Exam #2 (Chapters 3-5,9,10, 13.5,24)

Which of the answer choices is a cellular response to signal transduction? a change in the activity of an enzyme 1)All of these choices are correct. 2)Signal transduction can produce many changes in the cell, ranging from changes in gene expression to the release of signals to communicate with other cells. 3)the release of signaling molecules from the cella change in the proteins found in the cytosol

1)

A proton pump is needed in the lysosomal membrane because: A)All of these choices are correct. B)the interior of the lysosome needs to be acidic. C)protons are being moved from low to high concentration. D)protons cannot move across a membrane on their own.

A)

A researcher discovers a new single-celled bacterium very similar to Thiomargarita namibiensis. At first, she is confused because this organism is quite large compared with other bacteria. She also knows that because of diffusion, most bacterial cells don't exceed 17 μm in size. What might the researcher notice about the internal structure of her new bacterium? A)It contains a large vacuole, limiting the distance molecules need to diffuse. B)Vacuoles allow for certain compounds to be stored within the vacuoles. C)Vacuoles expand within the cell and minimize the distance across which diffusion has to occur.

A)

A researcher is studying a population of mutant fibroblasts that fail to flatten and attach to extracellular matrix proteins on a flat surface. This is likely the result of mutations in genes encoding: A) components of cell junctions. B)components of the cytoskeleton. C) components of motor proteins

A)

How do eukaryotic plant and animal cells differ from one another? A)Animal cells do not have chloroplasts and cell walls, and plant cells do. B)Animal cells have mitochondria but not chloroplasts, and plant cells have chloroplasts but not mitochondria. C)Animal cells have endoplasmic reticulum, and plant cells don't.

A)

Imagine that a primary RNA transcript from your favorite eukaryotic gene was processed incorrectly and had no 5' cap. What would be the result? A)The initiation complex for translation would fail to form properly, and translation would not occur. B)Translation would commence properly, but elongation would be severely affected. C)Termination would be affected, as release factors would be unable to bind to ribosomes. D)Translation would proceed normally. E)Translation would commence at an AUG site in the middle of the RNA sequence.

A)

Imagine that you have two blades of grass. One is from a normal plant, and the other is from a mutant plant that cannot absorb water into its vacuoles. How will the structures of these two blades of grass compare? A)The grass blade from the mutant plant will appear limp compared to that from the normal plant. B)The grass blade from the mutant plant will be sturdier compared to that from the normal plant.

A)

Microtubules can grow by addition of tubulin dimers to _______________, and they can shorten by removal of dimers from ______________. A)both plus and minus ends; both plus and minus ends B)the minus end; the plus end C)both plus and minus ends; the minus end

A)

Microtubules form from dimers of _____ and ______ subunits that polymerize into a ____________. A)alpha-tubulin; beta-tubulin; hollow tube B)an amino acid; phosphate; double helix

A)

Some lipid rafts are characterized by an accumulation of cholesterol. What does this mean for the fluidity of the lipid raft? A)Cholesterol decreases the fluidity of the membrane at normal temperatures. At normal temperatures, the hydrophobic rigid ring structures of cholesterol block the movement of phospholipids in the membrane and reduce membrane fluidity. B)Cholesterol is too polar to become part of the phospholipid bilayer. C)Cholesterol has no effect on the fluidity of the membrane at normal temperatures.

A)

The ability of microtubules to undergo rapid ___________ and slower ____________ is associated with the ability of the ______________ to explore the cell and locate chromosomes. A)depolymerization; polymerization; spindle apparatus B)synthesis; hydrolysis; microtubules C)synthesis; hydrolysis; cytoskeleton elements

A)

The basal lamina is: A)a specialized form of the extracellular matrix found beneath all epithelial tissues. B)an area found wherever two different types of tissues meet. C)a specialized form of the extracellular matrix found only in the skin.

A)

The cytoskeleton of animal cells includes: A)microtubules, microfilaments, and intermediate filaments. B)actin, microtubules, and intermediate filaments. C)microtubules and microfilaments.

A)

Which choice is considered an integral membrane protein? A)a protein with its amino-terminus in the cytoplasm and its carboxy-terminus in the extracellular space Integral membrane proteins are irreversibly embedded in the membrane. Some span the membrane with a hydrophobic bridge that connects the domains on either side of the membrane B)a protein attached to a phospholipid via ionic bonding with the head group of the lipid molecule C)a protein capable of diffusing throughout the cytoplasm of a cell

A)

Which statement explains why rRNAs are the most abundant type of RNA in a mammalian cell? A)rRNAs are an integral part of ribosomes, and it takes millions of ribosomes to translate all the proteins required for a cell's functions B)None of the other answer options is correct. rRNAs are not the most abundant type of RNA in a mammalian cell. C)A different type of ribosome is needed to synthesize all of a cell's proteins, and because most proteins are present in multiple copies, a huge number of ribosomes are needed. D)There are more different types of rRNA genes than all other types of genes combined. E)It takes several rRNAs to transcribe a single mRNA, so there are many more rRNAs needed in a cell than the number of proteins synthesized.

A)

Which substance could most easily cross a synthetic membrane composed of phospholipids but not proteins? A)oxygen (O2) B)sodium ions (Na+) C)water (H2O) D)glucose (C6H12O6)

A)

Which would be more likely to cause development of a microvillus on an intestinal epithelial cell? A)plus (+) end growth of microfilaments at the tip of the microvillus but no shrinkage at the minus (-) end B)plus (+) end growth of microfilaments at the tip of the microvillus and shrinkage at the minus (-) end

A)

In which cellular process is RNA involved? A)All of these choices are correct B).transcription and translation C)transcription D)translation E)splicing

A) all of these choices are correct

Which one of the types of proteins interacts directly with a stop codon? A)release factor B)initiation factor C)sigma factor D)transcription factor E)elongation factor

A) release factor

Which of the following lipid composition options has the least membrane fluidity? A)phospholipids with long-chain, saturated fatty acids B)unsaturated fatty acidsphospholipids with long-chain, C)saturated fatty acidsphospholipids with short-chain,

A)phospholipids with long-chain, saturated fatty acids

A researcher introduces a large polar signaling molecule produced by bacteria to eukaryotic cells that she is culturing in the laboratory. Remarkably, she notices that the signaling of the bacteria results in an increase in eukaryotic gene expression. How is this possible? A)This signaling is likely a steroid hormone that activates receptors in the eukaryotic cells. B)This signal is likely similar in structure to ligands utilized by eukaryotic cells.

B)

Based on the two-step model of glucose transport, what would happen if the rate of function of the sodium-potassium pump increased? A)The sodium-potassium pump would be unaffected, and therefore, there would be no effect on glucose transport. B)The sodium-potassium pump would make a stronger sodium gradient, so more glucose could be transported across the membrane. C)The sodium-potassium pump would make a weaker sodium gradient, but it would have no effect on glucose transport.

B)

Considering the amino acids that are found invidious domains of transmembrane proteins, which statement would be true? A) the r group of a basic amino acid would only be able to form covalent bonds B) the positively charged r group of a basic amino acid could bind to DNA

B)

During the signal transduction process, the signal often triggers a signal transduction cascade. For example, a single activated receptor can activate hundreds of protein A molecules. Each activated protein A molecule activates hundreds of protein B molecules, and so on, until a cellular response occurs. What purpose does this cascade serve? A)The cascade makes signaling easier to shut off or terminate. B)The cascade serves to amplify the signal so one activated receptor can have a significant response.

B)

Imagine a cell that has a membrane composed mostly of lipids with saturated fatty acid tails, and that this membrane also has low cholesterol content. What are the characteristics of this cell membrane? A)The characteristics of this cell membrane will closely mirror those of a membrane composed of only unsaturated fatty acids. B)Due to its low cholesterol content, the cell membrane would lose its fluidity at cold temperatures. Remember that cholesterol is a bulky nonpolar molecule with multiple ring structures that prevent tight packing of the phospholipids' tails and that cholesterol increases membrane fluidity at low temperatures.

B)

Imagine that a researcher was able to travel back in time, shortly after the appearance of the first RNAs on Earth. What would she most likely find? A)multiple polycistronic mRNAs, which could be translated to generate several proteins B)precursors of tRNAs bound to nucleotides, and not amino acids C)precursors of tRNAs bound only to specific amino acids, such as glycine D)proteins with complex primary, secondary, and tertiary structures E)functional ribosomes that behave similarly to those found today

B)

In many signaling pathways, once a signaling molecule binds to a receptor, the receptor becomes phosphorylated. This initial phosphorylation step best demonstrates: A)signal transduction. B)receptor activation. C)termination. D)either cellular response or signal transduction. E)cellular response.

B)

In the process of transcription, the RNA transcript is synthesized: A)from the 5' end to the 3' end. B)from the 3' end to the 5' end.

B)

Microtubules can grow by addition of tubulin dimers to _______________, and they can shorten by removal of dimers from ______________. A)the plus end; the minus end B)both plus and minus ends; both plus and minus ends C)the minus end; the plus end

B)

Predict how phospholipids would arrange if they were placed in a nonpolar solution rather than a polar solution like water. A)The phospholipids would form a normal bilayer. B)The phospholipid tails would orient toward the solution, and the heads would cluster away from the solution. C)Remember that nonpolar chemical groups interact with each other and avoid polar groups.

B)

When a G protein-coupled receptor binds a signal molecule, it activates a G protein. The active G protein is bound to a molecule of _______, and in its active state can _________. A)GDP; inactivate another target protein B)GTP; activate another target protein C)GTP; inactivate another target protein

B)

When an appropriate signal binds to a G protein-coupled receptor, what is the best description of how the information is passed across the plasma membrane? A)The signal molecule is transported across the plasma membrane by the receptor protein. B)Signal binding causes a conformational change in the cytoplasmic portion of receptor protein. C)Binding of the signal molecule triggers the cell to produce G protein.

B)

Which choice describes the hydrophilic component of cholesterol? A)the rigid group of planar rings B)the hydroxyl head group

B)

Which part of a cholesterol molecule is polar? A)the hydrocarbon tail B)the OH group

B)

Why does active transport of molecules across a membrane require ATP? A)An input of energy is needed to speed up the rate of facilitated diffusion B)An input of energy is needed to allow the movement of molecules from an area of low concentration to one of higher concentration. Diffusion leads to equalization of the concentration of molecules in different regions. Active transport results in unequal concentrations of molecules in different regions, which requires movement of molecules against the concentration gradient. C)An input of energy is needed to move all molecules across a membrane.

B)

In an RNA world: A)DNA functions in information storage, and RNA alone catalyzes reactions. B)RNA functions in information storage and also performs catalysis C).None of the other answer options is correct. D)RNA functions in information storage, and proteins perform catalysis. E)RNA functions in information storage, and there is no catalysis.

B) RNA functions in information storage and also performs catalysis

The strands in a double helix of DNA are: A)antiparallel. B)All of these choices are correct. C)complementary D).held together via hydrogen bonds. E)wound around each other with 10 base pairs per turn.

B) all of these are correct

Folding domains show how structure relates to function because: A)they create surfaces whose shape and charge allows them to interact with other folding domains. B)All of these choices are correct. C)they change the configuration of the polypeptide in such a way as to facilitate proper folding of other regions. D)they create regions whose shape and charge can bind specific small molecules.

B) all of these choices are correct

Scientists use which of the following as evidence that mitochondria and chloroplasts had prokaryotic origins? A)Both can survive on their own outside of the cell. B)Both contain their own circular DNA. C)Both are unable to reproduce themselves without assistance from other cellular organelles.

B) both contain their own circular DNA

Researchers seldom find prokaryotic cells that are greater than 100 micrometers in diameter. Why would the size of prokaryotic cells be restricted? A)Prokaryotic cells have multifunctional genes that can encode several proteins on a single mRNA. B)Prokaryotic cells do not have a phospholipid bilayer for a membrane. C)Prokaryotic cells must absorb all of their nutrients from their environment and therefore require a high surface area to volume ratio.

C

Based on the two-step model of glucose transport, what would happen if the supply of ATP was depleted from the cell? A)The sodium-potassium pump would be unaffected, and therefore, there would be no effect on glucose transport. B)The sodium-potassium pump would be unaffected, but the rate of glucose transport would increase. C)The sodium-potassium pump would make less of a sodium gradient, so less glucose could be transported across the membrane.

C)

Cadherin is an example of: A)an intermediate filament protein. B)a motor protein. C)a cell adhesion molecule. D)an extracellular matrix protein.

C)

Imagine that a scientist is able to travel back in time to when the first proteins appeared. What would she observe? A)None of these choices is correct. B)Proteins would have relatively complex folding domains. C)All proteins would be relatively short. D)Proteins would possess several folding domains. E)Proteins would be long compared to proteins today.

C)

Insulin is a protein hormone that helps to control the level of glucose in the blood. It is secreted from specialized cells in the pancreas. Based on this information, which path does insulin take out of the cell? A)vesicle → ER → Golgi apparatus → exterior of cell B)ER membrane → vesicle membrane → plasma membrane → exterior of cell C)ER → Golgi apparatus → vesicle → exterior of cell

C)

Microtubules are __________ because they __________ and depolymerize at their ends. A)stable; polymerize B)dynamic;hydrolyze C)dynamic; polymerize

C)

What is a growth factor? A) a signaling molecule involved in paracrine signaling D)a soluble molecule that can alter gene expression in a cell B)a small protein that influences cell growth and division C)All of these choices are correct.

C)

When a mixture of debris from killed virulent bacteria and live nonvirulent bacteria are injected into mice: A) the mice survive because none of the living bacteria are virulent. B)the mice are killed because the virulent bacteria are revived. C)the mice are killed because the nonvirulent bacteria are transformed into virulent bacteria. D)half the mice are killed, and the other half survive. E)the mice survive for a period of a few weeks and then die from an unrelated illness.

C)

Which molecule would most likely require a transport protein to cross the plasma membrane of a red blood cell? A)H2O B)O2 C)C6H12O6

C)

Which of the statements about amino acids is correct? A)At typical cellular pH, the R groups of basic amino acids are negatively charged. B)Every amino acid is asymmetric. C)The bridge between cysteines, which connects parts of a protein, is a stable covalent interaction. D)A turn or kink in a protein is more likely to be induced by a glycine than by a proline. E)The more asparagines that are found in a polypeptide's primary sequence, the more flexible the backbone of that polypeptide.

C)

Which of the statements best summarizes the function of G protein-coupled receptors? A)A G protein present on the outside of the cell leads to a change on the inside of the cell. B)A GTP molecule is bound to the receptor, which causes a conformational change inside the cell. C)A signal present on the outside of the cell leads to a change on the inside of the cell.

C)

Which statement about RNA is correct? A)RNA molecules are typically longer than DNA molecules. B)RNA molecules are incapable of evolving an enzymatic activity over time. C)The nucleotide at the 5' end of an RNA molecule is typically a nucleoside triphosphate D).RNA is usually found in double-stranded form, just like DNA. E)RNA molecules are synthesized in 3' to 5' direction.

C)

Why does active transport of molecules across a membrane require ATP? A)An input of energy is needed because the movement of molecules requires the synthesis of additional membrane. B)An input of energy is needed to speed up the rate of facilitated diffusion. C)An input of energy is needed to allow the movement of molecules from an area of low concentration to one of higher concentration.

C)

The discovery that DNA from killed virulent bacteria can transform live harmless bacteria into virulent forms means that DNA: A)codes for proteins.is transcribed into RNA. B)is double stranded C).contains information that controls an organism's traits.

C) contains information that controls an organism's traits

Secondary structures are stabilized by which type of interaction? A)van der Waals forces B)hydrophobic clustering C)hydrogen bonding D)disulfide linkages E)ionic bonding

C) hydrogen bonding

Refer to Animation: Central Dogma. What holds the complementary strands of DNA together? A)ionic bonds B)covalent bonds C)hydrogen bonds

C) hydrogen bonds

Why aren't nucleosides incorporated into DNA? A)The sugar is not in the right form. B)The peptide bonds don't form. C)There are no phosphates to make the phosphodiester bonds. D)The bases are not fully assembled.

C) there are no phosphates to make the phosphodiester bonds

Refer to Animation: Central Dogma. What is the process by which DNA is used as a template for the synthesis of an RNA molecule? A)transformation B)replication C)transcription D)translation

C) transcription

A biologist draws a tree of life having only three branches. Which groups did the biologist most likely choose for her diagram? A) fungi, Eukarya, and vertebrates B)vertebrates, Bacteria, and Archaea C)Eukarya, Bacteria, and fungi D)Archaea, Bacteria, and Eukarya E)Bacteria, fungi, and Archaea

D)

Alternative splicing allows for: A)multiple genes to be used to code for a single polypeptide chain. B)increased stability of a mature mRNA. C)enhanced recognition of an mRNA by a ribosome. D)different polypeptides to be made from a single gene.

D)

Enzymes present in the lumen of the Golgi apparatus are responsible for modifying proteins and lipids. Where must these proteins have been before they entered the Golgi apparatus? A)translated on free ribosomes B)in the nucleus C)floating in the cytosol D)in the rough endoplasmic reticulum

D)

If a mutation caused the G protein to become permanently bound to GTP, what result can be predicted? A)It constantly signals its pathway to be "off." B)It is unable to separate from the beta and gamma subunits. C)It is unable to signal subsequent steps in the pathway. D)It constantly signals its pathway to be "on."

D)

In eukaryotes, the messenger RNA consists of: A) primary RNA transcript with cap added and introns removed. B)primary RNA transcript. C)primary RNA transcript with cap added. D)an RNA transcript with cap added, introns removed, and poly(A) sequence added.

D)

In response to seasonal changes in temperature, many organisms must alter the composition of their plasma membranes to maintain the proper degree of fluidity. Which change in the fatty acids of phospholipids would be most effective in maintaining membrane fluidity in a colder environment? A)an increase in phospholipid fatty acid side chain length and a decrease in side chain saturation B)an increase in phospholipid fatty acid side chain length and an increase in side chain saturation C)a decrease in phospholipid fatty acid side chain length and an increase in side chain saturation D)a decrease in phospholipid fatty acid side chain length and a decrease in side chain saturation

D)

It is actually the component of a 30S ribosomal subunit that is responsible for recognition of a Shine-Dalgarno sequence on an mRNA. Which one of the sequences in the 16S rRNA would you predict is responsible for the interaction between a small subunit and mRNA? A)3'-UAC-5' B)5'-UGGAGGA-3' C)5'-AGGAGGU-3' D)3'-UCCUCCA-5' E)5'-UCCUCCA-3'

D)

Microfilaments are composed of ____________ in ____________ arrangement. A)polymers of actin protein; a hollow tube-like B)polymers of tubulin; a double-helix C)alpha and beta dimer subunits; a double-helix D)repeating actin subunits; a thin double-helix

D)

Prokaryotes absorb their nutrients from the environment. However, many prokaryotes have cell walls. What can you conclude from this information? A)Prokaryotic cell walls do not need to allow nutrients to pass through them, because prokaryotes produce their own nutrients. B)Prokaryotes produce all their own nutrients with enzymes in the cell wall. C)Prokaryotes live in hypertonic environments. D)Cell walls are permeable, allowing nutrients to pass through.

D)

Signal amplification relies on: A) increased activity of protein phosphatases. D)a sequential increase in the different components, wherein a single, activated component can activate many copies of the next component in the pathway. B)increasing amounts of ligand as signal transduction proceeds .C)increasing numbers of cell-surface receptors as the signal is transduced.

D)

Transmembrane proteins must have:a A)signal-anchor and a nuclear localization sequence. B)only a nuclear localization sequence. C)a mitochondrial localization sequence. D)a signal sequence and a signal-anchor sequence.

D)

Which is the correct order for these steps in cell signaling? A)receptor activation, response, signal transduction B)response, signal transduction, termination C)signal transduction, receptor activation, response D)receptor activation, signal transduction, response

D)

Which of the substances would be an example of a peripheral membrane protein associated with the plasma membrane of a cell? A)MEK, an enzyme that activates other proteins in the cytoplasm B)The Epidermal Growth Factor Receptor, which binds to signals outside the cell and phosphorylates proteins in the inside of the cell C)Myc, a transcription factor that binds to DNA and activates transcription of specific genes D)Grb2, a protein that binds to the intracellular domain of the Epidermal Growth Factor Receptor when it is activated

D)

Which one of the statements about translation in eukaryotes is correct? A)Translation continues until the ribosome comes to the end of mRNA. B)There is an untranslated region only at the 3' end of mature mRNA. C)All of these choices are correct. D)An initiation complex recognizes a 5' cap structure and scans for the first AUG triplet. E)A single mRNA can possess multiple protein coding regions.

D)

In a messenger RNA, the cap is present at the: A)3' end of the poly(A) sequence. B)5' end of the poly(A) sequence. C)3' end D).5' end.

D) 5' end

Refer to Animation: Central Dogma. Key information in DNA specifies the sequence of amino acid subunits that will compose enzymes and other proteins in the cell. Before these proteins can be synthesized, however, what intermediate molecule is synthesized to carry the information coded in the DNA? A)nucleotide B)deoxyribose C)ribose D)RNA

D) RNA

Transcription continues until: A) all bases in the DNA are copied. B)a ribosome pulls RNA polymerase off the DNA C).a transcription factor signals the end of the gene D).a terminator sequence is encountered. E)a stop codon is encountered.

D) a terminator sequence is encountered

Which choice is a component of a nucleotide? A) one or more phosphate groups B)a nitrogen-containing base C)a five-carbon sugar D)All of these choices are correct.

D) all of these choices are correct

Which type of post-transcriptional modification is common in eukaryotes? A) polyadenylation B)polyadenylation and intron removal C)5' cap addition D)All of these choices are correct. E)intron removal

D) all of these choices are correct

RNA processing occurs in: A)prokaryotes only. B)both prokaryotes and viruses. C)both prokaryotes and eukaryotes. D)eukaryotes only.

D) eukaryotes only

Refer to Animation: Central Dogma. In eukaryotic cells, where does protein synthesis take place? A)in the RNA D)in the cytoplasm B)in the nucleus C)in the DNA

D) in the cytoplasm

Select the answer option that arranges the components in order from smallest to largest. A) gene, nucleotide, genome, nucleoside B)nucleoside, nucleotide, genome, gene C)nucleotide, nucleoside, gene, genome D)nucleoside, nucleotide, gene, genome E)genome, gene, nucleotide, nucleoside

D) nucleoside,nucleotide,gene,genome

Refer to Animation: Central Dogma. A cell that is deficient in ribosomes is unable to complete what process? A)replication B)transformation C)transcription D)translation

D) translation

Arrange the descriptions of the steps in RNA splicing in order from earliest to latest. Consider the steps in RNA splicing. 1. Exon ends are covalently joined together. 2. Components of the spliceosome bind conserved regions in the intron and bring them together in close proximity. 3. Acceptor splice site is cut. 4. Donor splice site is cut, and the end of the intron is joined covalently to the branch site. A)3, 4, 1, 2 B)3, 2, 4, 1 C)3, 1, 2, 4 D)2, 4, 3, 1 E)2, 3, 1, 4

D)2,4,3,1

In the experiments conducted by Avery, McCarty, and MacLeod, which hypothetical result would indicate that protein, not nucleic acid, was Griffith's transforming substance? A) Only the extracts from heat-killed cells treated with RNase are unable to transform nonvirulent bacteria into virulent bacteria. B)Only the extracts from heat-killed cells treated with protease are unable to transform nonvirulent bacteria into virulent bacteria C).All of the extracts from heat-killed cells are able to transform nonvirulent bacteria. D)None of the extracts from heat-killed cells is able to transform nonvirulent bacteria. E)Only the extracts from heat-killed cells treated with DNase are unable to transform nonvirulent bacteria into virulent bacteria.

E)

Which of the statements is true regarding glycine? A)Glycine is a large, polar amino acid. B)Glycine is similar to tyrosine in terms of structure and chemical properties. C)Glycine is an asymmetric amino acid. D)Glycine is special because it contains a -SH group important in protein folding. E)Glycine increases the flexibility of the peptide backbone.

E)

Which statement is true regarding Frederick Griffith's experiments? A)He demonstrated that proteins serve as the genetic/hereditary material. B)His experiments relied on RNase and DNase to identify the genetic/hereditary material. C)He demonstrated that DNA serves as the genetic/hereditary material. D)He demonstrated that (only) dead virulent bacteria cause pneumonia in mice. E)He demonstrated that some unknown substance can transform a nonvirulent strain of bacteria to a virulent one. Griffith didn't use any techniques that would allow him to identify which molecule(s) carried information that cause virulence.

E)

In a nucleotide, the phosphate is attached to the sugar at the: A) 3′ and 5′ carbons. B)1′ C)carbon.to the nitrogen of the bigger ring of each base. D)3′ carbon. E)5′ carbon.

E) 5' Carbon

In eukaryotes, which component is specific to the synthesis of only one type of protein? A)an elongation factor B)a transfer RNA C)a ribosome D)an aminoacyl tRNA synthetase E)a messenger RNA

E) a messenger RNA

Which statement is true regarding the development of pyrimethamine resistance in malaria parasites? A)Rare mutations in the target protein increased the level of resistance. B)Eventually, the drug pyrimethamine became ineffective against malaria. C)In time, multiple different mutations were brought together to increase the level of resistance. D)Continued use of pyrimethamine treatment caused these mutations to increase in frequency. E)All of these choices are correct.

E) all of these choices are correct

Structurally and functionally related groups of proteins are referred to as: A)relatives. B)realms. C)tribes. D)domains. E)families.

E) families

A consecutive sequence of codons following a start codon is called a: A)template strand. B)gene. C)genetic code. D)peptide. E)reading frame.

E) reading frame

A cell that responds to an environmental condition by the release of a chemical is an example of which element of cellular communication? a responding cell a signaling cell a receptor protein

a signaling cell

Microtubules increase in length: All of these choices are correct. more quickly at one end than the other. in cycles, following rapid depolymerization. by adding tubulin dimers to the ends. by lengthening outward from the centrosome.

all of these are correct

Intermediate filaments: All of these choices are correct. undergo little change in length in comparison to microtubules and microfilaments. play an important role in preventing skin from tearing by shear stress. have a diameter that is larger than a microfilament, but smaller than a microtubule. play an important role in maintaining cell shape.

all of these choices are correct

Second messengers: amplify the effects of the signal .play a role in activation of intracellular signal transduction. are small intracellular molecules that participate in signal transduction. are removed in order to terminate a cellular signaling response. All of these choices are correct.

all of these choices are correct

The genome of viruses consists of: single-stranded DNA. All of these choices are correct .single-stranded RNA .double-stranded RNA. double-stranded DNA.

all of these choices are correct

Which types of cell junctions are found in skin? adherens junctions desmosomes hemidesmosomes All of these choices are correct. tight junctions

all of these choices are correct

Viruses that invade bacteria are called: prokaryphages. mosaicphages. adenoviruses .bacteriophages. macrophages.

bacteriophages

Which of the statements is true regarding a basic amino acid? A)All of these choices are correct. B)The hydrophilic R group of a basic amino acid will be located in the interior of a protein. C)The positively charged R group of a basic amino acid could bind DNA. D)A basic amino acid would be considered both polar and hydrophobic. E)The R group of a basic amino acid would only be able to form covalent bonds with other molecules.

c)

A virus is surrounded by a protein coat known as a(n): reverse transcriptase. capsid. protease .integrase. surface protein.

capsid

Cadherins are: proteins involved in attachment of cells to the basal lamina. proteins that provide a pathway for molecules to move between cells. cell adhesion molecules found in cell junctions.

cell adhesion molecules found in cell junctions

Which of the following is a pigment associated with chloroplasts that plays a role in energy harvesting? thylakoid ATP chlorophyll fibril melanin

chlorophyll

An amphipathic molecule is one that:

contains both polar and nonpolar regions

Which structures are linked to intermediate filaments of the cytoskeleton? adherens junctions tight junctions desmosomes gap junctions

desmosomes

The random movement of molecules within a solution down its concentration gradient is referred to as: transport. osmosis. diffusion.

diffusion

The random movement of molecules within a solution is referred to as:

diffusion

A cell can only respond to signals from other cells, not from the physical environment. true or false

false

Muscle cells make different proteins than nerve cells because they have different sequences of DNA. true or false

false

Protein families contain proteins with identical primary, secondary, and tertiary structures. T or F?

false

A lariat is composed of exons and does not contain any intron sequences. false its is composed of introns and does not contain any exons true

false it is composed of introns and does not contain any exons

Which type of cellular junction permits the movement of substances from the cytoplasm of one cell to the cytoplasm of an adjacent cell? adherens junctions desmosomes gap junctions tight junctions

gap junctions

All cells have: a cell wall. a nucleus. genetic information. internal compartments.

genetic info

The interior region of a phospholipid bilayer is characterized as: A) hydrophilic B) hydrophobic

hydrophobic

The plus ends of both microtubules and microfilaments differentiate from the minus ends: in that new tubulin or actin subunits are added more quickly .in that new tubulin or actin subunits are added rather than removed. in that the end that always grows in the direction the cell is moving.

in that new tublin or actin subunits are added more quickly

A virus with a narrow host range: All of these choices are correct .infects plants and bacteria but not animals .infects cells of only a few species .is usually highly virulent.is likely a retrovirus.

infects cells of only a few species

Some diseases, such as Tay-Sachs, are caused by defects in the breakdown of cellular components. Which organelle could be defective with such a disease? endoplasmic reticulum lysosome ribosome plasma membrane Golgi apparatus

lysosome

A cell has a mutation that prevents it from breaking down unwanted proteins present in vesicles. Which cellular structure is most likely to be disrupted by this mutation? the cytoskeleton lysosomes the Golgi apparatus the endoplasmic reticulum

lysosomes

Microfilaments help a cell ____________________ strengthen the plasma membrane .separate chromosomes during anaphase of mitosis. maintain its size and shape.

maintain its size and shape

Contraction of muscles is an example of how the motor protein _______ interacts with the cytoskeletal elements called _____________ to produce movement. A) myosin; actin filaments B) myosis; actin filaments

myosin; actin filaments

A receptor that is inside the cell would require a __________ signal molecule that can ____________________ the plasma membrane. nonpolar; pass through polar; bind to polar; pass through

nonpolar;pass through

The genetic material of a prokaryotic cell is located in its: nucleosome. nucleolus. nucleoid. nucleus.

nucleoid

G protein-coupled receptors are found: on the nuclear membrane. inside the nucleus .in the cytoplasm. on the cell surface.

on the cell surface

A cell's plasma membrane contributes to homeostasis by:

passive transport

Signal molecules that are _______ usually have their corresponding receptor ______________ of the cell. polar; in the cytoplasm polar; on the surface nonpolar; on the surface

polar; on the surface

What type of molecule is sometimes found spanning a cell's plasma membrane with part of the molecule on one side of the membrane, part embedded in the membrane, and part on the other side? phospholipid protein

protein

A _________ expresses a gene or genes that direct production of the signaling molecule, and the _______________ expresses a gene or genes that direct production of the _________________. responding cell; signaling cell; receptor protein responding cell; receptor protein; signal protein signaling cell; responding cell; receptor protein

signaling cell; responding cell; receptor protein

When cells communicate by the signaling process, one cell produces a _________________ that must be received by the ___________ on or in the responding cell. cell division signal;plasma membrane signaling particle; signal enzyme signaling molecule; signal receptor

signaling molecule; signal receptor

Animation Assessment motor proteins study

study

What is glycosylation?

the addition of sugars to lipids or proteins

One example of a cellular response to a signal is the triggering of cell division. If a mutation occurred in the gene for the signal receptor in this pathway that caused the receptor to reject binding of the signal, what response can be predicted? The cell divides repeatedly without the signal. The cell does not divide. The signal is not produced.

the cell does not divide

What determines the specificity of a receptor protein? the cytoplasmic domain the ligand-binding site the extracellular domain the transmembrane domain

the ligand binding site

Which best describes a role that microfilaments play in the structure and function of red blood cells? They provide a track for directing O2 to the proper cellular locations. They anchor and orient the O2-bearing hemoglobin protein molecules. They maintain the biconcave shape to maximize gas exchange.

they maintain the biocave shape to maximize gas exchange

How do cells connect to the extracellular matrix? through tight junctions through integrins through cadherins through gap junctions

through integrins

Which type of cellular junction prevents the passage of substances through the space between cells? gap junctions adherens junctions desmosomes tight junctions

tight junctions

Refer to Animation: Horizontal Gene Transfer. Genetic engineers sometimes insert genes of interest into a viral genome in order to get the gene into a target bacterium like E. coli so that it can be expressed. What natural process are they exploiting to achieve this genetic engineering? conjugation transformation mutation transduction

transduction

_____ is a type of horizontal gene transfer where genetic information is transferred from one bacterium to another by a virus. Conduction Transformation Transferation Conjugation Transduction

transduction

A cooperative effect can occur in some types of multi-subunit proteins, leading to improved function of the subunits when bound to each other. true false?

true

A lariat is a loop and tail of RNA formed during RNA splicing. false true

true

In eukaryotes, transcription is located in the nucleus, and translation takes place in the cytoplasm. false true Prokaryotes do not have a nuclear envelope while in eukaryotes transcription takes place in the nucleus, and translation in the cytoplasm

true

In the sequence 5'-AGGCCT-3', an available phosphate group would be found at the nucleotide labeled "A." true A DNA strand has polarity: free phosphate group is located at 5' end. false

true

Members of a protein family often contain the same folding domain. true or false?

true

Prokaryotes contain nucleoids, which are similar to nuclei in that nucleoids contain the prokaryotic chromosomes.

true

Some RNA molecules possess catalytic activity. true false

true

The energy to carry out the movement of a ribosome comes from ATP. true or false?

true

The frequency of mutations does not necessarily decrease or increase over time. true false?

true

True or False. All Polypeptides have tertiary structure.

true

A small infectious agent that contains a nucleic acid genome packaged inside a protein coat is called a(n): virus. archaeon. tRNA. bacterium.

virus

Turgor pressure is the result of: the rigidity of the plasma membrane. the activity of the contractile vacuole .water accumulation within a cell. All of these choices are correct.

water accumulation within a cell