BIOL230,EXAM4

smooth ER deals with

hormones and Ca2+ in cytosol for muscle contraction

The Retinoblastoma (Rb) protein blocks cells from entering the cell cycle by ______.

inhibiting cyclin transcription.

steps of mitosis (MPHASE)

prophase, Prometaphase, Metaphase, Anaphase, Telophase, Cytokinesis

microtubules must have organizing centers (ex: centrosome) in order to stay

protected from depolymerization(loss of dimers), (-) ends are protected by these organizing centers, (+) are usually free but can be stabilized by binding to capping proteins, when stabilized results in an organized system

clathrin

protein that coats the inward-facing surface of the plasma membrane and assists in the formation of specialized structures, like coated pits, for phagocytosis, pinches off the vesicle

p21

protein thatbinds to G1/S-Cdk and S-Cdk and inactivates them cell cycle regulatory protein that inhibits the cell cycle; its levels are controlled by p53

(Q007) Microtubules are made up of 13 ___________ that are linear chains of ___________.

protofilaments; tubulin dimers

(Q002) Which of the following is an important function of intermediate filaments?

providing tensile strength to the cell and the nucleus

(Q020) Shown below is a diagram of how theoretical intracellular signaling pathways could integrate incoming signals to produce a coordinated cell response. Which signal(s) would lead to activation of both kinase 1 and kinase 2?

signals A and D

anaphase A

sister chromatids are PULLED toward opposite poles (depolymerization)

anaphase B

sister chromatids are PULLED toward opposite poles (depolymerization)

anaphase

sister chromatids separate and pull at spindles and the microtubules get shorter and move apart

Lysosomes

small sacs of digestive enzymes degrade molecules and organelles by endocytosis, after going through endosomes which sort their shit

Parent cell doubles its contents and then divides in two which produces

two genetically identical daughter cells

Activated M-CdK→

turns ON APC/C

(Q005) Which of the following compartments receives proteins directly from cytosol?

peroxisomes

metaphase

chromosomes are aligned to the center between the spindle poles, the microtubules attach to opposite poles of the spindle

intermediate filaments polarity is??

both ends are the same so theres no polarity, monomer(single), dimer(double, tetramer(two dimers coiled in opposite directions)

(APC/C) marks the protein for destruction in proteasomes:

(M-cyclin degradation → events to exit M phase),

Contraction: from sliding:

1. Cell sends out protrusions 2. Protrusions adhere to surface (transmembrane proteins adhere to the ECM or surface of neighboring cell) 3. Rest of the cell drags

flagella move how

propel a cell through wavelike motions.

Two protein compartments help guide ER signal sequences to the ER membrane

SRP and SRP receptor

Tropomyosin

A protein of muscle that forms a complex with troponin regulating the interaction of actin and myosin in muscular contraction(binds ca2+)

receptor tyrosine kinase (RTK)

A receptor protein spanning the plasma membrane, the cytoplasmic (intracellular) part of which can catalyze the transfer of a phosphate group from ATP to a tyrosine on another protein. Receptor tyrosine kinases often respond to the binding of a signaling molecule by dimerizing and then phosphorylating a tyrosine on the cytoplasmic portion of the other receptor in the dimer.

seond step of contraction

AP causes opening of voltage-gated Ca2+ channel in the T-tubule

Actin monomer has a binding site for

ATP or ADP, the monomers within point in the same direction in a twist due to polarity. (+) end grows faster

first step of contraction

Action potential passes along the plasma membrane into T-tubules

Transcription regulators released ↓

Activate the transcription of genes required for entry into S phase

S phase: what happens (interphase)

Activates helicases, Promotes assembly of proteins at replication fork, Prevents re-replication by phosphorylating (inactivates) Cdc6 and ORC

how do proteins enter peroxisomes from ER

Arrive via vesicles that fuse, Vesicles form mature peroxisomes

Activated RTKs lead to

formation of signaling complexes on the cytosolic tail of RTK which activates a cascade of intracellular signaling pathways.

Akt phosphorylates and inactivates a cytosolic protein called

Bad

cilium move how

fully extend and move fluid over the surface of the cell, POWER STROKE

(Q009) Which of the following accurately describes a step in GTP-driven nuclear transport?

Binding of Ran-GTP to the receptor releases the cargo protein.

Exocytosis is

fusion of the vacuole membrane with the cell membrane which delivers whatever it was transporting.

(Q013) How do clathrin-coated vesicles select their cargo molecules?

Cargo receptors bind specifically to cargo proteins and to clathrin.

Ran-GEF (guanine nucleotide exchange factor):

Causes RAN-GDP to release GDP and bind GTP ***Nucleus side Only

M-Cdk is activated by

Cdc25 which removes the 2 phosphates

Cdk can be blocked by

Cdk inhibitor proteins

Ran

a GTPase that mediates nuclear transport,

What is GTPase activity?

Cleavage of a bound GTP to GDP.

The Cell-Cycle Control System

Depends on Cyclically Activated Protein Kinases Called Cdks:

Contraction is triggered by

a Sudden Rise in Cytosolic Ca2+ from the sarcoplasmic reticulum

(Q012) Which of the following is a difference between exocytic and endocytic pathways?

Exocytic pathways often start with synthesis of proteins, whereas endocytic pathways involve breaking down macromolecules like proteins.

(Q019) When an action potential excites a muscle cell,---- where do the calcium ions come from?

both the extracellular space and the sarcoplasmic reticulum

(Q017) Which of the following is NOT an intracellular signaling protein activated by an RTK?

G-protein

(Q002) Which of the following organelles is surrounded by a single membrane?

Golgi apparatus

(Q028) Akt promotes the survival of many cells by affecting the activity of Bad and Bcl2, as diagrammed in Figure 16-28.

In the absence of a survival signal, Bad is phosphorylated.

Activate G1-Cdks and G1/S Cdks ↓

Inactivate Rb(Rb = retinoblastoma protein (abundant in the nuclei of all vertebrate cells) ↓

What is the mechanism of transduction for a G protein-coupled receptor?

Initiating the exchange of bound GDP for GTP.

Separation of centrosomes begins in early

M phase(Form anti-parallel MTs = bipolar spindle)

What does Cdc25 regulate?

M-Cdk

M phase:

M-Cdk Drives Entry into Mitosis, Cohesins and Condensins Help Configure Duplicated Chromosomes for Separation,

(Q029) When the cytosolic tail of the __________ receptor is cleaved, it migrates to the nucleus and affects gene regulation.

Notch

(Q009) The figure below shows some steps involved in the initiation of DNA replication. What is the identity of the complex labeled "B"?

ORC

third step of contraction

Physical linkage opens the Ca2+-release channel in the sarcoplasmic reticulum

microtubules polarity:::

Polarity!!!, β-tubulin at one end (+), α-tubulin at other end (-) which goes towards γ-tubulin

(Q018) If Ras contains a mutation that leads to a defect in GTP hydrolysis, this could fuel uncontrolled proliferation in cancer because

Ras is able to signal to downstream pathways inappropriately.

What is the function of a phosphatase?

Removal of a covalently attached phosphate group from a protein.

fourth step of contraction

Results in the release of Ca2+ from the sarcoplasmic reticulum into the cytosol

In S phase(synthesis of DNA):

S-Cdk Initiates DNA Replication and Blocks Re-Replication, Replication needs to happen one time and only one time, Incomplete Replication Can Arrest the Cell Cycle in G2

Specific Rab proteins(monomeric GTPase that activates a tethering protein) on the surface of each type of vesicles are recognized by corresponding tethering proteins, additional recognition is provided by proteins called

SNAREs

how do proteins enter peroxisomes from cytosol

Sequence recognized by receptor protein in cytosol, Proteins can be escorted in, Translocators aids in pro transport (no unfolding!)

Ras

Small GTP-binding protein (monomeric GTPase) Bound to cytosolic side of membrane by lipid tail Resembles alpha subunit of a G protein Molecular switch (Activated by RTKs on= GTP off= GDP)

how microtubules be living

Some grow by adding dimers to (+) end, others shrink by loss of dimers

(Q016) How does the binding of a signal molecule activate an RTK for downstream signaling?

The RTK forms a dimer and cross-phosphorylates itself.

(Q016) If a chromosome is attached to two microtubules from opposite poles and one of the microtubules is experimentally severed, what occurs?

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

(Q019) What determines the position of the cleavage furrow of the dividing cell?

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

Endoplasmic Reticulum ER:

The transportation system of the cell. It moves materials around the cell

Akt indirectly activates

Tor (large serine/threonine kinase)

Inactivate Rb(Rb = retinoblastoma protein (abundant in the nuclei of all vertebrate cells) ↓

Transcription regulators released ↓

Unattached chromosome will stop things:

Unattached kinetochores send "stop" signal, Blocks activation of APC/C Sister chromatids remain glued *Also prevents cyclin degradation (prolongs mitosis)

in vesicular transport, Transport Vesicles Carry Soluble Proteins and Membrane Between Compartments

Usually goes from ER lumen or membrane to golgi to be modified, this transport is carried out by vesicle transporters

As soon as M-Cdk complex forms it is inhibited by

Wee 1 (adds 2 phosphates)

(Q011) A single-pass transmembrane protein destined for one of the organelles in the endomembrane system would be marked by what type of signal sequence?

a cleaved N-terminal ER signal sequence and an internal stop-transfer sequence

RAN-GAP (GTPase Activating Protein):

Will cause RAN to hydrolyze GTP to GDP ***Cytosol side Only

Sarcomeres:

Z discs at either end are attachment points for the (+) ends of the actin filaments

The nuclear envelope is supported by

a meshwork of intermediate filaments , intermediate filaments of the nuclear lamina line the inner face of the nuclear envelope in order to provide attachment sites for the chromosomes

The growth factor Superchick stimulates the proliferation of cultured chicken cells. The receptor that binds Superchick is a receptor tyrosine kinase (RTK), and many chicken tumor cell lines have mutations in the gene that encodes this receptor. Which of the following types of mutation would be expected to promote uncontrolled cell proliferation?

a mutation that inactivates the protein tyrosine phosphatase that normally removes the phosphates from tyrosines on the activated receptor

myosin I

binds and hydrolyzes ATP moves to the (+) end of actin filaments, then moves the vesicle attached to the other end of the myosin I tail.

(Q020) The contractile ring is composed of

actin and myosin.

Myosin-I can also bind to an

actin filament in the cell cortex, ultimately pulling the plasma membrane into a new shape

A web of actin filaments pushes the leading edge forward...

actin-binding proteins influence the type of protrusions formed at the leading edge, capping prevents them from dying off,

The cleavage furrow is formed by the

action of the contractile ring underneath the plasma membrane,

When the cell is in the M-phase, M-Cdk does what

activity increases

(Q036) Figure 16-36 shows how normal signaling works with a Ras protein acting downstream of an RTK. You examine a cell line with a constitutively active Ras protein that is always signaling. Which of the following conditions will turn off signaling in this cell line?

addition of a drug that blocks protein Y from interacting with its target

Conditions inside Golgi lead to

aggregation (acidic and high in Calcium ions)

intermediate nuclear lamins in

all animal cells

troponin complexes

binds to the grooves of actin preventing myosin from binding). Ca2+ binding to the troponin complex leads to movement of tropomyosin away from the myosin-binding site

after mitosis checkpoint

are all chromosomes hanging onto mitotic spindle

From cytosol to nucleus protein sorting

are transported by nuclear pores, pores act as a gate and only let in specific things but allows freedom to small boys

Cytosol to ER, mitochondria, or chloroplasts protein sorting

are transported by protein transporters in the membrane, the protein unfolds in order to cross the hydrophobic insides

(Q015) 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 _________,

at the plus ends of newly polymerized actin filaments

(Q006) Microtubules extend from organizing centers in the cell. Which is an example of an organizing center?

basal body of a cilium

Mitotic spindle:

begins to exist in prophase, form anti-parallel MTs:bipolar spindle, interactions promote stability(nono to depolymerization), chromosomes attach to the mitotic spindle at prometaphase due to tension in microtubules

Bad stops apoptosis by

binding to and inhibiting a protein called Bcl2

What is the mechanism of transduction for an ion-channel-linked receptor?

gating of an ion channel

Myosin II filaments

can slide TWO actin filaments of OPPOSITE orientation past each other, the head walks towards the plus end and brings the two actin filament's minus ends keeping both attached

Rac

causes the formation of an enormous lamellipodium,

Pinocytosis:

cell drinking, ingestion of fluid and small things using pinocytotic vesicles.. Material is rapidly delivered to endosomes

Phagocytosis:

cell eating, ingestion of large things, using large phagosome vesicles

activated bad causes

cell suicide aka apoptosis

position of cleavage furrow is determined by the

central spindle, Interpolar microtubules recruit proteins that generate a signal (during anaphase)

S-Cdks and M-Cdks need to be disabled by the end of M phase: to

complete division, to prevent another round of division without time in G1

intermediate vimentin filaments in

connective tissue, muscle, and glial cells,

(Q002) During nervous-system development in Drosophila, the membrane-bound protein Delta acts as an inhibitory signal to prevent neighboring cells from developing into neuronal cells. Delta is involved in __________ signaling.

contact-dependent

Peroxisomes

contain enzymes that break down lipids and toxic molecules produce hydrogen peroxide

The outer nuclear membrane

continuous with the ER

Notch:

controls the development of neural cells in Drosophila, when activated the Receptor is cleaved by a protease. The released part of the cytosolic tail of Notch migrates to the nucleus, where it activates Notch-responsive genes-

Due to chemical properties, hormones can

cross the membrane, when hormones are bound they act as transcription regulators, each hormone binds to a different nuclear receptor

Cdks

cyclin-dependent kinases egulation through phosphorylation, Active Cdks phosphorylate intracellular proteins that regulate major events in cell

(Q003) The expression levels of different ___________ fluctuate throughout the cell cycle.

cyclins

C-term

cytosol, Transfer process stops when hydrophobic stop-transfer sequence enters the translocator, Translocator releases polypeptide sideways into the lipid bilayer, N-term signal seq is cleaved

(Q011) M-Cdk is suddenly activated at the end of G2 by

dephosphorylation by Cdc25.

(Q018) What drives the reassembly of the nuclear envelope?

dephosphorylation of lamins

turns ON APC/C→

destroys M cyclin(ubiquitylation)

Signal sequence:

direct proteins to the correct compartment, proteins are labeled with amino acid sequences called sorting signal, which is usually cleaved from final sorted protein

notch is a what route??

direct route to nucleus to control gene expression

step 2 of DNA DAMAGE REPAIR

p53 stimulates transcription of p21 gene(inhibits Cdk)

Mitochondria and chloroplast:

double membranes, highly specialized to make ATP, POWERHOUSE OF the mMOTHER****ING CELLL BROOO

G1-Cdk:

drive toward S phase

Prophase

duplicated chromosomes condensation and the mitotic spindle begins to assemble

SRP receptor-

embedded in the ER membrane, recognizes the SRP and binds to it which the receptor passes the ribosome to a protein translocation in the ER

Nuclear envelope:

encloses nuclear DNAand defines nuclear department, perforated by nuclear pores where proteins enter. A large rug of proteins which contain random disordered parts (hase two membranes outer and inner)

M-Cdk:

entry into M phase and the levels fall mid-mitosis

PI-kinase:

enzyme that phosphorylates inositol phospholipids in the plasma membrane, RTKs activate a pathway using PI-kinase 3 to promote cell growth, phosphorylated lipids serve as docking sites for specific signaling proteins such as Akt

(Q008) Which type of cell-surface receptor(s), when activated, catalyze(s) a reaction inside the cell?

enzyme-coupled receptors

intermediate keratin filaments in

epithelial cells

endosymbiosis

eukaryote ate a bacteria that was the mitochondria

Secretory Proteins Are Released from the Cell by

exocytosis

Mitogens:

extracellular chemicals produced by other cells that stimulate cell division

True or false: If a lysosome exploded the acid hydrolase would be at 7.2 pH, the same as cytosol so no damage would occur.

false

Intermediate filaments: are built like???

fibrous proteins, mechanical strength Strong and ropelike, grow longer by the addition of tetramer arrays to either end,

Actin filaments built how

globular actin, support cell surface, crawling, muscle contraction, Thin and helical, made of actin, flexible, found in bundles

Microtubules:

globular tubulin, organize cytoplasm, movement(form cilia) Long, hollow and straight made of rigid tubulin,

DNA Damage repair

halting progression through G1:

Nucleoplasm

has a double membrane known as the nuclear envelope and communicates with the cytosol using nuclear pores

(Q010) Proteins encoded by nuclear genes and destined for the mitochondrial matrix

have a signal sequence for targeting to the mitochondria.

why do proteins unfold to enter mitochondria?

have double layers, inner membrane in between, proteins need to cross it all, protein has already been fully synthesized in cytosol < a signal sequence needs to be recognized by the import receptor and translocator

making inhibitor proteins : By

having multiple control mechanisms inactivation of Cdk activity is ensured!

Condensins:

help coil each DNA double helix into a smaller, more compact structure that can be more easily segregated during mitosis

G1/S Cdk:

help launch S phase and stimulates chromosome duplication and early mitotic events

Cyclins

help regulate the activity of Cdks

(Q001) Which of the cytoskeletal structures are made up of protein subunits that are fibrous?

intermediate filaments

(Q008) Nuclear pores restrict larger molecules from traversing the membrane due to their

interwoven meshwork of protein fibrils.

before mitosis checkpoint

is all DNA replicated and damage repaired?

The inner nuclear membrane

is binding sites for chromosomes and anchors nuclear lamina

before S phase checkpoint

is environment good

inactivate S-Cdks and M-Cdks by:

killing cyclins, blocking new cyclins

What is the enzymatic activity of M-cdk?

kinase:an enzyme that catalyzes the transfer of a phosphate group from ATP to a specified molecule.

Monomeric GTPases

large family of small GTP-binding proteins, cycles between two different modes: on when GTP is bound and off when GDP is bound

Plectin

links an intermediate filament to microtubules, cross-links filaments into bundles and connects them to cytoskeleton and cell-cell junctions

**N-term

lumen, directed protein to ER and also OPENS the translocator. ER signal sequence remains bound to the translocator, the rest of polypeptide is threaded through

The lumen of the lysosome is

maintained at an acidic pH by an ATP-driven H+ pump in the membrane that hydrolyzes ATP to pump H+ into the lumen.

Peroxisomes and proteinssss

membrane bound, break down lipids, perform synthesis(make myelin) and detoxification in organelles

(Q029) Which word or phrase below best describes the phase in mitosis depicted in Figure 18-29?

metaphase

which is bigger, microtubule or actin?

microtubule

(Q012) Microtubules participate in the spatial polarization of nerve cells because

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

(Q005) Which of the following represents the placement of microtubules in an epithelial cell?

middle one

M-Cdk phosphorylates (activates)

more Cdk-activating phosphatase (Cdc25), creating a positive feedback loop, If Cdc25 is inhibited the cell will stay in the S-phase, This happens if replication does not occur properly,

Movement of cells::

most eukaryotic cells move by pulling themselves across surfaces. (ex. growth of axons, amoebas, neutrophils) using cortical actin

A skeletal muscle is full of

myofibrils which contract and are made of sarcomeres

Q016) Which of the following motor proteins has one head domain, moves along actin toward the plus end, and is found in all cell types?

myosin-I

Cytokinesis:

mytotic spindle determines the plane of cytoplasmic cleavage, the contractile ring of animal cells is made of actin and myosin filaments,

SRP

n cytosol, binds to both the ribosome and ER signal sequence as it emerges the ribosomes, slows down protein synthesis done by ribosome

Golgi bodies:

near nucleus, receives proteins and lipids from the ER and modifies them to bring them places,, single membrane

intermediate neurofilaments in

nerve cells

RNA is exported and protein is imported through

nuclear pore gate

(Q007) Fully folded proteins can be transported into which of the following organelles?

nucleus

Microtubules organize the cell interior by providing

orientation for directional transport in a cell like in axon

step 3 of DNA DAMAGE REPAIR

p21 protein binds to G1/S-Cdk and S-Cdk and inactivates them

binding of_____ moves the active site and makes it inactive and pauses cycle

p27

Q008) In response to DNA damage, the ___________ protein is phosphorylated and activates the transcription of a Cdk inhibitor to halt cell cycle progression.

p53

step 1 of DNA DAMAGE REPAIR

p53 is activated (phosphorylation)

What is the enzymatic activity of Cdc25?

phosphatase: an enzyme that catalyzes the hydrolysis of organic phosphates in a specified (acid or alkaline) environment.

What is the mechanism of transduction for a RTK?

phosphorylation of receptor dimers on the intracellular side

Akt protein(

promotes growth and survival of many cells by inactivating the signaling proteins it phosphorylates,

Rho

promotes the rapid assembly of bundles

(Q018) The binding of ATP causes a conformational change in myosin that

releases the myosin head from the actin filament.

rough ER has

ribosomes that actively synthesize proteins

sister chromatids tied until the

rings are broken late in mitosis

soluble proteins are made _____ and released in _______

rough ER, ER lumen

Where would mRNA translate a protein that has a sequence for the ER?

rough ER, where ribosomes are

Duplication begins at the start of ____ and is complete by _____

s phase, G2(Triggered by G1/S-Cdk and S-Cdk)

Cilia and flagella contain

stable microtubules moved by dynein.

Prometaphase:

starts when nuclear envelope begins to breakdown, chromosomes can now attach to spindle microtubules

Cdc42

stimulates the protrusion of filopodia

p53

stimulates transcription of p21 gene(inhibits Cdk) Molecule that prevents mitosis in cells with damaged DNA. Changes in its activity can result in cancer.

Secretory vesicles do what now

store and release concentrated proteins. and are further modified and sorted in the golgi

Vesicle Budding Is Driven by

the Assembly of a Protein Coat: vesicles that bud from membranes usually have a protein coat on their surface so they are called coated vesicles, they shed their coat after budding in order to better interact with membrane,

cytokinesis

the cytoplasm is divided in two by a contractile ring of actin and myosin filaments which pinch the cell into two separate daughter cellios

Cytosol

the goop that organelles and shit float around in!

telophase

the two sets of chromosomes are on opposite sides and a new nuclear envelope start to form around each and the division of the cytoplasm begins

MAP-kinase signaling module,

three-kinase module, part of the Ras phosphorylation cascade, ends with change in the pattern of gene expression may help cell grow and become whatever cell it needs to be.

(Q012) What is the function of condensins?

to coil sister chromatids into a compact form

Enzyme-coupled receptors:

transmembrane proteins that display their ligand-binding domains (which acts as an enzyme or forms a complex) on the outer surface of the plasma membrane

From the ER to wherever, protein sorting

transport vesicles which pinch off from their sport in membrane to fuse to membrane of another part which deliver soluble cargo proteins

APC/C:

triggers the separation of sister chromatids by promoting the destruction of cohesins, by anaphase-promoting-complex (APC/C) marks securin for destruction in proteasomes

Skeletal muscle contraction is controlled by

tropomyosin and troponin complexes

Activated RTKs can be reversed by

tyrosine phosphatases which remove the phosphates that were added to the tyrosines on both the RTK and other proteins,

Ras can be mutated and locked on which can cause

uncontrolled cell growth

(Q014) In which process do Rab proteins function?

vesicle tethering

Lysosomes:

where many particles and molecules end up after ingestion, contain hydrolytic enzymes that degrade proteins and lipids and stuff,

without plectin

your cells cannot withstand the mechanical stress of a body