Chapter 26: RNA Metabolism Flashcards
DNA-dependent synthesis of RNA (process of copying a piece of DNA (a gene) as RNA)
Transcription
Which DNA strand is the template strand for transcription?
non-coding strand
Which Ribonucleic Acid encodes amino acid sequences of all the polypeptides found in the cell?
Messenger RNAs (mRNA)
Ribonucleic Acids?
Messenger RNAs (mRNA) Transfer RNAs (tRNA) Ribosomal RNAs (rRNA)
post-transcriptionally regulate the expression of genes, by binding to mRNA nucleotide sequences
miRNA
Transfer RNAs (tRNA)
During protein synthesis, match specific amino acids to triplet codons in mRNA
RNA component of the ribosome, interact with tRNA during translation
Ribosomal RNAs (rRNA)
Less understood RNA function in eurkaryotes?
micro RNA (miRNA)
Four ribonucleotide 5’-triphosphates
ATP, UTP, GTP, CTP
DNA-dependent RNA polymerase requires:
- DNA template, all
four ribonucleotide 5’-triphosphates (ATP, UTP, GTP, CTP)
-Mg2+
-*In transcription, UTP is used in place of TTP.
RNA polymerase elongates an RNA strand in what direction?
5’ to 3’ direction
3’ hydroxyl attack the alpha-phosphorous atom of the incoming nucleotide and release PPi.
RNA Polymerase elongation mechanism
What is “NTP”?
nucleoside triphosphate (NTP) molecule containing a nucleoside bound to 3 phosphate groups.
The DNA strand that serves as the template for RNA synthesis
Template strand (DNA non-coding region)
TRUE/FALSE:
DNA non-template (coding) strand sequence as the newly made RNA molecule (RNA transcript)
TRUE
RNA-DNA duplex of approximately 8 bp are created during elongation
After elongation, RNA peels away allowing the DNA duplex to reform.
A transcription bubble forms with about 17 bp of DNA unwound.
Polymerization
Large complex with 5 sub-units, alpha, alpha, Beta, Beta prime, and omega (core units), and a sixth subunit , sigma.
E. coli RNA polymerase
In E.Coli RNA Polymerase, the assembly and binding to UP elements (sequence upstream of promoter)
Two alpha subunits function
In E.Coli RNA Polymerase, main catalytic subunit in the large complex
Beta subunit
In E.Coli RNA Polymerase, responsible for DNA-binding in the large complex
Beta prime subunit
In E. Coli RNA Polymerase, protect the
polymerase from denaturation (structural but no catalytic function) in the large complex.
Omega subunit
In E. Coli RNA Polymerase, directs enzyme to the promoter (“the brains”) in the large complex.
Sigma subunit
What subunit directs the core complex to specific binding sites on the DNA and released from core complex once transcription started?
Sigma subunit
Why aren’t mistakes in RNA synthesis are
generally not critical?
many RNA copies are made from a single gene and they are rapidly degraded and replaced.