Chapter 15 Flashcards
The enzymatic process whereby the genetic information contained in one strand of DNA is used to specify a complementary sequence of bases in an RNA strand
transcription
A class of RNA molecules, each of which is complementary to one strand of DNA, that carry the genetic message from the chromosome to the ribosomes
messenger RNA (mRNA)
A class of RNA molecules (Mr 25,000 to 30,000), each of which combines covalently with a specific amino acid for use in protein synthesis.
transfer RNA (tRNA)
A class of RNA molecules serving as components of ribosomes.
Ribosomal RNA (rRNA)
One of the three eukaryotic RNA polymerases; Pol I transcribes genes encoding large rRNA precursors
RNA Polymerase I
One of the three eukaryotic RNA polymerases; Pol II transcribes most of the protein-coding genes.
RNA Polymerase II
One of the three eukaryotic RNA polymerases; Pol III transcribes genes encoding tRNAs, some snRNAs, 5S ribosomal RNA, and other small functional RNAs.
RNA Polymerase III
A transient subunit of the bacterial RNA polymerase that directs the enzyme to the promoter. Different sigma factors are specific for different promoters. The core RNA polymerase plus the sigma factor constitutes the RNA polymerase holoenzyme.
sigma factor
the first 3 stages of synthesis of DNA, RNA, and proteins
initiation
(1) The second of three stages of RNA synthesis, in which ribonucleotides are added to the 3′ end of the growing RNA molecule.
(2) The second of three stages of protein synthesis, in which amino acids are added to the C-terminal end of the growing peptide chain.
elongation
(1) The third of three stages of RNA synthesis, in which the RNA polymerase and the RNA product are released from the DNA template.
(2) The third of three stages of protein synthesis, in which the ribosome and the peptide product are released from the mRNA template.
termination
A DNA sequence at which RNA polymerase may bind, leading to initiation of transcription.
promoter
A DNA or amino acid sequence consisting of the residues that most commonly occur at each position in a set of similar sequences.
consensus sequence
An AT-rich sequence between positions −40 and −60 in the promoters of some highly expressed bacterial genes. The sequence is bound by an α subunit of RNA polymerase, improving the efficiency of transcription initiation for that gene.
upstream promoter (UP) element
A strand of nucleic acid used by a polymerase as a template to synthesize a complementary strand.
template strand
The strand of a double-stranded DNA that has the same sequence as the RNA transcript (with T in place of U) and is complementary to the template strand. Also called the nontemplate strand.
coding strand
A complex of the RNA polymerase bound to a promoter, in which the DNA is intact and double-stranded. Compare open complex
closed complex
(1) A complex of the RNA polymerase bound to a promoter, in which the bound DNA is partially unwound. Transcription initiation occurs in the open complex. Compare closed complex.
(2) A complex assembled on the E. coli origin of replication, oriC, at an early stage of replication initiation. It includes an oligomer of the AAA+ protein DnaA, ATP, and the histonelike protein HU.
open complex
The complex of proteins required for efficient synthesis of the RNA transcript after the RNA polymerase has moved beyond the promoter.
elongation complex
candidate DNA sequences are radiolabeled at one end. Then, a DNA-binding protein is added. Finally, chemical or enzymatic reagents are added to the mix in order to cleave the DNA randomly.
dna footprinting
Release of an 8 to 10 base pair RNA transcript from the bacterial RNA polymerase initiation complex before it clears the promoter and enters the elongation stage.
abortive initiation
The reverse of a nucleotide polymerization reaction, in which pyrophosphate reacts with the 3′-nucleotide monophosphate of an oligonucleotide, releasing the corresponding nucleotide triphosphate.
pyrophosphorolysis
A mechanism for error correction in complex biological processes that maximizes the speed of correct reactions while stalling and allowing incorrect reactions to reverse.
kinetic proofreading
A pathway for the correction of errors in an RNA transcript in which the RNA polymerase reverses direction by one or a few nucleotides on the template, and its endonuclease activity hydrolyzes the phosphodiester backbone of the transcript proximal to the mismatched base.
nucleolytic proofreading
