Cell Bio
The process of gene expression always involves which process(es) described in the central dogma? A. transcription B. translation C. replication D. transcription and translation
A
What performs the function of bacterial sigma factor in eukaryotes? A. general transcription factors B. initiation proteins C. nucleosomes D. promoters
A
How do point mutations typically arise? A. chemical carcinogens B. radiation C. replication errors D. cell-division errors
C
If one end of a DNA strand has a phosphate group on it, the chemical group on the other end must be A. phosphate. B. carboxyl. C. hydroxyl. D. methyl.
C
The transcription of an integrated retroviral DNA in the genome functions to supply what products for the replication virus? A. more RNA genome copies B. RNA for translation into protein for the viral coat/envelope C. more copies of the genome and protein for the viral coat/envelope D. RNA intermediates for direct integration into another location in the genome
C
The type of bond that holds together neighboring subunits in a single strand of DNA is a A. hydrogen bond. B. phosphoanhydride bond. C. phosphodiester bond. D. peptide bond.
C
Which type of RNA is converted into protein for performing its cellular function? A. tRNA B. rRNA C. mRNA D. miRNA
C
The catalytic sites for peptide bond formation during translation is found in which part of the ribosome? A. large subunit RNAs B. large subunit proteins C. small subunit RNAs D. small subunit proteins
A
The control of a gene product's levels or activity after transcription has taken place is called A. post-transcriptional control. B. cell memory. C. combinatorial control. D. epigenetic inheritance.
A
The energy for the polymerization reaction in DNA synthesis is powered by A. the breaking of high-energy phosphate bonds in the deoxynucleotides. B. the formation of the phosphodiester bonds between nucleotides. C. the breaking of the hydrogen bonds between complementary base pairs. D. the association/disassociation cycles of the DNA polymerase enzyme.
A
The sequence at which DNA replication begins tends to have which characteristic? A. AT-rich B. A-rich C. G-rich D. GC-rich
A
Using the technique shown below, Meselson and Stahl did an experiment where they grew cells in heavy medium for many generations, then after a single generation in light medium, they observed a single band of intermediate weight after centrifugation. This experiment ruled out which model of DNA replication? A. conservative B. semiconservative C. dispersive D. liberal
A
What is the first step that must occur to repair damage on one strand of the double helix? A. The damaged region must be removed. B. The gap caused by the damage must be filled. C. The DNA backbone must be sealed. D. The DNA backbone on both strands must be cut to make a double-strand break
A
Which of the following DNA sequences is the LEAST likely to accommodate mutations? A. ribosomal RNA sequence B. regulatory DNA sequences C. the coding sequence of a duplicated gene D. DNA sequences found between genes
A
When are chromosomes in their most compacted form? A. during interphase B. during mitosis C. during replication D. They are always equally compacted.
B
Mobile genetic elements can promote gene duplication and exon shuffling by A. serving as targets for homologous recombination. B. inserting into an exon and destroying its function. C. excising themselves from a gene. D. replicating genes during the mobilization process.
A
The consistent diameter of the DNA double helix arises because of which property? A. base pairing of pyrimidines with purines B. the use of deoxyribose sugar with a 3′ -OH C. phosphodiester linkages having a consistent bond length D. the antiparallel nature of the two strands of DNA
A
The total size of the human genome is approximately ___________ base pairs. A. 3.2 billion B. 3.2 million C. 3,200 D. 30,000
A
Which of the following is the main point of control for regulating gene expression levels? A. translation B. transcription C. protein degradation D. mRNA degradation
B
Which type of transposition mechanism leaves a copy of the transposon in its original position and copies the transposon to a new position? A. cut-and-paste transposition B. replicative transposition C. transposases D. mobilizing transposition
B
Which of the following specialized DNA sequences provides an attachment point for the segregation of duplicated chromosomes? A. centromeres B. telomeres C. replication origins D. nucleosomes
A
What types of bonds are formed between histone proteins and DNA to form nucleosome core particles? A. electrostatic interactions B. polar covalent bonds C. nonpolar covalent bonds D. phosphodiester bonds
A
Which characteristic of a replicating RNA polymerase allows multiple transcripts to be made simultaneously from the same region of DNA? A. The RNA transcript dissociates from the DNA template immediately once complete. B. RNA polymerase is very small. C. RNA remains bound to the gene and helps template more transcripts. D. RNA polymerases can jump over slower RNA polymerases to make more transcript.
A
Shown below is the end of a newly replicated chromosome. Which strand will telomerase elongate? A.the template of lagging strand B. the incomplete newly synthesized lagging strand C. both strands D. neither of the strands, this is done by polymerase
A
Single nucleotide changes from unrepaired DNA damage that lead to uncontrolled cell division can lead to which of the following conditions? A. cancer B. sickle cell anemia C. cell death D. aging
A
The bonds that link two DNA strands together are A. hydrogen bonds. B. electrostatic interactions. C. phosphodiester bonds. D. phosphoanhydride bonds.
A
The part of the DNA molecule that carries the information for producing proteins is A. the order of the nucleotide bases. B. the sequence of the deoxyribose sugar groups. C. the 3′ hydroxyl terminus. D. the phosphate groups at the 5′ end.
A
The percentage of human DNA that is in protein-coding exon sequences is ___________ compared to the percentage of human DNA that is in repetitive elements, including mobile genetic elements, which is ___________. A. 1.5%; 50% B. 3%; 10% C. 10%; 50% D. 50%; 1.5%
A
What is the benefit of protein synthesis in polyribosomes? A. More protein can be produced from a single RNA. B. Protein translation is more accurate. C. Ribosomes can stay in the nucleus. D. Uncharged tRNAs can be used.
A
What is the name of the DNA sequence where replication begins? A. replication origin B. initiator C. replication fork D. DNA template
A
What is the name of the complex that degrades proteins that have reached the end of their lifespan, are damaged, or are misfolded? A. proteasome B. nuclease C. ribosome D. nuclear pore complex
A
What is the name of the protein that binds the two separated DNA strands to keep them from base pairing again before they can be replicated? A. single-strand binding protein B. helicase C. primase D. sliding clamp
A
What is the name of the type of damage caused by an improperly paired base in the DNA? A. mismatch B. double-strand break C. depurination D. thymine dimer
A
Which of the following properties could help RNA be both an information storage unit and a self-replicating molecule? A. RNA can act as a template for making copies of itself. B. RNA is a short-lived molecule. C. RNA cannot catalyze reactions. D. RNA must be made from DNA.
A
Why is RNA thought to predate DNA in evolution? A. The sugar in RNA is easier to make with the organic molecules that were present on primitive Earth. B. RNA forms many different types of functional molecules, like snRNA, rRNA and tRNA. C. RNA is less stable than DNA. D. rRNA genes are more conserved through evolution.
A
When Griffith injected heat-killed infectious bacteria mixed with live harmless bacteria, he found that the mice died because A. the heat-killed infectious bacteria were not actually dead. B.the live harmless bacteria were transformed into infectious bacteria. C. the heat-killed infectious bacteria were able to kill the mice on their own. D. the live harmless bacteria were able to kill the mice on their own
B
Which of the following is a function of the protein component of chromosomes? a. It carries a portion of the genetic information. b.It packages the DNA strands. c. It contains the enzymes that replicate the DNA. d. It helps to translate the genetic message.
B
Which of the following is true about "junk DNA"? A. It serves no biological function and is all just a remnant from evolution. B. Portions of junk sequence are conserved between species and thus may be functional. C. It usually codes for proteins but the proteins are nonfunctional in the cell. D. It is found at the ends of chromosomes from over replication during each cell cycle.
B
A mutation in the ___________ of the gene encoding the enzyme lactase enables expression of this gene in adults. A. regulatory sequence B. coding sequence C. exon D. intron
A
Germ-line mutations that are deleterious are likely to A. be preserved in a population. B. be lost from a population. C. be preserved or lost depending on chance. D. expand and be duplicated in a population.
B
Humans have an estimated 24,000 protein-coding genes in their genome, whereas Arabidopsis, a small plant, has 28,000 genes. Which statement best describes how the number of genes relates to the complexity of the organism? A. Organisms that are more complex always have more genes. B. Organisms with more genes are always less complex. C. There is no relationship between organismal complexity and number of genes. D. A higher number of genes generally correlates with complexity, with exceptions.
D
At which step of gene expression can cells amplify the number of copies of a protein made from a single gene? A. transcription B. translation C. neither transcription nor translation D. both transcription and translation
D
How does methylation of histone tails affect the accessibility of DNA? A. It relaxes the chromatin to make DNA more accessible. B. It compacts the chromatin to make DNA less accessible. C. Histone methylation has no effect on chromatin. D. It can have different effects depending on the location.
D
How does Polymerase help maintain the accuracy of DNA replication? A. Polymerase never makes mistakes; bases are added based on strict complementarity. B. DNA polymerase can cut out improperly base-paired nucleotides and add the correct one during synthesis. C. Polymerase fixes its mistakes by adding the right base during the next round of replication. D. After DNA replication is complete, the polymerase re-scans the entire chromosome to check for errors.
B
In bacteria, how does the cell recognize which strand is the newly synthesized strand and thus contains the mismatch? A. The newly synthesized strand is methylated. B. The newly synthesized strand is unmethylated. C. The sequences on both strands are cut. D. The sequence on the newly synthesized strand is made of RNA.
B
In eukaryotes, multiple genes can be expressed simultaneously by A. the arrangement of multiple genes into an operon. B. the binding of a specific transcriptional regulator to several genes. C. the binding of a mediator complex to several genes at once. D. a repressor protein binding to multiple operators.
B
Mutations in which of the following elements would abrogate RNA polymerase's ability to activate gene expression? A. regulatory DNA sequence region B. promoter C. transcription termination site D. major groove
B
Mutations that occur in germ-line cells are the only ones that lead to evolutionary change because A. germ cells are the only ones that express their DNA. B. germ cells form progeny. C. germ cells undergo meiosis. D. germ cell mutations can lead to cancer.
B
The information in an mRNA molecule is converted into protein sequence using A. three consecutive bases, with one nucleotide overlapping between triplets. B. three consecutive bases, with no overlap between triplets. C. four consecutive bases, with two nucleotides overlapping between quadruplets. D. four consecutive bases, with no overlap between quadruplets.
B
The structural feature of DNA that hints at the mechanism for its replication is the A. antiparallel strands. B. complementary base pairing. C. double helix. D. constant diameter.
B
The technique whereby human chromosomes are stained and identified is called a A. chromosome display. B. karyotype. C. genotype. D. phenotype.
B
What is a function of the nucleolus? A. to enclose sex chromosomes into a membrane-bound organelle B. to assemble ribosomal RNA and proteins into ribosomes C. to assist in the segregation of chromosomes during mitosis D. to form the nuclear lamina
B
What is the name of the enzyme that fills the sequence gaps after primers are removed from a newly synthesized DNA strand? A. primase B. repair polymerase C. DNA ligase D. nuclease
B
What percentage of human genes have clearly recognizable homologs in the fruit fly? A. 10% B. 50% C. 99% D. 74%
B
Which protein complex mediates the RNAi silencing process by inhibiting RNA polymerase via histone methylation and heterochromatin formation? A. mediator B. RITS C. RISC D. RNase
B
Why does RNA polymerase make more mistakes than DNA polymerase? A. RNA polymerase does not use a template molecule. B. RNA polymerase does not have proofreading activity. C. RNA polymerase uses completely different base-pairing rules. D. RNA polymerase has a faulty mismatch repair system.
B
___________ is a sequence of DNA that contains the information required for making a particular functional RNA or protein. A. A genome B. A gene C. Genetics D. A chromosome
B
RNA sequencing can give a more accurate estimate of the number of genes in a genome than finding ORFs can because A. RNA sequencing can rule out potential ORFs that are not transcribed. B. RNA sequencing is more accurate than DNA sequencing. C. RNA sequencing always includes introns. D. RNA sequencing will not identify genes for functional or regulatory RNA.
A
The conservation of the organization of a region of a chromosome between species—that is, all of the genes in the same order in that region—is called A. conserved synteny. B. conserved sequence. C. phylogenetic. D. purified sequence.
A
The reading frame to use for translating an mRNA into functional protein is determined by the A. location of an AUG. B. promoter sequence. C. 5′ cap. D. replication origin.
A
The splicing of introns out of an mRNA molecule is catalyzed by A. RNA molecules that base pair with the splice sites to promote intron removal. B. proteins that contain metal ions to pull electrons from the phosphate bonds. C. RNA molecules that act as a template for new RNA synthesis using exons only. D. proteins that act as nucleases to chew away and remove the introns.
A
What can happen if heterochromatin spreads inappropriately into an area with active genes? A.The active genes can become silenced. B. Heterochromatin cannot spread into areas with active genes. C. The genes will resist and remain active. D. The region will convert into a telomere.
A
What recognizes the stop codons in an mRNA? A. release factor B. a specialized tRNA linked to methionine C. nothing D. the 3′ poly-A tail
A
Which double-strand break repair mechanism is a simple ligation mechanism? A. nonhomologous end joining B. homologous recombination C. DNA mismatch repair D. DNA ligase
A
Which nucleic acid often base pairs with itself to fold into complex three-dimensional shapes in the cell? A. RNA B. DNA C. both RNA and DNA D. neither RNA nor DNA
A
Which of the following is found only in eukaryotic genomes, and NOT in prokaryotic genomes? A. telomeres B. deoxyribose sugar C. packaging proteins D. chromosomes
A
Which retrotransposon makes up 15% of our genome and encodes its own reverse transcriptase enzyme for transposition? A. L1 element B. Alu sequence C. latent HIV D. bacterial transposons
A
A transcriptional regulator that activates expression of additional transcriptional regulators that induce production of a particular cell type or organ is called a A. master regulator. B. reprogramming regulator. C. feedback activator. D. terminal differentiator.
A
An open reading frame (ORF) is defined as a sequence that has about 100 codons that lack stop codons. Why is finding ORFs helpful in determining the gene number in an unknown sequence? A. A random sequence is expected have a stop codon every 20 codons. B. Stop codons are subject to positive selection and are very frequent. C. Open reading frames are always genes that are expressed. D. Open reading frames never occur randomly.
A
DNA is a better molecule for long-term storage of genetic information than RNA because A. the deoxyribose sugar stabilizes DNA chains. B. the uracil in DNA is less easily mutated. C. DNA is able to make complex folded secondary structures. D. DNA is able to autocatalyze its own repair.
A
Excess amounts of the amino acid tryptophan result in downregulation of the expression of the enzymes required for its synthesis due to A. the repressor binding to the operator. B. inactivation of the repressor protein. C. the inability of the repressor to bind to the operator. D. the inactivation of RNA polymerase.
A
Generally, bacterial promoters that are regulated by transcriptional activators bind ___________ to RNA polymerase on their own, but promoters that are regulated with transcriptional repressors bind ___________ to RNA polymerase. A. weakly; strongly B. strongly; weakly C. weakly; weakly D. strongly; strongly
A
Heterochromatin can spread along a chromosome until it encounters a A. barrier DNA sequence. B. heterochromatin-specific protein. C. histone modifying enzyme. D. unmodified histone tail.
A
How are the primers from which DNA synthesis starts different from the DNA itself? A. The primers are made up of RNA not DNA. B. The primers are not properly based paired so they can be removed. C. The primers have three phosphates on each nucleotide. D. The primers do not have a 3′ −OH.
A
How do tRNAs become attached to the correct amino acid? A. aminoacyl-tRNA synthetases B. RNA polymerases C. rRNA ribozymes D. translation initiation factors
A
If lactose and glucose are both available to a bacterial cell, which carbon source(s) will be used? A. glucose B. lactose C. both lactose and glucose D. cyclic AMP
A
In the cell, enhancer sequence functions are limited in their range of action by the formation of ___________ that hold specific genes and enhancers in close proximity. A. loops B. chromatin C. helices D. operons
A
In which direction, and on which strands does DNA replication proceed from a replication origin on a chromosome? A. in both directions, on both strands B. only on one strand in the 5′ à 3′ direction C. only on one strand in the 3′ à 5′ direction D. from the left to the right, on both strands
A
Long noncoding RNA (lncRNA) can function as a(n) A. protein scaffold. B. RNA polymerase. C.transcriptional regulator. D. telomerase.
A
Meselson and Stahl performed a classic experiment to explore three models for the mechanism of DNA replication. Which of the models held that the two parental strands would remain associated after replication? A. conservative B. semiconservative C. dispersive D. liberal
A
MicroRNAs block the expression of a specific gene product by binding to the ___________ and inhibiting ___________. A. mRNA; translation B. DNA; transcription C. protein; activity D. ribosome; translation
A
A housekeeping gene is a gene whose cellular function is A. involved in removal of waste products from cells. B. turned off periodically for maintenance. C. important for processes found in all cell types. D. critical for specialized activities in a specific cell type.
C
A reporter gene is an experimentally engineered regulatory DNA sequence from a gene of interest that has been fused to a gene that encodes a protein that is easily observed experimentally. Why is this approach useful? A. It can provide information as to where a gene is expressed. B. It can provide information as to when a gene is expressed. C. It provides information into where and when a gene is expressed. D. It provides information on the binding interactions of the gene product.
C
Eukaryotic repressor proteins can decrease transcription using which of the following mechanisms? A. binding an operon and preventing polymerase binding B. recruiting a histone acetyltransferase complex to modify histones C. preventing the assembly of the transcription initiation complex D. attracting a chromatin remodeling complex to open chromatin at the site
C
Export of RNA from the nucleus requires the RNA to have which characteristic(s)? A. 5′ cap B. poly-A tail C. 5′ cap and poly-A tail D. introns
C
Many transcriptional regulators function together to decide the expression level of a particular gene. This describes the concept of A. operons. B. repression. C. combinatorial control. D. activation.
C
Noncoding RNAs include all of the following EXCEPT A. rRNA. B. tRNA. C. mRNA. D. regulatory RNAs.
C
Transplanting the nucleus of an epithelial cell into an egg cell lacking genetic information leads to the formation of A. another epithelial cell. B. a dead cell. C. a normally developing embryo. D. a hybrid cell that has characteristics of both embryonic cells and epithelial cells.
C
What is a defining difference between viruses and mobile genetic elements? A. Mobile genetic elements can insert into genomes; viruses cannot. B. Viruses sometimes use cell machinery to replicate; mobile genetic elements always use their own enzymes. C. Viruses can leave the cell and move to other cells and organisms; mobile genetic elements generally just move around the genome within in a cell. D. Mobile genetic elements do not use RNA intermediates in their transposition process, whereas viruses use RNA intermediates for replication.
C
What is the function of a topoisomerase in DNA replication? A. It coils the DNA for tighter packaging. B. It separates the DNA strands. C. It relieves the tension in DNA strands. D. It binds the template DNA to hold in place.
C
What is the relationship between genome size and organismal complexity? A. The more complex the organism, the larger the genome, without exception. B. The more complex the organism, the smaller the genome, without exception. C. More complex organisms generally have larger genomes but there are many notable exceptions. D. There is no relationship between genome size and organismal complexity, it is random.
C
Which of the following mechanisms for genetic change involves the acquisition of genetic material from another organism? A.gene duplication B. transposition C. horizontal transfer D. mutation
C
If a stretch of DNA on the parental strand of a replicating chromosome has the sequence 5′-AGCTCGATCGGCTA-3′, what will the sequence of the newly synthesized strand made from this stretch of template be? A. 5′-AGCTCGATCGGCTA-3′ B. 3′-AGCTCGATCGGCTA-5′ C. 5′-TCGAGCTAGCCGAT-3′ D. 3′-TCGAGCTAGCCGAT-5′
D
Protein concentration can be regulated by all of the steps listed EXCEPT A. nuclear export. B. RNA processing. C. mRNA stability. D. DNA replication.
D
Which of the following describes the chromosomal makeup of a somatic cell of a human biological male? A. 23 pairs of autosomes B. 23 pairs of autosomes + 1 Y chromosome C. 23 pairs of autosomes + 1 X chromosome + 1 Y chromosome D. 22 pairs of autosomes + 1 X chromosome + 1 Y chromosome
D
Which of the following is NOT a common source of DNA damage for cells in our bodies? A. UV light B. spontaneous loss of amino groups on cytosine C. replication fork problems D. soap
D
Which of the following is a difference between the mechanisms of DNA polymerase and RNA polymerase? A. The direction of polymerization for DNA polymerase is 5′ to 3′, but RNA polymerase is 3′ to 5′. B. DNA polymerase uses DNA as a template for making DNA copies; RNA polymerase uses RNA as a template for making RNAs. C. DNA polymerase uses the energy from the hydrolysis of the nucleotide triphosphates to drive the reaction; RNA polymerase uses reduced electron carriers. D. DNA polymerase needs a base-paired 3′ −OH for a polymerization reaction to occur; RNA polymerase can polymerize two nucleotides without a base-paired 3′ −OH.
D
Which of the following mechanisms describes how eukaryotic activator proteins can regulate chromatin packaging to enhance transcription? A. binding to enhancer regions to promote formation of the transcription initiation complex B. activating polymerase binding through contacts made in the activation region C. recruiting histone deacetylase complexes to remove acetyl groups from histones D. recruiting chromatin-remodeling complexes to eject or slide nearby nucleosomes
D
