA box) and starts RNA synthesis.

Question 2

Elongation

Answer 2

RNA polymerase moves along the DNA template strand, adding RNA nucleotides in the 5’ to 3’ direction.

Question 3

Termination

Answer 3

RNA polymerase stops transcription when it reaches a termination signal; the RNA transcript is released.

Question 4

Processing

Answer 4

Post-transcriptional modifications of pre-mRNA: includes 5’ capping, 3’ polyadenylation, and splicing.

Question 5

Transcription Start Site (TSS)

Answer 5

The location on the DNA where transcription begins (usually a purine base).

Question 6

Transcription Termination Site (TTS)

Answer 6

The location on DNA where transcription ends.

Question 7

Direction of RNA Synthesis

Answer 7

RNA is synthesized in the 5′ to 3′ direction, using the 3′ to 5′ DNA template strand.

Question 8

RNA Polymerase II

Answer 8

Transcribes mRNA and some snRNA.

Question 9

RNA Polymerase I

Answer 9

Transcribes rRNA (except 5S rRNA).

Question 10

RNA Polymerase III

Answer 10

Transcribes tRNA, 5S rRNA, and other small RNAs.

Question 11

Template Strand

Answer 11

The DNA strand used as a template to synthesize RNA.

Question 12

Nontemplate (Coding) Strand

Answer 12

The DNA strand not used in transcription; its sequence matches the RNA (except T = U in RNA).

Question 13

TATA Box

Answer 13

A DNA sequence in the promoter that helps position RNA polymerase at the TSS.

Question 14

Enhancer

Answer 14

DNA sequences that can increase transcription from a distance via interaction with activator proteins.

Question 15

General Transcription Factors (GTFs)

Answer 15

Proteins required for transcription initiation by RNA polymerase II, including TFIID, TFIIH, and mediator proteins.

Question 16

Mediator Proteins

Answer 16

Act as a bridge between transcription factors and RNA polymerase II to initiate transcription.

Question 17

Specific Transcription Factors

Answer 17

Bind to enhancers or silencers to regulate gene expression in a cell- or signal-specific manner.

Question 18

5′ UTR (Untranslated Region)

Answer 18

The sequence upstream of the start codon; not translated into protein.

Question 19

3′ UTR

Answer 19

The sequence downstream of the stop codon; affects mRNA stability, localization, and translation efficiency.

Question 20

Exon

Answer 20

A coding region of a gene that remains in mRNA after splicing.

Question 21

Intron

Answer 21

A noncoding region removed during splicing.

Question 22

5’ Cap

Answer 22

A modified guanine nucleotide added to the 5’ end of mRNA for stability and ribosome binding.

Question 23

3′ Poly(A) Tail

Answer 23

A stretch of adenines added to the 3’ end of mRNA to protect from degradation and aid in export.

Question 24

PolyA Polymerase

Answer 24

Adds the poly(A) tail to the pre-mRNA’s 3′ end.

Question 25

Primary Transcript (pre-mRNA)

Answer 25

The initial RNA transcript before processing.

Question 26

Mature mRNA

Answer 26

Processed mRNA that includes exons, 5′ cap, and poly(A) tail, ready for translation.

Question 27

Spliceosome

Answer 27

A large complex of proteins and snRNAs that removes introns from pre-mRNA.

Question 28

Splicing (Order & Lariat)

Answer 28

1. 5′ splice site is cut 2. The intron loops into a lariat structure 3. 3′ splice site is cut, and exons are joined

Question 29

Alternative Splicing

Answer 29

Different combinations of exons are joined to create multiple proteins from one gene; adds diversity.

Question 30

Start of Translation

Answer 30

Begins at the start codon (AUG), which codes for methionine.

Question 31

End of Translation

Answer 31

Ends at a stop codon (UAA, UAG, or UGA), triggering release of the polypeptide.

Question 32

RNA Translation Initiation

Answer 32

Begins with ribosome assembly at the start codon on the mRNA, guided by initiation factors.

Question 33

RNA Nuclear Export

Answer 33

Processed mRNA is exported from the nucleus to the cytoplasm via nuclear pores.

Question 34

RNA Stability

Answer 34

Refers to how long mRNA remains intact in the cell; influenced by the 5′ cap, 3′ UTR, poly(A) tail, and RNA-binding proteins.

Question 35

Prokaryotic RNA Polymerase

Answer 35

A single RNA polymerase transcribes all types of RNA (mRNA, rRNA, tRNA).

Question 36

Sigma Factors

Answer 36

Proteins that guide prokaryotic RNA polymerase to specific promoters.

Question 37

Intronless

Answer 37

Most prokaryotic genes lack introns.

Question 38

Cotranscriptional Translation

Answer 38

In prokaryotes, translation begins on the mRNA while it’s still being transcribed—because there’s no nucleus.

Question 39

Polycistronic RNA

Answer 39

An mRNA molecule that encodes multiple proteins, common in prokaryotes.