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′