Bio 221 Final
TF- The methyl (CH3) groups on monosaccharides are reaction hot spots and can be replaced by other functional groups to produce derivatives of the original sugar
False
TF- The presence of double bonds in the hydrocarbon tail of a fatty acid does not greatly influence its structure
False
TF- Translation ends when the tRNA for a stop codon binds to the A site of the ribosome
False
Transcription regulators interact only with the sugar-phosphate backbone on the outside of the double helix to determine where to bind on the DNA helix Select one: True False
False
A protein chain folds into its stable and unique three-dimensional structure, or conformation, by making many noncovalent bonds between different parts of the chain. Such noncovalent bonds are also critical for interactions with other proteins and cellular molecules. From the list provided, choose the class of amino acids that are most important for the interactions detailed below. You may use some more than once and others not at all. Forming ionic bonds with negatively charged DNA- Localizing a membrane protein that spans a lipid bilayer- Tightly packing the hydrophobic interior core of a globular protein- Forming hydrogen bonds to aid solubility in water-
Forming ionic bonds with negatively charged DNA- positively charged Localizing a membrane protein that spans a lipid bilayer- nonpolar Tightly packing the hydrophobic interior core of a globular protein- nonpolar Forming hydrogen bonds to aid solubility in water- uncharged
G?
16
In the DNA from certain bacterial cells, 16% of the nucleotides contain Cytosine (C). What are the percentages of the other three nucleotides? Hint: consider the rules of complementary base pairing. A?
34
T?
34
To study membrane transport, you make two sets of small phospholipid-bilayer enclosures with aqueous solution inside and outside, called liposomes. Set #1 liposomes contain no membrane proteins, while Set #2 has ion channels and transporters. Categorize the following types of molecules as to whether they can pass into Set#1 liposomes only, Set #2 liposomes only, both, or neither: Small polar molecules Charged ions Large polar molecules Small nonpolar molecules
Small polar molecules- Set #1 only Charged ions- Set #2 only Large polar molecules- Set #2 only Small nonpolar molecules- both
TF- GTP-binding proteins typically have GTPase activity, and the hydrolysis of GTP transforms them to the "off" conformation, in which they're bound to GDP
True
TF- In eukaryotic cells, DNA is wound around protein complexes called histones, which can be covalently modified to regulate the expression of genes
True
TF- Membrane fluidity decreases when phospholipid chain lengths increase and fatty acids are fully saturated.
True
TF- Prokaryotic chromosomes have a single site of initiation of DNA replication
True
TF- The cytoskeleton is used as a transportation grid for the efficient, directional movement of cytosolic components
True
TF- The lipid bilayer is made up of phospholipids that have an amphipathic chemical structure.
True
The protein p53 is a tumor suppressor protein because it stops cells from proliferating. Select one: True False
True
The piece of RNA below includes the region that codes for the binding site for the initiator tRNA (bold) needed in translation. 5′-GUUUCCCGUAUACAUGCGUGCCGGGGGC-3′ Which anticodon will be found on the first tRNA to reach the E site? a. 5' - CAU - 3' b. 5' - GUA - 3' c. 5' - AUG - 3' d. 5' - UAC - 3'
a. 5' - CAU - 3'
The movement of a substance against its concentration gradient is called what? a. Active transport b. Osmosis c. Facilitated difusion d. Passive transport
a. Active transport
You have developed a promising anti-cancer agent, but it has poor solubility in water. Which of the following changes should improve water solubility? Please choose all correct answers. a. Adding a carboxyl group (COOH) b. Increasing the size of the drug c. Adding a methyl group (CH3) d. Adding a hydroxyl group (OH)
a. Adding a carboxyl group (COOH) d. Adding a hydroxyl group (OH)
Which statement best represents the cell theory? a. All cells are formed by the growth and division of existing cell. b. All cells resemble square or rectangular chambers. c. All cells can be seen using a microscope. d. All cells require a continual input of energy to sustain life. e. All cells contain DNA.
a. All cells are formed by the growth and division of existing cell.
Viral genomes a. All of these answers are true. b. can be either double-stranded or single-stranded. c. can be made of RNA. d. can be made of DNA.
a. All of these answers are true.
Which of the following statements is TRUE? a. Disulfide bonds stabilize but do not change a protein's final conformation. b. Disulfide bonds are formed by the cross-linking of methionine residues. c. Disulfide bonds are more common for intracellular proteins, compared to extracellular proteins. d. Disulfide bonds are formed mainly in proteins that are retained within the cytosol.
a. Disulfide bonds stabilize but do not change a protein's final conformation.
Which of the following statements about sequence proofreading during DNA replication is FALSE? a. If an incorrect base is added, it is "unpaired" before removal. b. The exonuclease activity is in a different domain of the DNA polymerase. c. The DNA proofreading activity occurs nearly simultaneously with strand elongation. d. The exonuclease activity removes nucleotides from the 5' end of a growing DNA strand
a. If an incorrect base is added, it is "unpaired" before removal.
Genes in eukaryotic cells often have intronic sequences coded for within the DNA. These sequences are ultimately not translated into proteins. Why? a. Intronic sequences are removed from RNA molecules by the spliceosome, which works in the nucleus. b. Introns are not transcribed by RNA polymerase. c. The ribosome will skip over intron sequences when translating RNA into protein. d. Introns are removed by catalytic RNAs in the cytoplasm.
a. Intronic sequences are removed from RNA molecules by the spliceosome, which works in the nucleus.
The core histones are small, basic proteins that have a globular domain at the C-terminus and a long, extended conformation at the N-terminus. Which of the following is NOT true of the N-terminal "tail" of these histones? a. It binds to DNA in a sequence-specific manner. b. It extends out of the nucleosome core. c. It helps DNA pack tightly. d. It is subject to covalent modifications.
a. It binds to DNA in a sequence-specific manner.
Which of the following statements most correctly describes meiosis? a. Meiosis involves a single round of DNA replication followed by two successive cell divisions. b. Meiosis involves a single round of DNA replication followed by four successive cell divisions. c. Meiosis involves four rounds of DNA replication followed by two successive cell divisions. d. Meiosis involves two rounds of DNA replication followed by a single cell division.
a. Meiosis involves a single round of DNA replication followed by two successive cell divisions.
Which of the following events usually occurs during interphase? Choose all that apply. a. Mistakes in DNA replication are repaired. b. Sister chromatids are separated. c. Cells grow in size. d. The nuclear envelope breaks down. e. DNA is replicated.
a. Mistakes in DNA replication are repaired. c. Cells grow in size. e. DNA is replicated.
Which of the following methods is not used by cells to regulate the amount of a protein in the cell? a. Nuclear pore complexes can regulate the speed at which newly synthesized proteins are exported from the nucleus into the cytoplasm. b. Proteins can be tagged with ubiquitin, marking them for degradation. c. Genes can be transcribed into mRNA with different efficiencies. d. Many ribosomes can bind to a single mRNA molecule.
a. Nuclear pore complexes can regulate the speed at which newly synthesized proteins are exported from the nucleus into the cytoplasm.
Which of the following statements about organoids is FALSE? a. Organoids can only be made for organs that are made up of a single type of differentiated cell. b. Organoids are self-assembling. c. Organoids can form multilayered structures. d. Organoids can be produced from ES and iPS cells.
a. Organoids can only be made for organs that are made up of a single type of differentiated cell.
What would happen in a cell that has a mutant form of S-cyclin in which the sites of ubiquitination are changed to an amino acid that can no longer have ubiquitin attached? a. The S-Cdk disassembles. b. DNA helicases are activated and the replication fork is prepared for replication. c. Cells would immediately exit into G2 phase. d. S-cyclin will get degraded by the APC/C complex.
a. The S-Cdk disassembles.
Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2? a. The cell would enter M phase under conditions when normal cells would not. b. The cell would be unable to enter G2. c. The cell would pass through M phase more slowly than normal cells. d. The cell would be unable to enter M phase.
a. The cell would enter M phase under conditions when normal cells would not.
Which of the following statements about the genetic code is CORRECT? a. The genetic code is redundant. b. All codons specify more than one amino acid. c. All amino acids are specified by more than one codon. d. All codons specify an amino acid.
a. The genetic code is redundant.
How does phosphorylation control protein activity? a. The phosphate group induces a change in the protein's conformation. b. The phosphate group, with its negative charges, prevents other negatively charged molecules from interacting with the protein. c. The phosphate group serves as an added source of energy for a protein. d. The phosphate group alters the primary structure of the protein. e. The phosphate group, with its positive charges, temporarily relieves feedback inhibition.
a. The phosphate group induces a change in the protein's conformation.
Which statement is true about the removal of a terminal phosphate from ATP? a. The reaction is energetically favorable b. The reaction is associated with a positive change in ΔG° c. The reaction is a condensation reaction
a. The reaction is energetically favorable
Which of the following statements correctly explains what it means for DNA replication to be bidirectional? a. The replication forks formed at the origin move in opposite directions. b. The replication fork can open or close, depending on the conditions. c. Replication-fork movement can switch directions when the fork converges on another replication fork. d. The DNA replication machinery can move in either direction on the template strand.
a. The replication forks formed at the origin move in opposite directions.
Which of the following does not occur before a eukaryotic mRNA is exported from the nucleus? a. The ribosome binds to the mRNA. b. The mRNA is polyadenylated at its 3´ end. c. RNA polymerase dissociates. d. A guanine nucleotide with a methyl group is added to the 5´ end of the mRNA.
a. The ribosome binds to the mRNA.
Which of the following happens when a G-protein-coupled receptor activates a G protein? a. The α subunit exchanges its bound GDP for GTP. b. The β subunit exchanges its bound GDP for GTP. c. The GDP bound to the α subunit is phosphorylated to form bound GTP. d. It activates the α subunit and inactivates the βγ complex.
a. The α subunit exchanges its bound GDP for GTP.
What is one way changes in histone modifications lead to changes in chromatin structure? a. They help recruit other proteins to the chromatin. b. They denature the DNA by interfering with hydrogen-bonding between base pairs c. They directly lead to changes in the positions of the core histones. d. They cause the histone N-terminal tails to become hyperextended.
a. They help recruit other proteins to the chromatin.
What do the phosphorylated tyrosines on activated RTKs do? a. They serve as binding sites for a variety of intracellular signaling proteins. b. They help the receptor dimerize. c. They activate the enzymatic activity of the RTKs. d. They serve as binding sites for G proteins. e. They promote receptor internalization.
a. They serve as binding sites for a variety of intracellular signaling proteins.
In comparing the complete genomes of five bacteria, one archaea, and one eukaryote (yeast), it was found that 239 families of genes have representatives in all three domains of life (are conserved through evolution in each domain of life). Which of the following families of genes would you NOT expect to be included here? a. Those involved in the trafficking of molecules in and out of the nucleus b. Those involved in the synthesis of ATP c. Those involved in the production and function of ribosomes d. Those involved in amino acid metabolism and transport
a. Those involved in the trafficking of molecules in and out of the nucleus
The type of bond that holds together neighboring subunits in a single strand of DNA is a Select one: a. phosphodiester bond. b. peptide bond. c. hydrogen bond. d. phosphoanhydride bond.
a. phosphodiester bond.
Which of the following is NOT a general mechanism that cells use to maintain stable patterns of gene expression as cells divide? a. proper segregation of housekeeping proteins when cells divide b. faithful propagation of condensed chromatin structures as cells divide c. a positive feedback loop, mediated by a transcriptional regulator that activates transcription of its own gene in addition to other cell-type-specific genes d. inheritance of DNA methylation patterns when cells divide
a. proper segregation of housekeeping proteins when cells divide
Which of the following is NOT a general mechanism that cells use to maintain stable patterns of gene expression as cells divide? a. proper segregation of housekeeping proteins when cells divide b. inheritance of DNA methylation patterns when cells divide c. a positive feedback loop, mediated by a transcriptional regulator that activates transcription of its own gene in addition to other cell-type-specific genes d. faithful propagation of condensed chromatin structures as cells divide
a. proper segregation of housekeeping proteins when cells divide
What type of macromolecule helps package DNA in eukaryotic chromosomes? a. proteins b. carbohydrates c. lipids d. RNA
a. proteins
Carbon atoms can form double bonds with other carbon atoms, nitrogen atoms, and oxygen atoms. Double bonds can have important consequences for biological molecules because they are __________ compared to single covalent bonds. a. rigid with respect to rotation b. long c. unstable d. weak
a. rigid with respect to rotation
Which of the following are ways cells can differ (check all that apply): a. shape b. size c. method of obtaining energy d. method of interpreting genetic information e. chemical composition
a. shape b. size e. chemical composition
A neuron and a white blood cell have very different functions. For example, a neuron can receive and respond to electrical signals, while a white blood cell defends the body against infection. This is because a. the neuron expresses some mRNAs that the white blood cell does not, and vice versa. b. all of the proteins found in a neuron are completely different from the proteins found in a white blood cell. c. the neuron and the white blood cell within an individual have the same genome. d. neurons and white blood cells are differentiated cells and thus no longer need to transcribe and translate genes.
a. the neuron expresses some mRNAs that the white blood cell does not, and vice versa.
In the α helices of single-pass transmembrane proteins, the hydrophobic side chains face which direction? a. the outside of the membrane-spanning helix b. the external or lumenal side of the membrane c. the inside of the membrane-spanning helix d. the cytosolic side of the membrane
a. the outside of the membrane-spanning helix
How do peripheral membrane proteins associate with the plasma membrane? a. through noncovalent bonding with an integral membrane protein b. through covalent linkage to an integral membrane protein c. through long strengths of nonpolar amino acids that promote insertion into the membrane interior d. through covalent linkage to a membrane lipid
a. through noncovalent bonding with an integral membrane protein
Select the option that best completes the following statement: Nonhomologous end joining (NHEJ) is a process by which a double-stranded DNA end is joined a. to the nearest available double-stranded DNA end. b. to a similar stretch of sequence on the complementary chromosome. c. after repairing any mismatches. d. after filling in any lost nucleotides, helping to maintain the integrity of the DNA sequence.
a. to the nearest available double-stranded DNA end.
The cell components that move materials from one organelle to another are called Select one: a. transport vesicles. b. Golgi apparatus. c. cytosol. d. endoplasmic reticulum.
a. transport vesicles.
Some types of cancer run in families: individuals in such predisposed families are prone to develop these cancers early in adult life. Mutations in which type of cancer-critical gene would most likely be responsible for "hereditary" cancers that are not immediately present in the phenotype of offspring but develop as age increases? a. tumor suppressor genes b. Mutations in cancer-critical genes cannot be inherited because cancer is not a hereditary condition. c. proto-oncogenes d. either proto-oncogenes or tumor suppressor genes
a. tumor suppressor genes
Organisms that reproduce sexually a. undergo a sexual reproductive cycle that involves an alternation of haploid cells with the generation of diploid cells. b. must be haploid, unlike organisms that reproduce asexually. c. can reproduce only with a partner that carries the same alleles. d. create zygotes that are genetically identical to each other.
a. undergo a sexual reproductive cycle that involves an alternation of haploid cells with the generation of diploid cells.
Viruses reproduce inside a host cell because a. viruses use host-cell ribosomes to produce viral coat proteins. b. viruses package DNA from the host-cell genome into the virus particle. c. all viruses must insert their genomes into the host-cell genome in order to be replicated. d. viruses need host-cell reverse transcriptase to convert its RNA into DNA.
a. viruses use host-cell ribosomes to produce viral coat proteins.
Which of the following would yield the most highly mobile phospholipid (listed as number of carbons and number of double bonds, respectively)? a. 16 carbons with no double bonds b. 15 carbons with two double bonds c. 20 carbons with two double bonds d. 24 carbons with one double bond
b. 15 carbons with two double bonds
Which of the following describes negative feedback regulation? Select one: a. A component generates an all-or-none, switch-like mechanism. b. A component late in the pathway inhibits an enzyme early in the pathway. c. A component amplifies the signal for a more robust response. d. A component acts to further activate the signaling pathway and enhance the cell's response.
b. A component late in the pathway inhibits an enzyme early in the pathway.
How does the cell rapidly reduce the concentration of cyclins in the cytosol? a. cAMP noncovalent binding to cyclin b. Covalently attach a molecule of ubiquitin to cyclin c. Block transcription of cyclin through chromatin remodeling d. Express a miRNA complementary to the mRNA for cyclin
b. Covalently attach a molecule of ubiquitin to cyclin
Which of the following statements is TRUE? a. A cell-surface receptor capable of binding only one type of signal molecule can mediate only one kind of cell response. b. Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior. c. Any foreign substance that binds to a receptor for a normal signal molecule will always induce the same response that is produced by that signal molecule on the same cell type. d. To function, all extracellular signal molecules must be transported by their receptor across the plasma membrane into the cytosol.
b. Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior.
Apoptosis differs from necrosis in that necrosis a. requires the reception of an extracellular signal. b. causes cells to swell and burst, whereas apoptotic cells shrink and condense. c. involves a caspase cascade. d. causes DNA to fragment.
b. causes cells to swell and burst, whereas apoptotic cells shrink and condense.
The principal microtubule-organizing center in animal cells is the a. cell cortex. b. centrosome. c. kinetochore. d. centromere.
b. centrosome.
During recombination a. cohesins keep the sister chromatids together until anaphase I. b. chiasmata hold chromosomes together. c. sister chromatids undergo crossing-over with each other. d. one crossover event occurs for each pair of human chromosomes.
b. chiasmata hold chromosomes together.
Which of the following choices BEST describes the role of the lysosome? a. transport of material to the Golgi apparatus b. clean-up, recycling, and disposal of macromolecules c. sorting of transport vesicles d. the storage of excess macromolecules
b. clean-up, recycling, and disposal of macromolecules
Operons a. can only be regulated by gene activator proteins. b. contain a cluster of genes transcribed as a single mRNA. c. are transcribed by RNA polymerase II. d. are commonly found in eukaryotic cells.
b. contain a cluster of genes transcribed as a single mRNA.
The N-terminal tail of histone H3 can be extensively modified, and depending on the number, location, and combination of these modifications, these changes may promote the formation of heterochromatin. What is the result of heterochromatin formation? a. recruitment of remodeling complexes b. decrease in gene expression c. displacement of histone H1 d. increase in gene expression
b. decrease in gene expression
miRNAs, tRNAs, and rRNAs all a. are packaged with other proteins to form RISC. b. do not code for proteins. c. form base pairs with mRNA molecules. d. act in the nucleus.
b. do not code for proteins.
Cells in the G0 state a. have duplicated their DNA b. do not divide c. have entered this arrest state from either G1 or G2 d. cannot reenter the cell cycle
b. do not divide
Cells in the G0 state a. have entered this arrest state from either G1 or G2. b. do not divide. c. cannot reenter the cell cycle. d. have duplicated their DNA.
b. do not divide.
Cells that are specialized for the secretion of proteins are likely to have which of the following features? a. small volume of cytoplasm b. enlarged endoplasmic reticulum c. large population of mitochondria d. long bundles of actin/myosin proteins
b. enlarged endoplasmic reticulum
The complete set of information in an organism's DNA is called its a. genetic code. b. genome. c. gene. d. coding sequence.
b. genome.
What type of bond connects base pairs? a. ionic b. hydrogen c. van der Waals d. covalent
b. hydrogen
Which of the following situations would facilitate the process of exon shuffling? a. exons that code for more than one protein domain b. introns that contain regions of similarity to one another c. shorter introns d. a haploid genome
b. introns that contain regions of similarity to one another
RNA in cells differs from DNA in that a. the sugar ribose contains fewer oxygen atoms than does deoxyribose. b. it is single-stranded and can fold up into a variety of structures. c. it is single-stranded and cannot form base pairs. d. it contains the base uracil, which pairs with cytosine.
b. it is single-stranded and can fold up into a variety of structures.
A malignant tumor is more dangerous than a benign tumor because a. its cells are proliferating faster. b. its cells invade other tissues. c. it causes neighboring cells to mutate. d. its cells attack and phagocytose neighboring normal tissue cells.
b. its cells invade other tissues.
Enzymes increase the speed of a chemical reaction because they Select one: a. increase the temperature to provide the necessary boost of energy. b. lower the activation energy needed to start the reaction. c. make the reaction spontaneous. d. make the reaction more energetically favorable.
b. lower the activation energy needed to start the reaction.
Muscle cells, which must use large amounts of energy very quickly to do work, contain more_____ than most other cells in the human body. a. chloroplasts b. mitochondria c. vacuoles d. lysosomes
b. mitochondria
Unlike what occurs when fuel is burned to make a fire, all living systems use the energy from heat-generating reactions to create and maintain a. movement. b. order. c. light. d. electricity.
b. order.
Which of the following correctly matches a G-protein-activated enzyme with the second messenger molecule it produces? Select one: a. adenylyl cyclase -> inositol triphosphate b. phospholipase C -> diacylglycerol c. protein kinase A -> Ca2+ d. guanylyl cyclase -> GTP
b. phospholipase C -> diacylglycerol
What determines the specificity an antibody has for its antigen? a. the summation of its disulfide bonds b. polypeptide loops in its variable domains c. its Y-shaped, bivalent structure d. polypeptide loops in its constant domain
b. polypeptide loops in its variable domains
What type of macromolecule helps package DNA in eukaryotic chromosomes? a. RNA b. proteins c. lipids d. carbohydrates
b. proteins
A base substitution mutation in a gene sometimes has no effect on the protein the gene codes for. Which of the following factors could account for this? a. the rarity of such mutations b. some amino acids have more than one codon c. a correcting mechanism that is part of the mRNA molecule d. A, and B e. A, B, and C
b. some amino acids have more than one codon
Which of the following examples does NOT describe a mechanism of post-transcriptional control of gene expression? a. the alternative splicing of a gene, leading to the production of a muscle-specific protein b. the action of the RNA component of telomerase c. the degradation of an mRNA by miRNA binding and RISC activity d. translational inhibition of an mRNA by the binding of a protein at the 5´ untranslated region of the message.
b. the action of the RNA component of telomerase
The potential energy stored in high-energy bonds is commonly harnessed when the bonds are split by the addition of __________ in a process called __________. a. acetate; acetylation b. water; hydrolysis c. ATP; phosphorylation d. hydroxide; hydration
b. water; hydrolysis
Which of the following would yield the most highly mobile phospholipid (listed as number of carbons and number of double bonds, respectively)? a. 20 carbons with two double bonds b. 16 carbons with no double bonds c. 15 carbons with two double bonds d. 24 carbons with one double bond
c. 15 carbons with two double bonds
How many replication forks are formed when an origin of replication is opened? a. 3 b. 1 c. 2 d. 4
c. 2
You have a piece of DNA that includes the following sequence:5´-ATAGGCATTCGATCCGGATAGCAT-3´3´-TATCCGTAAGCTAGGCCTATCGTA-5´Which of the following RNA molecules could be transcribed from this piece of DNA? a. none of these answers are correct. b. 5´-UACGAUAGGCCUAGCUUACGGAUA-3´ c. 5´-AUAGGCAUUCGAUCCGGAUAGCAU-3´ d. 5´-UAUCCGUAAGCUAGGCCUAUGCUA-3´
c. 5´-AUAGGCAUUCGAUCCGGAUAGCAU-3´
Which of the following best describes positive feedback regulation? a. A component generates an on-off, switch-like mechanism. b. A component amplifies the signal for a more robust response throughout the cytoplasm. c. A component acts to further activate the signaling pathway and enhance the cell's response. d. A component late in the pathway activates a protein earlier in the pathway. e. A component late in the pathway inhibits a protein earlier in the pathway
c. A component acts to further activate the signaling pathway and enhance the cell's response.
In water, hydrogen bonds can form between which of the following? a. The hydrogen atom of one water molecule and the hydrogen atom of another b. The one oxygen atom and two hydrogen atoms of one water molecule c. A hydrogen atom of one water molecule and an oxygen atom of another d. The oxygen atom of one water molecule and the oxygen atom of another
c. A hydrogen atom of one water molecule and an oxygen atom of another
Which of the following statements about cancer is FALSE? a. Viruses cause some cancers. b. Tobacco use is responsible for more than 20% of all cancer deaths. c. A mutation in even a single cancer-critical gene is sufficient to convert a normal cell into a cancer cell. d. Chemical carcinogens cause cancer by changing the nucleotide sequence of DNA.
c. A mutation in even a single cancer-critical gene is sufficient to convert a normal cell into a cancer cell.
Which is NOT one of the central tenants of Cell Theory: a. All living things are comprised of one or more cells b. The cell is the basic organizational unit in all organisms c. All cells contain DNA d. All cells come from pre-existing cells
c. All cells contain DNA
Compared to adding heat to the system, what is the advantage of using an enzyme to overcome an energy barrier? a. An enzyme speeds up a reaction more than heat does b. An enzyme generates multiple different products using multiple pathways c. An enzyme is specific for one desired pathway and end product d. An enzyme can catalyze a reaction in many different ways
c. An enzyme is specific for one desired pathway and end product
Oxidation is a favorable process in an aerobic environment, which is the reason cells are able to derive energy from the oxidation of macromolecules. Once carbon has been oxidized to __________, its most stable form, it can only cycle back into the organic portion of the carbon cycle through __________. a. CO; reduction. b. CH3; combustion. c. CO2; photosynthesis. d. CO2; respiration.
c. CO2; photosynthesis.
What is one advantage that channels exhibit for transport of substances across a membrane that transporters do not exhibit? a. Channels import small nonpolar molecules, but transporters typically do not b. Channels always select between different sizes of ions with the same charge, but transporters cannot c. Channels let many molecules of a substance cross the membrane with one conformational change, but transporters typically do not d. Channels can use energy to move substances against their concentration gradient, while transporters cannot
c. Channels let many molecules of a substance cross the membrane with one conformational change, but transporters typically do not
Which of the following types of cell signaling is long range and typically uses stable, small, nonpolar signal molecules? a. Contact-dependent b. Paracrine c. Endocrine d. Neuronal
c. Endocrine
Consider a scenario in which the cell line you're studying has a mutation in the G-protein in this pathway that prevents G-alpha from conducting GTP hydrolysis. Select the following changes that will restore Brainy transcription to normal levels: (select all that apply) a. Increasing the amount of GPCR ligand b. Decreasing the amount of GPCR ligand c. Increasing the activity of cAMP phosphodiesterase (the enzyme that turns cAMP into AMP) d. Decreasing the activity of cAMP phosphodiesterase (the enzyme that turns cAMP into AMP) e. Increasing the activity of phosphatases that act on Nerd f. Decreasing the activity of phosphatases that act on Nerd
c. Increasing the activity of cAMP phosphodiesterase (the enzyme that turns cAMP into AMP) e. Increasing the activity of phosphatases that act on Nerd
Genes in eukaryotic cells often have intronic sequences coded for within the DNA. These sequences are ultimately not translated into proteins. Why? a. The ribosome will skip over intron sequences when translating RNA into protein. b. Introns are not transcribed by RNA polymerase. c. Intronic sequences are removed from RNA molecules by the spliceosome, which works in the nucleus. d. Introns are removed by catalytic RNAs in the cytoplasm.
c. Intronic sequences are removed from RNA molecules by the spliceosome, which works in the nucleus.
How does an allosteric inhibitor work? a. It outcompetes the substrate molecule and binds to the active site, preventing substrate molecules from binding there. b. It binds to a site other than the active site, causing a conformational change in the enzyme that forces the product to leave the active site. c. It binds to a site other than the active site, causing a conformational change in the enzyme that makes the active site less accommodating to the substrate. d. It interacts covalently with the substrate, preventing it from fitting into the enzyme's active site.
c. It binds to a site other than the active site, causing a conformational change in the enzyme that makes the active site less accommodating to the substrate.
Which of the following statements about the newly synthesized strand of a human chromosome is TRUE? a. It was synthesized from a single origin solely by continuous DNA synthesis. b. It was synthesized from multiple origins solely by discontinuous DNA synthesis. c. It was synthesized from multiple origins by a mixture of continuous and discontinuous DNA synthesis. d. It was synthesized from a single origin by a mixture of continuous and discontinuous DNA synthesis.
c. It was synthesized from multiple origins by a mixture of continuous and discontinuous DNA synthesis.
What feature of DNA polymerase causes the end replication problem solved by telomerase? a. Its inability to ligate DNA b. Its 3'->5' RNA exonuclease activity c. Its requirement for an RNA primer to begin polymerization d. Its proofreading ability
c. Its requirement for an RNA primer to begin polymerization
Which of the following statements is FALSE? a. Asexual reproduction typically gives rise to offspring that are genetically identical. b. Gametes are specialized sex cells. c. Mutations in somatic cells are passed on to individuals of the next generation. d. Sexual reproduction allows for a wide variety of gene combinations.
c. Mutations in somatic cells are passed on to individuals of the next generation.
Which of the following statements about the human genome is FALSE? a. About 1.5% of the human genome codes for exons. b. More of the human genome comprises intron sequences than exon sequences. c. Only the exons are conserved between the genomes of humans and other mammals. d. About 50% of the human genome is made up of mobile genetic elements.
c. Only the exons are conserved between the genomes of humans and other mammals.
Sometimes, chemical damage to DNA can occur just before DNA replication begins, not giving the repair system enough time to correct the error before the DNA is duplicated. This gives rise to mutation. If the adenosine in the sequence TCAT is depurinated and not repaired, which of the following is the point mutation that you would observe after this segment has undergone two rounds of DNA replication? a. TCGT b. TGTT c. TCT d. TAT
c. TCT
Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2? a. The cell would be unable to enter G2. b. The cell would be unable to enter M phase. c. The cell would enter M phase under conditions when normal cells would not. d. The cell would pass through M phase more slowly than normal cells.
c. The cell would enter M phase under conditions when normal cells would not.
Telomeres serve as caps protecting the ends of linear chromosomes. Which of the following is FALSE regarding the replication of telomeric sequences? a. Telomeres are made of repeating sequences. b. The lagging-strand telomeres are not completely replicated by DNA polymerase. c. The leading strand doubles back on itself to form a primer for the lagging strand. d. Additional repeated sequences are added to the template strand.
c. The leading strand doubles back on itself to form a primer for the lagging strand.
Which of the following statements correctly explains what it means for DNA replication to be bidirectional? a. The replication fork can open or close, depending on the conditions. b. Replication-fork movement can switch directions when the fork converges on another replication fork. c. The replication forks formed at the origin move in opposite directions. d. The DNA replication machinery can move in either direction on the template strand.
c. The replication forks formed at the origin move in opposite directions.
Which of the following statements about how enzymes work is FALSE? a. The active site of an enzyme is specific, recognizing only one particular substrate b. When a substrate encounters the active site of its enzyme, the substrate and enzyme become held together by weak chemical bonds c. The shape of the active site is constantly changing, allowing the enzyme to bind many different substrates, catalyzing many different chemical reactions d. The shape of the active site is determined by the amino acid sequence of the enzyme
c. The shape of the active site is constantly changing, allowing the enzyme to bind many different substrates, catalyzing many different chemical reactions
What is the function of single-strand binding proteins in DNA replication? a. They unwind a DNA double helix to form two separate, single strands. b. They join DNA fragments by making a phosphodiester bond in the single stranded DNA. c. They bind to single-stranded DNA and prevent the single-strands from re-forming base pairs. d. They bind to single-stranded DNA and assist in the re-formation of double-stranded DNA.
c. They bind to single-stranded DNA and prevent the single-strands from re-forming base pairs.
An single base pair genetic change found in the conserved sequence of the regulatory region of a gene is likely to a. affect protein folding. b. be found in plants as well as humans. c. affect when and where the gene is expressed. d. be a new mutation.
c. affect when and where the gene is expressed.
Complete the sentence with the best option provided below. The primary structure of a protein is the a. amino acid composition. b. average size of amino acid side chains. c. amino acid sequence. d. lowest energy conformation.
c. amino acid sequence.
The energy used by the cell to generate specific biological molecules and highly ordered structures is stored in the form of a. heat. b. light waves. c. chemical bonds. d. Brownian motion.
c. chemical bonds.
Energy cannot be created or destroyed, but it can be converted into other types of energy. Cells harvest some of the potential energy in the chemical bonds of foodstuffs to generate stored chemical energy in the form of activated carrier molecules, which are often employed to join two molecules together in __________ reactions. a. oxidation b. hydrolysis c. condensation d. dehydrogenation
c. condensation
During sexual reproduction, novel mixtures of alleles are generated. This is because a. in all diploid species, two alleles exist for every gene. b. a diploid individual has two different alleles for every gene. c. during meiosis, the segregation of homologs is random such that different gametes end up with different alleles of each gene. d. every gamete produced by a diploid individual has several different alleles of a single gene.
c. during meiosis, the segregation of homologs is random such that different gametes end up with different alleles of each gene.
DNA replication is considered semiconservative because a. after many rounds of DNA replication, the original DNA double helix is still intact. b. new DNA strands must be copied from a DNA template. c. each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand. d. each daughter DNA molecule consists of two new strands copied from the parent DNA molecule.
c. each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand.
Which of the following types of cell signaling is long range and uses hormones as signals? Select one: a. contact-dependent b. neuronal c. endocrine d. paracrine
c. endocrine
Cells that are specialized for the secretion of proteins are likely to have which of the following features? a. large population of mitochondria b. small volume of cytoplasm c. enlarged endoplasmic reticulum d. long bundles of actin/myosin proteins
c. enlarged endoplasmic reticulum
When an organism has inherited two nonidentical alleles, it is said to be Select one: a. recessive. b. dominant. c. heterozygous. d. homozygous.
c. heterozygous.
Combinatorial control of gene expression a. involves every gene using a different combination of transcriptional regulators for its proper expression. b. is seen only when genes are arranged in operons. c. involves groups of transcription regulators working together to determine the expression of a gene. d. involves only the use of gene activators used together to regulate genes appropriately.
c. involves groups of transcription regulators working together to determine the expression of a gene.
Nucleotides are comprised of a. nitrogenous bases + 6 carbon sugar + phosphate b. none of the above c. nitrogenous bases + 5 carbon sugar + phosphate d. nitrogenous bases + 5 carbon sugar e. purine bases
c. nitrogenous bases + 5 carbon sugar + phosphate
What repair mechanism is most likely to be responsible for this change? a. mismatch repair b. double-strand break repair c. non-homologous end joining d. homology directed repair
c. non-homologous end joining
Transcription is similar to DNA replication in that a. it uses the same enzyme as that used to synthesize RNA primers during DNA replication. b. the newly synthesized RNA remains paired to the template DNA. c. nucleotide polymerization occurs only in the 5´-to-3´ direction. d. an RNA transcript is synthesized discontinuously and the pieces are then joined together.
c. nucleotide polymerization occurs only in the 5´-to-3´ direction.
Proteins that are associated with the membrane by noncovalent interactions with other membrane proteins are called ___________ proteins. Select one: a. integral membrane b. monolayer-associated c. peripheral membrane d. peripheral-membrane
c. peripheral membrane
The set of traits of an organism that are determined by the genetic makeup is referred to as the Select one: a. genotype. b. haplotype. c. phenotype. d. flavor.
c. phenotype.
The central dogma provides a framework for thinking about how genetic information is copied and used to produce structural and catalytic components of the cell. From the choices below, select the order of biochemical processes that best correlates with the tenets of the central dogma. a. translation, replication, transcription b. translation, transcription, replication c. replication, transcription, translation d. replication, translation, transcription
c. replication, transcription, translation
Transporters, in contrast to channels, work by a. filtering solutes by charge. b. a gating mechanism. c. specific recognition of transport substrates. d. filtering solutes by size.
c. specific recognition of transport substrates.
Progression through the cell cycle requires a cyclin to bind to a Cdk because a. cyclin binding inhibits Cdk activity until the appropriate time in the cell cycle. b. the cyclins are the molecules with the enzymatic activity in the complex. c. the binding of a cyclin to Cdk is required for Cdk enzymatic activity. d. without cyclin binding, a cell-cycle checkpoint will be activated.
c. the binding of a cyclin to Cdk is required for Cdk enzymatic activity.
A neuron and a white blood cell have very different functions. For example, a neuron can receive and respond to electrical signals, while a white blood cell defends the body against infection. This is because a. all of the proteins found in a neuron are completely different from the proteins found in a white blood cell. b. neurons and white blood cells are differentiated cells and thus no longer need to transcribe and translate genes. c. the neuron expresses some mRNAs that the white blood cell does not. d. the neuron and the white blood cell within an individual have the same genome.
c. the neuron expresses some mRNAs that the white blood cell does not.
What would happen to the eventual protein product if the T on the right hand side of the break (one base pair) gets removed during repair? a. most amino acids in the protein that are coded for after the break would be different b. all the amino acids in the protein that are coded for after the break would be different c. the protein would be severely shortened d. the protein would just be missing one amino acid
c. the protein would be severely shortened
In a DNA double helix, a. thymine pairs with cytosine. b. purines pair with purines. c. the two DNA strands run antiparallel. d. the two DNA strands are identical.
c. the two DNA strands run antiparallel.
In a lipid bilayer, where do lipids rapidly diffuse? a. back and forth from one monolayer to the other in the bilayer b. in and out of the bilayer c. within the plane of their own monolayer d. not at all, because they remain in place within the bilayer e. within the plane of one monolayer and back and forth between the monolayers
c. within the plane of their own monolayer
Which of the following are components of the eukaryotic plasma membrane? (check all that apply) carbohydrates proteins lipids nucleic acids
carbohydrates proteins lipids
A diploid cell containing 32 chromosomes will make a haploid cell containing __________ chromosomes. a. 30 b. 64 c. 8 d. 16
d. 16
Homologous recombination is an important mechanism in which organisms use a "backup" copy of the DNA as a template to fix double-strand breaks without loss of genetic information. Which of the following is NOT necessary for homologous recombination to occur? a. a long stretch of sequence similarity on a neighboring piece of DNA b. nucleases c. 3´ DNA strand overhangs d. 5´ DNA strand overhangs
d. 5´ DNA strand overhangs
Which of the following statements is FALSE? a. In an evolutionary sense, somatic cells exist only to help propagate germ-line cells. b. All mutations in an asexually reproducing single-celled organism are passed on to the progeny. c. A mutation is passed on to offspring only if it is present in the germ line. d. A mutation that arises in a mother's somatic cell often causes a disease in her daughter.
d. A mutation that arises in a mother's somatic cell often causes a disease in her daughter.
Activated carriers are small molecules that can diffuse rapidly and be used to drive biosynthetic reactions in the cell. Their energy is stored in a readily transferable form such as high-energy electrons or chemical groups. Which of the molecules below donates a chemical group rather than electrons? a. NADH b. NADPH c. FADH2 d. ATP
d. ATP
Where would you find shorter DNA amplicons? a. All of the amplicons will travel the same distance if the voltage is not high enough. b. At the top of the gel. c. Shorter amplicons would not be separated in an agarose gel because polyacrylamide is needed. d. At the bottom of the gel.
d. At the bottom of the gel.
The best way to know if an organic molecule has been reduced is to see if there was an increase in the number of __________ bonds. a. C-N b. H-H c. C-O d. C-H
d. C-H
During respiration, energy is retrieved from the high-energy bonds found in certain organic molecules. Which of the following, in addition to energy, are the ultimate products of respiration? a. CO2; O2 b. CH2OH; O2 c. CH3; H2O d. CO2; H2O
d. CO2; H2O
How are most eukaryotic transcription regulators able to affect transcription when their binding sites are far from the promoter? a. by unwinding the DNA between their binding site and the promoter b. by attracting RNA polymerase and modifying it before it can bind to the promoter c. by binding to their binding site and sliding to the site of RNA polymerase assembly d. by looping out the intervening DNA between their binding site and the promoter
d. by looping out the intervening DNA between their binding site and the promoter
Which of the following choices BEST describes the role of the lysosome? a. the storage of excess macromolecules b. transport of material to the Golgi apparatus c. sorting of transport vesicles d. clean-up, recycling, and disposal of macromolecules
d. clean-up, recycling, and disposal of macromolecules
Operons a. are transcribed by RNA polymerase II. b. are commonly found in eukaryotic cells. c. can only be regulated by gene activator proteins. d. contain a cluster of genes transcribed as a single mRNA.
d. contain a cluster of genes transcribed as a single mRNA.
Select the option that correctly finishes the following statement: A cell's genome a. constantly changes, depending upon the cell's environment. b. is altered during embryonic development. c. is defined as all the genes being used to make protein. d. contains all of a cell's DNA.
d. contains all of a cell's DNA.
Mitogens are a. transcription factors important for cyclin production. b. kinases that cause cells to grow in size. c. produced by mitotic cells to keep nearby neighboring cells from dividing. d. extracellular signals that stimulate cell division.
d. extracellular signals that stimulate cell division.
The main function of the nucleus is to Select one: a. provide energy for the cell. b. allow cells to segregate enzymes. c. make proteins using the genetic material. d. house the DNA in a separate cell compartment.
d. house the DNA in a separate cell compartment.
Some proteins have α helices, some have β sheets, and still others have a combination of both. What makes it possible for proteins to have these common structural elements? a. the hydrophobic-core interactions b. side-chain interactions c. specific amino acid sequences d. hydrogen bonds along the protein backbone
d. hydrogen bonds along the protein backbone
Unlike DNA, which typically forms a helical structure, different molecules of RNA can fold into a variety of three-dimensional shapes. This is largely because RNA a. nucleotides use a different chemical linkage between nucleotides compared to DNA. b. bases cannot form hydrogen bonds with each other. c. contains uracil and uses ribose as the sugar. d. is single-stranded.
d. is single-stranded.
RNA in cells differs from DNA in that a. the sugar ribose contains fewer oxygen atoms than does deoxyribose. b. it contains the base uracil, which pairs with cytosine. c. it is single-stranded and cannot form base pairs. d. it is single-stranded and can fold up into a variety of structures.
d. it is single-stranded and can fold up into a variety of structures.
Microtubules capture chromosomes by binding specifically to which of the following? a. cohesins on the sister chromatids b. telomeres on the condensed chromosomes c. condensins on the condensed chromosomes d. kinetochores on the sister chromatids
d. kinetochores on the sister chromatids
Transcription is similar to DNA replication in that a. the newly synthesized RNA remains paired to the template DNA. b. an RNA transcript is synthesized discontinuously and the pieces are then joined together. c. it uses the same enzyme as that used to synthesize RNA primers during DNA replication. d. nucleotide polymerization occurs only in the 5´-to-3´ direction.
d. nucleotide polymerization occurs only in the 5´-to-3´ direction.
The chromosomes we typically see in images are isolated from mitotic cells. These mitotic chromosomes are in the most highly condensed form. Interphase cells contain chromosomes that are less densely packed and a. share the same nuclear territory as their homolog. b. are restricted to the nucleolus. c. are completely tangled with other chromosomes. d. occupy discrete territories in the nucleus.
d. occupy discrete territories in the nucleus.
An oncogene is different from a tumor suppressor gene in that Select one: a. oncogenes have mutations causing decreased activity of the protein. b. oncogene mutations more rarely lead to cancer. c. mutation of the gene can contribute to cancer. d. oncogenes have mutations causing increased activity of the protein.
d. oncogenes have mutations causing increased activity of the protein.
In eukaryotes, but not in prokaryotes, ribosomes find the start site of translation by a. recognizing an AUG codon as the start of translation. b. binding an initiator tRNA. c. binding directly to a ribosome-binding site preceding the initiation codon. d. scanning along the mRNA from the 5´end.
d. scanning along the mRNA from the 5´end.
Which of the following is NOT a common characteristic that distinguishes cancer cells from normal cells? a. reduced dependence on external signals from other cells b. genetic instability c. highly metabolically active d. sensitivity to cell cycle checkpoints
d. sensitivity to cell cycle checkpoints
In a DNA double helix, a. purines pair with purines. b. the two DNA strands are identical. c. thymine pairs with cytosine. d. the two DNA strands run antiparallel
d. the two DNA strands run antiparallel
The artificial introduction of three key __________ into an adult cell can convert the adult cell into a cell with the properties of ES cells. a. hormones b. chromosomes c. viruses d. transcription factors
d. transcription factors
Although the chromatin structure of interphase and mitotic chromosomes is very compact, DNA-binding proteins and protein complexes must be able to gain access to the DNA molecule. Chromatin-remodeling complexes provide this access by a. recruiting other enzymes. b. modifying the N-terminal tails of core histones. c. denaturing the DNA by interfering with hydrogen-bonding between base pairs. d. using the energy of ATP hydrolysis to move nucleosomes.
d. using the energy of ATP hydrolysis to move nucleosomes.
Lipid bilayers are highly impermeable to which molecule(s)? a. oxygen b. carbon dioxide c. water d. steroid hormones e. Na+ and Cl-
e. Na+ and Cl-
What is typically true of ion channels? a. They hydrolyze ATP b. They are open all the time c. They operate by active transport d. They are nonselective e. They are gated
e. They are gated
Which parts of amino acids are involved in a peptide bond? a. amino group of one amino acid and side chain of the other b. amino groups of both amino acids c. carboxyl group of one amino acid and side chain of the other d. side chains of both amino acids e. amino group of one amino acid and carboxyl group of the other f. carboxyl groups of both amino acids
e. amino group of one amino acid and carboxyl group of the other
The type of chromatin that participates in the active transcription of DNA to RNA is a. 30-nm chromatin fiber b. X chromatin c. nucleosome d. heterochromatin e. euchromatin
e. euchromatin
TF- Short pieces termed primers are removed by primase that degrades RNA
False
For each of the following sentences, fill in the blanks with the best word or phrase selected from the list below. Not all words or phrases will be used; each word or phrase should be used only once. 1) By definition, catalysis allows a reaction to occur more rapidly . 2) Chemical reactions occur only when there is a loss of free energy. 3) Enzymes act more selectively than other catalysts. 4) A catalyst decreases the activation energy of a reaction.
1. rapidly 2. free 3. selectively 4. activation
TF- The cytosol is fairly empty, containing a limited number of organelles, which allows room for rapid movement and diffusion of molecules
False
Select all the cell types in which the listed structure or molecule can be found. Note that the structure or molecule can be found in more than one type of cell. DNA- Nucleus- Cell Wall- Mitochondria- Golgi Apparatus- Plasma membrane- Lysosome-
DNA- Animal, plant and bacteria Nucleus- Animal and plant Cell Wall- Plant and bacteria Mitochondria- Plants and animals Golgi Apparatus- Animal and plant Plasma membrane- Animal, plant and bacteria Lysosome- Animal and plant
A cell's DNA is replicated during the M phase of the cell cycle Select one: True False
False
Phosphatases remove a phosphate from GTP bound to trimeric G-proteins, to turn them off Select one: True False
False
Since endocrine signals are circulated throughout the body, all cells respond to the hormone Select one: True False
False
TF- Electrons are always shared equally between covalently bonded atoms
False
TF- Enzymes lower the free energy released by the reaction that they facilitate
False
TF- Eukaryotic genes are distributed across multiple DNA molecules, which can be packaged into linear or circular chromosomes
False
TF- For a gene to function properly, every exon must be removed from the pre-mRNA in the same fashion on every mRNA molecule produced from the same gene
False
TF- Generally, the total number of nonpolar amino acids has a greater effect on protein structure than the exact order of amino acids in a polypeptide chain
False
Match the monomer subunit with the polymer form that the monomers are linked together to build. Lipids- Nucleic acids- Proteins- Carbohydrates-
Lipids- fattyacids Nucleic acids- nucleotides Proteins- amino acids Carbohydrates- monosaccharides
Match the monomer subunit with the polymer form that the monomers are linked together to build. Lipids: Nucleic acids: Proteins: Carbohydrates:
Lipids: fatty acids Nucleic acids: nucleotides Proteins: amino acids Carbohydrates: monosaccharides
A neutral mutation is similar to a synonymous mutation. Select one: True False
True
At the G1 checkpoint, the cell determines whether conditions are appropriate for DNA replication Select one: True False
True
In eukaryotes, exons are separate components that generally encode individual protein domains. Select one: True False
True
Chemical reactions carried out by living systems depend on the ability of some organisms to capture and use atoms from nonliving sources in the environment. The specific subset of these reactions that break down nutrients in food can be described as a. biosynthetic. b. catabolic. c. metabolic. d. anabolic.
b. catabolic.
The DNA duplex consists of two long covalent polymers wrapped around each other many times over their entire length. The separation of the DNA strands for replication causes the strands to be "overwound" in front of the replication fork. How does the cell relieve the torsional stress created along the DNA duplex during replication? a. Topoisomerases break the covalent bonds of the backbone, allowing the local unwinding of DNA ahead of the replication fork. b. Helicase unwinds the DNA and rewinds it after replication is complete. c. Nothing needs to be done because the two strands will be separated after replication is complete. d. DNA repair enzymes remove torsional stress as they replace incorrectly paired bases.
a. Topoisomerases break the covalent bonds of the backbone, allowing the local unwinding of DNA ahead of the replication fork.
Bacteria can become resistant to tetracycline in various ways. Please match the mechanism of resistance with the most likely genetic variation event. a. tetracycline no longer binds to the ribosome b. extra ribosomal subunits are made to "soak up" the tetracycline c. a tetracycline-inactivating enzyme appears that is unrelated to other enzymes in the bacterium d. a new tetracycline pump arises that is related to an existing pump in the bacterium
a. a mutation within a gene b. a mutation within the regulatory DNA of a gene c. horizontal gene transfer d. gene duplication and divergence
The movement of an ion against its concentration gradient is called what? a. active transport b. facilitated diffusion c. passive transport d. osmosis
a. active transport
The consistent diameter of the DNA double helix arises because of which property? Select one: 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. base pairing of pyrimidines with purines
A pluripotent cell a. can give rise to all the tissues and cell types in the body. b. is considered to be terminally differentiated. c. can only give rise to stem cells. d. can only be produced in the laboratory.
a. can give rise to all the tissues and cell types in the body.
An adult hematopoietic stem cell found in the bone marrow a. can undergo self-renewing divisions for the lifetime of a healthy animal. b. will occasionally produce epidermal cells when necessary. c. can produce only red blood cells. d. will express all the same transcription factors as those found in an unfertilized egg.
a. can undergo self-renewing divisions for the lifetime of a healthy animal.
Plasma membrane proteins that move ions in and out of cells using passive transport are called Select one: a. channels. b. receptors. c. transporters. d. anchors.
a. channels
Which method or methods of controlling eukaryotic gene expression is NOT employed in prokaryotic cells? Select all that apply. a. controlling which mRNAs are exported from the nucleus to the cytosol b. controlling which mRNAs are translated into protein by the ribosomes c. controlling how an RNA transcript is spliced d. controlling how often a gene is transcribed
a. controlling which mRNAs are exported from the nucleus to the cytosol c. controlling how an RNA transcript is spliced
vels of Cdk activity change during the cell cycle, in part because a. cyclin concentration changes during the cycle. b. Cdk degradation precedes entry into the next phase of the cell cycle. c. the Cdks phosphorylate each other. d. the Cdks activate the cyclins.
a. cyclin concentration changes during the cycle.
Which of the following substances is most commonly used to help purify a membrane protein? a. detergent b. high salt solution c. sucrose d. ethanol
a. detergent
Which type of mutation will generally be lost from the population most rapidly? Select one: a. dominant/deleterious b. dominant/beneficial c. recessive/neutral d. recessive/deleterious
a. dominant/deleterious
DNA replication is considered semiconservative because a. each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand. b. new DNA strands must be copied from a DNA template. c. each daughter DNA molecule consists of two new strands copied from the parent DNA molecule. d. after many rounds of DNA replication, the original DNA double helix is still intact.
a. each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand.
A chemical reaction is defined as spontaneous if there is a net loss of free energy during the reaction process. However, spontaneous reactions do not always occur rapidly. Favorable biological reactions require __________ to selectively speed up reactions and meet the demands of the cell. a. enzymes b. ATP c. heat d. ions
a. enzymes
Match the type of phenotypic change below with the type of genetic change most likely to cause it. Each type of genetic change may be used more than once, or may not be used at all. a. Tandem copies of a gene are found in the genome b. A protein acquires a DNA-binding domain. c. A protein normally expressed only in the liver is now expressed in blood cells d. A protein becomes much more unstable. e. A copy of a bacterial gene is now found in a bacterial cell of a different species
a. gene duplication b. exon shuffling c. mutation in a regulatory region d. mutation within a gene e. horizontal gene transfer
Two or three α helices can sometimes wrap around each other to form coiled-coils. The stable wrapping of one helix around another is typically driven by __________ interactions. a. hydrophobic b. van der Waals c. ionic d. hydrophilic
a. hydrophobic
If a reaction is energetically favorable (exergonic), then it must produce a(n) Select one: a. increase in entropy. b. decrease in heat. c. increase in activation energy. d. decrease in reaction time.
a. increase in entropy.
Which of the following organelles has both an outer and an inner membrane? a. mitochondrion b. endoplasmic reticulum c. lysosome d. peroxisome
a. mitochondrion
According to current thinking, the minimum requirement for life to have originated on Earth was the formation of a a. molecule that could catalyze its own replication. b. molecule that could provide a template for the production of a complementary molecule. c. molecule that could direct protein synthesis. d. double-stranded DNA helix.
a. molecule that could catalyze its own replication.
You engineer a set of liposomes to contain a special K+ channel. You can change the K+ concentration inside and outside the liposomes, as well as the overall net charge inside and outside of the liposomes. Under what conditions will you see the most K+ flow into the liposomes? a. Lower concentration of K+ outside the liposomes and more negatively charged molecules outside than inside b. Higher concentration of K+ outside the liposomes and more negatively charged molecules inside than outside c. Lower concentration of K+ outside the liposomes and more negatively charged molecules inside than outside d. Higher concentration of K+ outside the liposomes and more negatively charged molecules outside than inside
b. Higher concentration of K+ outside the liposomes and more negatively charged molecules inside than outside
__________ play an important role in organizing lipid molecules with long hydrocarbon tails into biological membranes. a. Hydrogen bonds b. Hydrophobic forces c. Ionic bonds d. Van der Waals attractions
b. Hydrophobic forces
Which of the following is not a mechanism of genetic variation? a. Gene duplication and divergence b. Misreading of an mRNA by a ribosome c. Exon shuffling d. Mutation within the regulatory DNA of a gene e. Mutation within the coding sequence of a gene
b. Misreading of an mRNA by a ribosome
Ribosomes are made up of a. Nucleic acids, proteins, and lipids b. RNA and proteins c. RNA, DNA, and proteins d. RNA only
b. RNA and proteins
How does the binding of a signal molecule activate a receptor tyrosine kinase (RTK) for downstream signaling? Select one: a. The RTK undergoes a cleavage event to release the cytosolic portion. b. The RTK forms a dimer and cross-phosphorylates itself. c. The RTK is an ion channel that opens in response to ligand binding. d. The RTK changes conformation to stimulate a G-protein.
b. The RTK forms a dimer and cross-phosphorylates itself.
ow does the binding of a signal molecule activate a receptor tyrosine kinase (RTK) for downstream signaling? Select one: a. The RTK is an ion channel that opens in response to ligand binding. b. The RTK forms a dimer and cross-phosphorylates itself. c. The RTK changes conformation to stimulate a G-protein. d. The RTK undergoes a cleavage event to release the cytosolic portion.
b. The RTK forms a dimer and cross-phosphorylates itself.
You are studying a set of mouse genes whose expression increases when cells are exposed to the hormone cortisol, and you believe that the same cortisol-responsive transcriptional activator regulates all of these genes. If your hypothesis is correct, which of the following statements below should be TRUE? a. The cortisol-responsive genes must all be in an operon. b. The cortisol-responsive genes share a DNA sequence in their regulatory regions that binds the cortisol-responsive transcriptional activator. c. The cortisol-responsive genes must not be transcribed in response to other hormones. d. The transcriptional regulators that bind to the regulatory regions of the cortisol-responsive genes must all be the same.
b. The cortisol-responsive genes share a DNA sequence in their regulatory regions that binds the cortisol-responsive transcriptional activator.
Given that large, charged molecules cannot cross the cell membrane, what might be directly impacted by such a drug acting on a tyrosine kinase receptor (RTK) to limit cell proliferation? a. The drug prevents adaptor protein binding to activated receptors. b. The drug prevents receptor dimerization. c. The drug prevents receptor coupling to G proteins. d. The drug prevents changes in gene expression by preventing transcription factor phosphorylation.
b. The drug prevents receptor dimerization.
Which of the following statements about the genetic code is CORRECT? a. All codons specify more than one amino acid. b. The genetic code is redundant. c. All codons specify an amino acid. d. All amino acids are specified by more than one codon.
b. The genetic code is redundant.
Which of the following is most likely to occur after the lipid bilayer is pierced? a. The membrane collapses. b. The membrane reseals. c. The membrane expands. d. A tear is formed.
b. The membrane reseals.
Which of the following events does NOT usually occur during interphase? a. DNA is replicated. b. The nuclear envelope breaks down. c. The centrosomes are duplicated. d. Cells grow in size.
b. The nuclear envelope breaks down.
Which of the following scenarios demonstrates apoptosis? Select all that apply. a. Muscle fibers are signaled to contract and move. b. Webbing between an embryo's toes is eliminated during embryological development. c. A severe burn causes skin cells to die. d. An immune cell self-destructs once it is no longer needed by the immune system
b. Webbing between an embryo's toes is eliminated during embryological development. d. An immune cell self-destructs once it is no longer needed by the immune system
Proteins are important architectural and catalytic components within the cell, helping to determine its chemistry, its shape, and its ability to respond to changes in the environment. Remarkably, all of the different proteins in a cell are made from the same 20 __________. By linking them in different sequences, the cell can make protein molecules with different conformations and surface chemistries, and therefore different functions. a. fatty acids b. amino acids c. sugars d. nucleotides
b. amino acids
Which term correctly describes the entire phospholipid molecule? a. apathetic b. amphipathic c. hydrophobic d. hydropathic e. hydrophilic
b. amphipathic
Bacterial mRNAs __________________________ a. are translated after they are exported from the nucleus. b. are transcribed and translated simultaneously. c. are processed in the same way as eukaryotic mRNAs. d. must be folded into the correct three-dimensional shape before they can be translated.
b. are transcribed and translated simultaneously.
In which phase of the cell cycle do cells check to determine whether the DNA is fully and correctly replicated? a. when cells enter G0 b. at the end of G2 c. during M d. at the transition between G1 and S
b. at the end of G2
How do protein, nucleic acid, and polysaccharide molecules polymerize (grow in length)? a. by oxidation reactions b. by condensation reactions c. none of these d. by hydrolysis reactions
b. by condensation reactions
Cells that are terminally differentiated a. will undergo apoptosis within a few days. b. can no longer undergo cell division. c. no longer produce RNAs. d. are unable to move.
b. can no longer undergo cell division.
Enhancers can act over long stretches of DNA, but are specific about which genes they affect. How do eukaryotic cells prevent these transcription regulatory sequences from looping in the wrong direction and inappropriately turning on the transcription of a neighboring gene? a. The cell will group neighboring genes into operons so that they are transcribed as a single unit, regulated by a single enhancer. b. The cell uses histone acetyltransferase to prevent enhancer binding to the DNA. c. There is no mechanism to prevent inappropriate enhancer action on neighboring genes. The cells will degrade inappropriately produced mRNA molecules. d. Chromosome loop-forming proteins arrange the DNA into topological associated domains such that individual genes and their associated enhancer binding regions are in proximity.
d. Chromosome loop-forming proteins arrange the DNA into topological associated domains such that individual genes and their associated enhancer binding regions are in proximity.
Schizophrenia is a psychiatric disorder that is caused, in part, by excessive dopamine signaling (dopamine receptors are a type of GPCR). A commonly prescribed antipsychotic, haloperidol, can sometimes lead to parkinsonian-like symptoms like muscle tremors (Parkinson's disease results from a loss of dopamine-producing neurons in the brain). What is the most likely explanation for this phenomenon? a. Haloperidol leads to excessive phosphorylation of MAP kinase kinase kinase b. Haloperidol decreases length of time the G-alpha subunit is bound to GDP c. Haloperidol is a dopamine receptor agonist d. Haloperidol is a dopamine receptor antagonist
d. Haloperidol is a dopamine receptor antagonist
What type of reaction is the reverse of a condensation reaction? a. Decondensation b. Oxidation c. Reduction d. Hydrolysis
d. Hydrolysis
When the cytosolic tail of the __________ receptor is cleaved, after binding to Delta, it migrates to the nucleus and affects gene regulation. a. nuclear b. G-protein coupled c. growth factor d. Notch
d. Notch
To produce the amplicons by the polymerase chain reaction, a student mixed the following reagents in the tube before loading into a thermocycler. Which of the following does NOT belong? a. Deoxyguanosine triphosphate. b. Deoxyadenosine triphosphate. c. DNA template. d. RNA polymerase. e. Buffer containing cations. f. Forward primer. g. Reverse primer.
d. RNA polymerase.
Which of the following functions of the plasma membrane is possible without membrane proteins? a. Cellular movement b. Intercellular communication c. Import/export of ions d. Selective permeability
d. Selective permeability
Why are α helices and β sheets common folding patterns in polypeptides? a. Due to their hydrophobic nature, these are the most naturally occurring folding patterns b. Particular enzymes tend to fold polypeptides in these common folding patterns c. The unique amino acid sequences that generate these folding patterns are common in polypeptides d. Side chains are not involved in forming the hydrogen bonds, allowing many different amino acid sequences to adopt these folding patterns
d. Side chains are not involved in forming the hydrogen bonds, allowing many different amino acid sequences to adopt these folding patterns
Which of the following occurs when a cell repairs a double-strand DNA break by the process of nonhomologous end joining (NHEJ)? a. The DNA sequence at the site of repair contains a short segment of telomere DNA b. The DNA sequence at the site of repair matches that of a homologous chromosome c. The original DNA sequence at the site of repair is reconstituted with 100% accuracy d. The DNA sequence at the site of repair is altered by a short deletion
d. The DNA sequence at the site of repair is altered by a short deletion
Which small genetic change in or near an essential gene would likely cause the most harm to a cell? Select one: a. A deletion of two nucleotides at the end of a coding region b. A synonymous mutation at the beginning of a coding region c. The insertion of three nucleotides at the beginning of a coding region d. The insertion of one nucleotide at the beginning of a coding region
d. The insertion of one nucleotide at the beginning of a coding region
To fight COVID-19, the pharmaceutical company, Eli Lilly and Co., designed and developed a treatment of a monoclonal antibody (bamlanivimab) that recognizes the spike protein found on the surface of the novel coronavirus. The spike protein is required for entry into human cells, so the antibody protein binding to it blocks the ability of the virus to infect our cells. On Nov. 9, 2020, the US FDA granted an emergency use authorization for the antibody to be used to fight severe COVID-19 infections. By April 2021, the FDA revoked its authorization because the coronavirus had mutated and the antibody was no longer effective at inhibiting the new variants from infecting our cells. Based on the finding that new variants of coronavirus are no longer inhibited by the monoclonal antibody bamlanivimab, which of the following statements is true about the interaction between bamlanivimab and the mutated coronavirus spike protei
d. The number of noncovalent bonds between antibody and mutant spike protein decreased
How do chromatin-remodeling complexes work? a. They bind to telomeric DNA sequences to induce heterochromatin formation. b. They add methyl groups to the tails of histones in order to attract other protein c. They use a DNA helicase to unwind the DNA for remodeling. d. They use ATP to alter nucleosomes and make regions of the DNA more accessible to other proteins.
d. They use ATP to alter nucleosomes and make regions of the DNA more accessible to other proteins.
Why would it be important to check for DNA damage before S phase? a. To ensure that all the other cell components have been duplicated first b. If there's DNA damage, the chromosomes won't segregate properly c. Because the right genes won't be expressed to synthesize DNA d. To avoid making a mutation permanent
d. To avoid making a mutation permanent
Polypeptides are synthesized from amino acid building blocks. The condensation reaction between the growing polypeptide chain and the next amino acid to be added involves the loss of a. a carbon atom. b. a carboxylic acid group. c. an amino group. d. a water molecule.
d. a water molecule.
Loss-of-function mutations a. will usually show a phenotype when heterozygous. b. are only present in a population at barely detectable levels. c. cause the production of proteins that are active in inappropriate circumstances. d. are usually recessive.
d. are usually recessive.