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63 Cards in this Set
- Front
- Back
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What enzyme cleaves the 5' end of tRNA?
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RNase P
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What does nucleotidyl tranferase do?
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Adds CCA to 3' end of tRNA
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Where is CCA added to on tRNA, and by what?
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Its added to the 3' end by Nucleotidyl Transferase
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2 subunits of Eukaryotic Ribosomes
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40s and 60s
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2 subunits of prokaryotic ribosomes
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50S and 30S
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Where are rRNA genes transcribed and processed
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Nucleolus
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Which RNA polymerases synthesize which RNA's?
(mRNA, tRNA, rRNA) |
mRNA = RNA polymerase 2
rRNA = RNA polymerase 1 tRNA = RNA polymerase 3 |
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What adds the "cap" to eukaryotic mRNA. Where? What kind of linkage is this?
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Guanyltransferase adds cap to 5' end via a 5' to 5' linkage
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What do Histone mRNA's lack?
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polyA tail
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True / false:
polyA tails are encoded in the DNA |
False. Added as processing step.
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Group 1 splicing applies to what types of RNA?
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Mostly rRNA, some mRNA
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Group 2 splicing applies to what types of RNA?
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mRNA
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tRNA splicing involves what?
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removal of introns from anticodon loop.
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True / False :
Energy is required in group 1 and group 2 splicing |
False!!
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What two residues are found at the 5' splice on mRNA?
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GU
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What two residues are found at the 3' splice on mRNA?
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AG
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How many ATPs to assemble and form active spliceosome?
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3
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two ways to get more than one mRNA from a gene?
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1)alternate polyA addition sites
2)alternate splicing events |
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Degeneracy most often involves the _____ codon position
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third
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Stop codon(s)
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UAG, UAA, UGA
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Start codon(s)
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AUG
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Where are the aa attatched to on tRNA?
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the 3' end
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at the 5' end of anticodon, G reads
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C or U
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at the 3' end of anticodon G reads
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C
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at the 5' end of anticodon U reads
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G or A
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at the 5' end of anticodon, I reads
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U, C, or A
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at the 3' end of the anticodon, U reads
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A
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at the 5' end of the anticodon, A reads
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U
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at the 5' end of the anticodon, C reads
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G
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Five stages of protien synthesis
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1)Activation of aa
2)initiation 3)elongation 4)termination 4)post-translational processing |
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Aminoacylation occurs in how many steps?
3, 2, or 1? |
2
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protiens are made in which direction?
(C- to N-) or (N- to C-) |
(N- to C-)
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3 initiation factors and thier jobs (prokaryotic)
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IF-1 assists IF-3
IF-2 binds initiator tRNA and GTP IF-3 aids in binding of 30S subunit to mRNA |
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initiator tRNA?
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fmet
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Shine-delgarno seuquence has what qualities
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purine rich, attracts 16S rRNA, right before start codon.
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once fmet is bound to reading frame - what happens?
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50S subunit binds and initiation factors are releasted
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What are the analogs to prokaryotic EF-Tu and EF-Ts in eukaryotes?
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eEF-alpha
and eEF-βγ |
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how many release factors needed in eukaryotic protein synthesis for termination?
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one
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What does Ubiquitin do?
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targets protien for degredation.
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true/false:
trp repressor will bind to trp operon if any aa is present |
False, trp repressor is only active in presenece of tryptophan.
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5' end of trp leader mRNA contains what?(2 things)
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Shine Delgarno sequence and tandem trp condons
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What is the purpose of the tandem trp condons in the leader?
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to sense levels of trp tRNA
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The 1:2 and 3:4 loop structures give what signal
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to terminate transcription
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what stem loop structure is this anti-terminator?
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2:3
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Which eukaryotic Polymerase Promoters are at the 5' end of the gene?
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Pol1 and Pol2
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Which eukaryotic Polymerase Promoters are in the middle of the gene?
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Pol3
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What does the addition of an acetyl group do to lys residues on a histone?
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Eliminate a + charge, weakening association with phosphodiester backbone of DNA
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How can we make more DNA available for transcription on a histone
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By acetylating the histone.
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In Eukaryotes, RNA Polymerase to needs ______ in order to bind to DNA
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Transcription Factors
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in eukaryotic gene expression, what does methylation of DNA at GC accomplish?
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Prevention of transcription via binding protiens...gene inactivation
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What are some eukaryotic promoters? (3)
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TATA = for TF IID
CAAT Box GC Box |
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6 steps for transcription by RNA Polymerase 2...
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1)TFIID binds to TATA
2)TFIIA and B bind 3)TFIIF and RNA Pol2 Bind 4)TFIIH and TFIIE bind 5)DNA unwound, polymerase phosphorylated 6)Transcription Begins |
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3 structural motifs for DNA binding proteins
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Helix-Turn-Helix
Zinc Finger Leucine Zipper |
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What 4 residues is Zn complexed with in a Zn finger?
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2 his and 2 cys
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What does Rifampicin do?
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Blocks initiation of RNA synthesis
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What the heck does Actinomycin D do?
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Binds to DNA and prevents transcription (into RNA).
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What does a strong termination signal consist of?
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a stem loop and a string of U's.
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What does a weak termination signal require?
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Rho Factor
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Where does RNA polymerase pause so that Rho Factor might bind?
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G-C rich regions.
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What is methylation carried about by in pre-tRNA?
a. 1-Methylguanosine b. S-Adenosyl-methionine c. nucleotidyl transferase |
b. S-Adenosyl-methionine
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how do snRNPs bind to branch sites and splice junction?
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Complimentary, antiparallel base pairing.
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True/False:
the wobble hypothesis applies to the 5' end of the mRNA |
False:
The Wobble hypothesis applies ONLY to the 5' end of the ANTICODON |
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initiator tRNA requires what two things to bind to 30S subunit?
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GTP and IF-2
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