exam four Flashcards by Paige Renschler

Which molecule is primarily responsible for providing tensile strength in the connective tissues of animals?
intermediate filaments
collagen
lignin
cellulose

collagen

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Which of the following cell types is responsible for removing matrix for renewal in bone tissue?
fibroblasts
osteoblasts
epithelial
osteoclasts

osteoclasts

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Cancerous cells can accumulate mutations more quickly for all the following reasons EXCEPT
a mutation that causes mistakes in mitosis
a mutation in a gene involved in DNA replication
a mutation in a cell proliferation gene
a mutation in a DNA repair gene

a mutation in a cell proliferation gene

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A passenger mutation in cancer is different from a driver mutation in that it
is a mutation that leads to genetic instability
is a mutation in an oncogene
is not necessary for the formation of the cancerous changes
is sufficient to promote cancer cell growth

is not necessary for the formation of the cancerous changes

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What is the difference between a malignant tumor and a metastasis?
a malignant tumor does not proliferate excessively
a metastasis does not invade surrounding tissue
a metastasis is a tumor in different distant tissue
a malignant tumor is not able to invade neighboring tissue

a metastasis is a tumor in different distant tissue

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Hemopoietic stem cells in the bone marrow produce all of the following specialized cells EXCEPT
osteoclasts
heart muscle cells
neutrophils
red blood cells

heart muscle cells

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Stem cells in the gut epithelium form precursor cells that differentiate as they move ___________ to the epithelial sheet, whereas precursor cells formed from the skin epidermis stem cells move ___________ to the epithelial sheet.
perpendicular; perpendicular
parallel; perpendicular
parallel; parallel
perpendicular; parallel

parallel; perpendicular

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Which of these tissues has the fastest turnover rate?
bone
nerves
blood
instestinal epithelium

intestinal epithelium

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Which of the following junctions binds a cell to another cell and is linked to keratin intermediate filaments?
tight junction
desmosome
hemidesmosome
adherens junction

desmosome

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Epithelial cells attach to a sheet of extracellular matrix composed of
plectin and actin
collagen and laminin
keratin and lamins
fibronectin and vimentin

collagen and laminin

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What is a function common to all epithelia?
secretion of hormones
sensing light signals
absorption of nutrients
creation of a barrier

creation of a barrier

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What is an epithelium?
a sphere of closely packed cells
a sheet of cells joined tightly together
tissue with dense extracellular matrix and sparse cells
a meshwork of laminin protein

a sheet of cells joined tightly together

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The figure below shows the attachment of a cell to a collagen molecule in the extracellular matrix. What is the identity of the molecule labeled B?
actin molecules
integrin
fibronectin
G-protein coupled receptor

integrin

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An oncogene is different from a tumor suppressor gene in that
oncogene mutations more rarely lead to cancer
oncogenes have mutations causing decreased activity of the protein
mutation of the gene can contribute to cancer
oncogenes have mutations causing increased activity of the protein

oncogenes have mutations causing increased activity of the protein

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Cancer cells often lack normal DNA damage response and cell-cycle control mechanisms. Why does this make them more susceptible to DNA-damaging chemotherapies?
cancer cells might ignore the normal mechanisms that halt the cell cycle in response to damage, and subsequent division with damage leads to death
cancer cells have the ability to repair the DNA properly and thus will not accumulate mutations as quickly
cancer cells with activating mutations in Ras will amplify the damage through the Ras signaling pathway
cancer cells will arrest in the cycle and will not grow further

cancer cells might ignore the normal mechanisms that halt the cell cycle in response to damage, and subsequent division with damage leads to death

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Under a microscope, how would the connective tissue of an animal generally appear?
a network of extracellular matrix fibers with no cells
densely packed cells filled with tight fibers of collagen and keratin
loosely scattered cells among large amounts of extracellular matrix
many densely packed cells with thin bundles of extracellular matrix between them

loosely scattered cells among large amounts of extracellular matrix

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What is a difference between a primary and a secondary cell wall in plants?
secondary cell walls are located juxtaposed to the plasma membrane
secondary cell walls are often formed when plant cells specialize
primary cell walls are only formed once cell growth ceases
primary cell walls provide a waxy waterproofing layer to plant tissues

secondary cell walls are often formed when plant cells specialize

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What is the force that drives plant cell growth?
spindle force
cellulose fibers
turgor pressure
intermediate filament tension

turgor pressure

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Figure 1 shows a model of a plant cell wall. The blue structures are cellulose fibrils, which are responsible for providing tensile strength. Figure 2 shows the attachment of a cell to a collagen molecule in the extracellular matrix. Which polymer in figure 2 commonly provides the same function in animal connective tissue as cellulose fibril does in a plant cell wall?
collagen
integrin
keratin
actin

collagen

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Which represents the order of these from smallest unit of organization to the largest?
tissues and organs are at the same level of organization
cells < tissues < organs
tissues < cells < organs
organs < tissues < cells

cells < tissues < organs

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In response to an apoptotic stimulus, initiator caspases
degrade procaspases
degrade executioner caspases
cleave and activate executioner caspases
cleave a transcription factor to activate gene expression

cleave and activate executioner caspases

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The contractile ring is composed of
tubulin and dynein
actin and myosin
keratin fibers
tubulin and kinesin

actin and myosin

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What determines the position of the cleavage furrow of the dividing cell?
the two spindle poles send signals to the plasma membrane so that the cleavage furrow forms in the same plane as the two poles
astral microtubules contact the membrane and activate proteins to form a central furrow
the cleavage furrow position is determined randomly
the interpolar microtubules send signals to form a cleavage furrow between the poles

the interpolar microtubules send signals to form a cleavage furrow between the poles

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What drives the reassembly of the nuclear envelope?
invagination of the ER membrane
dephosphorylation of lamins
destruction of cohesin
expression of all new lamin proteins

dephosphorylation of lamins

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Cohesin is cleaved by the enzyme ___________, which is held in an inactive state by ___________ until it is degraded by the APC/C complex. nuclease; securin securin; separase separase; kinetochores separase; securin

separase; securin

If a chromosome is attached to two microtubules from opposite poles and one of the microtubules is experimentally severed, what occurs? the severed microtubule immediately regenerates and reattaches the chromosome migrates quickly to the pole to which it is still attached the remaining microtubule releases the chromosome contacts the chromosome remains aligned along the equator of the metaphase spindle

the chromosome migrates quickly to the pole to which it is still attached

How are spindle microtubules attached to chromosomes? the minus ends of the microtubules bind directly to a protein complex on DNA the plus ends of the microtubules bind directly to DNA the microtubules bind to the kinetochore complexes through a connecting protein the microtubules bind to cohesion complexes on the DNA

the microtubules bind to the kinetochore complexes through a connecting protein

In which phase of mitosis does the nuclear envelope break down? metaphase anaphase prophase prometaphase

prometaphase

Shown below is the structure of a bipolar mitotic spindle. Which element(s) is/are the interpolar microtubules? A B C none of these

What is the function of condensins? to break down the nuclear envelope to coil sister chromatids into a compact form to hold sister chromatids together to shorten the contractile ring

to coil sister chromatids into a compact form

M-Cdk is suddenly activated at the end of G2 by destruction of cyclins phosphorylation by Wee1 activation of APC/C dephosphorylation by Cdc25

dephosphorylation by Cdc25

How does S-Cdk prevent re-replication? degradation of DNA polymerase inactivation of G1-Cdk activation of helicases to denature DNA phosphorylation of ORC and Cdc6

phosphorylation of ORC and Cdc6

The figure below shows some steps involved in the initiation of DNA replication. What is the identity of the complex labeled "B"? DNA polymerase Cdc6 pre-replication complex ORC

ORC

In response to DNA damage, the ___________ protein is phosphorylated and activates the transcription of a Cdk inhibitor to halt cell cycle progression. p21 p27 Rb p53

p53

Rb is an important protein for controlling cell proliferation by blocking entry into S phase. How does it exert its effect? in its phosphorylated state, Rb is active and blocks G1-Cdk activity Signaling through mitogen-activated pathways activates Rb kinase pathway When phosphorylated by G1-Cdk, Rb binds to DNa and activates the transcription In its unphosphorylated state, Rb is active and blocks transcriptional regulators

In its unphosphorylated state, Rb is active and blocks transcriptional regulators

At the end of M phase, cells shut down Cdk activity through which of the following mechanisms? deployment of Cdk inihibtors degrading the Rb protein mitogen-activated signaling shutting down all gene expression

deployment of Cdk inhibitors

What accounts for the difference in the curve shapes depicting concentration of M-cyclin versus M-Cdk activity during the cell cycle? the M-Cdk activity levels reach their peak slowly due to the time required for synthesis of the proteins The M-Cdk complex is not activated until M-cyclin is bound and M-Cdk is dephosphorylated The M-Cdk complex is not activated until it is dephosphorylated in mitosis The M-Cdk complex is not activated until M-cyclin is fully bound

The M-Cdk complex is not activated until M-cyclin is bound and M-Cdk is dephosphorylated

The slow rise of S cyclin levels throughout G1 phase is due to ___________, and the abrupt decrease is caused by ___________. transcription; proteolysis phosphorylation; translation synthesis; mitosis import; export

transcription; proteolysis

The expression levels of different ___________ fluctuate throughout the cell cycle. phosphates cyclins Cdks cyclins and Cdks

cyclins

Which is NOT a transition point where the cell cycle control system regulates progression through the cell cycle? G2/M transition S/G2 transition G1/S transition chromosome segregation

S/G2 transition

Which of the following correctly matches the phase of the eukaryotic cell cycle with an event that takes place in that phase? G2 phase - mitosis M phase - cytokinesis G1 phase - DNA synthesis S phase - cell growth

M phase - cytokinesis

How do calcium ions stimulate contraction in nonmuscle cells and smooth muscle cells? Calcium ions bind to troponin and lead to a conformational change in tropomyosin that exposes the myosin binding sites on the actin filament Calcium ions trigger an action potential in the cell, leading to gene expression changes that influence contraction Calcium ions lead to activation of a kinase that phosphorylates nonmuscle myosin to alter is conformation and enable actin binding Calcium ions released into the cell promote the release of secretory vesicles that send neurotransmitters to neighboring cells to stimulate an action potential

calcium ions bind to tropronin and lead to a conformational change in tropomyosin that exposes the myosin binding sites on the actin filament

When an action potential excites a muscle cell, where do the calcium ions come from? the calcium secretory vesicles the sarcoplasmic reticulum the extracellular space both the extracellular space and the sarcoplasmic reticulum

both the extracellular space and the sarcoplasmic reticulum

The binding of ATP causes a conformational change in myosin that moves the myosin head one step forward on the actin filament attaches the myosin head to the actin filament move the actin filament in a force-generating "power stroke" releases the myosin head from the actin filament

releases the myosin head from the actin filament

A ___________ is a long structure found in abundance in the cytoplasm of a single skeletal muscle fiber, and is composed of many bundles of actin and myosin filaments that are arranged in repeating units. contractile ring sarcomere myofibril thick filament

myofibril

Which of the following motor proteins has one head domain, moves along actin toward the plus end, and is found in all cell types? kinesin cytoplasmic dynein myosin-I myosin-II

myosin-I

At the leading edge of a cell, ARP proteins help form new branches on actin filaments to push the leading edge forward using the force of the polymerization, as shown in the figure below. from the capped ends of actin filaments in branches off of existing actin filaments at the plus ends of newly polymerized actin filaments at the minus ends of depolymerizing actin filaments

at the plus ends of newly polymerized actin filaments

Which motor protein is an ATPase, has two globular heads, moves toward the (-) end of a microtubule, and generally interacts with cargo via an adaptor protein? myosin-I myosin-II cytoplasmic dynein kinesin

cytoplasmic dynein

Microtubules participate in the spatial polarization of nerve cells because microtubules have no polarity microtubules are only located in the nerve cell body microtubule (-) ends originate near the cell body allowing (+) end-directed transport along the axon microtubules extend through the axon with (-) ends toward the terminal and bind vesicles there

microtubule (-) ends originate near the cell body allowing (+) end-directed transport along the axon

Taxol and colchicine are used to treat cancer because they arrest dividing cells in mitosis. What is the mechanism of action of these drugs? taxol prevents polymerization of microtubules, colchicine prevents disassembly of microtubules both drugs stabilize microtubules both drugs contain the dynamic instability of microtubules both drugs destabilize microtubules

both drugs contain the dynamic instability of microtubules

Microtubules are inherently unstable unless they are bound to kinesin able to bind GTP stabilized by a (+) end attachment assembled in the nucleus

stabilized by a (+) end attachment

Shown below is a diagram of a centrosome and associated microtubules. What is the identity of the structure in red, indicated by the black dashed arrow? microtubule /gamma-tubulin ring complex centriole kinesin molecule

/gamma-tubulin ring complex

the end of the microtubule that has /alpha-tubulin exposed is the neither end has /alpha-tubulin exposed (+) end both (+) and (-) ends (-) end

(-) end

Microtubules extend from organizing centers in the cell. Which is an example of an organizing center? centromere of a chromosome vesicle membrane basal body of a cilium nuclear periphery

basal body of a cilium

Which of the following represents the placement of microtubules in an epithelial cell? A B C none of these

In terms of structure, if cytoplasmic intermediate filaments are described as ropes, nuclear lamins could be best described as string wood glass mesh

mesh

How do the intermediate filament proteins keratin, vimentin, and neurofilaments differ from each other? They are different at the head and tail domains that are exposed at the surface The dimers assemble into filaments in a completely different way Their central rod domains are very different and do not all form coiled-coils They do not differ. All intermediate filament proteins are identical

They are different at the head and tail domains that are exposed at the surface

Which of the following is an important function of intermediate filaments? forming attachments for cells to move along a substrate providing tensile strength to the cell and the nucleus moving vesicles from location to location in the cell separating chromosomes during mitosis

providing tensile strength to the cell and the nucleus

Which of the cytoskeletal structures are made up of protein subunits that are fibrous? None. All of the protein subunits that make up cytoskeletal structures are globular actin filaments intermediate filaments microtubules

intermediate filaments

Which of the following occur during M-phase of the cell cycle (select all that apply) Chromosome alignment at the spindle equator DNA replication Nuclear division Chromosome separation and movement towards the spindle pores

Chromosome alignment at the spindle equator Nuclear division Chromosome separation and movement towards the spindle pores

Which of the following processes is APC required for during M-phase aster and spindle formation dissociation of cohesin rings and chromosome separation nuclear envelope degradation binding of replication machinery to the origin of replication

dissociation of cohesin rings and chromosome separation

What TWO epithelial types are shown in the image above simple cuboidal epithelium stratified columnar epithelium simple squamous epithelium stratified squamous epithelium

simple cuboidal epithelium stratified squamous epithelium

Which of the following are normally found in the Extracellular Matrix (ECM) (select all that apply) collagen actin tubulin elastin

collagen elastin

Which of the following are known epidemiological risk factors for cancer (select all that apply) viruses inflammation chemicals such as smoking bacteria

all of the above

With regards to the development of Cancer, what kind of gene is RAS? dominant oncogene cell death gene cell cycle checkpoint gene recessive tumor suppresor

dominant oncogene

What is the main signalling pathway that maintains the stem cell niche (active cell cycle region) in gut epithelial crypts? BMP signaling EGFR signaling Wnt signaling Notch signaling

Wnt signaling

What is the main difference between embryonic stem cells (ESCs) and induced pluripotent stem cells (IPSCs). ESCs are collected from a blastocyst, while IPSCs are generated using adult cells (like fibroblasts) ESCs can differentiate into any cell type, while IPSCs can only differentiate into some but not all cell types ESCs require more cell survival cues than IPSCs ESCs have a faster cell cycle than IPSCs

ESCs are collected from a blastocyst, while IPSCs are generated using adult cells (like fibroblasts)

Which of the following are features of intermediate filaments? (select all that apply) are connected to desmosomes and hemidesmosomes can lead to early aging (progeria) when mutated transport vesicles around the cytoplasm resisting mechanical stress across cells in a tissue

are connected to desmosomes and hemidesmosomes can lead to early againg (progeria) when mutated resisting mechanical stress across cells in a tissue

What forms the contractile ring required for cytokinesis? keratin and myosin tubulin and dynein actin and myosin tubulin and kinesin

actin and myosin

Which of the following animal models can be used to study cell biology? (select all that apply) frogs yeast fish human cells

all of the above

When do Chromosomes attach to the mitotic spindle? telophase prophase metaphase prometaphase

prometaphase

Which of the following are not associated with intermediate filament assembly? dimers line up to form staggered, antiparallel tetramer pairs of monomers associate to form a coiled dimer staggered profilaments assemble end-to-end into the final rope-like intermediate filament

staggered profilaments

Which of the following stabilize microtubules (select all that apply) taxol profillin ATP tubuline Capping proteins

taxol ATP tubuline capping proteins

Which of the following motor proteins are associated with microtubules (select all that apply) Myosin I Myosin II Kinesin Dynein

Kinesin Dynein

In which direction do Kinesins move? + to - - to + + to + - to -

- to +

What is the function of cilia on the surface of epithelial cells to generate energy for the cell to move fluid across the epithelial surface to increase the surface area of the epithelial surface to propel a cell through a fluid

to move fluid across the epithelial surface

Which cytoskeletal element is the primary structural component of lamellipodia microtubules actin intermediate filaments myosin

actin

Which motor protein is associated with muscle contractions kinesin dynein myosin I myosin II

myosin II

Which motor protein is associated with vesicle fusion during neurotransmitter release kinesin dynein myosin I myosin II

myosin I

During which phase of the cell cycle does chromosome duplication occur? G2 G1 M S

At what point in the cell cycle is cyclin M at its highest expression level? G1 M S G2

Which of the following are targets of APC Wee1 Cdk-M p27 Cyclin M

Cyclin M

What complex is inactivated by p27 cyclin-Cdk complexes Cdc25 complex p53 complex APC complex

cyclin-Cdk complexes

Which of the following cell cycle regulators are activated/deactivated by DNA damage (select all that apply) p53 S-Cdk complex cdc25 p21

p53 S-Cdk complex p21

Which of the following sequence elements are required for mitosis (select all that apply) centromere telomere TATA replication origin

centromere replication origin

Which of the following protein/s inhibit cell cycle when replication is incomplete (select all that apply) p53 Wee1 cdc25 p23

Wee1

S-Cdk acts on what target to activate the replication machinery DNA polymerase DNA helicase Cdc6 Origin recognition complex

DNA helicase

What type of microtubule is attached to the chromosomes during mitosis kinetochore spindal astral interpolar

kinetochore

What APC target is involved with cohesion cleavage during anaphase condensin separase securin cohesin

securin

Which form of cell death requires activation of Caspase genes? necrosis phagocytosis autophagy apoptosis

apoptosis

Which of the following cell types exist in a haploid state? germ cells gametes somatic cells parental cells

gametes

When does crossing-over occur mitosis II mitosis I meiosis II meiosis I

meiosis I

What holds homologous chromosomes together during meiosis I cadherins connexins synaptonemal complex cohesins

synaptonemal complex

Which cytoskeletal element is most commonly associated with Desmosomes microtubules myosin II actin filaments intermediate filaments

intermediate filaments

Cadherin adhesion proteins are associated with which of the following junctions (select all that apply) adherins junctions hemidesmosomes gap junctions desmosomes

adherins junctions desmosomes

Bending in epithelial sheets is most important for the development of the connective tissue skeletal muscles extracellular matrix neural tube

neural tube

The following are critical element of most tissues that together are assembled to form organs (select all that apply) connective tissue squamous cells endothelial cells epithelial cells

connective tissue endothelial cells epithelial cells

Which adherens proteins are most commonly associated with hemidesmosomes? connexins cadherins integrins claudins

integrins

What name is given to the junctions connect plant cells and allow passage of molecules between neighbouring cells? gap junctions plasmodesmata cell wall junctions desmosomes

plasmodesmata

Microtubules attach to chromosomes via centromeres and kinetochores cohesin and condensin rings telomeres and replication origins actin and collagen filaments

centromeres and kinetochores

Which of the following is FALSE membrane-enclosed organelles must be distributed to daughter cells when a cell divides nuclear division occurs during s phase cytokinesis in plant cells involves the formation of a new cell wall the mitotic spindle determines the plane of cytoplasmic cleavage

nuclear division occurs during s phase

At what point in the cell cycle do chromosomes move towards the spindle poles prometaphase prophase anaphase metaphase

anaphase

Which Cdk drives entry into M phase G1-Cdk S-Cdk APC/C M-Cdk

M-Cdk

What are the 3 protein filaments of the cytoskeleton?

actin, microtubules, and intermediate filaments

Which filament am I describing? strong and ropelike strengthens cells against mechanical stress supports the nuclear envelope in a meshwork pattern

intermediate filament

The intermediate filaments in each cell are indirectly connected to those of neighboring cells through __________

desmosomes

The intermediate filament monomer consists of

alpha-helical central rod domain

What are the 4 major classes of intermediate filaments?

keratin, vimentin, neurofilaments, lamin

What strengthens cells against mechanical stress?

intermediate filaments

What network in the skin provides mechanical tensile strength?

keratin filament network

How do intermediate filaments support and strengthen the nuclear envelope?

they provide attachment sites for the chromosomes

What connects cytoskeletal elements and bridges the nuclear envelope?

linker proteins

What filament am I describing? hollow tubes with structurally distinct ends organize the cell interior

microtubules

The ____ end of each microtubule is embedded in the centrosome, having grown from a p-tubulin ring, whereas the _____ end of each microtubule extends into the cytoplasm

minus; plus

do microtubules grow and shrink independently or dependently of their neighbors

independently

the independent growth of microtubules and thus their ever changing array is an example of what property?

dynamic instability

a newly formed microtubule will persist only if both its ends are protected from ________

depolymerization

what biases the orientation of the microtubule array, such that an organized system of microtubules is set up?

selective stabilization/plus ends encountering a capping protein

what controls the dynamic instability of microtubules?

GTP-hydrolysis

tubulin dimers carrying _______ bind more tightly to one another than do tubulin dimers carrying _______-

GTP; GDP

what causes microtubule growth?

GTP hydrolysis

what causes microtubule shrinking?

losing a GTP cap

what guides the transport of organelles, vesicles, and macromolecules in both directions along a nerve cell axon?

microtubules

in what direction do microtubules point on an axon?

plus end toward the axon terminal

how do microtubules help position organelles in a cell?

acting like the cell's mass-transit system

how do motor proteins transport cargo?

they walk along a microtubule, towards the plus end

what mediates motor protein transport towards the minus end?

dynein

do kinesins and dyneins move in the same or opposite direction?

opposite

how are microtubules in a cilium arranged?

9 + 2 array

the movement of _____ causes the flagellum to bend

dynein

What filament am I describing? thin and flexible underlies the plasma membrane of most eukaryotic cells

actin

All of these are examples of what? microvilli contractile bundles filopodia contractile ring of dividing cells

actin filaments

what provides a binding site for ATP and ADP in an actin monomer

cleft

what prevents the 2 strands of an actin monomer from separating?

multiple, lateral interactions

what 2 molecules polymerize by similar mechanisms?

actin and tubulin

ATP-actin adds to the plus end of an actin filament at the same rate that ADP-actin is lost from the minus end. What is this called?

treadmilling

what does cell crawling depend on?

cortical actin

flattened leading edge

lamellipodia

fine protrusions extending edge

filapodia

what pushes the leading edge of lamellipoidum forward?

web of polymerizing actin filaments

what goes on the plus end to stabilize actin filaments

capping proteins

what goes on the minus end to stabilize actin filaments

ARP complex

activation of what can have a dramatic effect on the organization of actin filaments in fibroblasts

Rho-family GTPases

what does actin associate with to shuttle more organelles and form contractile structures

myosin

what is the simplest myosin

myosin I

what does muscle contraction depend on

interacting filaments of actin and myosin II

what are the contractile units of muscle

sarcomeres

by what mechanism do muscles contract

sliding-filament

skeletal muscle contraction is triggered by the release of ____ from the _______ into the cytosol

Ca 2+; sarcoplasmic reticulum

4 phases of the eukaryotic cell cycle

G1, S, G2, M

what phases comprise interphase?

G1, S, G2

which cell cycle phase is the most variable in length

which cell cycle phases are relatively constant

G2 and M

at what phase do cells make their commitment to divide

what does the cell-cycle control system depend on

Cdks

what regulates cyclin concentrations

transcription and proteolysis

what must a Cdk do before it can become enzymatically active

bind a cyclin

what Cdk-cyclin binding complex triggers S phase

S-Cdk bound to S cyclin

ubiquitylation of S or M cyclin by ______ marks the protein for destruction in proteasomes

APC/C

what phosphorylates M-Cdk to keep it inactive

Wee1

what dephosphorylates M-Cdk to activate it

Cdc-25

what binds to an activated cyclin-Cdk complex to prevent the Cdk from phosphorylating target proteins required for progress through G1 into S phase

p27

incomplete DNA replication/DNA damage leads to what

inhibition of Wee1 kinase or activating phosphatase Cdc25 blocks M

what happens when the environment isn't favorable

Cdk inhibitors (p27) block entry to S phase

why would inhibition of APC/C to delay exit of mitosis occur?

chromosome is unattached to spindle

in what phase are Cdks stably inactivated

what promotes the production of the cyclins that stimulate cell division

mitogens

what are the 3 choices a cell has when it encounters a G1 checkpoint

1. enter another cell cycle (s) 2. pause temporarily (G0) 3. withdraw completely (differentiation)

what is one way that mitogens stimulate cell proliferation?

inhibit Rb protein

what do protein kinases activate when DNA is damaged

p53

what does p53 activate to inactivate G1 and S-Cdk to stop the cell cycle

p21

what 3 DNA sequence elements are needed to produce a chromosome that can be duplicated

1. telomere 2. replication origin 3. centromere

what initiates DNA replication and blocks re-replication

S-Cdk

what binds to the ORC and thus loads a pair of DNA helicases to form the prereplicative complex

Cdc6

how does S-Cdk block re-replication

phosphorylating Cdc-6 and the ORC

Which phase am I describing? cell growth and prepare for M phase check for DNA damage check DNA is completely replicated

Which phase am I describing? cohesins and condensins help configure duplicated chromosomes for separation mitosis and cytokinesis

M phase

M-Cdk drives entry into M phase through _______

positive feedback loop

what are the 2 cytoskeletal structures that mediate M phase?

mitotic spindle and contractile ring

what filament is the mitotic spindle made of

microtubules

what filament is the contractile ring made of

actin and myosin

when does the mitotic spindle start to assemble

prophase

in what phase do chromosomes attach to the mitotic spindle

prometaphase

at what phase do chromosomes line up at the spindle equator

metaphase

what triggers sister-chromatid separation at anaphase

proteolysis

what prevents sister-chromatid separation

an unattached chromosome

in what phase does the nuclear envelope reassemble

telophase

what phase am I describing? chromosomes condense centrosomes move apart mitotic spindles assemble

prophase

how is the bipolar mitotic spindle formed?

selective stabilization of interacting microtubules

what phase am I describing? nuclear envelope breaks down chromosome centromeres attach via kinetochores chromosomes actively move

prometaphase

dynamic microtubules extending throughout the cytoplasm

astral

what connects and stabilizes the spindle

interpolar microtubules

what has the ability to direct the assembly of a functional bipolar spindle in the absence of centrosomes

motor proteins and chromosomes

APC/C triggers the separation of sister chromatids by promoting the destruction of ________

cohesins

the force that PULLS sister chromatids apart is generated where?

kinetochore

what are the 2 forces that PUSH spindle poles apart?

1. elongation and sliding of the interpolar microtubules 2. forces exerted on the astral microtubules

what phase am I describing? sets of chromosomes arrive at spindle pores nuclear envelope reassembles contractile ring appears

telophase

what triggers the reformation of the nuclear envelope

de-phosphorylation of nuclear pore proteins and lamins

what determines the plane of cytoplasmic cleavage

mitotic spindle

what does the contractile ring do

divides the cell in two

exam four Flashcards

(200 cards)