Transcription RNA Synthesis Flashcards
what is the synthesis of RNA from a DNA template
transcription
what do RNA polymerases do?
they catalyze the synthesis of RNA from a DNA template; more specifically, they catalyze the formation of ester bonds between nucleotides that base pair with the complementary nucleotides on the DNA template.
do RNA polymerases require a primer?
no
T/F, RNA polymerases lack a 3’-5’ exonuclease activity and do not perform rudimentary proofreading via other means?
Lack 3’-to-5’ exonuclease activity although they do perform rudimentary proofreading via other mechanisms.
what direction does the RNA polymerase move on the DNA template?
DNA copied in 3’-to-5’ direction and synthesized in a 5’-to-3’ direction
what are the substrates of the RNA polymerase?
ribonucleoside triphosphates (ATP, CTP, GTP, UTP) [T:A, C:G, G:C, A:U] DNA:RNA
cleavage of the high energy bond in the nucleoside triphosphate and release of pyrophosphate provides energy, T/F?
T
what is the overall error rate for RNA polymerases?
1 in 100,000
what is the purpose of transcription?
segment of DNA copied that functions as a unit to generate an RNA product or eventually a polypeptide chain through the process of translation
what 2 things must the RNA polymerase do?
recognize the start point and appropriate strand of DNA
and
be sensitive to signals that reflect need and control frequency of transcription
how does the RNA polymerase start?
with a promoter and other regulatory sequences all upstream of the start point, closer to the 5’ end
what is the promoter in terms of usage for the RNA polymerase?
region of regulatory sequences that controls the binding of RNA polymerase to DNA and identifies the start point.
what are the other regulatory sequences in terms of usage for the RNA polymerase?
Control frequency of transcription and stabilize polymerase to promoter
what is the RNA polymerase in prokaryotes?
a single RNA polymerase that generates all types of RNA (mRNA, rRNA, tRNA)
how many subunits do the RNA polymerase subunits contain?
4 (α2ββ’) that form the core
how is the σ (sigma) factor important for RNA polymerase in prokaryotes?
it binds to the core enzyme and directs RNA polymerase to the promoter
the RNA polymerase has many different types
the major σ (sigma) factor is σ70 relating to its molecular weight of 70,000 Da
what are the types of RNA polymerase in Eukaryotes?
3 RNA polymerases
All have the same mechanism of action but recognize different types of promoters
RNA polymerase I,II,III
product of RNA polymerase I in Eukaryotes?
rRNA
product of RNA polymerase II in Eukaryotes?
mRNA + micro RNA
product of RNA polymerase III in Eukaryotes?
tRNA + other small RNA’s
what is α-amanitin? side effects?
an inhibitor of eukaryotic RNA polymerases; particularly RNA polymerase II; : Gastrointestinal disturbances, electrolyte imbalance, and fever. Eventually the patient will have liver and kidney dysfunction.
A family, while on a picnic, picked some wild mushrooms to add to their picnic salad. Shortly after, all the members of the family became ill, with the youngest child showing the most severe symptoms. The family is suffering these effects owing to a primary inability to accomplish which one of the following in their cells and tissues?
a) Synthesize proteins
b) Synthesize lipids
c) Synthesize DNA
d) Synthesize carbohydrates
e) Repair damage in DNA
a)Synthesize proteins
what does the dsDNA consist of?
coding strand and template strand
of the coding strand and template strand, what does the RNA polymerase use for transcription?
the DNA template strand
