Chapter 17 - Transcription, RNA Processing, Translation Flashcards
Sigma
Part of Initiation Phase - A Protein that binds to DNA before RNA polymerase. Can only bind in one orientation!
Holoenzyme
Combination of Sigma and RNA Polymerase
Where does Sigma bind?
Promoters
What is a Promoter?
A section of DNA that Sigma binds to.
In what direction are RNTPs added?
5’ to 3’ direction just like NTPs!
When does Transcription end?
When a transcription termination signal region of DNA is read. When this area is read, the RNA forms a hairpin loop.
-10 Element
Part of Prokaryotic Promoter. Contains TATAAT box. Essential for Transcription
-35 Element
Part of Prokaryotic Promoter. Causes high transcription rate.
What is one of the Eukaryotic Promoters?
TATA box
RNA Processing - RNA Cap
Guanosine cap @ 5’ end
RNA Processing - RNA Tail
PolyA tail at 3’ end. Where prokaryotic would have a hairpin. Increases rna’s longevity.
What type of cell uses RNA caps and tails?
Eukaryotes
What is the first letter of the transcription template called?
+1 site
How many RNA polymerases do Eukaryotes have?
Three
What do Eukaryotes use instead of Sigma?
Basal Transcription Factors
Which part of the RNA is discarded in RNA processing?
Introns because exons (exit) the nucleus
What is the wobble hypothesis?
Many amino acids are specified by more than one codon and the codons have the same nucleotides at the first and second positions but a different nucleotide at the third position.
Spliceosome
snRNPs form spliceosomes. Act as ribozyme
What is an example of a ribozyme?
Spliceosome
What does a mature RNA transcript contain?
Untranslated regions, coding region, 5’ cap, PolyA tail
A site
Holds the aminoacyl tRNA
P Site
Holds tRNA with growing polypeptide attached
E site
Holds a tRNA that will exit soon
aminoacyl tRNA synthetases
Adds amino acids to tRNA. Specific synthetases for each amino acid.
What does it mean to charge tRNA?
This happens when amino acids bind to the right tRNA. This process requires energy. Aminoacyl tRNA synthetases charges the tRNA
How are tRNA joined to amino acids?
Covalent bonding
What is the binding site for amino acids on tRNA?
A CCA sequence at the 3’ end of each tRNA
What is the final shape of tRNA?
L-shape tertiary form
Where is the anti-codon located?
At the opposite end of the tRNA from the amino acid.
What makes up a ribosome?
Protein and rRNA
What does the small ribosome subunit do?
Holds mRNA in place
What does the large ribosome subunit do?
This is where the peptide bond forms
What are the three steps of prokaryotic translation initiation?
- mRNA binds to small ribosome subunit
- Initiator f-met binds to start codon at the P site
- Large ribosome subunit binds
How does Prokaryotic translation terminate?
A site recognizes stop codon and release factor enters the site.
Molecular Chaperones
Speed up protein processing folding into higher structural forms
