Elongation factors
check the accuracy of codon-anticodon pairing and increase the rate of translation
RNA polymerase II
requires general
... [Show More] transcription factors to help position it correctly at the promoter
Polyribosomes (complexes of two or more ribosomes) can be seen in the electron microscope. What is holding the ribosomes together?
mRNA
In eukaryotes, but not prokaryotes, ribosomes find the start site of translation by
scanning along the mRNA from the 5' end
Which of the following enzymes is most directly responsible for the synthesis of the primary RNA transcript from the beta-globin gene in red blood cells?
RNA polymerase II
What is the function of a snRNP or "snurp"?
it is involved in editing the primary transcript to create a functional mRNA molecule
exons
they are transcribed and are found in the mature mRNA
multiple codons
can encode the same amino acid
transcription unit
transcripted part of a gene
elF-2
helps initiate translation
amino-acyl tRNA synthetase
adds amino acids to tRNAs
TFIID
binds to the TATA box
If a protein consists of 199 peptide bonds, and the gene that codes for it has 50 percent intron nucleotides, then the number of nucleotides in the gene will be closest to
1200
TFIIH
not directly needed for the translation of a eukaryotic mRNA
the distinct characteristics of differential cell types in a multicellular organism are produced mainly by the differential regulation of the
transcription of genes transcribed by RNA polymerase II
homeodomain, zinc finger, and leucine zipper are examples of
DNA binding domains
Which of the following statements about ribosomes and protein synthesis is TRUE?
a. ribosomal RNA codes for proteins that make up ribosomes
b. a ribosome binds one tRNA at a time
c. ribosomes are large RNA structures composed solely of rRNA
d. the large subunit contains the peptide transferase activity central to protein synthesis
e. ribosomes are synthesized entirely in the cytoplasm
d. the large subunit contains the peptide transferase activity central to protein synthesis
Which of the following statements is TRUE of introns?
a. they are translated
b. they are removed from the mRNA after it leaves the nucleus
c. they are part of the open reading frame of a gene
d. they are found in both prokaryotic and eukaryotic genes
e. they are transcribed
e. they are transcribed
The antibiotic erythromycin blocks the movement of the ribosome along prokaryotic mRNA. If erythromycin is administered, which of the following immediate effects would be expected in bacterial cells?
a. inhibition of translation without direct effect on transcription
b. inhibition of amino acid synthesis
c. inhibition of translation as well as inhibition of transcription of mRNA, tRNA, and rRNA
d. inhibition of rRNA transcription
e. inhibition of DNA replication
a. inhibition of translation without direct effect on transcription
Which of the following statements about the genetic code is false?
a. many codons specify more than one amino acid
b. there are three stop codons
c. the genetic code is redundant
d. many amino acids are specified by more than one codon
e. the genetic code is the same in prokaryotes and eukaryotes
a. many codons specify more than one amino acid
A genomic DNA library
a. contains DNA copies of processed mRNAs
b. contains both transcribed and non transcribed parts of the genome
c. is generated using reverse transcriptase
d. both a and c
e. both a and b
b. contains both transcribed and non transcribed parts of the genome
A cDNA library
a. contains DNA copies of processed mRNAs
b. contains both transcribed and non transcribed parts of the genome
c. is generated using reverse transcriptase
d. both a and c
e. both a and b
d. both a and c
phosphorylates the CTD of RNA Pol II
TFIIH
adaptor for protein synthesis
tRNA
binds to the TATA box
TBP
-component of the spliceosome
-direct the splicing of pre mRNA to form mRNA
snRNA
rRNA
form the core of ribosomes
tRNA
form the adaptors that select amino acids and hold them in place on a ribosome for incorporation into protein
Which of the following statements is false?
a. RNA splicing is catalyzed by an assembly of snRNPs plus other proteins, which together constitute the spliceosome
b. bacterial cells use one type of RNA polymerase to transcribe all classes of RNA, whereas eukaryotic cells use three different types of RNA polymerases
c. RNA splicing occurs in the cell nucleus, out of reach of the ribosomes, and mRNA is exported to the cytoplasm only when processing is complete
d. different RNA polymerase start sites function with very different efficiencies, so that some genes are transcribed at much higher rates than others
e. since introns are largely genetic "junk", they do not have to be removed from the primary transcript during RNA splicing
e. since introns are largely genetic "junk", they do not have to be removed precisely from the primary transcript during RNA splicing
All of the following types of molecules are directly needed during translation EXCEPT
a. mRNA
b. EF-Tu
c. rRNA
d. EF-G
e. RNA Pol II
e. RNA Pol II
If a protein consists of 149 peptide bonds, and the gene that codes for it has 50 percent intron nucleotides, then the number of nucleotides in the gene will be closest to
a. 150
b. 149
c. 450
d. 300
e. 900
e. 900
The base in the "wobble position" of a codon
a. is in the 3' base
b. is in the 5' base
c. may form a nonstandard base pair with an anticodon
d. both A and C
e. both B and C
d. both A and C
Elongation factors
a. are required for the specific pairing of tRNA to amino acid
b. are required for the recognition of the start codon bu initiator tRNA
c. hydrolyze GTP and increase the rate of transcription
d. hydrolyze GTP and increase the rate of translation
e. add poly-adenosine to the 3' end of the mRNA
d. hydrolyze GTP and increase the rate of translation
Transcription in bacteria differs from transcription in a eukaryotic cell because
a. RNA polymerase (along with its sigma subunit) requires the general transcription factors to assemble at the promoter
b. the sigma subunit must associate with the appropriate type of RNA polymerase to produce mRNAs
c. RNA polymerase must be phosphorylated at its C terminal tail for transcription to proceed
d. RNA polymerase (along with its sigma subunit) can initiate transcription on its own
d. RNA polymerase (along with its sigma subunit) can initiate transcription on its own
Which of the following statements about RNA splicing is FALSE?
a. small RNA molecules in the nucleus perform the splicing reactions necessary for the removal of introns
b. conventional introns are not found in bacterial genes
c. for a gene to function properly, every exon must be removed from the primary transcript in the same fashion on every mRNA molecule produced from the same gene
d. splicing occurs after the 5' cap has been added to the primary transcript
e. the 5' and 3' axons of a eukaryotic gene include some untranslated regions
c. for a gene to function properly, every exon must be removed from the primary transcript in the same fashion on every mRNA molecule produced from the same gene
General transcription factors
a. are called "general" because they assemble on all promoters used by RNA polymerase II
b. help position DNA polymerase correctly at the promoter
c. are called "general" because they assemble on all promoters in all living cells
d. are required for the proper translation of all mRNAs
e. are called "general" because they assemble on all promoters of operons
a. are called "general" because they assemble on all promoters used by RNA polymerase II
The spliceosome
a. is an editing signal located at either end of an intron
b. removes the axons and fuses the introns of the mRNA together
c. adds the "cap" to the 5' end of the messenger RNA
d. is involved in cleaving the 3' termination signal and adding the poly-A tail
e. is a large assembly of snRNAs and proteins
e. is a large assembly of snRNAs and proteins
Which of the following statements is FALSE?
a. proteins begin folding while being synthesized during translation
b. incompletely folded proteins may be tagged by acetylation, which targets them to be degraded by the proteasome
c. molecular chaperons like hsp70 bind to unfolded proteins to prevent the formation of proteins aggregates
d. proteins may form aggregates if not folded proteins
e. molecular chaperons help proteins fold by binding to exposed hydrophobic patches on proteins
b. incompletely folded proteins may be tagged by acetylation, which targets them to be degraded by the proteasome
the way a gene is packaged into chromatin can affect
how the RNA transcript of that gene is ultimately spliced [Show Less]