Bio Final pt 1
During DNA replication one of the strands has multiple short segments. What is the name of the strand? What is the term used for the segments? Explain why this occurs.
During DNA replication, the lagging strand cannot be made in one long segment as it runs from 3' to 5' these short segments are called OkaZaki Fragments. These fragments are due to DNA Polymerase 1's inability to run in the 3' to 5' direction. The fragments are fused together by ligase.
Which of the following types of cell signaling is long range and typically uses stable, small, nonpolar signal molecules? a. Neuronal b. Contact-dependent c. Endocrine d. Paracrine
Endocrine
What type of reaction is the reverse of a condensation reaction? a. Reduction b. Decondensation c. Oxidation d. Hydrolysis
Hydrolysis
__________ play an important role in organizing lipid molecules with long hydrocarbon tails into biological membranes. a.Van der Waals attractions b.Hydrogen bonds c.Hydrophobic forces d.Ionic bonds
Hydrophobic forces
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 helps DNA pack tightly. b.It binds to DNA in a sequence-specific manner. c.It extends out of the nucleosome core. d.It is subject to covalent modifications.
It binds to DNA in a sequence-specific manner.
How does an allosteric inhibitor work? a. It interacts covalently with the substrate, preventing it from fitting into the enzyme's active site. b. 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. c. It outcompetes the substrate molecule and binds to the active site, preventing substrate molecules from binding there. d. 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.
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 by a mixture of continuous and discontinuous DNA synthesis. b.It was synthesized from multiple origins by a mixture of continuous and discontinuous DNA synthesis. c.It was synthesized from multiple origins solely by discontinuous DNA synthesis. d.It was synthesized from a single origin solely by continuous DNA synthesis.
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 requirement for an RNA primer to begin polymerization b. Its inability to ligate DNA c. Its proofreading ability d. Its 3'->5' RNA exonuclease activity
Its requirement for an RNA primer to begin polymerization
When the cytosolic tail of the __________ receptor is cleaved, after binding to Delta, it migrates to the nucleus and affects gene regulation. a.G-protein coupled b.Notch c.nuclear d.growth factor
Notch
Which of the following methods is not used by cells to regulate the amount of a protein in the cell? a.Proteins can be tagged with ubiquitin, marking them for degradation. b.Many ribosomes can bind to a single mRNA molecule. c.Nuclear pore complexes can regulate the speed at which newly synthesized proteins are exported from the nucleus into the cytoplasm. d.Genes can be transcribed into mRNA with different efficiencies.
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 the human genome is FALSE? a.More of the human genome comprises intron sequences than exon sequences. b.About 50% of the human genome is made up of mobile genetic elements. c.About 1.5% of the human genome codes for exons. d.Only the exons are conserved between the genomes of humans and other mammals.
Only the exons are conserved between the genomes of humans and other mammals.
Which of the following statements about organoids is FALSE? a.Organoids are self-assembling. b.Organoids can be produced from ES and iPS cells. c.Organoids can form multilayered structures. d.Organoids can only be made for organs that are made up of a single type of differentiated cell.
Organoids can only be made for organs that are made up of a single type of differentiated cell.
Phosphatases remove a phosphate from GTP bound to trimeric G-proteins, to turn them off False
Phosphatases, on the other hand, catalyze the removal of phosphate groups from proteins, nucleotides, or other molecules, but they do not directly target the phosphate bound to GTP in trimeric G-proteins to turn them off.
Which of the following functions of the plasma membrane is possible without membrane proteins? a.Intercellular communication b.Selective permeability c.Import/export of ions d.Cellular movement
15 carbons with two double bonds
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.15 carbons with two double bonds c.16 carbons with no double bonds d.24 carbons with one double bond
15 carbons with two double bonds
A diploid cell containing 32 chromosomes will make a haploid cell containing __________ chromosomes. a.30 b.16 c.64 d.8
16
How many replication forks are formed when an origin of replication is opened? a.3 b.4 c.2 d.1
2
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? G? T?
34%, 16%, 34%
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? 5' - AUG - 3' 5' - UAC - 3' 5' - GUA - 3' 5' - CAU - 3'
5' - CAU - 3'
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.5´ DNA strand overhangs b.nucleases c.3´ DNA strand overhangs d.a long stretch of sequence similarity on a neighboring piece of DNA
5´ DNA strand overhangs
Which amino acid would you expect a tRNA with the anticodon 5´-UGC-3´ to carry?
5´- GCA- 3 '
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.5´-AUAGGCAUUCGAUCCGGAUAGCAU-3´ b.5´-UAUCCGUAAGCUAGGCCUAUGCUA-3´ c.5´-UACGAUAGGCCUAGCUUACGGAUA-3´ d.none of these answers are correct.
5´-AUAGGCAUUCGAUCCGGAUAGCAU-3´
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-H b.C-O c.C-N d.H-H
C-H
Which of the following pairs of codons might you expect to be read by the same tRNA as a result of wobble? a.CUU and UUU b.AAU and AGU c.CAC and CAU d.GAU and GAA
CAC and CAU
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
CO2; H2O
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.CO2; photosynthesis. c.CH3; combustion. d.CO2; respiration.
CO2; photosynthesis.
Which of the following events usually occurs during interphase? Choose all that apply. a. Cells grow in size. b. DNA is replicated. c. The nuclear envelope breaks down. d. Sister chromatids are separated. e. Mistakes in DNA replication are repaired.
Cells grow in size. DNA is replicated Mistakes in DNA replication are repaired
What is one advantage that channels exhibit for transport of substances across a membrane that transporters do not exhibit? a. Channels let many molecules of a substance cross the membrane with one conformational change, but transporters typically do not b. Channels import small nonpolar molecules, but transporters typically do not c. Channels can use energy to move substances against their concentration gradient, while transporters cannot d. Channels always select between different sizes of ions with the same charge, but transporters cannot
Channels let many molecules of a substance cross the membrane with one conformational change, but transporters typically do not
The energy used by the cell to generate specific biological molecules and highly ordered structures is stored in the form of a.heat. b.Brownian motion. c.light waves. d.chemical bonds.
Chemical bonds
What type of macromolecule helps package DNA in eukaryotic chromosomes? a.RNA b.proteins c.carbohydrates d.lipids
Proteins
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.TCT c.TAT d.TGTT
TCT
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 matches that of a homologous chromosome b. The original DNA sequence at the site of repair is reconstituted with 100% accuracy c. The DNA sequence at the site of repair contains a short segment of telomere DNA d. The DNA sequence at the site of repair is altered by a short deletion
The DNA sequence at the site of repair is altered by a short deletion
How does the binding of a signal molecule activate a receptor tyrosine kinase (RTK) for downstream signaling? Select one: a.The RTK forms a dimer and cross-phosphorylates itself. b.The RTK is an ion channel that opens in response to ligand binding. c.The RTK changes conformation to stimulate a G-protein. d.The RTK undergoes a cleavage event to release the cytosolic portion.
The RTK forms a dimer and cross-phosphorylates itself.
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 changes conformation to stimulate a G-protein. c.The RTK forms a dimer and cross-phosphorylates itself. d.The RTK is an ion channel that opens in response to ligand binding.
The RTK forms a dimer and cross-phosphorylates itself.
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. DNA helicases are activated and the replication fork is prepared for replication. b.The S-Cdk disassembles. c. Cells would immediately exit into G2 phase. d. S-cyclin will get degraded by the APC/C complex.
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 be unable to enter M phase. 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 enter M phase under conditions when normal cells would not.
The cell would be unable to enter M phase.
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 M phase. b. The cell would pass through M phase more slowly than normal cells. c.The cell would be unable to enter G2. d.The cell would enter M phase under conditions when normal cells would not.
The cell would enter M phase under conditions when normal cells would not.
Which statement is true about the removal of a terminal phosphate from ATP? a. The reaction is energetically favorable b. The reaction is a condensation reaction c. The reaction is associated with a positive change in ΔG°
The reaction is energetically favorable
4) 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? Deoxyadenosine triphosphate. DNA template. Reverse primer. RNA polymerase. Deoxyguanosine triphosphate. Forward primer. Buffer containing cations.
RNA polymerase.
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, transcription, replication b.replication, transcription, translation c.replication, translation, transcription d.translation, replication, transcription
Replication, transcription and translation
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. The unique amino acid sequences that generate these folding patterns are common in polypeptides c. Particular enzymes tend to fold polypeptides in these common folding patterns d. Side chains are not involved in forming the hydrogen bonds, allowing many different amino acid sequences to adopt these folding patterns
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 are ways cells can differ (check all that apply): a. size b. chemical composition c. method of obtaining energy d. shape e. method of interpreting genetic information
Size, Method, and Shape
Which of the following happens when a G-protein-coupled receptor activates a G protein? a.The β subunit exchanges its bound GDP for GTP. b.The α 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.
The α subunit exchanges its bound GDP for GTP.
Since endocrine signals are circulated throughout the body, all cells respond to the hormone False
Therefore, the responsiveness of cells to hormones is determined by the presence or absence of specific receptors for those hormones, rather than simply by the circulation of the hormones throughout the body.
What is typically true of ion channels? a. They are open all the time b. They are nonselective c. They operate by active transport d. They hydrolyze ATP e. They are gated
They are gated
What is the function of single-strand binding proteins in DNA replication? a.They bind to single-stranded DNA and prevent the single-strands from re-forming base pairs. b.They bind to single-stranded DNA and assist in the re-formation of double-stranded DNA. c.They join DNA fragments by making a phosphodiester bond in the single stranded DNA. d.They unwind a DNA double helix to form two separate, single strands.
They bind to single-stranded DNA and prevent the single-strands from re-forming base pairs.
What is one way changes in histone modifications lead to changes in chromatin structure? a. They denature the DNA by interfering with hydrogen-bonding between base pairs b.They cause the histone N-terminal tails to become hyperextended. c.They help recruit other proteins to the chromatin. d. They directly lead to changes in the positions of the core histones.
They help recruit other proteins to the chromatin.
What do the phosphorylated tyrosines on activated RTKs do? a. They activate the enzymatic activity of the RTKs. b. They serve as binding sites for G proteins. c. They help the receptor dimerize. d. They serve as binding sites for a variety of intracellular signaling proteins. e. They promote receptor internalization.
They serve as binding sites for a variety of intracellular signaling proteins.
How do chromatin-remodeling complexes work? a.They use a DNA helicase to unwind the DNA for remodeling. b.They bind to telomeric DNA sequences to induce heterochromatin formation. c.They add methyl groups to the tails of histones in order to attract other protein d.They use ATP to alter nucleosomes and make regions of the DNA more accessible to other proteins.
They use ATP to alter nucleosomes and make regions of the DNA more accessible to other 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 production and function of ribosomes b. Those involved in the synthesis of ATP c. Those involved in the trafficking of molecules in and out of the nucleus d. Those involved in amino acid metabolism and transport
Those involved in the trafficking of molecules in and out of the nucleus
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. To avoid making a mutation permanent d. Because the right genes won't be expressed to synthesize DNA
To avoid making a mutation permanent
A cell's DNA is replicated during the M phase of the cell cycle False
a cells DNA is replicated in s phase
You are interested in how cyclic-AMP-dependent protein kinase A (PKA) functions to affect learning and memory, and you decide to study its function in the brain. It is known that, in the cells you are studying, PKA works via a signal transduction pathway like the one depicted in Figure 16-15. Furthermore, it is also known that activated PKA phosphorylates the transcriptional regulator called Nerd that then activates transcription of the gene Brainy. Which situation described below will lead to an increase in Brainy transcription?
a mutation in the gene that encodes the α subunit of the G protein that slows the rate of GTP hydrolysis
The movement of an ion against its concentration gradient is called what? a. passive transport b. facilitated diffusion c. osmosis d. active transport
active transport
An single base pair genetic change found in the conserved sequence of the regulatory region of a gene is likely to a.be found in plants as well as humans. b.be a new mutation. c.affect protein folding. d.affect when and where the gene is expressed.
affect when and where the gene is expressed.
Which is NOT one of the central tenants of Cell Theory: a. The cell is the basic organizational unit in all organisms b. All cells come from pre-existing cells c. All cells contain DNA d. All living things are comprised of one or more cells
all cells contain DNA
Below is a sequence of DNA that codes for a protein (coding strand). A double strand break (DSB) in the DNA occurs at the location of the asterisk(*) ...atgaagtcagctatt*ttaaccggtttgcttttcgtc... 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? What repair mechanism is most likely to be responsible for this change?
all the amino acids in the protein that are coded for after the break would be different non-homologous end joining
Complete the sentence with the best option provided below. The primary structure of a protein is the a.amino acid composition. b.amino acid sequence. c.average size of amino acid side chains. d.lowest energy conformation.
amino acid sequence.
Which parts of amino acids are involved in a peptide bond? a. amino group of one amino acid and carboxyl group of the other b. amino groups of both amino acids c. carboxyl group of one amino acid and side chain of the other d. amino group of one amino acid and side chain of the other e. side chains of both amino acids f. carboxyl groups of both amino acids
amino group of one amino acid and carboxyl group of the other
Which term correctly describes the entire phospholipid molecule? a. amphipathic b. hydrophobic c. hydrophilic d. hydropathic e. apathetic
amphipathic
Bacterial mRNAs __________________________ a.are processed in the same way as eukaryotic mRNAs. b.are transcribed and translated simultaneously. c.must be folded into the correct three-dimensional shape before they can be translated. d.are translated after they are exported from the nucleus.
are transcribed and translated simultaneously.
Loss-of-function mutations a.are usually recessive. b.will usually show a phenotype when heterozygous. c.cause the production of proteins that are active in inappropriate circumstances. d.are only present in a population at barely detectable levels.
are usually recessive.
In which phase of the cell cycle do cells check to determine whether the DNA is fully and correctly replicated? a.at the end of G2 b.at the transition between G1 and S c.during M d.when cells enter G0
at the end of G2
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
base pairing of pyrimidines with purines
How do protein, nucleic acid, and polysaccharide molecules polymerize (grow in length)? a. none of these b. by hydrolysis reactions c. by condensation reactions d. by oxidation reactions
by condensation reactions
How are most eukaryotic transcription regulators able to affect transcription when their binding sites are far from the promoter? a.by binding to their binding site and sliding to the site of RNA polymerase assembly b.by attracting RNA polymerase and modifying it before it can bind to the promoter c.by looping out the intervening DNA between their binding site and the promoter d.by unwinding the DNA between their binding site and the promoter
by looping out the intervening DNA between their binding site and the promoter
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.denaturing the DNA by interfering with hydrogen-bonding between base pairs. b.modifying the N-terminal tails of core histones. c.using the energy of ATP hydrolysis to move nucleosomes. d.recruiting other enzymes.
using the energy of ATP hydrolysis to move nucleosomes.
Viruses reproduce inside a host cell because a.viruses use host-cell ribosomes to produce viral coat proteins. b.all viruses must insert their genomes into the host-cell genome in order to be replicated. c.viruses need host-cell reverse transcriptase to convert its RNA into DNA. d.viruses package DNA from the host-cell genome into the virus particle.
viruses use host-cell ribosomes to produce viral coat proteins.
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.a water molecule. d.an amino group.
water
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.ATP; phosphorylation b.acetate; acetylation c.hydroxide; hydration d.water; hydrolysis
water; hydrolysis
In a lipid bilayer, where do lipids rapidly diffuse? a. in and out of the bilayer b. within the plane of one monolayer and back and forth between the monolayers c. back and forth from one monolayer to the other in the bilayer d. not at all, because they remain in place within the bilayer e. within the plane of their own monolayer
within the plane of their own monolayer
A pluripotent cell a.can only give rise to stem cells. b.is considered to be terminally differentiated. c.can only be produced in the laboratory. d.can give rise to all the tissues and cell types in the body.
can give rise to all the tissues and cell types in the body.
Cells that are terminally differentiated a.no longer produce RNAs. b.can no longer undergo cell division. c.are unable to move. d.will undergo apoptosis within a few days.
can no longer undergo cell division.
An adult hematopoietic stem cell found in the bone marrow a.will occasionally produce epidermal cells when necessary. b.can undergo self-renewing divisions for the lifetime of a healthy animal. c.can produce only red blood cells. d.will express all the same transcription factors as those found in an unfertilized egg.
can undergo self-renewing divisions for the lifetime of a healthy animal.
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.metabolic. b.catabolic. c.biosynthetic. d.anabolic.
catabolic
Apoptosis differs from necrosis in that necrosis a.causes DNA to fragment. b.requires the reception of an extracellular signal. c.causes cells to swell and burst, whereas apoptotic cells shrink and condense. d.involves a caspase cascade.
causes cells to swell and burst, whereas apoptotic cells shrink and condense.
The principal microtubule-organizing center in animal cells is the a.kinetochore. b.centromere. c.centrosome. d.cell cortex.
centrosome.
Plasma membrane proteins that move ions in and out of cells using passive transport are called Select one: a.transporters. b.channels. c.anchors. d.receptors
channels
During recombination a.one crossover event occurs for each pair of human chromosomes. b.cohesins keep the sister chromatids together until anaphase I. c.chiasmata hold chromosomes together. d.sister chromatids undergo crossing-over with each other.
chiasmata hold chromosomes together.
Which of the following choices BEST describes the role of the lysosome? a.clean-up, recycling, and disposal of macromolecules b.the storage of excess macromolecules c.sorting of transport vesicles d.transport of material to the Golgi apparatus
clean-up, recycling, and disposal of macromolecules
Which of the following choices BEST describes the role of the lysosome? a.transport of material to the Golgi apparatus b.sorting of transport vesicles c.clean-up, recycling, and disposal of macromolecules d.the storage of excess macromolecules
clean-up, recycling, and disposal of macromolecules
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.condensation c.dehydrogenation d.hydrolysis
condensation
Operons a.are transcribed by RNA polymerase II. b.contain a cluster of genes transcribed as a single mRNA. c.can only be regulated by gene activator proteins. d.are commonly found in eukaryotic cells.
contain a cluster of genes transcribed as a single mRNA.
Operons a.contain a cluster of genes transcribed as a single mRNA. b.are transcribed by RNA polymerase II. c.are commonly found in eukaryotic cells. d.can only be regulated by gene activator proteins.
contain a cluster of genes transcribed as a single mRNA.
Select the option that correctly finishes the following statement: A cell's genome a.is defined as all the genes being used to make protein. b.is altered during embryonic development. c.constantly changes, depending upon the cell's environment. d.contains all of a cell's DNA.
contains all of a cell's DNA.
Which method or methods of controlling eukaryotic gene expression is NOT employed in prokaryotic cells? Select all that apply. a. controlling how often a gene is transcribed b. controlling which mRNAs are exported from the nucleus to the cytosol c. controlling which mRNAs are translated into protein by the ribosomes d. controlling how an RNA transcript is spliced
controlling which mRNAs are exported from the nucleus to the cytosol controlling how an RNA transcript is spliced
Levels of Cdk activity change during the cell cycle, in part because a.cyclin concentration changes during the cycle. b.the Cdks phosphorylate each other. c.Cdk degradation precedes entry into the next phase of the cell cycle. d.the Cdks activate the cyclins.
cyclin concentration changes during the cycle.
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.decrease in gene expression b.recruitment of remodeling complexes c.increase in gene expression d.displacement of histone H1
decrease in gene expression
Which of the following substances is most commonly used to help purify a membrane protein? a.ethanol b.high salt solution c.detergent d.sucrose
detergent
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.
do not code for proteins
Cells in the G0 state a. do not divide b. cannot reenter the cell cycle c. have entered this arrest state from either G1 or G2 d. have duplicated their DNA
do not divide
Cells in the G0 state a.cannot reenter the cell cycle. b.do not divide. c.have duplicated their DNA. d.have entered this arrest state from either G1 or G2.
do not divide.
Which type of mutation will generally be lost from the population most rapidly? Select one: a.recessive/neutral b.dominant/deleterious c.dominant/beneficial d.recessive/deleterious
dominant/deleterious
During sexual reproduction, novel mixtures of alleles are generated. This is because a.a diploid individual has two different alleles for every gene. b.in all diploid species, two alleles exist 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.
during meiosis, the segregation of homologs is random such that different gametes end up
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.each daughter DNA molecule consists of two new strands copied from the parent DNA molecule. c.after many rounds of DNA replication, the original DNA double helix is still intact. d.new DNA strands must be copied from a DNA template.
each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand.
DNA replication is considered semiconservative because a.new DNA strands must be copied from a DNA template. b.after many rounds of DNA replication, the original DNA double helix is still intact. 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.
each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand.
Cells that are specialized for the secretion of proteins are likely to have which of the following features? a.large population of mitochondria b.enlarged endoplasmic reticulum c.long bundles of actin/myosin proteins d.small volume of cytoplasm
enlarged endoplasmic reticulum
Cells that are specialized for the secretion of proteins are likely to have which of the following features? a.large population of mitochondria b.long bundles of actin/myosin proteins c.enlarged endoplasmic reticulum d.small volume of cytoplasm
enlarged endoplasmic reticulum
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.ions b.heat c.enzymes d.ATP
enzymes
Which step(s) will gradually reduce further production of Protein X? Explain why in 1-2 sentences. (there may be more than one plausible answer, but you only need to pick one to explain)
errors in the translation of transcription
The type of chromatin that participates in the active transcription of DNA to RNA is a. nucleosome b.30-nm chromatin fiber c. X chromatin d. euchromatin e. heterochromatin
euchromatin
Mitogens are a.kinases that cause cells to grow in size. b.extracellular signals that stimulate cell division. c.produced by mitotic cells to keep nearby neighboring cells from dividing. d.transcription factors important for cyclin production.
extracellular signals that stimulate cell division.
The complete set of information in an organism's DNA is called its a.coding sequence. b.genetic code. c.genome. d.gene.
genome
When an organism has inherited two nonidentical alleles, it is said to be Select one: a.dominant. b.recessive. c.homozygous. d.heterozygous.
heterozygous.
The main function of the nucleus is to Select one: a.make proteins using the genetic material. b.house the DNA in a separate cell compartment. c.provide energy for the cell. d.allow cells to segregate enzymes.
house the DNA in a separate cell compartment.
What type of bond connects base pairs? a. covalent b. hydrogen c. ionic d. van der Waals
hydrogen
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.hydrogen bonds along the protein backbone b.the hydrophobic-core interactions c.side-chain interactions d.specific amino acid sequences
hydrogen bonds along the protein backbone
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.ionic b.hydrophilic c.hydrophobic d.van der Waals
hydrophobic
If a reaction is energetically favorable (exergonic), then it must produce a(n) Select one: a.increase in activation energy. b.decrease in reaction time. c.increase in entropy. d.decrease in heat.
increase in entropy
Which step will gradually increase levels of Protein X? Explain why in 1-2 sentences.
increased ubiquitination
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
introns that contain regions of similarity to one another
Combinatorial control of gene expression a.involves every gene using a different combination of transcriptional regulators for its proper expression. b.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. d.is seen only when genes are arranged in operons.
involves groups of transcription regulators working together to determine the expression of a gene.
Combinatorial control of gene expression a.is seen only when genes are arranged in operons. b.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. d.involves every gene using a different combination of transcriptional regulators for its proper expression.
involves groups of transcription regulators working together to determine the expression of a gene.
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.bases cannot form hydrogen bonds with each other. b.nucleotides use a different chemical linkage between nucleotides compared to DNA. c.is single-stranded. d.contains uracil and uses ribose as the sugar.
is single-stranded.
RNA in cells differs from DNA in that a.it contains the base uracil, which pairs with cytosine. b.it is single-stranded and cannot form base pairs. c.the sugar ribose contains fewer oxygen atoms than does deoxyribose. d.it is single-stranded and can fold up into a variety of structures.
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.it causes neighboring cells to mutate. b.its cells are proliferating faster. c.its cells invade other tissues. d.its cells attack and phagocytose neighboring normal tissue cells.
its cells invade other tissues.
Microtubules capture chromosomes by binding specifically to which of the following? a. cohesins on the sister chromatids b. condensins on the condensed chromosomes c. kinetochores on the sister chromatids d.telomeres on the condensed chromosomes
kinetochores on the sister chromatids
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.double-stranded DNA helix. c.molecule that could direct protein synthesis. d.molecule that could provide a template for the production of a complementary molecule.
molecule that could catalyze its own replication.
Nucleotides are comprised of a. purine bases b. nitrogenous bases + 5 carbon sugar + phosphate c. nitrogenous bases + 5 carbon sugar d. none of the above e. nitrogenous bases + 6 carbon sugar + phosphate
nitrogenous bases + 5 carbon sugar + phosphate
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.nucleotide polymerization occurs only in the 5´-to-3´ direction. c.an RNA transcript is synthesized discontinuously and the pieces are then joined together. d.the newly synthesized RNA remains paired to the template DNA.
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.are restricted to the nucleolus. b.occupy discrete territories in the nucleus. c.share the same nuclear territory as their homolog. d.are completely tangled with other chromosomes.
occupy discrete territories in the nucleus
An oncogene is different from a tumor suppressor gene in that Select one: a.oncogene mutations more rarely lead to cancer. b.oncogenes have mutations causing increased activity of the protein. c.mutation of the gene can contribute to cancer. d.oncogenes have mutations causing decreased activity of the protein.
oncogenes have mutations causing increased activity of the protein.
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.order. b.light. c.movement. d.electricity.
order
Proteins that are associated with the membrane by noncovalent interactions with other membrane proteins are called ___________ proteins. Select one: a.integral membrane b.lipid-linked c.monolayer-associated d.peripheral membrane FEEDBACK: A protein that is associated with the membrane simply by virtue of interacting with another membrane protein are called peripheral membrane proteins. On the other hand, transmembrane, monolayer associated, and lipid-linked proteins are all directly associated with the membrane and are called integral membrane proteins.
peripheral membrane
The set of traits of an organism that are determined by the genetic makeup is referred to as the Select one: a.phenotype. b.flavor. c.genotype. d.haplotype.
phenotype.
The variety and arrangement of chemical groups on monomer subunits contribute to the conformation, reactivity, and surface of the macromolecule into which they become incorporated. What type of chemical group is circled on the nucleotide shown in Figure 2-41?Figure 2-41 a.phosphate b.pyrophosphate c.carboxyl d.carbonyl
phosphate
The type of bond that holds together neighboring subunits in a single strand of DNA is a Select one: a.peptide bond. b.phosphodiester bond. c.phosphoanhydride bond. d.hydrogen bond.
phosphodiester bond.
Which of the following correctly matches a G-protein-activated enzyme with the second messenger molecule it produces? Select one: a.guanylyl cyclase à GTP b.protein kinase A à Ca2+ c.adenylyl cyclase à inositol triphosphate d.phospholipase C à diacylglycerol
phospholipase C -> diacylglycerol
What determines the specificity an antibody has for its antigen? a. polypeptide loops in its variable domains b. its Y-shaped, bivalent structure c. polypeptide loops in its constant domain d. the summation of its disulfide bonds
polypeptide loops in its variable domains
5) Short pieces termed primers are removed by primase that degrades RNA: False 6) Prokaryotic chromosomes have a single site of initiation of DNA replication: True 7) Translation ends when the tRNA for a stop codon binds to the A site of the ribosome: False 8) 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
primase does not degrade RNA primers; instead, it synthesizes RNA primers. Primase is an enzyme responsible for synthesizing short RNA sequences called primers during DNA replication. Translation ends when it binds at the p site not every mRNA molecule produced from the same gene needs to have exactly the same combination of exons.
Which of the following is NOT a general mechanism that cells use to maintain stable patterns of gene expression as cells divide? a.a positive feedback loop, mediated by a transcriptional regulator that activates transcription of its own gene in addition to other cell-type-specific genes b.inheritance of DNA methylation patterns when cells divide c.faithful propagation of condensed chromatin structures as cells divide d.proper segregation of housekeeping proteins when cells divide
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.inheritance of DNA methylation patterns 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.proper segregation of housekeeping proteins when cells divide
proper segregation of housekeeping proteins when cells divide
What type of macromolecule helps package DNA in eukaryotic chromosomes? a.proteins b.carbohydrates c.RNA d.lipids
proteins
Which of the following are components of the eukaryotic plasma membrane? (check all that apply) proteins carbohydrates lipids nucleic acids
proteins carbohydrates lipids
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.weak d.unstable
rigid with respect to rotation
In eukaryotes, but not in prokaryotes, ribosomes find the start site of translation by a.binding directly to a ribosome-binding site preceding the initiation codon. b.binding an initiator tRNA. c.scanning along the mRNA from the 5´ end. d.recognizing an AUG codon as the start of translation.
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. genetic instability b. reduced dependence on external signals from other cells c. sensitivity to cell cycle checkpoints d. highly metabolically active
sensitivity to cell cycle checkpoints
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
some amino acids have more than one codon
Transporters, in contrast to channels, work by a.filtering solutes by size. b.specific recognition of transport substrates. c.filtering solutes by charge. d.a gating mechanism.
specific recognition of transport substrates.
Which of the following examples does NOT describe a mechanism of post-transcriptional control of gene expression? a.the degradation of an mRNA by miRNA binding and RISC activity b.translational inhibition of an mRNA by the binding of a protein at the 5´ untranslated region of the message. c.the alternative splicing of a gene, leading to the production of a muscle-specific protein d.the action of the RNA component of telomerase
the action of the RNA component of telomerase
Progression through the cell cycle requires a cyclin to bind to a Cdk because a.the cyclins are the molecules with the enzymatic activity in the complex. b.without cyclin binding, a cell-cycle checkpoint will be activated. c.the binding of a cyclin to Cdk is required for Cdk enzymatic activity. d.cyclin binding inhibits Cdk activity until the appropriate time in the cell cycle.
the binding of a cyclin to Cdk is required for Cdk enzymatic activity.
ΔG° indicates the change in the standard free energy as a reactant is converted to product. Given what you know about these values, which reaction below is the LEAST favorable?
the highest positive ΔG° will be the lest favorable
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 and the white blood cell within an individual have the same genome. d.the neuron expresses some mRNAs that the white blood cell does not, and vice versa.
the neuron expresses some mRNAs that the white blood cell does not, and vice versa.
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. b.all of the proteins found in a neuron are completely different from the proteins found in a white blood cell. c.neurons and white blood cells are differentiated cells and thus no longer need to transcribe and translate genes. d.the neuron and the white blood cell within an individual have the same genome.
the neuron expresses some mRNAs that the white blood cell does not.
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 inside of the membrane-spanning helix c. the external or lumenal side of the membrane d. the cytosolic side of the membrane
the outside of the membrane-spanning helix
In a DNA double helix, a.thymine pairs with cytosine. b.the two DNA strands run antiparallel. c.purines pair with purines. d.the two DNA strands are identical.
the two DNA strands run antiparallel
In a DNA double helix, a.the two DNA strands run antiparallel. b.thymine pairs with cytosine. c.purines pair with purines. d.the two DNA strands are identical.
the two DNA strands run antiparallel.
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
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.after filling in any lost nucleotides, helping to maintain the integrity of the DNA sequence. b.to a similar stretch of sequence on the complementary chromosome. c.after repairing any mismatches. d.to the nearest available double-stranded DNA end.
to the nearest available double-stranded DNA end.
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.chromosomes b.hormones c.transcription factors d.viruses
transcription factors
The cell components that move materials from one organelle to another are called Select one: a.Golgi apparatus. b.endoplasmic reticulum. c.transport vesicles. d.cytosol.
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. proto-oncogenes c. Mutations in cancer-critical genes cannot be inherited because cancer is not a hereditary condition. d. either proto-oncogenes or tumor suppressor genes
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.
undergo a sexual reproductive cycle that involves an alternation of haploid cells with the generation of diploid cells.
What needs to happen first before homologous recombination can occur?a.Double-strand DNA break b.Mismatch of a single base pair c.Transcription factors binding to an enhancer d.Acetylation of histone tails
Double-strand DNA break
PCR is a laboratory technique that we completed twice this semester. A) Write out the full name of the acronym. B) Name the three different stages and describe each. C) What is the temperature setting for each stage? D) Starting with one double-strand DNA molecule, how many cycles of PCR would you have to perform to produce about 100 double-strand copies (assuming 100% efficiency per cycle)?
1. Polymerase chain reaction 2. Denaturation, Annealing,extenstion 3. 90C, 50C, 70C 4. it would take about 6 cycles
Consider the following three mRNA sequences that come from the first 12 bases of the 1,182 base open reading frame of the tumor suppressor gene TP53. The first comes from a wild type DNA sequence, the next three come from mutant DNA sequences (mutations in bold and underlined). Sequence name Sequence Wild type (WT) 5' - AUG GAG GAG CCG ... - 3' Mutant 1 (M1) 5' - AUG GAG UAG CCG ... - 3' Mutant 2 (M2) 5' - AUG GAA GAG CCG ... - 3' Mutant 3 (M3) 5' - AUG GAU GAG CCG ... - 3' A. Write the amino acid sequences of each of the mRNA sequences provided. Label them WT, mutant 1, mutant 2, mutant 3. B. Rank the mutants in order of most deleterious to protein function to least deleterious to protein function and provide an explanation for each of your rankings.
A wt: Met,Glu,Glu, Pro mutant 1: Met,Glu, Stop mutant 2: Met, Glu, Glu, Pro mutant 3: Met,Asp, Glu, Pro B mutant 1 would be the most deleterious because the mutation changed the third codon into a stop codon mutant 3 would be in the middle because the altered codon would change the amino acid made which could change the function/ shape of the protein mutant 2 would be the lest deleterious because even with the change in the codon this still produced the same protein
Which of the following best describes positive feedback regulation? a. A component late in the pathway inhibits a protein earlier in the pathway b. A component acts to further activate the signaling pathway and enhance the cell's response. c. A component amplifies the signal for a more robust response throughout the cytoplasm. d. A component late in the pathway activates a protein earlier in the pathway. e. A component generates an on-off, switch-like mechanism.
A component late in the pathway activates a protein earlier in the pathway.
In water, hydrogen bonds can form between which of the following? a. The oxygen atom of one water molecule and the oxygen atom of another b. The hydrogen atom of one water molecule and the hydrogen atom of another c. A hydrogen atom of one water molecule and an oxygen atom of another d. The one oxygen atom and two hydrogen atoms of one water molecule
A hydrogen atom of one water molecule and an oxygen atom of another
Which of the following statements about cancer is FALSE? a.Tobacco use is responsible for more than 20% of all cancer deaths. b.Viruses cause some cancers. c.Chemical carcinogens cause cancer by changing the nucleotide sequence of DNA. d.A mutation in even a single cancer-critical gene is sufficient to convert a normal cell into a cancer cell.
A mutation in even a single cancer-critical gene is sufficient to convert a normal cell into a cancer cell.
Which of the following statements is FALSE? a.All mutations in an asexually reproducing single-celled organism are passed on to the progeny. b.A mutation is passed on to offspring only if it is present in the germ line. c.A mutation that arises in a mother's somatic cell often causes a disease in her daughter. d.In an evolutionary sense, somatic cells exist only to help propagate germ-line cells.
A mutation that arises in a mother's somatic cell often causes a disease in her daughter.
3) Where would you find shorter DNA amplicons? a. At the bottom of the gel. b. At the top of the gel. c. All of the amplicons will travel the same distance if the voltage is not high enough. d. Shorter amplicons would not be separated in an agarose gel because polyacrylamide is needed.
At the bottom of the gel.
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.ATP b.FADH2 c.NADPH d.NADH
ATP
The movement of a substance against its concentration gradient is called what? a. Passive transport b. Osmosis c. Active transport d. Facilitated difusion
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 hydroxyl group (OH) b. Increasing the size of the drug c. Adding a methyl group (CH3) d. Adding a carboxyl group (COOH)
Adding a hydroxyl group (OH) Adding a carboxyl group (COOH)
Which statement best represents the cell theory? a. All cells are formed by the growth and division of existing cell. b. All cells contain DNA. c. All cells resemble square or rectangular chambers. d. All cells can be seen using a microscope. e. All cells require a continual input of energy to sustain life.
All cells are formed by the growth and division of existing cell.
Viral genomes a.All of these answers are true. b.can be made of DNA. c.can be made of RNA. d.can be either double-stranded or single-stranded.
All of these answers are true.
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.sugars b.fatty acids c.nucleotides d.amino acids
Amino Amino acids
Compared to adding heat to the system, what is the advantage of using an enzyme to overcome an energy barrier? a. An enzyme generates multiple different products using multiple pathways b. An enzyme can catalyze a reaction in many different ways c. An enzyme speeds up a reaction more than heat does d. An enzyme is specific for one desired pathway and end product
An enzyme is specific for one desired pathway and end product
What is the phase that comes next, when the chromosomes get pulled to opposite poles? a.Prometaphase b.Anaphase c.Telophase d.Cytokinesis
Anaphase
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.Chromosome loop-forming proteins arrange the DNA into topological associated domains such that individual genes and their associated enhancer binding regions are in proximity. b.The cell uses histone acetyltransferase to prevent enhancer binding to the DNA. c.The cell will group neighboring genes into operons so that they are transcribed as a single unit, regulated by a single enhancer. d.There is no mechanism to prevent inappropriate enhancer action on neighboring genes. The cells will degrade inappropriately produced mRNA molecules.
Chromosome loop-forming proteins arrange the DNA into topological associated domains such that individual genes and their associated enhancer binding regions are in proximity.
How does the cell rapidly reduce the concentration of cyclins in the cytosol? a. Covalently attach a molecule of ubiquitin to cyclin b. cAMP noncovalent binding to cyclin c. Block transcription of cyclin through chromatin remodeling d. Express a miRNA complementary to the mRNA for cyclin
Covalently attach a molecule of ubiquitin to cyclin
Which of the following statements is TRUE? a.Disulfide bonds are formed by the cross-linking of methionine residues. b.Disulfide bonds are more common for intracellular proteins, compared to extracellular proteins. c.Disulfide bonds stabilize but do not change a protein's final conformation. d.Disulfide bonds are formed mainly in proteins that are retained within the cytosol.
Disulfide bonds stabilize but do not change a protein's final conformation.
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.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. c.To function, all extracellular signal molecules must be transported by their receptor across the plasma membrane into the cytosol. d.Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior.
Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior.
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 decreases length of time the G-alpha subunit is bound to GDP b. Haloperidol is a dopamine receptor agonist c. Haloperidol is a dopamine receptor antagonist d. Haloperidol leads to excessive phosphorylation of MAP kinase kinase kinase
Haloperidol is a dopamine receptor antagonist
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? Higher concentration of K+ outside the liposomes and more negatively charged molecules inside than outside Lower concentration of K+ outside the liposomes and more negatively charged molecules outside than inside Higher concentration of K+ outside the liposomes and more negatively charged molecules outside than inside Lower concentration of K+ outside the liposomes and more negatively charged molecules inside than outside
Higher concentration of K+ outside the liposomes and more negatively charged molecules inside than outside
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) Increasing the amount of GPCR ligand Decreasing the amount of GPCR ligand Increasing the activity of cAMP phosphodiesterase (the enzyme that turns cAMP into AMP) Decreasing the activity of cAMP phosphodiesterase (the enzyme that turns cAMP into AMP) Increasing the activity of phosphatases that act on Nerd Decreasing the activity of phosphatases that act on Nerd
Increasing the activity of cAMP phosphodiesterase (the enzyme that turns cAMP into AMP) Increasing the activity of phosphatases that act on Nerd
Select whether the following statements are TRUE or FALSE. For each statement that is false, explain why it is false in 1-2 sentence in the space below. 1) The lipid bilayer is made up of phospholipids that have an amphipathic chemical structure.: True 2) Membrane fluidity decreases when phospholipid chain lengths increase and fatty acids are fully saturated.: True 3) Eukaryotic genes are distributed across multiple DNA molecules, which can be packaged into linear or circular chromosomes: false 4) In eukaryotic cells, DNA is wound around protein complexes called histones, which can be covalently modified to regulate the expression of genes:True
Instead, eukaryotic genes are typically located on linear chromosomes within the nucleus of the cell. Each chromosome contains many genes arranged along its length.
Genes in eukaryotic cells often have intronic sequences coded for within the DNA. These sequences are ultimately not translated into proteins. Why? a.Introns are removed by catalytic RNAs in the cytoplasm. b.The ribosome will skip over intron sequences when translating RNA into protein. c.Intronic sequences are removed from RNA molecules by the spliceosome, which works in the nucleus. d.Introns are not transcribed by RNA polymerase.
Intronic sequences are removed from RNA molecules by the spliceosome, which works in the nucleus.
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 removed by catalytic RNAs in the cytoplasm. c.Introns are not transcribed by RNA polymerase. d.Intronic sequences are removed from RNA molecules by the spliceosome, which works in the nucleus.
Intronic sequences are removed from RNA molecules by the spliceosome, which works in the nucleus.
Lipid bilayers are highly impermeable to which molecule(s)? a. steroid hormones b. Na+ and Cl- c. carbon dioxide d. oxygen e. water
Na+ and Cl-
Mutations in the nucleic acid sequence of a gene can sometimes direct the substitution of one amino acid for another in the encoded protein. Which amino acid substitution would be most likely to severely disrupt the normal structure of a protein? a. Valine to Alanine b. Serine to Threonine c. Lysine to Arginine d. Lysine to Glutamic acid e. Valine to isoleucine
Lysine to Glutamic acid
Which of the following statements most correctly describes meiosis? a.Meiosis involves a single round of DNA replication followed by four successive cell divisions. b.Meiosis involves four rounds of DNA replication followed by two successive cell divisions. c.Meiosis involves two rounds of DNA replication followed by a single cell division. d.Meiosis involves a single round of DNA replication followed by two successive cell divisions.
Meiosis involves a single round of DNA replication followed by two successive cell divisions.
Which of the following is not a mechanism of genetic variation? a.Mutation within the regulatory DNA of a gene b.Gene duplication and divergence c.Misreading of an mRNA by a ribosome d.Exon shuffling e.Mutation within the coding sequence of a gene
Misreading of an mRNA by a ribosome
Which of the following statements is FALSE? a.Mutations in somatic cells are passed on to individuals of the next generation. b.Sexual reproduction allows for a wide variety of gene combinations. c.Asexual reproduction typically gives rise to offspring that are genetically identical. d.Gametes are specialized sex cells.
Mutations in somatic cells are passed on to individuals of the next generation.
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 transcriptional regulators that bind to the regulatory regions of the cortisol-responsive genes must all be the same. b.The cortisol-responsive genes must not be transcribed in response to other hormones. c.The cortisol-responsive genes must all be in an operon. d.The cortisol-responsive genes share a DNA sequence in their regulatory regions that binds the cortisol-responsive transcriptional activator.
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 changes in gene expression by preventing transcription factor phosphorylation. b. The drug prevents receptor coupling to G proteins. c. The drug prevents receptor dimerization. d.The drug prevents adaptor protein binding to activated receptors.
The drug prevents receptor dimerization.
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 DNA proofreading activity occurs nearly simultaneously with strand elongation. c.The exonuclease activity removes nucleotides from the 5' end of a growing DNA strand d.The exonuclease activity is in a different domain of the DNA polymerase.
The exonuclease activity removes nucleotides from the 5' end of a growing DNA strand
Which of the following statements about the genetic code is CORRECT? a.All amino acids are specified by more than one codon. b.All codons specify an amino acid. c.All codons specify more than one amino acid. d.The genetic code is redundant.
The genetic code is redundant.
Which of the following statements about the genetic code is CORRECT? a.The genetic code is redundant. b.All codons specify an amino acid. c.All codons specify more than one amino acid. d.All amino acids are specified by more than one codon.
The genetic code is redundant.
Which small genetic change in or near an essential gene would likely cause the most harm to a cell? Select one: A deletion of two nucleotides at the end of a coding region A synonymous mutation at the beginning of a coding region The insertion of three nucleotides at the beginning of a coding region The insertion of one nucleotide at the beginning of a coding region
The insertion of one nucleotide at the beginning of a coding region
Telomeres serve as caps protecting the ends of linear chromosomes. Which of the following is FALSE regarding the replication of telomeric sequences? a.The leading strand doubles back on itself to form a primer for the lagging strand. b.Telomeres are made of repeating sequences. c.The lagging-strand telomeres are not completely replicated by DNA polymerase. d.Additional repeated sequences are added to the template strand.
The leading strand doubles back on itself to form a primer for the lagging strand.
Which of the following is most likely to occur after the lipid bilayer is pierced? a.The membrane reseals. b.The membrane collapses. c.The membrane expands. d.A tear is formed.
The membrane reseals.
Which of the following events does NOT usually occur during interphase? a.Cells grow in size. b.The centrosomes are duplicated. c.The nuclear envelope breaks down. d.DNA is replicated.
The nuclear envelope breaks down.
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 protein: The number of covalent bonds between antibody and mutant spike protein increased The number of noncovalent bonds between antibody and mutant spike protein increased The number of covalent bonds between antibody and mutant spike protein decreased The number of noncovalent bonds between antibody and mutant spike protein decreased
The number of noncovalent bonds between antibody and mutant spike protein decreased
How does phosphorylation control protein activity? a. The phosphate group alters the primary structure of the protein. b.The phosphate group induces a change in the protein's conformation. c. The phosphate group, with its negative charges, prevents other negatively charged molecules from interacting with the protein. d. The phosphate group serves as an added source of energy for a protein. e. The phosphate group, with its positive charges, temporarily relieves feedback inhibition.
The phosphate group induces a change in the protein's conformation.
Which of the following statements correctly explains what it means for DNA replication to be bidirectional? a.The DNA replication machinery can move in either direction on the template strand. b.The replication fork can open or close, depending on the conditions. c.The replication forks formed at the origin move in opposite directions. d.Replication-fork movement can switch directions when the fork converges on another replication fork.
The replication forks formed at the origin move in opposite directions.
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.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. d.Replication-fork movement can switch directions when the fork converges on another replication fork.
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.RNA polymerase dissociates. b.A guanine nucleotide with a methyl group is added to the 5´ end of the mRNA. c.The ribosome binds to the mRNA. d.The mRNA is polyadenylated at its 3´ end.
The ribosome binds to the mRNA.
Which of the following statements about how enzymes work is FALSE? a. The shape of the active site is determined by the amino acid sequence of the enzyme b. The active site of an enzyme is specific, recognizing only one particular substrate c. When a substrate encounters the active site of its enzyme, the substrate and enzyme become held together by weak chemical bonds d. The shape of the active site is constantly changing, allowing the enzyme to bind many different substrates, catalyzing many different chemical reactions
The shape of the active site is constantly changing, allowing the enzyme to bind many different substrates, catalyzing many different chemical reactions
Which step is most likely to result in the fastest, most immediate reduction of protein product? Explain why in 1-2 sentences.
The transcptional repressor protien binidng to the promter upstrem becuase then none of the other steps would be able to take place
2) Which option below is NOT a reason for adding loading dye to the DNA sample? a. Add negative charge to sample. b.To visualize the sample by natural light. c. To visualize the sample by UV. d. To provide density to the sample.
To visualize the sample by UV.
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.Helicase unwinds the DNA and rewinds it after replication is complete. b.Nothing needs to be done because the two strands will be separated after replication is complete. c.DNA repair enzymes remove torsional stress as they replace incorrectly paired bases. d.Topoisomerases break the covalent bonds of the backbone, allowing the local unwinding of DNA ahead of the replication fork.
Topoisomerases break the covalent bonds of the backbone, allowing the local unwinding of DNA ahead of the replication fork.
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 False
Transcription regulators interact with sequences of nucleotides
Which of the following scenarios demonstrates apoptosis? Select all that apply. a. Muscle fibers are signaled to contract and move. b. A severe burn causes skin cells to die. c. 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
Webbing between an embryo's toes is eliminated during embryological development. An immune cell self-destructs once it is no longer needed by the immune system
Enzymes increase the speed of a chemical reaction because they Select one: a.make the reaction spontaneous. b.make the reaction more energetically favorable. c.increase the temperature to provide the necessary boost of energy. d.lower the activation energy needed to start the reaction.
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. mitochondria b. chloroplasts c. lysosomes d. vacuoles
mitochondria
Which of the following organelles has both an outer and an inner membrane? a.lysosome b.endoplasmic reticulum c.peroxisome d.mitochondrion
mitochondrion
