1-9 Transcription & RNA processing

Question 1

DNA coding strand

Answer 1

matches the mRNA

Question 2

DNA template strand

Answer 2

the strand polymerase actually reads in order to transcribe a mRNA for the desired coding strand

Question 3

Pol 1

Answer 3

rRNA

Question 4

Pol 2

Answer 4

protein encoding, most snRNA

Question 5

Pol 3

Answer 5

small RNA subunits

Question 6

Non-template dependent polymerase

Answer 6

polyadenylate pol -> polyA of mRNA

PARP -> protein modification

Question 7

POLRMT

Answer 7

polymerase for mitochondrial RNA

Question 8

Distribution of elements over chromosomes

Answer 8

• satellite dna near centromere
• ribosomal genes near telomeres
• tandem repeats: same genes near each other replicated
• interspersed retrotransposons: SINES, LINES

some chromosomes gene rich some gene poor

Question 9

Transcription/processing of rRNA

Answer 9

1. internally transcribed spacers within transcript
2. chemical modifications: used for folding help
3. ITS removed and diff subunits formed

Happens in nucleolus, requires small rnas to help cleave and form, exports small and large subunits into cytosol and they only come together when initiation of translation has started

Question 10

Processing/maturation of tRNA

Answer 10

transcribed in nucleus
removes introns
forms stem loops
modifes bases and CCA sequence added to 3' tail
exported
AA attached to A of CCA tail

Question 11

Components of RNA pol II transcribed genes

Answer 11

proximal control elements: GC box , CAAT box
core promoter: TATA box
+1 (first base of translation)
Exons/introns

Question 12

Initiation of pol II transcription

Answer 12

Basal transcription factors associate with start site/TATA box, other factors recruited and RNA pol II now joins, pol II get phosphorylated on “tail” signaling transcription to occur

tail contains: capping factors, splicing factors, polyA factors to all process the mRNA immediately

enhancers/regulators effect this process

Question 13

Enhancers

Answer 13

activity of promoter increase/decreased by

specific DNA sequence to which REGULATORY PROTEINS can bind

Question 14

Mech of pre-mRNA splicing

Answer 14

1. SnRNPs bind sequences for splice donor/acceptor and recuit complex
2. middle branch site initiates nuclophilic attach on splice donor, makes lariat loop
3. acceptor site cleaved and ligated to donor end

Question 15

Cryptic splice site

Alternate slice sites

Answer 15

make new/mutant proteins, pathological, can truncate of lengthen 3UTR based on differ splice sites and addition of AAA tail location

healthy normal, method of making protein isoforms

Question 16

Nuclear export of processed mRNAs

Answer 16

Once mRNA fully transcribed, “exon junction complex” and “cap binding protein” still associated with transcript to allow export through nuclear pore complex

Exon jucntion complex stays bound in cytosol as a proofreaded to show to translation machinery that made correctly

cap binding protein exchanged for cytosol cap