Cell Biology Final

Which of the following hydrocarbon tail would yield the most highly mobile phospholipid? 24 carbons with 1 double bond 20 carbons with 2 double bonds 16 carbons with 2 double bonds 16 carbons with no double bonds

16 carbons with 2 double bonds shorter the tail, the higher the mobility more double bonds, higher mobility (provide a curve) unsaturated lipids: higher mobility

An animal cell that has 8 chromosomes in G1 phase. How many of each of the following structures will the cell have during mitosis? sister chromatids/centromeres/kinetochores/centrosomes 8/16/8/2 16/16/16/2 16/8/16/2 16/2/16/16

16/16/16/2

A DNA sample contains 20% of A. Calculate the amount of G. 20% 30% 40% 60%

30% 20% A, 20% T 60% of C and G (30% each)

In an immunofluorescence experiment, you will visualize the specimen using red fluorescence with a wavelenth of 600 nm. The resolution limit of your image should be around ______. 20 nm 200 nm 300 nm 60 nm

300 nm limit is 1/2 of wavelength you use

Given the sequence of a coding strand: 5'- GCATTCGTGGGTAG-3' give the sequence of the mRNA and label the 5' and 3' ends. 5'- CGUAAGCACCCAUC-3' 5'- GCAUUCGUGGGUAG-3' 5'-CTACCCACGAATGC-3' 5'-CUACCCACGAAUGC-3'

5'- GCAUUCGUGGGUAG-3'

Give the sequence of the mRNA based on sequence of a gene: 5'-GCATTCGTGGGTAG-3' 5'-GCAUUCGUGGGUAG-3' 5'-CUACCCACGAAUGC-3' 5'-CTACCCACGAATGC-3' 5'-CGUAAGCACCCAUC-3'

5'-GCAUUCGUGGGUAG-3' all gene sequences are coding sequence just replace all T with U don't convert to complementary sequence template sequence is not the same as mRNA sequence

To image a fluorescent dye with excitation wavelength of 500 nm, which of the following emission wavelength may you chose? 200 nm 500 nm 540 nm any of them

540 nm emission light has lower energy and longer wavelength than excitation light

Which of the following mutations would lead to excess glucoses in skeletal muscle cells? A GPCR mutant form that loses the binding ability to G-protein A G-protein mutant form that loses GTP-binding ability A PKA mutant in which inhibitory subunits lose the binding ability to kinase subunits A PKA mutant form that loses cAMP-binding ability

A PKA mutant in which inhibitory subunits lose the binding ability to kinase subunits

Which of the following compounds may NOT be developed as an anti-cancer drug? A compound that inhibits the docking of Akt to PIP3 A compound that inhibits binding of Bad to Bcl2 A compound that inhibits binding of Akt to Bad A compound that inhibits mTOR activity

A compound that inhibits binding of Bad to Bcl2

Which of the following statements is CORRECT? A gain-of-function mutation in only one allele of oncogene can stimulate cell survival or division. Loss-of-function mutations in a tumor suppressor gene make the coding protein hyperactive. A loss-of-function mutation in an oncogene makes the coding protein hyperactive.. Loss-of-function mutation in one allele of tumor suppressor gene may be sufficient to stimulate cell division.

A gain-of-function mutation in only one allele of oncogene can stimulate cell survival or division.

Which is FALSE? The N-terminal tails of core histones can be covalently modified A nucleosome contains a histone core with DNA wrapped around it approximately two times. A histone core contains two of each of the core histones (H1, H2, H3, H4) Chromatins are present in eukaryotic cells, but not in prokaryotic cells

A histone core contains two of each of the core histones (H1, H2, H3, H4)

Which of the following statements is FALSE? Cancer cells proliferate indefinitely, presumably related with the stabilization of telomeres. Telomerase carries a RNA template, synthesizes and extends template DNA strand at telomere. A loss-of-function mutation of telomerase will convert a normal cell to a cancer cell. Somatic cells only divide a limited number of cycles, likely due to the shorten of telomeres.

A loss-of-function mutation of telomerase will convert a normal cell to a cancer cell.

Which of the following statements about cancer is FALSE? Many cancer cells have abnormal chromosomes representing genetic instability. Cancers are caused by the accumulation of a series mutations on oncogenes and tumor suppressor genes. Carcinogens cause cancer by changing the nucleotide sequence of DNA. A mutation in a single cancer-critical gene is sufficient to convert a normal cell into a cancer cell.

A mutation in a single cancer-critical gene is sufficient to convert a normal cell into a cancer cell.

Which statement about nuclear (gated) protein transport is CORRECT? A nuclear localization signal is both necessary and sufficient for a protein to enter the nucleus Most proteins can freely diffuse into the nucleus because the size of nuclear pores is big enough The protein needs to be unfolded to pass through the nuclear pore complex energy from ATP is required for the transport of nuclear proteins

A nuclear localization signal is both necessary and sufficient for a protein to enter the nucleus necessary: if removed, protein will not go through nucleus energy from GTP is required

Which of the following statements about receptor tyrosine kinases (RTKs) is TRUE? A RTK always contains multiple crossmembrane alpha helixes After signal molecule binding, RTKs are dimerized and phosphorylated Phosphorylated serine residues on RTKs serve as docking sites for signaling complexes The activated RTK can serve as docking site for Akt

After signal molecule binding, RTKs are dimerized and phosphorylated

Induction of G-protein pathways can activate the following enzymes except _________ PKA Akt PKC AC

Akt

Which of the following statements about apoptosis is TRUE? The Fas ligand and Fas receptor work to inhibit apoptosis. Cells that constitutively express Bcl2 will be more prone to undergo apoptosis. Bax and Bak promote apoptosis by binding to procaspases in the apoptosome. Apoptosis can be promoted by the release of cytochrome c into the cytosol from mitochondria.

Apoptosis can be promoted by the release of cytochrome c into the cytosol from mitochondria.

The following genes could become oncogene except ___________ E2F Bcl2 BAD mTOR Rho

BAD this is a tumor suppressor (induces cell deaths; inhibits Bcl2) the others promote cancer

In a gene cloning experiment, you insert the genomic DNA of a human gene and into plasmid and transfer into E. coli. You found that the gene is successfully transcribed but no protein is synthesized in the bacteria. What could be the most likely reason? Bacteria cannot synthesize the mRNA Bacteria cannot splice the mRNA to remove introns Bacteria always degrade human proteins Bacteria cannot translate the human mRNA

Bacteria cannot splice the mRNA to remove introns all human genes have an intron that needs to be removed to get mature mRNA and produce protein. Should use cDNA in a genomic experiment

Which of these DNA fragments (show one strand) has a higher Tm (melting temperature)? ATCGGCTAA ATATCG CCCGGGTAGGCCGC ATACGTTTAAATTA

CCCGGGTAGGCCGC the longer the DNA, the higher the more CG groups, the higher

Which of the following groups is a hydrophobic group? CH3 OH COO- none of them

CH3 hydrophobic: non-polar, non-charged OH is polar COO- is charged

Which of the following does NOT directly participate in the formation of endocytic vesicles? clathrin COP SNARE Receptor

COP mediates transport between ER and golgi

What would be the consequence of inactivation of E2F? Cells would enter S phase. The Rb protein would become activated. Cells would develop cancer. Cells would be unable to enter the S phase.

Cells would be unable to enter the S phase.

Which of the following statements about chaperons if FALSE? Chaperons are proteins Chaperons help assemble large protein complexes from protein subunits Chaperons can help correct mis-folded proteins Chaperons are usually synthesized more in cells that are treated with higher temperature

Chaperons help assemble large protein complexes from protein subunits Chaperons help protein folding mediated by noncovalent bonds not chaperons higher temperature makes protein folding harder

The activity of a protein can be posttranscriptionally regulated by any of the methods except___________ Protein interaction Ligand binding that induces allosteric conformation Covalent modification Controlling gene expression

Controlling gene expression

Theoretically, a cell contains 1000 IP3 molecules should have the same amount of _____________. PLC cAMP DAG PIP3

DAG

Which of the following is NOT a mechanism that mediates RNAi (RNA interference) DNA cleavage RNA cleavage translation repression heterochromatin formation

DNA cleavage RNAi starts from miRNA which produces double stranded RNA which is recognized by RNA machinery and produces siRNA and recruit protein complex to inhibit mRNA and translation

Which of the following can NOT be a mechanism of gene silencing? De-condensation of the chromatin structure Transcription repressors Trapping a transcription activator in the cytosol Expression of miRNA

De-condensation of the chromatin structure this facilitates gene expression, once chromatin structure is more open, transcription factors initiate transcription Transcription repressors bind to specific DNA sequence on promoter region and prevent the binding of RNA polymerase II complex trapping transcription activator in cytosol, which prevents them from going into the nucleus and find gene to transcript them expression of miRNA induces RNAi which is a gene silencing mechanism

If the anaphase promoting complex (APC/C) is temperature sensitive (active at 30 degree, but inactive at 40 degree), shifting to the higher temperature (40 degree) at the start of M phase would prevent which of the following? Degradation of M-Cdk. DNA replication. Entrance into M phase. Degradation of securin and separation of sister chromatids.

Degradation of securin and separation of sister chromatids.

Which of the following statements is TRUE for Notch signaling? Delta is an endocrine hormone that binds to Notch receptor Delta binding induces cleavage of Notch, whose cytosolic fragment enters nucleus and functions as transcription factor To silence the signaling, the nuclear Notch fragment shuttles back to the plasma membrane all the above

Delta binding induces cleavage of Notch, whose cytosolic fragment enters nucleus and functions as transcription factor

Which of the following can NOT be found in a tRNA molecule? Ribose Deoxyribose double helix Cytosine

Deoxyribose can only be found in DNA Ribose is backbone of RNA cytosine is base of RNA RNA can also form double helix

Which of the following statements about antibodies is TRUE? Each antibody is composed of two polypeptide chains alpha helices establish domains in the polypeptide chains Disulfide bonds are formed between the polypeptide chains Antibodies adapt different overall shapes so that they can bind to different antigens

Disulfide bonds are formed between the polypeptide chains

Which of the following statements about euchromatin and heterochromatin is FALSE? Genes that are packaged into heterochromatin are generally silenced Specific histone modifications can trigger formation of either euchromatin or heterochromatin During interphase, euchromatin and heterochromatin randomly diffuse in the nucleus During cell division, both euchromatin and heterochromatin are packaged into highly condensed mitotic chromosomes

During interphase, euchromatin and heterochromatin randomly diffuse in the nucleus This is wrong because: in the nucleus heterochromatin are associated with nuclear envelope, euchromatin are in the center each molecule has their own territories heterochromatin packages DNA into condensed structures so transcription factors cannot access the promoter region so genes can't be translated

To study a protein that controls the phosphorylation of RNA polymerase II, which of the following model organisms can NOT be chosen? E. Coli Yeast Drosophila Arabidopsis

E. Coli during transcription, RNA polymerase 11 needs to be translated, only in eukaryotic cells so NOT E. coli

If you label clathrin with GFP tag, you would find the green fluorescence associated with all of the following structures except ________ plasma membrane Golgi endocytic vesicle ER

ER only COP found on ER

Which of the following statements about enzyme is FALSE? The interaction between the enzyme and substrate is generally mediated by noncovalent bonds Enzymes speed reactions by decreasing delta-G (energy difference between reactant and product) Enzymes generally remain unchanged after finishing catalyzing a reaction Enzymes do not change the equilibrium of reactions

Enzymes speed reactions by decreasing delta-G (energy difference between reactant and product)

About eukaryotic transcription and prokaryotic transcription, which statement is FALSE? Eukaryotic transcription occurs in the nucleus, prokaryotic transcription in the cytoplasm Eukaryotic mRNAs have a 5' cap and a 3' polyA tail, prokaryotic mRNAs don't Eukaryotic initiation requires specific DNA sequences at promoter, prokaryotic initiation doesn't Prokaryotic transcription can be coupled with translation, eukaryotic transcription cannot

Eukaryotic initiation requires specific DNA sequences at promoter, prokaryotic initiation doesn't false because in bacteria transcription factors recognize dna sequences at promoter region, which helps recruit RNA polymerase to initiate transcription. In eukaryotic cells there are more transcription factors and more regulatory mechanisms bacteria don't have nucleus, once mRNA is synthesized, immediately recognized by ribosomes and start translation

Which of the following statements is TRUE? Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor To function, all extracellular signal molecules must be transported by their receptor across the plasma membrane into the cytosol a receptor bound by only one type of signal molecule can mediate only one kind of cell response each type of receptor must induce an independent signaling pathway and avoid interference with other intracellular signaling pathways

Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor

Which of the following statements about molecular switches is TRUE? Phosphatase can turn on a protein through adding phosphorylation groups to the protein Kinase can turn off a protein by removing phosphorylations from the protein GEF catalyzes the removal of GTP from the target protein GEF switches a protein on by replacing GDP with GTP on this protein

GEF switches a protein on by replacing GDP with GTP on this protein

Researchers attempting to ssemble microtubules in vitro. When MTOC and tubuliin dimers were added in test tube, no microtubule was generated. What were they missing? cAMP ATP GTP Ca2+

GTP

Which organelle can be found in both animal and plant cells? chloroplast Golgi vacuole all of the above

Golgi chloroplast and vacuole only in plant cells

Which of the following molecule has the lowest permeability to plasma membrane? H20 amino acid H+ steroid hormone

H+ charged molecules cannot pass plasma membrane highest: steroid hormone

Irradiated mammalian cells usually stop dividing and arrest at a G1 checkpoint. Place the following events in the order in which they occur. I. production of p21 II. DNA damage III. inhibition of cyclin-Cdk complexes IV. activation of p53 II-IV-III-I II-IV-I-III I-II-III-IV II-I-IV-III

II-IV-I-III

Which of the following can serve as a second messenger? ACh PIP3 IP3 all of them

IP3

A malignant tumor is more dangerous than a benign tumor because its cells ________________. cause neighboring normal cells to mutate proliferate faster invade other tissues attack and phagocytose neighboring cells

Invade other tissues

Which statement about ATP-synthase is FALSE? It can be found only in eukaryotic cells, not in bacteria It uses energy from cross-membrane proton gradient to produce ATP Providing enough ATP, it can also function as a proton pump It couples with oxidative phosphorylation to synthesize ATP in mitochondria

It can be found only in eukaryotic cells, not in bacteria

Ethanol can be used for sterilization. Why can ethanol kill bacteria? It denatures proteins by disrupting noncovalent bonds. it denatures proteins by digesting them into amino acids. It denatures proteins through disrupting covalent bonds It alters the amino acid sequences of proteins

It denatures proteins by disrupting noncovalent bonds Ethanol competes with H bonds amino acids can only be broken down by enzymes

Highly concentrated ethanol can be used for sterilization. Why can ethanol kill bacteria? It unfolds proteins through disrupting covalent bonds. It denatures proteins by digesting them into amino acids It denatures proteins by unfolding them It alters the amino acid sequences of proteins

It denatures proteins by unfolding them

Why taxol can be used to treat cancer? it inhibits mitosis by stabilizing microtubules it inhibits mitosis by removing microtubules it inhibits cell proliferation by blocking mTOR It inhibits cell division by blocking MAPK

It inhibits mitosis by stabilizing microtubules

Which of the following is FALSE of the sodium-potassium pump? It has enzyme activity to catalyze hydrolysis of ATP to ADP It transports 2 Na+ ions out of the cell and 3 K+ ions into the cell each time It creates an electrochemical gradient across the cell membrane The sodium gradient created by the pump is used by neurons to transmit electrical signal

It transports 2 Na+ ions out of the cell and 3 K+ ions into the cell each time 3 sodiums and 2 potasiums

Which of the following ion is usually abundant at the cytosolic side of the plasma membrane? K+ Na+ Ca2+ Cl-

K+ abundant sodiuim and calcium outside potassium inside

Which group of enzymes control protein activate by adding phosphate groups to the protein? Protease Ligase Kinase Phosphatase

Kinase

A drug that inhibits Akt will immediately block the following pathways except _______________ MAPK signaling mTOR pathway Bad/Bcl2 pathway GLUT4 exocytosis

MAPK signaling

In a muscle cell, which internal organelle would you expect to be particularly abundant?

Mitochondria

In a muscle cell, which internal organelle would you expect to be particularly abundant? lysosome endoplasmic reticulum mitochondria chloroplast

Mitochondria contraction needs lots of energy which can be produced by mitochondria

Which of the following statements about genome is FALSE? Most of the human genome code for proteins Human genome is distributed on 46 chromosomes in most normal cells Most of the human genes contain intron Many human genes are believed to undergo alternative splicing.

Most of the human genome code for proteins

Which of the following statements it TRUE? highly concentrated salts can denature a protein and digest it into amino acids. Heat can unfold a protein molecule and break it into small peptides hydrophilic interactions help the folding of proteins in water none of the above

None of the above salts can denature a protein but cannot digest it into amino acids heat cannot break it down, can only unfold hydroPHOBIC interactions help folding of proteins in water not hydrophilic

A particular strain of yeast produces strains with a mutant cdc2 (M-Cdk) gene, resulting in little to no production of the M-Cdk protein kinase. As a result, what would be expected? These cells will have chromosome condensation. These cells will have the nuclear envelope disperse. None of these. These cells will enter M phase.

None of these

Which of the following statements it true? - All hydrophilic molecules form only hydrogen bonds with water molecules - Phospholipids have both hydrophilic and hydrophobic components - Ionic bonds are strong bonds that make molecules unsoluble in water - Hydrophobic interactions are most likely to occur on the surface of a water-soluble protein

Phospholipids have both hydrophilic and hydrophobic components

The recovery result of a FRAP (Fluorescence Recovery After Photobleach) assay of three membrane proteins (A, B, C) is shown. Which protein has the highest mobility?

Protein A, it is the highest and furthest to the left on the graph C is stable (straight line and lowest; no mobility)

Which statement about transmembrane transport to mitochondria is TRUE? all proteins in mitochondria are synthesized in cytosol Protein translations are initiated in cytosol and finished in the mitochondria proteins pass through outer and inner membranes simultaneously proteins need to be folded tightly to pass through the membrane

Proteins pass through outer and inner membranes simultaneously proteins need to be UNFOLDED

Which of the followin gphenomena si NOT required for cell motility? nucleation of new actin filaments release of Ca2+ from the ER Myosin-mediated contraction integrin association with the extracellular matrix

Release of Ca2+ from the ER

You have generated antibodies that recognize the extracellular domain of the Ca2+ pump. Adding these antibodies to living animal cells blocks the active transport of Ca2+ from the cytosol into the extracellular environment. What do you expect to observe with respect to intracellular Ca2+ level? Dramatically increases in the cytosol Remains low in the cytosol Decreases in ER Increases in Golgi

Remains low in the cytosol most calcium is stored in ER

Which of the following groups can be found in the backbone of RNA molecules? Ribose Deoxyribose Thymine Uracil

Ribose backbone: ribose sugar connected with phosphate group base: forms connection with another backbone Deoxyribose: DNA backbone

Which of the following mechanisms may increase the activity of a transcription factor in the cell? silencing its coding gene trapping it in the cytosol enhancing the level of its inhibitor protein switching it on by phosphorylation

Switching it on by phosphorylation Phosphorylation is an important molecular switch All transcription factors are proteins silencing the coding reduces protein synthesis trapping it in the cytosol gives it less chance to activate gene transcription Many proteins regulated by protein interaction, including inhibitors. Enhancing level of inhibitors further inhibits transcription factor

Which statement about synapse is TRUE? The presynaptic cell and postsynaptic cell are connected by tight junctions Neurotransmitters are released by the presynaptic cell and absorbed by the postsynaptic cell Synapse converts electronical signal to chemical signal then converts it back to electronical signal one neuronal cell should receive signal from only one synapse

Synapse converts electronical signal to chemical signal then converts it back to electronical signal they are not connected

Which of the following microscopy has the highest resolution? Phase contrast SEM fluorescence microscopy TEM

TEM

Which of the following microscopy has the highest resolution? TEM phase contrast SEM fluorescence microscopy

TEM uses electron as light resource, small wavelength phase contrast and fluorescence microscopy use visible light as light resource

Which of the following statements about fluorescence microscopy is false?- The excitation wavelength of GFP is longer than its emission wavelength - GFP protein can be used to track specific proteins in living cells - The resulution limit of a regular fluorescence microscopy is around 200 nm - Phase contrast microscopy can directly visualize cells without fixation and staining

The excitation wavelength of GFP is longer than its emission wavelength

What will NOT happen if too many misfolded proteins are accumulated in the ER? The misfolded proteins will be packaged and secreted outside to keep the cell healthy More chaperon proteins will be produced to correct misfolded proteins Protein synthesis will be reduced to avoid more misfolded proteins Cell will attempt suicide if the problem can't be solved in time

The misfolded proteins will be packaged and secreted outside to keep the cell healthy

Which of the following statements about translation is TRUE? the start and stop codons do not code any amino acids the newly synthesized peptide always begins with methionine (Met) The assembly of a ribosome on mRNA prevents the binding of other ribosome units to this mRNA all of the above

The newly synthesized peptide always begins with methionine (Met) In eukaryotic cells, we can see polyribosomes, which can conduct translation together (1 ribosome starts translation, moves down the line)

Which of the following statements is FALSE? The sequence of the atoms in the polypeptide backbone varies among different proteins A polypeptide chain starts with an amino group and ends in a free carboxyl group In a higher temperature, more chaperons can be synthesized to guide the folding of proteins. Hydrogen bonds along the protein backbone allow the formation of an alpha helices and beta sheets

The sequence of the atoms in the polypeptide backbone varies among different proteins

Which of the following statements about transcription factors is TRUE? They all bind to the small groove of DNA They always function as dimers They can bind to anywhere of the genome all of the above

They always function as dimers They bind to large groove of DNA Transcription factors bind to specific DNA sequence

Many drugs are enzyme inhibitors. Which of the following statements about allosteric inhibitors is TRUE? They bind to the substrate binding sites of enzymes They bind to the catalyzing sites of enzymes They bind to the ligand-binding sites of enzymes all of the above

They bind to the ligand-binding sites of enzymes enzymes have an activity site(catalyzing site) and ligand binding site allosteric inhibitor mimic the ligand and compete with it to bind to the ligand binding site to inhibit enzyme substrate binds to the catalyzing site competitive inhibitors inhibit activity site

Which of the following amino acid can be most found on the surface of a protein? Phe Thr Val Met

Thr has a polar group, so exposed on surface the others are nonpolar, hydrophobic and hide inside protein during proteins folding, hydrophobic interactions with water hide hydrophobic groups inside and expose hydrophilic groups outside

Which of the following neurotoxins directly blocks the removal of acetylcholine neurotransmitter? tetradotoxin botulinum toxin VX Curare

VX inhibits AchE tetradotoxin inhibits voltage gated sodium channel BTX inhibits SNARE, inhibits release of acetylcholine Curare inhibits sodium potassium pump

Which of the following statements is FALSE? Chromatins are present in eukaryotic cells, but not in prokaryotic cells a histone core contains two of each of the core histones including H1, H2, H3, and H4. A nucleosome contains a core of histone with DNA wrapped around it approximately two circles. The N-terminal tails of core histones can be covalently modified.

a histone core contains two of each of the core histones including H1, H2, H3, and H4. This is false because it is H2A, H2B, H3, and H4, these are further linked by H1

A point mutation change a codon from AAA to UAA in the middle of a gene. This will produce ___________. a protein with normal amino acid sequence a protein with one amino acid change a truncated protein that loses the following amino acids a protein in which the whole following amino acid sequence changed

a truncated protein that loses the following amino acids This is a stop codon, causes a nonsense mutation protein with normal amino acid sequence: caused by silence mutation protein with one amino acid changed: missense mutation all amino acids changed: frameshift mutation

A drug can bind to GTP and blocking its interaction with any other proteins. Treating cells with this drug will immediately inhibit the following processes EXCEPT ______________ microtubule assembly actin filament assembly activation of Ras signaling nuclear (gated) protein transport

actin filament assembly

Which of the following filaments can rapidly grow or shrink at both ends? microtubules actin filaments intermediate filaments all the above

actin filaments

Which of the following statements about the cytoskeleton is TRUE? all eukaryotic cells have actin, microtubules, and intermediate filaments in the cytoplasm cytoskeletal filaments are assembled from protein monomers by covalent bonds actin filaments and microtubules are polar, while intermediate filaments are non-polar all the above

actin filaments and microtubules are polar, while intermediate filaments are non-polar

In which of the following transports protein syntheses are initiated in cytosol? gated transport into nucleus transmembrane transport into mitochondria vesicular transport into Golgi all of the above

all of the above

Protein transport to mitochondria requires ____________ specific signal sequence receptor translocator all of the above

all of the above

Proteins that are fully translated in the cytosol could end up in the ________ cytosol mitochondria interior of the nucleus all of the above

all of the above

Which of the following statements about enzymes is TRUE? Enzymes speed reactions by reducing the activation energy enzymes remain unchanged after finishing catalyzing a reaction enzymes do not change the equilibrium of reactions all of the above

all of the above

Which of the following transcription factors is needed to convert an adult cell into an induced pluripotent stem (iPS) cell? Klf4 Oct4 Sox2 All of the above

all of the above

You use GFP tag to track a protein that will ultimately be on the plasma membrane. Where would you find the green fluorescence? ER golgi appartus cell membrane all of the above

all of the above

Which of the following programs requires a normal function of cytoskeleton? cell migration cell division exocytosis al of the above

all of the above cell migration needs actin filament dynamics cell division needs MT and AF exocytosis needs MT and AF

Histone modifications can _________. Directly affect nucleosome packaging serve as docking sites for other regulatory proteins retain after cell division all of the above

all of the above ex: acetylation provides histone tails with a charge allowing them to conduct more extended structure to keep adjacent nucleus away: chromatin de-condensation

To study the functions of a novel protein, which of the following approaches can be employed? Imaging assays to check its subcellular localization genetic studies to examine the mutants that lack this protein molecular analyses to identify the interacting partners of this protein all of the above

all of the above if we want to study a gene or protein: microscopy, genetics (mutate gene coding for protein), molecular analysis (isolate protein out and study it)

Lysosomes contain __________ transporters hydrolytic enzymes H+ pumps all of the above

all of the above proton pumps help maintain a low pH

The folding of a protein can be mediated by __________. disulfide bonds ionic bonds hydrogen bonds all of them

all of them

To design a drug that inhibits insulin secretion, which protein may be chosen as the target? SNARE Kinesin Clathrin all of them

all of them

Which of the following mechanisms can be retained after cell division? histone methylation DNA methylation miRNA all of them

all of them cell memory

Which of the following RNAs are coded by genes? snRNA miRNA mRNA all of them

all of them snRNA: RNA splicing miRNA: RNAi

Which of the following molecules have asymmetric distribution on both sides of the plasma membrane? glycoproteins glycolipids phospholipids all of them

all of them sugar groups (glyco) noncytosolic side

Different RNA molecules can ________. carry genetic information during transcription participate in translation regulate gene expression all of them

all of them mRNA, rRNA, tRNA participates in translation non-coding RNA regulate gene expression mRNA carries genetic info during transcription

Which of the following mechanisms may contribute to the silencing of a G-protein-coupled signaling pathway? removal of GPCR through endocytosis Negative feedback loop that inhibits GPCR Automatic switch-off of G-protein all the above

all the above

Which of the following statements about the human genome is FALSE? Most of the human genes contain intron human genome is distributed on 46 chromosomes all the human genes code for proteins human genes compose less than 2% of the genome

all the human genes code for proteins some genes code for non-coding RNA

Which of the following structures can be a transmembrane domain? alpha-helix containing 20 polar amino acids alpha-helix containing 8 amino acids alpha-helix containing 20 nonpolar amino acids all of the above

alpha-helix containing 20 nonpolar amino acids needs to be nonpolar because they are hydrophobic 20 amino acids

During the vesicular transport, a small vesicle containing a transmembrane protein with N-terminus in the vesicle nd C-terminus outside. Predict the signal sequences that are required to produce this protein an ER signal sequence an ER signal sequence and a stop-transfer sequence A start-transfer sequence a start-transfer sequence and a stop-transfer sequence

an ER signal sequence and stop-transfer sequence without stop-transfer sequence it is fully synthesized in ER lumen transmembrane protein: stop transfer sequence required

Which organism should have the highest percentage of unsaturated phospholipids in the membrane? arctic salmon polar bear desert snake bacterium living in hot spring

arctic salmon unsaturated phospholipids raise membrane fluidity required for cold-blood animals

Cholesterols _______________ contain a hydrophilic head and two hydrophobic tails in each molecule increase the fluidity of membrane have asymmetry distribution across the membrane are transported in blood by lipoproteins including LDL and LDL

are transported in blood by lipoproteins including LDL and HDL cholesterol has only one tail decrease fluidity symmetric distribution; even on both sides of membrane

Hydrophilic molecules can form _______ with water molecules? ionic bonds hydrogen bonds both ionic and hydrogen bonds covalent bonds

both ionic and hydrogen bonds

Which of the statements about cDNA is TRUE? cDNAs are produced through mRNA splicing cDNAs are synthesized through reverse transcription cDNAs are produced by all the eukaryotic cells all of the above

cDNAs are synthesized through reverse transcription cDNAs come from mRNAs that undergo reverse transcription into cDNA

To release skeleton muscle spasm (contraction), a drug can be designed to block troponin binding to myosin calcium binding to tropomyosin calcium binding to troponin all of the above

calcium binding to troponin

A multipotent cell _________. can give rise to some cell types in the body can give rise to all the tissues and cell types in the body is considered to be terminally differentiated can only give rise to stem cells

can give rise to some cell types in the body

An adult hematopoietic stem cell found in the bone marrow ______________________. can produce only red blood cells can undergo self-renewing divisions for the lifetime will occasionally produce epidermal cells when necessary can produce only white blood cells

can undergo self-renewing divisions for the lifetime

In plant cells, membrane fluidity can be affected by all of the following except _____________ temperature lipid tail saturation lipid tail length cholesterols

cholesterols not found in plant plasma membrane

The activity of a protein can be post-transcriptionally regulated by any of the methods except ________. ligand binding covalent modification protein interaction chromatin regulation

chromatin regulation this controls transcription not post transcriptional regulation transcriptional regulation targets to genes

Phospholipids are synthesized at ___________ cytosol cytosolic face of ER lumen of ER Golgi

cytosolic face of ER

Which of the following statements about antibodies is TRUE? Disulfide bonds are formed between the polypeptide chains Each IgG antibody is a dimer (composed of two polypeptide chains). alpha helices establish domains in the polypeptide chains all of the above

disulfide bonds are formed between the polypeptide chains each IgG antibody is a tetramer (4 subunits)

A drug can directly inhibit the flagellar movement of a monad cel. This drug likely binds to ___________ actin filament myosin kinesin dyenin

dyenin

Which of the following statements is FALSE? G-protein-coupled receptors are multipass transmembrane proteins with 7 alpha-helixes each PKA is bound and activated by one cAMP Each calmodulin is bound and activated by 4 calcium ions Receptor tyrosine kinases (RTK) always form dimers after binding with signal molecules

each PKA is bound and activated by one cAMP

In a eukaryotic transcription , the 5' cap is added to the mRNA during _______ initiation elongation termination mRNA splicing

elongation during elongation, mRNA 5' is already synthesized then cap can be added. after finishing transcription 3' poly-A added after termination

Insulin molecules target to multiple types of cells through ___________ signaling paracrine synaptic autocrine endocrine

endocrine

Mutations in cadherin gene are highly associated with cancer because cadherin ______________ promotes cell proliferation through Ras-MAPK signaling forms intermediate filaments that strengthen epithelium cells essentially mediates cell-cell junctions and prevents cancer cell migration all the above

essentially mediates cell-cell junctions and prevents cancer cell migration

The microtubule networks can participate in all the following functions except ___________ placing internal organelles leading vesicular transport forming a contractile structure supporting cilia

forming a contractile structure

Which of the following proteins can be found ONLY in the centrosome? alpha-tubulin beta-tubulin gamma-tubulin actin

gamma-tubulin

Which of the following components can NOT be found on the cytosolic side of ER membrane? phospholipids cholesterol glycolipids membrane proteins

glycolipids for all membranes, endomembrane system sugar group avoids the cytoplasm, only in lumen

During development, cells can permanently silence some genes by packaging them into________ euchromatin heterochromatin mitotic chromosome ribosome

heterochromatin genes expressed are in euchromatin

Which of the following could be a mechanism to activate gene expression? DNA methylation histone methylation RNAi all of the above

histone methylation DNA methylation always causes gene silencing RNAi does as well histone methylation depends on which amino acid side chain it is 3 histone modification: acetylation, methylation, and phosphorylation all induce gene silencing or gene activation

Which of the following mechanisms could induce heterochromatin formation? histone methylation histone acetylation Pol II phosphorylation all of the above

histone methylation If the reader protein is a heterochromatin protein, methylation induces heterochromatin formation histone acetylation cannot, it is associated with open chromatin and gene activation Pol II phosphorylation is required for elongation, not associated with control of chromatin structure

To release muscle spasm caused by the un-normal accumulation of acetylcholine in the neuromuscular junction, you may design a drug to ______________ on the membrane of muscle cells inhibit acetylcholinesterase (AChE) inhibit ACh receptors block the inhibitory glycine receptors activate ACh receptors

inhibit ACh receptors

Which of the following is NOT a mechanism of active transport? coupled transport ATP-driven pump ion flux through a channel light-driven pumps

ion flux through a channel ion channels are all passive transport atp driven pump and light driven pump are active transport

Which of the following statements correctly describes the behavior of a gated channel? it stays open continuously it can open in response to a signal driven by ATP it can actively move ions all of the above

it can open in response to a signal

Which of the following statements about lamin is FALSE? Lamin and lamin-like proteins can be found in almost all eukaryotic cells it undergoes disassembly and reassembly during cell division it controls chromatin organization and gene expression it protects epithelial cells from mechanical damage

it protects epithelial cells from mechanical damage

In an experiment you generated a fusion protein with a kinesin head and a dyenin tail. Which of the following predicts the behavior of this fusion protein when supplied with microtubule and ATP? It will move to the plus end of microtubule it will move randomly it wil move to the minus end of microtubule it will not move

it will move to the plus end of microtubule

To design a drug that can inhibit cell migration, which protein may NOT be chosen as the target? ARP kinesin myosin II integrin

kinesin

You isolated a nuclear acid and found it contains 23% C and 27% G. This molecules is very likely ______. DNA double strand RNA mRNA protein

mRNA C and G are not equal, in DNA A=T and C=G not a double-stranded DNA, must be RNA (single strand) double strand RNA: A=U and C=G

The Akt kinase promotes cell growth through the activation of __________ pathway mTOR Bcl2 GLUT4 MAPK

mTOR

Which of these is NOT the function of sugars on the outer surfaces of cells cell recognition cell to cell contact and adherence protecting cell surface with a slimy layer metabolism to produce energy

metabolism to produce energy

Which type of RNA in the following controls gene silencing? miRNA rRNA snRNA tRNA

miRNA miRNA induces RNAi involving gene silencing rRNA is in translation snRNA mediates mRNA splicing tRNA is in translation

Which of the following statements about cytoskeleton dynamics is TRUE? microtubule filaments are stable once they are formed microtubule assembly occurs at both plus and minus ends microtubule assembles at the plus end and disassembles at the minus end microtubule assembly and disassembly occurs at the same end

microtubule assembly and disassembly occurs at the same end

Which of the following would you expect to see in a cell that has been exposed to colchicine? mis-organized endomembrane system inability to regulate cell size disappearance of the nucleus an increased synthesis of cellular proteins

mis-organized endomembrane system

Which gene mutation causes substitution of one amino acid in a protein sequence? silent mutation nonsense mutation missense mutation frameshift mutation

missense mutation silence mutation codes for amino acid nonsense mutation reaches a stop codon (UAA UAG UGA) Missense mutation is a change frameshift mutation is deletion or insertion of 1 or 2 base pairs

Which of the following organelles is NOT a part of the endomembrane system? nuclear envelope Golgi mitochondria lysosome

mitochondria endomembrane system: nuclear envelope connected with ER, lysosome, endosome, golgi, transport vesicles

Which of the following proteins can move cargos through an actin filament? myosin I myosin II dyenin kinesin

myosin I

Which type of proteins can be removed from membrane by relatively gently treatments? transmembrane proteins monolayer associated proteins lipid-linked proteins peripheral proteins attaching to other membrane proteins

peripheral proteins attaching to other membrane proteins noncovalent bonds soluble in water, easy to be removed

Which type of enzymes should mediate the removal of a histone phosphorylation code? kinase ligase phosphatase polymerase

phosphatase kinase add phosphate group phosphatase remove phosphate group

Embryonic stem cells are such a powerful possible treatment for disease because they are______. derived from fetuses pluripotent well understood multipotent

pluripotent

When a terminally differentiated cell in an adult body dies, it can typically be replaced in the body by a stock of ________. cells more apically located than the terminally differentiated cells embryonic stem cells proliferating precursor cells that are derived from adult stem cells induced pluripotent cells

proliferating precursor cells that are derived from adult stem cells

Proteins that are tagged with poly-Ub will be delivered to _________. spliceosome ribosome lysosome proteasome

proteasome poly-Ub are small proteins connected to a chain

In a neuromuscular junction, acetylcholine molecules are released through constitutive exocytosis regulated exocytosis receptor mediated endocytosis crossmembrane transport

regulated exocytosis

Which of the following structures shortens during skeleton muscle contraction? sarcomeres Z discs actin filaments myosin II (thick) filaments

sarcomeres

Many of the membrane functions depend on the presence of specialized membrane proteins. Which of the following membrane functions could still occur if the bilayer were lacking these proteins? intercellular communication Selective permeability Import/export of molecules ATP genertation

selective permeability

Which gene mutation gives rise to unchanged amino acid sequence in a protein? silent frameshift missence nonscence

silent

Which type of RNA in the following controls mRNA splicing? mRNA snRNA rRNA tRNA

snRNA

Prokaryotic cells do NOT contain _________. mRNA snRNA rRNA tRNA

snRNA snRNA is involved in RNA splicing to remove introns - RNA splicing only in eukaryotic cells

You identified a yeast strain in which introns cannot be removed from mRNAs. Which of the following genes could be mutated? RNA pol II gene rRNA genes snRNA genes tRNA genes

snRNA genes RNA splicing mediated by snRNP mediated by snRNA

Years mutations are used to study exocytosis of a secretary protein shown as dots (left: ER, right: Golgi), which of these yeast strains most likely has a mutation on clathrin? Strain A strain B strain C strain D

strain C clathrin disrupted, cargo stuck in Golgi cop problem: cargo stick in ER

Which of these lipid movements generally does NOT occur spontaneously in membranes? switching of lipids between lipid layers lateral movement in plane of the membrane rotation of lipids flexing of hydrocarbon chains

switching of lipids between lipid layers cannot happen without enzyme

Which of the following happens when a G-protein-coupled receptor activates a G protein? The alpha subunit exchanges its bound GDP for GTP The beta subunit exchanges its bound GDP for GTP Activated G protein produces 3 separate subunits that function independently it activates the alpha subunit and inactivates the betagamma complex

the alpha subunit exchanges its bound GDP for GTP

Progression through the cell cycle requires a cyclin to bind to a Cdk because _________. the binding of a cyclin to Cdk is required for Cdk enzymatic activity the cyclins are the molecules with the enzymatic activity in the complex without cyclin binding, a cell-cycle checkpoint will be activated cyclin binding inhibits Cdk activity until the appropriate time in the cell cycle

the binding of a cyclin to Cdk is required for Cdk enzymatic activity

What will happen if you add an ER signal sequence to the N-terminus of a cytosolic protein? The ER signal sequence will not be recognized and the protein will remain in the cytosol The ER signal sequence will be cleaved off and the protein will remain in the cytosol The protein will be fully synthesized in the cytosol and then be delivered into the ER the protein will be delivered to the ER and fully synthesized in the ER

the protein will be delivered to the ER and fully synthesized in the ER

Which of the statements velow about intermediate filaments is TRUE? They are made of ropelike subunits They are found only in the cytoplasm the assembly is mediated by covalent bonds each filament is about 25 nm in diameter

they are made of ropelike subunits

Which of the following statements about nuclear receptors is TRUE? they are cell-surface receptors they bind with signal molecules in the cytoplasm they are found only in the nucleus all of the above

they bind with signal molecules in the cytoplasm

Which pathway will NOT end up with lysosomal degradation? autophagy endocytosis phagocytosis ubiquitination

ubiquitination (garbage can of the cell) other 3 all send cargo into lysosome

Which of the following is NOT the function of Golgi? protein sorting glycosylation unfolded protein response exocytosis

unfolded protein response This happens in the ER

Which type of intermediate filament is abundant in cytoplasm of muscle cells? lamin neurofilament vimentin keratin

vimentin

To study the function of keratin, which of the following models can be chosen? yeast drosophila zebra fish all of them

zebra fish