Cell Biology Final Exam Part Two
nucleus
DAPI (4',6-diamidino-2-phenylindole) is a chemical compound that emits blue fluorescence. it is used extensively in fluorescence microscopy to identify
RNA
DNA is an information storage molecule, whose sequences serve as a template to make
each daughter DNA molecule consists of one strand form the parent DNA molecule and one new strand
DNA replication is considered semiconservative because
all of the above
HeLa cells are tumor cells derived from cervical cancer tissue and used in medical research. they have been cultured for numerous generations since their isolation in 1952, therefore HeLa cells are immortalized are a line cell all of the above are transformed
it is single-stranded and can fold up into a variety of structures
RNA in cells differs from DNA in that
3'-->5' along the template strand
RNA polymerase moves in which direction along the DNA?
RNA splicing
Ribozymes are known to catalyze which of the following reactions in cells?
Introns; pre-mRNA
_____ are parts of ____ molecules that do not contain information about a protein's primary structure
stroma of the chloroplast
_____ is the location where the Calvin cycle takes place
the unique microenvironments
______ are responsible for specific functions of proteins
short sequence of amino acids in a newly synthesized protein that directs the protein to its proper cellular destination
a "signal peptide" is a
Ras
a GTP-binding protein involved in mitosis
separate different types of cells
a fluorescence-activated cell sorted (FACS) is most useful to
all of the above
a functional protein is made of 1 peptide, therefore, it has primary structure secondary structure tertiary structure all of the above
stop codon
a gene typically includes following elements except promoter coding region terminator stop codon
on the inside of the folded chain, away from water
a hydrophobic amino acid R group (side chain) would be found where in a protein?
it could be a small bacterium
a mycoplasma is an organism with a diameter between 0.1 and 1.9 um. what does its size tell you about how it might be classified?
the neuron expresses some mRNAs that the white blood cell does not
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
is the most basic structural unit of chromatin
a nucleosome
3' UCA 5'
a particular triplet of bases in the template strand of DNA is 5' AGT 3'. the corresponding codon for the mRNA transcribed is
a protein that causes termination of translation
a release factor is
carbon, hydrogen, nitrogen, oxygen
about 25 of the 92 natural elements are known to be essential to life. which four of these 25 elements make up approximately 96% of living matter?
protein
according to the fluid mosaic model of cell membranes, which types of molecule spans the membrane, from its inner to outer surface?
embedded in a lipid bilayer
according to the fluid mosaic model of membrane structure, proteins of the membrane are mostly
attachment of amino acids to tRNAs
accuracy in the translation of mRNA into the primary structure of a polypeptide depends on specificity in the
proofreading ability of tRNA synthetase
accuracy in the translation of mRNA into the structure of a polypeptide depends on specificity in the
the accumulation of lactic acid
after intense exercise, your muscles feel sore because of _____ when O2 is insufficient
conformational change
all carrier proteins on the membrane critically depend on which of the following for their function? covalent binding with their ligans concentration gradient conformational change supply of ATP
centrosome
all of the following are different parts of a eukaryotic chromosome, except centromere telomere centrosome chromatid
they exhibit polarity after assembly from subunits
all of the following statements describe intermediate filaments except the subunits are rod-like they exist in various forms and expressed in different cells they are relatively stable compared with MT and AF, but they are also dynamic they exhibit polarity after assembly from subunits
removes introns and rejoins exons in different combinations to create mRNAs with different function
alternative RNA splicing
lysozyme
an enzyme that hydrolyzes polysaccharides in the bacterial wall and causes lysis of bacteria
is exocytic if it is traveling toward the plasma membrane
an individual transport vesicle derived from Golgi
the formation of H+ gradient
assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. this damage will have the most direct effect on which of the following processes?
transferring electrons from one atom to the other
atoms for ionic bonds with each other by
tissue formation
brewer's yeast, apart from being an irreplaceable asset in the brewery and in the bakery, is an experimental organism used to study eukaryotic cells. however, it does have some limitation. select all the processes below that cannot be studied in yeast. tissue formation motility ATP formation cell division
ATP
carries and transfers energy; a precursor of RNA; participates in many biochemical reactions
polymerases
catalyze polymerization reactions such as the synthesis of DNA and RNA
protein phophatases
catalyze the removal of a phosphate group from a protein
hypertonic to fresh water but hypotonic to the salt solution
celery stalks that are immersed in fresh water for several hours become stiff and hard. similar stalks left in a salt solution become limp and soft. from this we can deduce that the cells of the celery stalks are
interactions with other cell types as in a whole organism are lost
cell culture is in vitro study because
the bleached molecules would diffuse laterally though the membrane and intermix with unbleached molecules
cell surface molecules are labeled with a fluorescent tag and then a portion of them are bleached with a laser beam. what would one observe after the cell is incubated for a few minutes?
ER --> Golgi --> Vesicles --> plasma membrane
cells of the pancreas will incorporate radioactively labeled amino acids into proteins. this "tagging" of newly synthesized insulin molecules enables a researcher to track their location. in this case, we are tracking insulins secreted by pancratic cells. what is its most likely pathway? ER --> lysosomes --> vesicles that fuse with plasma membrane --> blood golgi --> ER --> lysosome --> blood nucleus --> ER --> golgi --> blood ER --> golgi --> vesicles --> plasma membrane
Na+
cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. which of the following ions is the most abundant outside a typical mammalian cell? Ca2+ Cl- K+ Na+
charge
centrifugation is a laboratory technique to separate organelles of the cell based on the following properties except: density charge shape size
conformational change/allosteric reaction
change affinity between the enzyme and its substrate- this is the most common and rapid regulatory mechanism, known as
amphipathic
cholesterol is an essential component of biological membranes. although it is much smaller than the typical phospholipids and glycolipids in the membrane, it is a/an _____ molecule
in the interior of the membrane
consider the currently accepted fluid mosaic model of the plasma membrane. where in the plasma membrane would cholesterol most likely be found?
retained in the pyruvate
during glycolysis, when glucose is catabolized to pyruvate, most of the energy of glucose is
activation of a protein kinase
during mitosis, nuclear lamin disassembly is triggered by
the splitting of water
during photosynthesis, oxygen is released during
are motor proteins that are involved in vesicular transport
dynein and kinesin
primary cells
endothelial cells isolated from normal umbilical cords have limited life span in culture. they are
phagocytosis
engulfing of bacteria by white blood cells is known as
protein catalysts
enzymes are highly specific
facilitated diffusion
following a meal, glucose must move from the gut lumen where there is a high glucose concentration into the intestinal cell where there is a relatively low level of glucose. this movement is called
the stroma to the thylakoid space
for chemiosmosis to take place, protons are translocated from the matrix into the intermembrane space in mitochondria, whereas in chloroplasts protons are translocated protons from
the small subunit of ribosome is assembled at the start codon AUG of mRNA with the initiator tRNA, Met-tRNA
from the following list, which is the first event in translation in eukaryotes? the small subunit of ribosome is assembled at the start codon AUG of mRNA with the initiator tRNA, Met-tRNA the larger ribosomal subunit binds to smaller ribosomal subunits base pairing of activated methionine-tRNA to AUG of the messenger RNA covalent bonding between the first two amino acids
a nuclear localization signal
gated transport of a protein from the cytosol to the nucleus requires
transcription
gene expression is primarily regulated at the level of
highly specific for their ligands (substrates); highly efficient; speed up reactions without being consumed; several enzymes can form a complex to speed up a series of reactions in a metabolic pathway; the activities of enzymes are highly regulated
general properties of enzymes
introns 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?
carbohydrates
glucose, starch, cellulose, and glycogen are classified as
no oxygen is required
glycolysis is an anaerobic process used to catabolize glucose. what does it mean for this process to be anaerobic?
ER
glycosylation of a protein, a mechanism of post-translational modification, occurs in
attach it to another cellular protein as a fluorescence marker, enabling scientists to localize the protein in the cell
green fluorescent protein (GFP) is a protein in the jellyfish Aequorea Victoria that exhibits green fluorescence when exposed to light. biologists often use GFP for which of the following: transform cells from other organisms to jellyfish produce antibodies with green fluorescent protein attach it to another cellular protein as a fluorescence marker, enabling scientists to localize the protein in the cell study photosynthesis
none of the above
how is the head and the tail part within a phospholipid molecule held together? none of the above non-covalent interaction ionic interaction hydrophobic interaction
to provide electrons
how is water used in photosynthesis?
ATPases
hydrolyze ATP
nucleases
hydrolyze nucleic acids
proteases
hydrolyze proteins
950 bp
if a gene produces a pre-RNA that is 1200 base pairs (bp) long and has the following intron-exon structure: exon 1 (200 bp); intron 1 (100 bp); exon 2 (50 bp); intron 2 (150 bp); exon 3 (700 bp). how many base pairs long would we expect the mRNA to be?
the two DNA strands run antiparallel
in a DNA double helix,
inner mitochondrial membrane
in a plant cell, where are the ATP synthase complexes located?
serum
in cell culture, the growth factors and hormones essential for cell growth are provided by
RNA polymerase II
in eukaryotes there are several different types of RNA polymerase. which type is involved in transcription of mRNA for a globin protein?
all of the choices are correct
in eukaryotic cells, internal membranes all of the choices are correct provide additional area where many metabolic processes occur form membranous compartments called organelles contain proteins essential for the function of different organelles
oxidative phosphorylation in cellular respiration
in mechanism, phosphorylation is most similar to
the stroma to the thylakoid space
in mitochondria, chemiosmosis translocated protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis translocates protons from
it can accommodate more ATP synthases
in muscle cells, the inner mitochondrial membranes are about 5 X the area of the outer mitochondrial membranes, and about 17 X that of the cell's plasma membrane. what purpose must this serve?
transmission electron microscopy
in order to visualize the fine structure of viruses and cytoskeletal filaments at 10-25 nanometers in diameter the type of microscopy that would be ideal is
as soon as transcription has begun
in prokaryotic cells, translation begins
certain proteins are unique to each membrane
in what way do the membranes of a eukaryotic cell vary?
their filamentous subunits form coiled-coils
intermediate filaments are relatively stable structures because
their presence allows exons to be alternatively spliced
introns are significant to biological evolution because
selectively allow passage of certain ions
ion channels
proteins located on the surface of the cell membrane that are covalently attached to the membrane lipids
lipid-anchored proteins (also known as lipid-linked proteins) are
Gene expression; cellular localization; degradation by proteases; conformational change
mechanisms in the cell that regulate enzyme activity
a-tubulin/b-tubulin heterodimers
microtubules are made from
chromatin remodeling
modifications of a histone that cause the interaction with the DNA to change in chromatin. what is this event called?
microtubules
movement of neurotransmitters in an axon of the neuron are mediated through _____ that serve as cytoskeletal tracks
you forgot to add penicillin and streptomycin to your media
one of your dishes of mammalian cells has bacterial contamination? what is the most likely reason?
diffusion
osmosis is a special case of
is a spontaneous process that does not need input of energy
passive diffusion is the process by which molecules move from an area of low concentration to an area of high concentration is a spontaneous process that does not need input of energy will only occur in a lipid bilayer, but not in cell membrane requires the presence of a transmembrane protein
actinfilaments
phalloidin belongs to a class of toxins called phallotoxins, which are found in the death cap mushroom. it is a rigid bicylic heptapeptide that is lethal after a few days when injected into the bloodstream. phalloidin containing fluorescent tags are used widely in microscopy to visualize
are synthesized from monomers by dehydration reactions
polysaccharides, lipids, and proteins are similar in that they
highly efficient under the physiological conditions; highly specific; speed up reactions by lowering activation energy
properties of enzymes
covalent modification
protein phosphorylation is the most important and best studied example of what?
antibodies
proteins that bind very tightly to their targets; they are produced in vertebrates as a defense against infection
active transport
pumps are transporters that are able to harness energy provided by other components in the cells to drive the movement of solutes across membranes, against their concentration gradient. this type of transport is called
needs chaperones
regarding the import of an RNA polymerase into the nucleus, which of the following statements is not true? requires a nuclear-localization signal sequence in the protein to be imported the signal sequence can be anywhere in the protein needs chaperones the protein to be transported is synthesized in the cytosol
high levels of unsaturated fatty acyl tails within the lipid bilayer
scientists unearth a wooly mammoth from the siberian ice sheath and discover that a eukaryotic "amoeba"-like cell is still alive. which component of the cell membrane might contribute to maintaining the fluidity of plasma membranes under freezing conditions? high levels of unsaturated fatty acyl tails within the lipid bilayer absence of cholesterol high levels of long fatty acyl tails within the lipid bilayer high levels of saturated fatty acyl tails within the lipid bilayer
secondary active transport
sodium concentrations are higher outside and glucose concentrations are higher inside the cell. using the same membrane protein for Na+ and glucose transport, what is it called when a Na+ electrochemical gradient is used to drive glucose transport into the cell against its concentration gradient?
phosphorylation, acetylation, ubiquitination
some known modifications of proteins
keratins
some rare human genetic diseases are caused by mutations in genes that disrupt intermediate filaments. for example, the skin of people with epidermolysis bullosa simplex is very susceptible to mechanical injury; people with this disorder have mutations in the genes that encode
microtubules
spindle fibers are made of
stretches of hydrophobic amino acids
stop-transfer sequence is sequence of ____ that cause transport of a protein to stop, leaving the protein embedded in the membrane
nucleolus
synthesis of pre-tRNA occurs in the
translocators
targeting proteins to chloroplasts is through
substrate-level phosphorylation
the ATP made during glycolysis is generated by
ratio of A+T to G+C
the DNA from two different species can often be distinguished by a difference in the
manufacturing
the ER can be considered to be in which general category of organelles? breakdown energy-processing manufacturing communication between cells
the pump is phosphorylated
the Na+-K+ATPase is also known as the Na+-K+ pump. it is responsible for maintaining the high extracellular sodium ion concentration and the high intracellular potassium ion concentration. what happens immediately after the pump hydrolyzes ATP?
acts to position RNA polymerase for transcription initiation
the TATA box
is a transcription factor that binds specifically to the promoter region
the TATA-binding protein
GTP-binding proteins
the activity is determined by the association with GTP or GDP
to do all of the above
the cell has highly regulated mechanisms to control gene expression. a reason for gene regulation is to do all of the above to make proteins at specific stages of development to respond to environmental changes to make proteins in specific cell types
genome
the complete set of information in an organism's DNA is called its
all of the above
the destination of proteins synthesized on the free ribosomes in the cytosol could be the cytosol mitochondria peroxisome all of the aobve
expression of specific genes
the distinct characteristics of different cell types in a multicellular organism are produced mainly be the differential regulation of the
transcription of genes transcribed by RNA polymerase II
the distinct characteristics of different cell types in a multicellular organism result mainly from the differential regulation of the
feedback inhibition
the end product of a biosynthetic pathway inhibits the first enzyme of that pathway to avoid unnecessary accumulation
RNA polymerase
the enzyme catalyzing RNA transcription is
keeping proteins targeted to mitochondria at the unfolded state
the function of chaperone proteins during protein targeting is
all of the above
the functions of the plasma membrane include all of the above cell-cell communication intercellular joining membrane transport
a carbohydrate coat covering the cell
the glycocalyx is
energy can be harvested in a stepwise manner to make ATP
the high efficiency of cell to harvest energy from glucose during cellular respiration compared with its combustion to CO2 and H2O in a single step is due to
results in depolymerization of microtubules
the hydrolysis of GTP carried out by tubulin molecules
400x
the magnification of a specimen viewed with a 10x eyepiece and 40x objective lens is
y-tubulin
the major component of centrioles is
chemiosmosis
the mechanism by which both cellular respiration and photosynthesis harvests the most chemical energy is
presence of a nucleus
the most reliable feature distinguishing a eukaryotic cell from a prokaryotic cell is the
symporter
the movement of sucrose and H+ into the cell by the same membrane protein reflects the actions of what type of transporter?
decrease in gene expression
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?
the free amine group (-NH2) located at the end of a polypeptie
the n-terminus (the amino terminus) is the start of a protein or polypeptide referring to
accepting electrons at the end of the electron transport chain
the oxygen consumed during cellular respiration is involved directly in which process or event?
is used to generate sodium and potassium gradients across the membrane
the plasma membrane Na+/K+-ATPase pump
active (catalytic) site
the region of the enzyme that recognizes the substrate and catalyzes the reaction; determines the specific interaction between the enzyme and the substrate
genetic
the relationship between the nucleic acid sequence over a stretch of DNA and the order of amino acids in the resulting protein is referred to as the ______ code.
hydrolysis
the reverse reaction of condensation; adding H2O to the covalent bond between two adjacent sugar groups in polysaccharide chains and causing the bond to break
the enzyme that catalyzes peptide bond formation is a ribosomal RNA
the ribosome is important for catalyzing the formation of peptide bonds. which of the following statements is true? the enzyme that catalyzes peptide bond formation is a ribosomal RNA the large subunit of the ribosome is permanently attached to the mRNA the large and small subunits of the ribosome are preassembled before translation starts once the large and small subunits of the ribosome are assembled, they will not separate from each other until degraded by the proteasome
regulated exocytosis
the secretion of hormones, like insulin, out of a cell upon stimulation can be considered an example of
is a subunit of RNA polymerase that specifically binds to the promotor and initiates transcription
the sigma factor in bacterial RNA polymerase
recognizes promoter sites in the DNA
the sigma subunit of bacterial RNA polymerase
the minimal distance of two points can be distinguished
the term "resolution" describing a microscope refers to which of the following? the contrast of the image the times an object enlarged the increase in the size of an object the minimal distance of two points can be distinguished
sequence
the variations in the physical characteristics between different proteins are influenced by the overall amino acid compositions, but even more important is the unique amino acid
the rules for base pairing between the third base of a codon and tRNA are flexible
there are 61 mRNA codons that specify amino acids, but only 45 tRNAs. this is best explained by the fact that
the third base of the codon is a wobble position
there are 61 mRNA codons that specify an amino acid, but only 45 tRNAs. this is best explained by the fact that
fluorescence microscopy
to localize an ion channel protein in the cell membrane, you would use
mRNA
total nucleic acids are extracted from a culture of yeast cells and are then mixed with resin beads to which the polynucleotide 5'-TTTTTTTTTTTTTTTTTTTTTTTTT-3' has been covalently attached. after a short incubation, the beads are then extracted from the mixture. when you analyze the cellular nucleic acids that have stuck to the beads, which of the following is most abundant? tRNA DNA mRNA rRNA
transcription factors
transcription in eukaryotes requires which of the following in addition to RNA polymerase? start codon the protein product of the promotor sigma factor transcription factors
transcription factors
transcription in eukaryotes requires which of the following in addition to RNA polymerase? the protein product of the promoter start and stop codons ribosomes and tRNA transcription factors
both follow base-pair rules during synthesis
transcription is similar to DNA replication in that
coupling glucose transport to Na+ movement
transepithelial glucose transport uses a symport to transport glucose up a concentration gradient by
transmission electron microscopy shows two-dimensional ultrastructure, while the scanning electron microscopy shows the three-dimensional structure
transmission and scanning electron microscopy differ mainly because
specific binding with the substance to be transported
transporters, in contrast to channels, work by
49
upon chemical analysis, a particular polypeptide was found to contain 50 amino acids. how many peptide bonds are present in this protein?
RNA allow for the formation of polyribosomes, increasing the efficiency of protein synthesis
using RNA as a template for protein synthesis instead of translating proteins directly from the DNA is advantageous for the cell because
RNA can be modified in multiple ways for the regulation of gene expression
using RNA as a template for protein synthesis instead of translating proteins directly from the DNA is advantageous for the cell because
presence of aquaporin channels for facilitated diffusion of water
water diffuses through certain organs such as the kidneys and bladder must faster than would occur by passive diffusion through a lipid bilayer alone. what accounts for this more rapid rate of water transport in these organs?
groups of ribosomes reading a single mRNA simultaneously
what are polyribosomes?
clusters of ribosomes linked together by a mRNA molecule that are engaged in protein synthesis
what are polysomes?
exons
what are the coding segments of a stretch of eukaryotic DNA called?
the nucleotide sequence of the template strand
what determines the nucleotide sequence of the newly synthesized RNA?
cell division stops
what happens when taxol is added to a eukaryotic cell?
an RNA with enzymatic activity
what is a ribozyme?
it is the movement of lipids and integral proteins within the lipid bilayer
what is meant by the term "fluid mosaic model"?
hydrolysis
what is the chemical reaction by which cells break down biopolymers to monomers?
absorb photons and transfer light energy to chemical energy
what is the main role of the pigment molecules within the photosystem in chloroplasts?
it allows cellular components, such as organelles, to be studied in isolation
what is the purpose for the use of cell fractionation in cell biology?
recruit RNA polymerase and transcription factors to DNA
what is the role of the promoter region in the regulation of gene expression?
46
what is the total number of chromosomes found in each of the somatic cells in your body?
all of the above
what of the following statements below characterizes the three cytoskeletal filaments? polymer of protein subunits all haver quaternary level of protein structure subunits are connected to one another by weak, noncovalent bonds all of the above
hydrogen bond
what type of chemical bond is commonly used to connect two water molecules, to form base pairs in DNA double helix, and to stabilize alpha-helix in a protein?
phospholipids
what type of lipids are found in all biological membranes?
proteins
what type of macromolecule helps package DNA in eukaryotic chromosomes?
reduced
when a molecule of FAD gains an electron the molecule becomes
as soon as transcription has begun
when does translation begin in prokaryotic cells?
on both thylakoid membrane of chloroplasts and inner membrane of mitochondira
where are the molecules of the electron transport chain found in plant cells?
saliva, tears, and other secretions
where is lysozyme found?
all integral membrane proteins contain hydrophobic regions
which is a property of integral membrane proteins? all integral membrane proteins contain carbohydrate groups within the membrane all integral membrane proteins span the entire membrane all integral membrane proteins contain hydrophobic regions all integral membrane proteins transport non-polar molecules through the membrane
cotranslational translocation
which mechanism is used for proteins targeted to the endoplasmic reticulum (ER) are transported across the membrane after their synthesis is complete are synthesized on free ribosomes in the cytosol cotranslational translocation cross the membrane in a folded state
transmembrane proteins
which membrane component is most important for allowing large, charged molecules to pass through the membrane?
5'-AAGCGTT-3'
which of the following DNA strands can form a DNA duplex by pairing with itself at each position? 5'-AAGCCGAA-3' 5'-AAGCGCAA-3' 5'-AAGCCGTT-3' 5'-AAGCGCTT-3'
small RNA
which of the following RNA serves the regulatory functions including splicing and gene expression? mRNA rRNA tRNA small RNA
serine
which of the following amino acids has a side chain that can be phosphorylated? aspartate serine cysteine methionine
all of the above
which of the following are noncovalent interactions? hydrophobic interaction ionic bonds Van der Waals interactions all of the above
ATP and NADPH
which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
an aquaporin
which of the following channels would not be expected to generate a change in voltage by movement of its substrate across the membrane where it is found? a proton channel an aquaporin a sodium channel a calcium channel
six-carbon sugar
which of the following chemical groups is NOT used to construct a DNA molecule? phosphate six-carbon sugar nitrogen-containing base five-carbon sugar
the ribosome binds to the mRNA
which of the following does not occur before a eukaryotic mRNA is exported from the nucleus? the mRNA is polyadenylated at its 3' end RNA splicing a guanine nucleotide with a methyl group is added to the 5' end of the mRNA the ribosome binds to the mRNA
the action of protein that blocks TATA box binding protein function
which of the following examples does not describe a mechanism of post-transcriptional control of gene expression? translational inhibition of an mRNA by the binding of a protein to the ribosome the activation of a protein when it is phosphorylated by a protein kinase the action of protein that blocks TATA box binding protein function the alternative splicing of a gene, leading to the production of a muscle-specific protein
selective permeability
which of the following functions of the plasma membrane is possible without membrane proteins? cellular movement import/export of ions selective permeability intercellular communication
nucleosomes
which of the following has beads on a string structure? telomeres chromatids chromosomes nucleosomes
5' cap and poly (A) tail
which of the following help(s) to stabilize mRNA by inhibiting its degradation? exons ribozymes 5' cap and poly (A) tail introns
it exhibits a specificity for a particular type of molecule
which of the following is a characteristic feature of a carrier protein in a plasma membrane? it is a peripheral membrane protein it exhibits a specificity for a particular type of molecule it works against diffusion it requires the expenditure of cellular energy to function
peptidyltransferase
which of the following is a ribozyme? tRNA synthetase peptidyltransferase RNA polymerase sigma factor
chemiosmosis
which of the following is common to both cellular respiration and photosynthesis? glycolysis the Calvin cycle NADPH oxidation chemiosmosis
consume H2O molecules
which of the following is false of condensation reactions? produce many biological polymers from monomers consume H2O molecules are the opposite of hydrolysis reactions are usually catalyzed in cells by enzymes
oxidative phosphorylation
which of the following is likely to stop working when O2 is not present in plant cells?
the membrane reseals
which of the following is most likely to occur after the lipid bilayer is pierced? a hole is formed the membrane expands the membrane collapses the membrane reseals
sulfhydryl
which of the following is not a common chemical group commonly found on histones for chromatin regulation? phosphoryl methyl sulfhydryl acetyl
vitamin c
which of the following is not a macromolecule? vitamin C starch cellulose hemoglobin
starch
which of the following is not the part of culture medium for animal culture? glucose starch vitamins inorganic salts
ribosome
which of the following is present in a prokaryotic cell? mitochondrion ribosome nuclear envelope chloroplas
fluorescence microscopy
which of the following is the best choice to localize a histone protein in the nucleus with its antibody? bright-field microscopy fluorescence microscopy phase contrast microscopy scanning electron microscopy
transmission electron microscopy
which of the following is the best choice to study the detailed internal structures of nucleolus? bright-field microscopy scanning electron microscopy transmission electron microscopy phase contract microscopy
primary structure
which of the following levels of structure in a protein would not be disrupted by chemicals that break hydrogen bonds? secondary structure tertiary structure primary structure quaternary structure
cholesterol
which of the following membrane lipids does not contain a fatty acid tail? phosphatidylserine glycolipid phospholipid cholesterol
all of the above
which of the following methods are used by cells to regulate the activity of amount of a protein in the cell? alternative splicing protein phosphorylation/dephosphorylation translocation by polysomes all of the above
different copies DNA can be replicated according to different physiological processes
which of the following methods is not used by cells to regulate the amount of a protein in the cell? genes can be transcribed into mRNA with different efficiencies different copies DNA can be replicated according to different physiological processes proteins can be regulation by post translational modification alternative splicing
nuclear pore complexes can regulate the speed at which newly synthesized proteins are exported from the nucleus into the cytoplasm
which of the following methods is not used by cells to regulate the amount of a protein in the cell? many ribosomes can bind to a single mRNA molecule genes can be transcribed into mRNA with different efficiencies proteins can be tagged with ubiquitin, marking them for degradation nuclear pore complexes can regulate the speed at which newly synthesized proteins are exported from the nucleus into the cytoplasm
a mutation that introduced extensive sequence changes into the DNA that precedes the gene's transcription start site
which of the following might decrease the transcription of only one specific gene in a bacterial cell? a mutation that introduced a stop codon into the DNA that precedes the gene's coding sequence a decrease in the amount of RNA polymerase a mutation that introduced extensive changes into the DNA that precedes the gene's transcription start site a decrease in the amount of sigma factor
5′-CCCUAAAAAAAAAAAAAAAAUUUUUUUUUUUUUUUUAGGG-3′
which of the following molecules of RNA would you predict to be the most likely to fold into a specific structure as a result of intramolecular base-pairing? 5′-GGAAAAGGAGAUGGGCAAGGGGAAAAGGAGAUGGGCAAGG-3′ 5′-CCCUAAAAAAAAAAAAAAAAUUUUUUUUUUUUUUUUAGGG-3′ 5′-AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA-3′ 5′-UGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUGUG-3′
e. coli
which of the following organisms was the simplest and the key model organism for the advancement of molecular biology (understanding DNA replication, decoding the DNA to make proteins, etc.)? e. coli fruit fly yeast c. elegans
passive transport
which of the following processes includes all others? transport of an ion down its electrochemical gradient facilitated diffusion passive transport osmosis
oxidative phosphorylation
which of the following stages in the breakdown of the piece of toast you had for breakfast generates the most ATP?
destroys double-stranded viral RNA as a cellular defense system
which of the following statements about RNAi is true? is an essential component for splicing is an essential component for protein synthesis destroys double-stranded viral RNA as a cellular defense system destroys mRNA that have no poly A tails
all amino acids contain an NH2 and a COOH group
which of the following statements about amino acids is true? twenty-two amino acids are commonly found in each protein almost all the amino acids used in protein biosynthesis have charged side chains amino acids are often linked together to form branched polymers all amino acids contain an NH2 and COOH group
no signal sequence is needed since the nuclear pore is large enough
which of the following statements about import of a protein into the nucleus is not true? requires a nuclear-localization signal sequence the signal sequence can be anywhere in the protein no signal sequence is needed since the nuclear pore is large enough the protein to be transported is synthesized in the cytosol
miRNAs are produced from rRNAs
which of the following statements about miRNAs is false? miRNAs regulate gene expression by affecting mRNA stability miRNAs are made by RNA polymerase miRNAs are transcribed in the nucleus from genomic DNA miRNAs are produced from rRNAs
ribosomes must bind to the 5' cap before initiating translation
which of the following statements about prokaryotic mRNA molecules is false? ribosomes must bind to the 5' cap before initiating translation mRNAs do not have to be edited as eukaryotic mRNA ribosomes can start translating an mRNA molecule before transcription is complete prokaryotic mRNA are transcribed by the same RNA polymerase that make rRNA and tRNA
AUG serves as start codon in all mRNAs
which of the following statements about the genetic code is correct? all codons specify more than one amino acid AUG serves as start codon in all mRNAs every amino acid is specified by more than one codon there are three start codons and three stop codons
the genetic code is redundant
which of the following statements about the genetic code is correct? all codons specify more than one amino acid every amino acid is specified by more than one codon the genetic code is redundant there are three start codons and three stop codons
chaperones are involved
which of the following statements about the import of proteins into mitochondria is true? the signal sequences on mitochondrial proteins are usually at the C terminus mitochondrial proteins cross the membrane in their native, folded state most mitochondrial proteins are synthesized inside the mitochondria chaperones are invovled
photosynthesis makes the molecules that store energy, while cellular respiration releases the energy from fuel molecules
which of the following statements best describes the relationship between photosynthesis and cellular respiration? cellular respiration and photosynthesis are exactly opposite cellular events photosynthesis makes the molecules that store energy, while cellular respiration releases the energy from fuel molecules photosynthesis occurs only in plants and cellular respiration occurs only in animals ATP molecules are produced in photosynthesis and are directly used up in cellular respiration
membrane carbohydrates function primarily in cell-cell recognition
which of the following statements concerning carbohydrates associated with the plasma membrane is correct? membrane carbohydrates function primarily in cell-cell recognition carbohydrates are found associated with the membranes of immune cells only the carbohydrate composition of most eukaryotic plasma membranes is quite similar carbohydrates associated with the plasma membrane are located on both surfaces of the membrane
the physical state of the chromosome can affect gene expression
which of the following statements describes the eukaryotic chromosome? it is composed of DNA alone the nucleosome is its most basic gene expression unit the number of genes on each chromosome is different in different cell types of an organism the physical state of the chromosome can affect gene expression
a ribosome is a large rRNA and protein complex
which of the following statements is TRUE? ribosomes are synthesized in the nucleus ribosomes are large RNA structures composed solely of rRNA a ribosome binds only one tRNA at a time a ribosome is a large rRNA and protein complex
the only known function of RNA molecules is their involvement in translation
which of the following statements is false? RNA polymerase is responsible for catalyzing the formation of the phosphodiester bonds between nucleotides if two genes are to be expressed in a cell, these two genes can be transcribed with different efficiencies a new RNA molecule can begin to be synthesized from a gene before the previous RNA molecule's synthesis is completed the only known function of RNA molecules is their involvement in translation
membrane lipids frequently diffuse within the plane of the membrane
which of the following statements is true? phospholipids will spontaneously form liposomes in nonpolar solvents membrane lipids frequently flip-flop between one monolayer and the other membrane lipids frequently diffuse within the plane of the membrane in eukaryotes, all membrane-enclosed organelles are surrounded by one lipid bilayer
a ribosome is a large rRNA and protein complex
which of the following statements is true? ribosomes are large RNA structures composed solely of rRNA ribosomes are synthesized entirely in the nucleus a ribosome is a large rRNA and protein complex a ribosome binds only one tRNA at a time
uniform left-handed twist
which of the following structural characteristics is not normally observed in a DNA duplex? antiparallel strands uniform left-handed twist purine-pyrimidine pairs external sugar-phosphate backbone
microtubules
which of the following structures is important for flagellar movement?
carbon dioxide
which of the following substances does not require a protein carrier in order to cross a membrane? hydrogen ion carbon dioxide an amino acid glucose
a deletion of 2 nucleotides
which of the following types of mutations, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product? an insertion of a codon a deletion of 2 nucleotides a substitution of the third nucleotide in an ACC codon a deletion of a codon
smooth ER
which one of the following organelles would be especially abundant in cells that produce a large amount of lipids? rough ER smooth ER endosomes cytoplasm
a peroxisome
which organelle contains enzymes used in a variety of oxidative reactions that break down lipids and destroy toxic molecules?
a lysosome
which organelle is essentially a small sac of digestive enzymes that function in degrading worn-out organelles, as well as macromolecules and particles taken into the cell by endocytosis?
receptor-mediated endocytosis
which statement best describes the uptake of low-density lipoprotein (LDL) particles at the cell membrane? constitutive exocytosis receptor-mediated endocytosis regulated exocytosis a process mediated by a specific receptor at the cell membrane by exocytosis
chloroplasts
which structure is not part of the endomembrane system? nuclear envelope chloroplasts golgi apparatus plasma membrane
hydrogen bonds
which type of interaction is mainly responsible for the stabilization of the alpha helix and the beta sheet structures of proteins?
phospholipids
which type of lipids are the most abundant in the plasma membrane?
peptide bond
which type of the following is the strongest bond that links amino acids in a protein? hydrogen bond hydrophobic interaction ionic bond peptide bond
to ensure accurate distribution of genetic material into daughter cells
why are chromatin are condensed to chromosomes during cell division?
all of the above
why is ATP an important molecule in the cell? all of the above its terminal phosphate group is used for protein phosphorylation it is a monomer for the synthesis of nucleic acids it provides energy for cellular activities
the nucleus
with a light microscope, it is likely that you can see
because double-stranded genomes have equal amounts of A and T
you are a virologist interested in studying the evolution of viral genomes. you are studying two newly isolated viral strains and have sequenced their genomes. you find that the genome of strand 1 contains 25% A, 55% G, 20% C, and 10% T. you report that you have isolate a virus with a single-stranded DNA genome. based on what evidence can you make this conclusion?
5'-AUAGGCAUUCGAUCCGGAUAGCAU-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? 5′-AUAGGCAUUCGAUCCGGAUAGCAU-3′ none of these answers are correct 5′-UACGAUAGGCCUAGCUUACGGAUA-3' 5′-UAUCCGUAAGCUAGGCCUAUGCUA-3′