ADVANCED BIOCHEMISTRY EXAM 3 QUESTIONS AND 100% VERIFIED ANSWERS

All RNAs are synthesized from DNA templates by __? - ANSWER DNA-
dependent RNA polymerases


__ direct the synthesis of proteins. - ANSWER mRNAs


RNA polymerases link __ in the order specified by base pairing with a DNA
template. - ANSWER NTPs


RNA polymerase moves along the template strand in the __ direction, and the
RNA chain grows in the __ direction. - ANSWER 3' --> 5'; 5' --> 3'


__ of Ppi to inorganic phosphate by __ makes the polymerase reaction
thermodynamically favorable. - ANSWER hydrolysis; pyrophosphatases


Transcription is initiated in prokaryotes by __. - ANSWER RNA polymerase
holoenzyme


Subunits of RNA polymerase holoenzyme. - ANSWER alpha x 2, beta, beta-
prime, sigma

,Function of alpha subunit of RNA polymerase holoenzyme in prokaryotes. -
ANSWER scaffold and regulation; dimerize


Function of beta subunit of RNA polymearse holoenzyme in prokaryotes. -
ANSWER Part of polymerase active site


Function of beta prime subunit of RNA polymerase holoenzyme in prokaryotes.
- ANSWER binds to and unwinds DNA


Function of sigma subunit of RNA polymerase holoenzyme in prokaryotes -
ANSWER


Core polymerase structure - ANSWER alpha x 2, beta, beta-prime


Core polymerase can transcribe DNA into RNA, but cannot __. - ANSWER
recognize promoters and initiate transcription


Binding of __ subunit allows polymerase to recognize __. - ANSWER sigma;
different DNA sequences that act as promoters


Promoters - ANSWER nucleotide sequences that identify the location of
transcription start sites


RNA polymerases (do/do not) require a primer. - ANSWER do not


Four stages of transcription - ANSWER 1. Binding of RNA pol holoenzyme to
template DNA at promoter sites; 2. initiation of polymerization; 3. chain
elongation; 4. chain termination

, RNA pol holoenzyme binds __ to DNA with __ affinity and migrates __
looking for a sigma promoter region. - ANSWER nonspecifically; low;
downstream


Holoenzyme + promoter - ANSWER closed promoter complex


open promoter complex - ANSWER polymerase unwinds 12 base pairs in the -
9 to +3 region


Operon: Promoter - ANSWER DNA sequence which identifies and binds to
the primary transcription site where transcription begins


Prokaryotic Promoters - ANSWER TATA box at -10 region; -35 region
TTGACA


Operon: Operators - ANSWER sequence near the promoter which regulates
the transcription start


Operon: Structural Genes - ANSWER a gene that codes for any RNA or
protein product other than a regulatory factor


Lac Operon - ANSWER consists of 3 structural genes (LacZ, LacY, LacA),
promoter, terminator, regulator, and operator


Lac Operon Structural Genes - ANSWER LacZ - encodes beta-galactosidase
LacY
LacA