Exam 2 MCBio Flashcards
In the nucleus, introns are removed form transcripts by ________.
a. RNA polymerase
b. Splicing
c. Exonucleases
d. DNA polymerase
b. Splicing
Which of the following is not part of the nucleosomes core particle?
a. Histone H1
b. Histone H2A
c. Histone H2B
d. Histone H3
a. Histone H1
Kinetochores are the _____________.
a. Sites of spindle fiber attachment to chromosomes
b. Regions where two chromosomes remain attached during and after mitosis
c. Same as centromere
d. Centrosomes of DNA sequence
a. Sites of spindle fiber attachment to chromosomes
The DNA sequence to which an RNA polymerase binds to initiate transcription of a gene is called a(n) ___________.
a. Enhancer
b. Promoter
c. Polymerase-binding element
d. Origin of transcription
b. Promoter
Transcriptional __________ bind to regulatory DNA sequences and stimulate transcription. These factors have two independent domains. One region binds DNA to other stimulates transcription by interacting with other proteins such as Mediator.
a. Promoters
b. Activators
c. Carboxyl terminal domains
d. TFIIE factors
b. Activators
The role of the sigma factor in prokaryote transcription is to __________.
a. Terminate transcription
b. Direct RNA polymerases to bind to different transcription start sites under different condition
c. Recognize the splicing site of tRNA
d. All of the above
b. Direct RNA polymerases to bind to different transcription start sites under different condition
RNA synthesis continues until the polymerase encounters a stop signal. The most common stop signal of prokaryotes is _________.
a. Formation of DNA methylation
b. Binding of Rho protein to the end of the mRNA
c. Binding of a sigma () factor to the end of the mRNA
d. Inverted repeat of GC-rich sequence followed by seven A residues
d. Inverted repeat of GC-rich sequence followed by seven A residues
Eukaryotic RNA polymerase I genes code for __________.
a. mRNAs
b. tRNAs
c. snRNAs and scRNAs
d. ribosomal RNAs
c. snRNAs and scRNAs
Processing of pre-tRNAs to produce tRNAS involves the following except ___________.
a. Cleavage of the pre-tRNA by the enzyme RNase P
b. Addition of CCA terminus to the 3ā end
c. Modification of base at specific positions
d. Methylation of lysine and arginine residues and phosphorylation of serine residues
d. Methylation of lysine and arginine residues and phosphorylation of serine residues
Processing of RNA transcripts occurs __________.
a. Only in eukaryotic cells
b. Only with mRNA transcripts
c. Only with rRNA and tRNA transcripts
d. With tRNA, rRNA, and mRNA transcripts
d. With tRNA, rRNA, and mRNA transcripts
Splicing of pre-mRNA takes place in large complexes, called spliceosomes, which have five types of __________.
a. Small cytoplasmic RNAs
b. Small nuclear RNAs (snRNA)
c. microRNAs
d. siRNAs
b. Small nuclear RNAs (snRNA)
Which of the following is not an example of a transcription factor DNA-binding domain?
a. Helix-turn-helix
b. Acidic-basic
c. Helix-loop-helix
d. Zinc finger
b. Acidic-basic
In eukaryotes, pre-mRNA are extensively modified before export form the nucleus. The 5ā end of the transcript is modified by __________?
a. Acetylation
b. Adding a poly-A tail
c. Adding a 7-methylguanosine cap
d. Adding the CCA sequence
c. Adding a 7-methylguanosine cap
Promoters contain several different sequence elements surrounding their transcription sites. The ________ resembles the -10 sequence of bacterial promoters.
a. TATA box
b. AAAAAA
c. Polymerase II
d. Mediator
a. TATA box
Eukaryotic gene repressor proteins are thought to act by __________.
a. Binding to DNA sites in competition and prevent binding of activators to the DNA
b. Interacting with mediator, inhibiting transcription
c. Interacting with transcription factors, inhibiting transcription
d. All of the above
d. All of the above
Aminoacyl tRNA synthetases are enzymes that __________.
a. Synthesize transfer RNAs and microRNA
b. Attach amino acids to specific transfer RNAs
c. Connect nucleotides while they are held in place on ribosomes by transfer RNAs
d. Attach the terminal CCA sequence to transcription factor
b. Attach amino acids to specific transfer RNAs
Ribosomes are named according to their sedimentation rates in ultra-centrifugation. The combined sizes of prokaryotic and eukaryotic ribosomes are ________.
a. The same
b. 30S and 50S, respectively
c. 40S and 60S, respectively
d. 70S and 80S, respectively
d. 70S and 80S, respectively
During translation, the codons on the mRNA are recognized by complementary base pairing to the anticodon on the ___________.
a. Ribosome
b. Transfer RNA
c. Small cytoplasmic RNA
d. Aminoacyl tRNA synthetase
b. Transfer RNA
Translation occurs in 3 stages. Which one is NOT one of these stages?
a. Initiation
b. Elongation
c. Epigenetic modification
d. Termination
c. Epigenetic modification
The ribosome has three binding sites. Which one is incorrect?
a. T (termination)
b. P (peptidyl)
c. A (aminoacyl)
d. E (exit) sites
a. T (termination)
The elongation factor that bring the aminoacyl tRNA to the eukaryotic ribosome and then releases it with GTP hydrolysis following the correct codon-anticodon base pairing is _________.
a. eIF-1
b. eRF-1
c. eIF-2
d. eEF-1alpha
d. eEF-1alpha
In eukaryotes, translation always starts with ___________.
a. Any amino acid
b. Glutamine
c. Methionine
d. Arginine
c. Methionine
Elongation continues until a stop codon is translocated into the A site. __________ recognizes the signals and terminate protein synthesis.
a. Any tRNA
b. Release factors
c. eIF5
d. Methionyl tRNA
b. Release factors
The amount of a protein in a cell is regulated by the rate of ___________.
a. Transcription of its gene
b. Translation of it mRNA
c. Degradation of the protein
d. All of the above
d. All of the above
Which one is incorrect about Small interfering RNAs (siRNAs)?
a. siRNA is produced from double-stranded RNAS by the nuclease Dicer
b. One strand of siRNA is incorporated into an RNA-induced silencing complex (RISC)
c. siRNAs generally pair with their targets and induce cleavage of the mRNA
d. Most siRNAs form mismatches their targets and repress translation
d. Most siRNAs form mismatches their targets and repress translation
Phosphorylation of eukaryotic initiation factors 2 (eIF2) and 2B (eIF2B) by regulatory protein kinases ____________.
a. Allows them to elongate transcription
b. Allow them to initiate translation
c. Blocks their exchange of bound GDP to GTP, inhibiting initiation of translation
d. Block the termination of translation
c. Blocks their exchange of bound GDP to GTP, inhibiting initiation of translation
Proteins that facilitate the folding of other proteins are called _________.
a. Foldases
b. Binding proteins
c. Chaperone
d. Escorts
c. Chaperone
___________ catalyzes disulfide bond formation. It is abundant in the ER, where an oxidizing environment allows (SāS) linkages.
a. Acetyltranferases (HAT)
b. Peptidyl prolyl isomerase
c. HSP
d. Protein disulfide isomerase (PDI)
d. Protein disulfide isomerase (PDI)
A __________ removes a signal sequence from a polypeptide chain after it passes through a channel into the rough ER
a. Signal peptidase
b. RFI
c. Chaperonin
d. HSP70
a. Signal peptidase
Cells can regulate the amount of the activities of their proteins by the following mechanisms.
a. Regulation by small molecules
b. Phosphorylation
c. Protein-protein interactions
d. A and C
e. All of the above
e. All of the above
Proteins are often regulated by phosphorylation by enzymes called _________.
a. Protein phosphatases
b. Phosphoproteases
c. Protein phosphorylases
d. Protein kinases
d. Protein kinases
In a major protein degradation pathway, a short polypeptide called ________ is attached to a protein to target it for destruction.
a. Glutathione
b. Ubiquontone
c. Ubiquitin
d. KDEL
c. Ubiquitin
The signals that identify initiation codons are different in prokaryotic and eukaryotic cells. Initiation codons in bacterial mRNAs are preceded by __________ that aligns the mRNA on the ribosome.
a. Apo-B100
b. 5ā methylguanosine cap
c. The Shine-Dalgarno sequence
d. Elongation factor
c. The Shine-Dalgarno sequence
cAMP activates cAMP-dependent protein kinase by _____________.
a. Stimulating its phosphorylation
b. Stimulating the dimerization of kinase subunits
c. Stimulating the release of a translational inhibitory protein bound to its mRNA
d. Binding regulatory subunits and inducing their release form the catalytic subunits
d. Binding regulatory subunits and inducing their release form the catalytic subunits
Eukaryotic ribosomes recognize and initially bind to what structure on the mRNA?
a. A Shine-Dalgarno sequence
b. The 7-methylguanosine cap
c. An operon sequence
d. A CCAAT sequence
b. The 7-methylguanosine cap
Entry of cells into mitosis is controlled in part by cyclin ________, a regulatory subunit for Cdk1 protein kinase.
a. A
b. B
c. C
d. D
b. B
________ is activated in nutrient starvations, allowing cells to degrade intracellular nonessential proteins and organelles and reutilize the components.
a. Autophagy
b. Endocytosis
c. Pinocytosis
d. Phagocytosis
a. Autophagy
The nuclear envelope consists of the following structures, ___________.
a. Two nuclear membranes
b. An underlying nuclear lamina
c. Nuclear pore complexes
d. All of the above
d. All of the above
Cajal bodies are thought to represent sites of ________.
a. DNA replication
b. snRNP processing and assembly
c. large ribosomal subunit assembly
d. small ribosomal subunit assembly
b. snRNP processing and assembly
The nucleolus is the site where _______ is (are) assembled.
a. Ribosomal subunits
b. Nuclear pores
c. Chromatin
d. The lamina
a. Ribosomal subunits
Nuclear export signals (NES) are recognized by receptors in the nucleas _________, which direct protein transport to the cytoplasm.
a. GAP
b. Lamin B receptor (LBR)
c. Exportins
d. GEP
c. Exportins
The eukaryotic 45S pre-rRNA transcript codes for the ________.
a. 28S rRNA
b. 28S and 18S rRNAs
c. 28S, 18S, and 5.8S rRNAs
d. 28S, 18S, 5.8S, and 5S rRNAs
c. 28S, 18S, and 5.8S rRNAs
_________ transport does not involve karyopherins and is independents of Ran. A distinct transporter complex moves the ________ through the nuclear pore.
a. tRNAs
b. rRNAs
c. mRNAs
d. MiRNAs
c. mRNAs
Which of the following does not take place in the nucleus?
a. DNA replication
b. Translation
c. RNA processing
d. Transcription
d. Transcription
The outer nuclear membrane is contiguous with the _________.
a. Endoplasmic reticulum
b. Nuclear lamina
c. Chromosomes
d. Plasma membrane
a. Endoplasmic reticulum
Eukaryotic RNA polymerase II genes code for __________.
a. mRNAs
b. tRNAs
c. snRNAs and scRNAs
d. ribosomal RNAs
a. mRNAs
Processing of pre-tRNAs to produce tRNAs involves _________.
a. Cleavage of the pre-tRNAs by the enzyme RNase P
b. Addition of CCA terminus to the 3ā end
c. Modification of bases at specific positions
d. All of the above
d. All of the above
The nuclear lamina is built of protiens called ________.
a. Lamins
b. Laminons
c. Nucleins
d. Nucleoplasmins
a. Lamins
Nuclear pores are organized with __________ symmetry
a. Six-fold
b. Eight-fold
c. Nine-fold
d. Ten-fold
b. Eight-fold
The nuclear localization signals is typically a(n) _______, rich in the amino acids ______.
a. alpha helix; Pro, Lys, and Arg
b. alpha helix; Leu, Phe, and Gly
c. Short sequence; Lys and Arg
d. Short sequence; Pro, Leu, and Gly
c. Short sequence; Lys and Arg
The nuclear localization signal is recognized by and binds to which protein in the process of nuclear proteins import?
a. Ran
b. Importin
c. Exportin
d. The outer fibril protein
b. Importin
Export of RNAs from the nucleus occurs primarily by __________.
a. Passive diffusion through nuclear pore complexes
b. Passive diffusion through the nuclear envelope membrane
c. Selective transport through nuclear pore complexes
d. Release from the nucleus when it breaks down at mitosis
d. Release from the nucleus when it breaks down at mitosis
Which of the following statements about snRNA is true?
a. They are synthesized in the nucleus and function in the cytoplasm
b. They are synthesized in the cytoplasm and function in the nucleus
c. They are synthesized in the nucleus and function the nucleus without passing into the cytoplasm
d. They are synthesized in the nucleus, move to the cytoplasm to pick up proteins to become function, and then return to the nucleus
d. They are synthesized in the nucleus, move to the cytoplasm to pick up proteins to become function, and then return to the nucleus
Highly condensed, transcriptionally inactive chromatin is called _________.
a. Euchromatin
b. Heterochromatin
c. A chromatin domain
d. Histone-containing chromatin
c. A chromatin domain
In the cotransitional translocation, as they emerge from the ribosome, signal sequences are recognized and bound by a(n) __________.
a. tRNA
b. signal peptides
c. signal recognition particle (SRP)
d. miRNA
c. signal recognition particle (SRP)
The sequence Lsy-Asp-Glu-Leu (KDEL) servers as an ER retention signal for proteins by binding to KDEL receptors that _________.
a. Hold the proteins in the rough ER
b. Hold the proteins in the smooth ER
c. Hold the proteins in both the smooth ER and rough ER and prevent their transport to the Golgi apparatus
d. Transport the proteins form the Golgi apparatus back to the ER
d. Transport the proteins form the Golgi apparatus back to the ER
Protein folding in the ER is assisted by the chaperone called ________.
a. BiP
b. PiP
c. Hsp60
d. Hsp90
a. BiP
Which of the following classes of lipids is synthesized in the Golgi apparatus
a. Phosphatidylcholine
b. Glycolipids
c. Cholesterol
d. Ceramide
b. Glycolipids
Many proteins are inserted directly into the ER membrane by _________. These sequences are recognized by SRP, but not cleaved by signal peptidase.
a. Glycosylation sites
b. Internal signal sequences
c. Phosphorylation sites
d. Sulfation sites
b. Internal signal sequences
New phospholipids are added only to the cytosolic half of the ER membrane. Some must be transferred to the other half. This requires passage of polar head groups through the membrane, facilitated by membrane proteins called ________.
a. Flippases
b. Signal peptidase
c. Chaperone
d. cAMP
a. Flippases
The primary function of rRNAs in the ribosome is __________.
a. To serve as a scaffold for the ribosomal proteins
b. To assist in the proper positioning of tRNAs along the mRNA template
c. To catalyze peptide bond formation
d. To assist in the proper folding of ribosomal proteins
c. To catalyze peptide bond formation
The factor that escorts the aminoacyl tRNA to the eukaryotic ribosome and then releases it with GTP hydrolysis following the correct codon-anticodon base pairing is _______.
a. eIF-1
b. eRF-1
c. eIF-2
d. eEF-1alpha
d. eEF-1alpha
During translation, the codons on the mRNA are recognized by complementary base pairing to the anticodon on the __________.
a. Ribosome
b. Transfer RNA
c. Small cytoplasmic RNA
d. Aminoacyl tRNA synthetase
b. Transfer RNA
The amount of a protein in a cell is regulated by the rate of __________.
a. Transcription of its gene
b. Translation of its mRNA
c. Degradation of the protein
d. All of the above
d. All of the above
tRNA genes are transcribed by
a. RNA polymerase I
b. RNA polymerase II
c. RNA polymerase III
d. a separate mitochondrial RNA polymerase
c. RNA polymerase III
The first step in the formation of a transcription complex for mRNA transcription is the binding of ________ to the TATA box.
a. TFIA
b. TFIIA
c. TFIIIA
d. TFIID
d. TFIID
DNA sequences that prevent enhancers from acting on promoters located in adjacent domains are called
a. insulators
b. isolators
c. repressors
d. boundaries
a. insulators
Processing of RNA transcripts occurs
a. only in eukaryotic cells
b. only with mRNA transcripts
c. only with rRNA and mRNA transcripts
d. with tRNA, rRNA, and mRNA transcripts
d. with tRNA, rRNA, and mRNA transcripts
The role of the sigma factor in prokaryotic transcription is to
a. unwind the DNA during transcription
b. direct RNA polymerase to bind to different promoter regions
c. recognize the transcription initiation site
d. terminate transcription
b. direct RNA polymerase to bind to different promoter regions
