Cell Biology Exam 4- Torres

which type of cytoskeletal element is described as tough, ropelike fibers composed of a variety of related proteins like keratin?

a. microfilaments

b. microtubules

c. intermediate filaments

d. macrofilaments

c. intermediate filaments

_____ attach to kinetochores and mediate chromosomal segregation during mitosis.

a. actin filaments

b. microtubules

c. intermediate filaments

d. myosin

b. microtubules

Microtubules are the intracellular tracks for two classes of motor proteins: _____ and _____. These proteins move cargo _____.

kinesin ; dynein ; to opposite ends of the microtubule

the energy source for the molecular motors dynein, kinesin, and myosin is ____

a. GTP

b. GDP

c. ATP

d. ADP

c. ATP

the amorphous, electron-dense material that surrounds the two barrel-shaped centrioles and is part of the centrosome is called ____.

a. chromatin

b. MTOC

c. y-TuRC

d. pericentriolar material

d. pericentriolar material

which of the following components of the cytoskeleton is present only in animal cells?

a. actin filaments

b. microtubules

c. intermediate filaments

c. intermediate filaments

which of the following components of the cytoskeleton is an essential part of the contractile ring?

a. actin filaments

b. microtubules

c. intermediate filaments

a. actin filaments

which of the following components of the cytoskeleton is composed of monomers that when free, are bound to GTP?

a. actin filaments

b. microtubules

c. intermiedate filaments

b. microtubules

which of the following components of the cytoskeleton, along with Tau, is associated with Alzheimers disease?

a. actin filaments

b. microtubules

c. intermediates filaments

b. microtubules

MAPs comprise a variety of proteins with different functions, including

a. promoting assembly and stability of microtubules

b. promoting disassembly and depolymerization of microtubules

c. affecting protein folding

d. inducing movement of chromosomes to the poles during mitosis

e. promoting binding of myosin to microtubules

a. promoting assembly and stability of microtubules

movement of vesicles from the cell body to the synapse is mediated by ____, while movement from the synapse to the cell body is mediated by _____

a. kinesins; dyneins

b. dyneins; kinesins

c. actin filaments; microtubules

d. alpha-tubulin; beta-tubulin

a. kinesins; dyneins

cytoplasmic vesicles move in both directions within an axon. the only way to accomplish this, is that nerve cells have some microtubules oriented with their plus end facing the axon terminus and others oriented with the opposite polarity.

True or False

false

the ____ end of microtubules is associated with the centrosome. the ____ end is situatedat the opposite (growing) tip

minus ; plus

the diagram below shows a cell in ____. At this stage, a cell has 2 ____ and 4 ____.

a. metaphase; centrosomes; centrioles

b. prophase; centrioles; centrosomes

c. metaphase; basal bodies; centrosomes

d. anaphase; kinetochores; basal bodies

e. metaphase; centromeres; centrioles

a. metaphase; centrosomes; centrioles

this image shows a centrosome stained with y-tubulin antibodies. which side of the microtubule is associated with the stained portion?

a. the plus end, because an alpha subunit will be located next to the y-tubulin

b. the plus end, because an beta-tubulin subunit will be located next to the y-tubulin

c. the minus end, because an alpha-subunit will be located next to the y-tubulin

d. the minus end, because a beta-subunit will be located next to y-tubulin

c. the minus end, because an alpha-subunit will be located next to the y-tubulin

a primary cilium is a kind of motile cilium found in most human cells.

True or False

false

the axoneme is defined as

a. the structure that powers movement of cilia

b. the core of the cilium

c. the monomers of intermediate filaments

d. the structure that supports the axon

b. the core of the cilium

cilia and flagella are able to move because their microtubules _____

a. go through cycles of assembly and disassembly

b. shrink and expand longitudinally

c. expand and contract in diameter

d. slide over one another

d. slide over one another

which MTOC gives rise to cilia and flagella?

a. centrsome

b. centrioles

c. axoneme

d. basal bodies

d. basal bodies

what is the result of defects in cilia in the development of the congenital condition situs inversus?

a. kidney failure

b. abnormal brain development

c. abnormal positioning of internal organs

d. overall GI track failure

c. abnormal positioning of internal organs

how would you name the motile structures spermatozoa, chlamydiomonas and paramecium

a. flagella, cilia, cilia

b. flagella, flagella, cilia

c. cilia, cilia, flagella

d. cilia, flagella, flagella

b. flagella, flagella, cilia

during one of your cell bio labs, you treat an organism with a compound that inhibits myosin. how do you expect this treatment would affect movement of this organism?

a. it will immed. stop moving

b. it will take a few minutes to slow down motion of the flagellum and eventually stop

c. it will be able to start swim faster

d. this treatment should not affect motion of the flagellum

d. this treatment should not affect motion of the flagellum

nucleation of microtubules occurs at MTOCs. Two examples of MTOCs include

a. axoneme and centrosome

b. axoneme and centriole

c. basal body and centrosome

d. basal body and centriole

c. basal body and centrosome

motility of cilia and flagella is mediated by interaction with ____

a. kinesin

b. dynein

c. myosin

d. intermediate filaments

b. dynein

what is the name of the process by which particles move in the space between the peripheral doublets of cilium or flagellum and the surrounding plasma membrane?

a. interflagellar transport

b. intraflagellar transport

c. extraflagellar transport

d. dynoflaglellary transport

b. intraflagellar transport

a and b are the ends of the flagellum. (end) A is associated with the ____ end of microtubules while B (base) with the _____ end. Cargo from point A to point B would be transported using the motor protein ____

a. plus; minus; dynein

b. plus; minus; kinesin

c. minus; plus; dynein

d. minus; plus; kinesin

e. minus; plus; myosin

a. plus; minus; dynein

mutations in the PDK1 gene cause autosomal recessive polycystic kidney disease. this leads to the accumulation of fluid and enlarged kidneys, caused by defects in _____

a. motile cilia

b. nonmotile cilia

c. flagella

b. nonmotile cilia

if there is no flow of extraembryonic fluid over a mouse embryo, ____

a. embryos

b. most embryose orient correctly

c. half develop situs inversus

d. all develop situs inversus

c. half develop situs inversus

unlike actin filaments (microfilaments), intermediate filaments are nonpolar.

True or false

true

to study assembly in vitro, "seeds" or short pre-formed actin filaments are incubated with ATP-actin monomers. How do you expect this filament to grow?

a. faster from the plus end

b. faster from the minus

c. only from the plus end

d. only from the minus

e. equally from both ends

a. faster from the plus end

individual monomers of a microfilament move down the length of the microfilament from plus end to the minus end in vitro in a process known as ____.

a. walking

b. transposition

c. treadmilling

d. negative substition

c. treadmilling

the molecular motors of the ____ superfamily are the only ones known to operate in conjunction with actin filaments. with one exception, these molecular motors move toward the ____ end of an actin filament.

a. dynein; minus

b. myosin; plus

c. kinesin; plus

d. myosin; minus

b. myosin; plus

which type of motor protein assembles into filaments and is an essential component of the sarcomere?

a. kinesin

b. dynein

c. myosin I

d. myosin II

e. myosin V

d. myosin II

Intermediate filaments are polymers of

a. actin

b. tubulin

c. filamentin

d. intermediatin

e. variety of polypeptide subunits

e. variety of polypeptide subunits

the fibroblast is fluorescently labeled for the three main elements of the cytoskeleton. actin is lebeled in _____ microtubules in ____ and intermediate filaments in ____

a. blue; red; green

b. green; red; blue

c. red; green; blue

d. blue; green; red

d. blue; green; red

some ways in which synthesis of microtubules and intermediate filaments differ is/are _____

a. energy requirements

b. sites where subunits are incorporated

c. polarity

d. all of the above

d. all of the above

the polarity of an actin filament is visualized by the binding of the myosin subfragment. Which of the following best describes the barbed end?

a. the barbed end is the plus end

b. the barbed end is the minus end

a. the barbed end is the plus end

Macrophages are best known for their protective search and destroy functions against invading micro-organisms. Both of the processes require cytoskeletal remodeling to produce ____ membrane structure called lamellipodia and phagocytic cups

a. intermediate filament-rich

b. microtubule- rich

c. actin- rich

d. dynein- rich

c. actin-rich

the motor protein ____ is associated with organelle transport in the periphery of the cell, and ____ in transport across microvilli

a. myosin I ; myosin II

b. myosin II ; myosin V

c. myosin V ; myosin I

d. myosin I ; kinesin

e. myosin V ; myosin II

c. myosin V ; myosin I

long-distance transport of melanocytes (pigment granules) from melanosomes to hair follicles is mediated by

a. microtubules and myosin II

b. actin filaments and myosin V

c. microtubules and myosin V

d. microtubules and kinesin

d. microtubules and kinesin

what are the components of the I band in a sarcomere?

a. actin filaments and myosin II

b. only myosin II

c. only actin filaments

d. only microtubules

e. microtubules and myosin II

c. only actin filaments

the shortening of individual sarcomeres results from:

a. depolymerization of actin filaments

b. denaturation of myosin fibers

c. treadmillining

d. sliding of actin filaments

d. sliding of actin filaments

based on cell activities readily visible in the light microscope, there are two major cell cycle phases, ____ and ____

a. M phase; cytokinesis

b. interphase; cytokinesis

c. G1; G2 phase

d. M phase; interphase

d. M phase ; interphase

what did scientists discover in the experiments with radiolabeled thymidine?

a. that membrane-bound ribosomes are essential in actively- dividing cells

b. that actively dividing cells spend most of their time synthesizing DNA

c. that actively dividing cells spend most of their time in M phase

d. that actively dividing cells synthesize DNA only during a portion of interphase

d. that actively dividing cells synthesize DNA only during a portion of interphase

you supply a cell with H-thymidine for a period of 30 minutes. What has happened during the 30 minute-incubation?

a. all the polysaccharides synthesized during this period were radiolabeled

b. all the RNA synthesized during this period was radiolabeled

c. all the DNA synthesized during this period was radiolabeled

d. DNA synthesis was inhibited during the incubation period

c. all the DNA synthesized during this period was radiolabeled

studies with frog oocytes demonstrated that some agents control different stages of the cell cycle. Entry of a cell into M phase is initiated by the interaction between ____

a. phosphodiesterases and kinases

b. cdks and cyclins

c. cdks and helicases

d. thymidine phosphatase and G2 kinase

e. aurora kinase and cyclins

b. cdks and cyclins

the cell cycle is controlled at three checkpoints known as:

a. G1, G2, and M

b. G1, G2, and S

c. G0, G1, and G2

d. G0, S, and M

e. G0, G1, and M

a. G1, G2, and M

which group of cells would you expect to have radiolabeled nuclei after a brief exposure (~30min) to H-thymidine?

a. cells engaged in mitosis

b. cells engaged in interphase

b. cells engaged in interphase

why did mitotic cells have unlabeled chromosomes after brief exposures to H-thymidine?

a. because they were not replicating DNA

b. because DNA replication occurs only during G2

c. because DNA replication only occurs during S

d. because DNA replication occurs in all phases of interphase, not M phase

e. a and c

e. a and c

the first cells which showed radiolabeled mitotic (compacted) chromosomes, were probably engaged in ____ when incubation with H-thymidine started

a. G1 phase

b. G2 phase

c. S phase

d. M phase

c. S phase

Mitosis lasts one hour. in the experiment below how long is G1?

a. 3 hours

b. 6 hours

c. 10 hours

d. 15 hours

c. 10 hours

Assume the total cell cycle lasts 20 hours. If mitosis lasts one hour, and G1 lasts 10 hours, how long is G2?

a. 1 hour

b. 3 hours

c. 5 hours

d. 9 hours

b. 3 hours

Do you know the difference between M, G1, S, and G2 phases of the cell cycle?

a. yes

b. no

a. yes

what does the M in M phase stand for?

a. metastasizing phase

b. moving phase

c. mitotic phase

d. meristem phase

c. mitotic phase

what happens during the G1 phase?

a. the phase where the cell experiences growth

b. the phase where the cell prepares for gene flow

c. the phase where the cell is in a paused state

d. the phase where the cell experiences a decline in growth

e. both a and b

a. the phase where the cell experiences growth

What does the S in S phase stand for?

a. synthesis phase

b. stabilization phase

c. silent phase

d. sophies phase

e. b and c

a. synthesis phase

what happens during the G2 phase?

a. growth decline phase

b. another growth phase

c. growth fluctuation phase

b. another growth phase

what did scientists discover in the experiment with fused cells?

a. M phase cytoplasm contains enzymes that degrade DNA

b. M phase cyotplasm contains enzymes that degrade histones

c. S phase cytoplasm contains enzyme that degrade DNA

d. M phase cytoplasm contains factors that induce mitosis in non-mitotic cells

d. M phase cytoplasm contains factors that induce mitosis in non-mitotic cells

When MPF peaks, what happens? select all that apply

1. The cell goes through S phase

2. Kinases are phosphorylated

3. Kinases are activated

4. The cell enters mitosis

5. The cell enters G1 phase

6. The cell enters apoptosis

a. 1,2

b. 3,4

c. 2,3,5

d. 1,4,6

e. 1-6

b. 3,4

assume you set up an experiment where you block the ability of CDKs to be activated. What would you expect will happen to cells?

a. they will remain arrested in G1

b. they will remain arrested in S

c. they will remain in prophase

d. they will remain in telophase

e. they will remain in anaphase

a. they will remain arrested in G1

binding to cyclin is sufficient to activate cdk1

True or false

false

phosphorylation and dephosphorylation of specific amino acids in cdc2 regulates progression of yeast cells from G2 to mitosis. how many enzymes are involved in this regulatory process?

a. three kinases

b. two dehygrogenases and one phosphatase

c. two phosphatases and one kinase

d. two kinases and one phosphatase

d. two kinases and one phosphatase

what happens if a cell has a mutation that affects function of the kinase wee1?

a. the cell enters mitosis prematurely, producing smaller cells

b. the cell has a shorter G1 phase, producing smaller cells

c. the cell has a shorter S phase, producing smaller cells

d. the cell stays arrested in G2 and never enters mitosis

a. the cell enters mitosis prematurely, producing smaller cells

" the site of attachment of the chromosme to the dynamic microtubules of hte mitotic spindle" best describes the ____

a. kinetochore

b. centrosome

c. mitotic spindle

d. aster

a. kinetochore

the type of microtubules that link the centrosome and the kinetochores are known as

a. polar microtubules

b. metaphase plate microtubules

c. astral microtubules

d. chromosomal microtubules

e. centrosomal microtubules

d. chromosomal microtubules

The multiprotein complex that keeps replicated chromatids associated with one another until they are separated during anaphase is known as ____

a. cohesin

b. condensin

c. cdk1

d. centrosome

a. cohesin

important events take place during anaphase that allow the completion of mitosis and reentry into G1, including degradation of _____ by ____

a. condensin; chaperonins

b. cohesin; MPF

c. CDKs; hydrolases

d. G1 cyclin/S cyclin

e. mitotic cyclins; proteasome

e. mitotic cyclins; proteasome

the spindle assembly checkpoint prevents the separation of chromosomes until they are properly aligned and attached to the spindle apparatus. This mechanism, also known as the ____, operates during the transition between _____

a. M checkpoints; prophase to metaphase

b. G1 checkpoints; G1 to G2

c. M checkpoint; Metaphase to anaphase

d. G2 checkpoint; S to G2

e. M checkpoint; anaphase to metaphase

c. M checkpoint; metaphase to anaphase

Why are chromosomes condensed during mitosis?

a. because the daughter cells are smaller and can only fit compacted DNA

b. because DNA would leak out of the nucleus if it is not compacted

c. because only compacted chromsomes can be replicated during mitosis

d. condensed chromosmes are more susceptible to degradation

e. condensed chromosomes can move smoothly, without becoming entangled and breaking

e. condensed chromosomes can move smoothly, without becoming entangled and breaking

condensin is a multiprotein complex that is activated early in mitosis by phosphorylation. which of the following enzymes are involved in activation of condensin?

a. G1/S cyclins

b. mitotic cyclins

c. CDKs

d. phosphorylases

e. phosphatases

c. CDKs

sister chromatids, shown in Fig ___ are the result of DNA replication that occurred during _____

a. A; interphase

b. B; interphase

c. A; M-phase

d. B; M-phase

a. A; interphase

Following replication, sister chromatids are held together by ______

a. condensin

b. topoisomerase

c. Cdk1

d. cohesin

e. cyclin

d. cohesin

what happens if condensin is removed from frog eggs extracts in vitro?

a. there is no effect in the cell

b. sister chromatids separate earlier, leading to aneuploidy

c. sister chromatids stay together and never separate, arresting the cell in metaphase

d. compaction of the chromsomes occurs more quickly than normal

e. compaction of the chromosomes is prevented

e. compaction of the chromosomes is prevented

In the following image, what are the names of the structures labeled as A and B respectively?

a. centrosome; mitotic spindle

b. microtubules; kinetochore

c. centromere; centriole

d. kinetochore; aster

c. centromere; centriole

the kind of microtubules that position mitotic spindle and guide cytokinesis are ____

a. chromosomal microtubules

b. polar microtubules

c. mitotic microtubules

d. astral microtubules

e. centrosomal microtubules

d. astral microtubules

The multiprotein complex _____ is activated during metaphase, and is involved in ___

a. APC; protein degradation

b. centromeric heterochromatin; migration of chromosomes

c. cyclin B; protein activation

d. centrosome; microtubule nucleation

e. kinetochore; chromosomal migration

a. APC; protein degradation

Cleavage of ____ triggers the ____, which markes the beginning of anaphase

a. mitotic cyclin; separation of homologous chromosomes

b. nuclear envelope; formation of mitotic spindle

c. cdk; degradation of nuclear envelope

d. condensin; formation of contractile ring

e. cohesin; separation of sister chromatids

e. cohesin; separation of sister chromatids

a rare genetic disorder (MVA) is associated with mutations in BUB1B, a key components of the human spindle assembly checkpoint. which of the following phenotypes would your directly associate with individuals who suffer mva?

a. multinucleated cells

b. individual cells will be larger

c. individual cells will be smaller

d. abnormal number of chromosomes

e. cancer

d. abnormal number chromosomes

GPCR, also known as _____, interact with ______ to mediate a variety of cellular response

a. 5TM receptors; heterotrimeric G proteins

b. 6TM receptors; cAMP

c. 7TM receptors; heterotrimeric G proteins

d. 7TM receptors; cAMP

c. 7TM receptors; heterotrimeric G proteins

Where is the guanin nucelotide-binding site of the G protein located?

a. on G-alpha subunit

b. on G-beta subunit

c. on G-gamma subunit

d. on G-beta/gamma subunit

e. on all three subunits

a. on G-alpha subunit

sometimes an enzyme is activated by a receptor and brings about the cellular response by generating a second messenger. such an enzyme is called a(n) _____

a. activator

b. effector

c. refactor

d. generator

b. effector

to regain sensitivity to future stimuli, the activated GPCR must be returned to an inactive state by a process known as _____

a. receptor dimerization

b. receptor monomerization

c. desensitization

d. dephosphorylation

e. arrestin phosphorylation

c. desensitization

low levels of glucose in the blood induce:

a. synthesis of glucagon and breakdown of epi

b. synthesis of epi and breakdown of glycogen

c. synthesis of glycogen and glucagon

d. synthesis of glycogen and breakdown of insulin

e. synthesis of glucagon and breakdown of glycogen

e. synthesis of glucagon and breakdown of glycogen

which of the following statements about second messengers is false?

a. a small molecule that transmits a cellular response

b. a molecule that can stimulate multiple activaties

c. a molecule that can only bind to a single receptor

d. a small molecule or ion that can relay signals received by cell-surface receptors

c. a molecule that can only bind to a single receptor

How would you classify the proteins that carry the reacitions A and B?

a. A is phosphorylase and B is dephosphorylase

b. A is phosphorylase and B is phosphatase

c. A is kinase and B is dekinase

d. A is kinase and B is dephosphatase

e. A is kinase and B is phosphatase

e. A is kinase and B is phosphatase

What do heterotrimeric G proteins activate?

a. second messengers, like cAMP

b. the alpha-subunit of other proteins

c. effectors, like adenylyl cyclase

d. GPCRs, like rhodopsin

e. kinases, like GTPase

c. effectors, like adenylyl cyclase

In this image is the G protein on or off? Explain

a. it is ON, because its bound to GPCR

b. It is ON, because its bound the beta and gamma subunits

c. It is OFF, because its bound to a GPCR

d. It is OFF, because its bound to GDP

d. it is OFF, because its bound to GDP

Assume the heterotrimeric G protein activated the effector adenylyl cyclase. which second messenger will be produced?

a. cGMP

b. cAMP

c. insulin

d. glucagon

e. PKA

b. cAMP

what does cAMP activate?

a. cGMP

b. cAMP

c. insulin

d. glucagon

e. PKA

e. PKA

excess of glucose in our system induces the synthesis of _____

a. glucagon

b. epinephrine

c. glycogen

d. starch

e. cellulose

c. glycogen

When the concentration of glucose in the bloodstream is low

1. glycogen synthesis is induced

2. glycogen breakdown is induced

3. gluconeogenesis is induced

4. insulin is synthesized

5. glucagon is synthesized

a. 1,2,3

b. 1,3,4

c. 1,3,5

d. 2,3,4

e. 2,3,5

e. 2,3,5

our ability to see, taste and smell depends largely on interactions with _____.

a. RTKS

b. GPCRs

c. Monomeric G-proteins

d. cAMP signaling

b. GPCRs

what provides humans with the perception of different aromas?

a. Activation of olfactory receptors, more specifically GPCRs, in the neruons of the olfactory bulb

b. activation of olfactory receptors, more specifically RTKs, in the neurons of the olfactory bulb

c. activation of olfactory receptors, more specifically sodium channels, in the surface of the olfactory bulb

d. activation of olfactory receptors, more specifically potassium channels, in the surface of the olfactory bulb

a. activation of olfactory receptors. more specifically GPCRs, in the neurons of the olfactory bulb

Ligand-mediated dimerization of certain RTKs results in addition of phosphate groups to the cytoplasmic domain of the other receptor subunit. this process is known as _____.

a. competition inhibition

b. competitive phosphorylation

c. kinase-specific phosphorylation

d. RTK-activation

e. Trans-autophosphorylation

e. trans-autophosphorylation

which of the following types of genes would be more likely to become an oncogene?

a. a GTPase like ras

b. a subunity of the insulin receptor

c. the first enzyme of the glycolysis pathway

d. adenylyl cyclase, which synthesizes cAMP

a. a GTPase like ras

the ras-MAPK pathway can be activated when ____ bind to _____

a. glucagon; GPCRs

b. growth factors; RTKs

c. insulin; GPCRs

d. epinephrine; GPCRs

e. neurotransmitters; RTKs

b. growth factors ; RTKs

How does the activation of rhodopsin lead to the perception of light?

a. it activates a downstream signaling pathway that opens potassium channels

b. it causes the hyperpolarization of the rod cell

c. it stimulates the release of dopamine from the rod cells

d. it directly sends signals to the brain

b. it causes the hyperpolarization of the rod cell

which type of receptors and cells are involved in olfactory perception?

a. GPCRs in olfactory bulb cells

b. RTKs in olfactory neurons

c. the insulin receptor in olfactory stem cells

d. integrins in the nasal cavity

e. GPCRs in olfactory receptor neurons

e. GPCRs in olfactory receptor neurons

Perception of sour tastes depends upon:

a. a compound interacting with a G protein coupled receptor on the receptor cell surface

b. sodium ions in the food that enter cation channels in the taste receptor plasma membrane, leading to a membrane depolarization

c. protons in the food that enter cation channels in the taste receptor plasma membrane, leading to a membrane depolarization

d. potassium ions in the food that enter cation channels in the taste receptor plasma membrane, leading to a membrane depolarization

e. protons in the food acting as ligands for a G protein coupled receptor on the taste receptor cell surface

c. protons in the food that enter cation channels in the taste receptor plasma membrane, leading to a membrane depolarization

What kind of receptors percieve 'spicy' signals?

a. receptors have not been named yet

b. we still don't know

c. it is perceived by olfactory receptors

d. we sense it as pain

e. i don't like spicy food

d. we sense it as pain