BSC300 Yoder Cell Bio Exam 3

LDL (low density lipoproteins)

"bad" cholesterol, synthesized in the liver and delivers cholesterol to body cells via the bloodstream

adherens junctions

"belts" near apical surface, complexes that promote tight cell-cell contact

HDL (high density lipoproteins)

"good" cholesterol, transport cholesterol from tissues to the liver for excretion and are associated with lowering "bad cholesterol" levels

filopodia

(aka microspikes) probing extensions that reside within lamellipodia

*Current model of movement through the Golgi complex: cisternae mature and progress from cis to trans side of the complex. Transport vesicles move in a retrograde fashion (from trans toward medial and cis) delivering Golgi resident proteins (enzymes) back to appropriate locations.

*Current model of movement through the Golgi complex: cisternae mature and progress from cis to trans side of the complex. Transport vesicles move in a retrograde fashion (from trans toward medial and cis) delivering Golgi resident proteins (enzymes) back to appropriate locations.

*Newly synthesized proteins leave the ER via transport vesicles through the ERGIC which fuse with the cis-Golgi network (CGN). Proteins pass through the medial to the trans-Golgi network (TGN), and along the way are further modified, depending on protein function and final destination.

*Newly synthesized proteins leave the ER via transport vesicles through the ERGIC which fuse with the cis-Golgi network (CGN). Proteins pass through the medial to the trans-Golgi network (TGN), and along the way are further modified, depending on protein function and final destination.

*The Golgi complex is not uniform from one end to the other. The various Golgi regions have different compositions of enzymes that modify and process proteins differently.

*The Golgi complex is not uniform from one end to the other. The various Golgi regions have different compositions of enzymes that modify and process proteins differently.

*Though distinct for each tissue, the ECM is generally composed of: long, fibrous proteins that form a mesh-like network surrounding the cell, highly glycosylated proteoglycans that cushion the cell, transmembrane proteins that are interconnected to these extracellular molecules and respond to both mechanical and chemical signals.

*Though distinct for each tissue, the ECM is generally composed of: long, fibrous proteins that form a mesh-like network surrounding the cell, highly glycosylated proteoglycans that cushion the cell, transmembrane proteins that are interconnected to these extracellular molecules and respond to both mechanical and chemical signals.

unfolded protein response (UPR)

1)halt protein translation to prevent accumulation of misfiled proteins 2)degrade misfolded proteins 3)activate signaling pathways that lead to increased production of ER chaperones triggered in condition of extreme stress (heat, sickness) where misfoled proteins are generated more quickly than ERAD system can process them

organelle-specific enzymes interconvert lipids, inclusion/exclusion process during vesicle formation, lipid-transfer proteins bind and transport lipids without the use of vesicle transport

3 factors contributing to variation of organelle lipid composition

central sheath, radial spoke, interdoublet bridge

A proteinaceous _______________ connects the inner microtubule pair of an axoneme to the outer tubule doublets by _____________ protein complexes. Doublets are interconnected to one another by an _______________.

flippases

ATP-dependent and lipid specific, catalyze uni-directional leaflet translocation, responsible for establishing lipid asymmetry (for example, the cytoplasmic leaflet localization of phosphatidylserine), help to establish the asymmetry of the membrane

motor proteins

ATP-hydrolysis protein machines that bind specific cargo, like vesicles or organelles, via adapter proteins; move unidirectionally along the appropriate cytoskeletal track in a step-wise manner

transverse (T) tubules

Action potential in muscles is propagated into the cell interior by _______________, plasma membrane involutions that connects to the SR (sarcoplasmic reticulum).

phosphorylation state

Activity of MAPs is controlled by their _______________.

dolichol phosphate

All proteins originating in the endomembrane system are initially glycosylated by a core carbohydrate chain of 14 sugar monomers. It is assembled and covalently linked to the lipid carrier ________________ (2NAG, 9 mannose, 3 glucose monomers arranged in trident orientation).

AP2

Binding of a(n) ______________ adapter to PI(4,5)P2 causes a conformational change exposing the cargo binding site, allowing interaction with specific membrane receptors.

caged lattice

COPII Coated Vesicles: Adapter complex (adapter proteins) recruits two additional sec proteins that aggregate the cargo and spontaneously assemble as a ________________ surrounding the membrane vesicle, pinching it free of the ER membrane.

free ribosomes

Cytosolic proteins, peripheral membrane proteins, nuclear proteins, and proteins destined for chloroplasts, mitochondria, and peroxisomes are generated by ______________________.

neural plate

During embryonic development, ectodermal cells elongate and form a _____________ as microtubules become oriented parallel to the cell's axis.

connexin, connexon

Each channel of a gap junction is composed of six copies of the transmembrane protein __________ which are organized into a complex called a ____________. These complexes between adjacent cells create a gap junction.

N-terminus signal sequence

Free or RER synthesis is determined by amino acid sequences. Proteins destined for RER synthesis possess a _____________________.

Rabs

G-protein family that provide specificity between vesicle and target membrane, motor proteins deliver the vesicles via movement along the microtubule network

keratin

Hemidesmosomes contain a dense plaque with intermediate filaments consisting of the protein ____________ projecting into the cytoplasm.

integrins

IM receptor proteins that hold the ECM in stable attachment to the cell, animal-specific transmembrane heterodimers with distinct alpha and beta subunits, critical in anchoring cells to substratum or other cells and in integrating extracellular and intracellular environments via 2-way signaling

prolines and lysines

In collagen, ____________________ (amino acids) are heavily hydroxylated by specific enzymes allowing cross linking via H-bonds stabilizing the trimer.

hyaluronic acid

In the ECM, proteoglycans are cross-linked to a non sulfated GAG (glycosaminoglycan), _________________________, forming a giant complex that resists crushing forces, cushions cells, provides binding sites for growth hormones to protect from proteases, and regulates diffusion of small signaling molecules in developing embryos.

inactive, cannot

In the GDP bound state, G-proteins are (active/inactive) and (can/cannot) interact with target proteins.

active, can

In the GTP bound state, G-proteins are (active/inactive) and (can/cannot) regulate other proteins via direct allosteric interactions.

troponin, tropomyosin

In the unstimulated state, tropomyosin blocks myosin binding sites on actin monomers. Following impulse, released Ca2+ binds to _____________, causing a conformational change that shifts ____________ exposing myosin binding sites

ATP

Kinesin moves in a hand-over-hand model at a velocity proportional to the concentration of ______________.

ER

Most membrane lipids are synthesized entirely within the ______________.

oligosaccharide additions

Most proteins produced in the ER and processed in the Golgi are extensively modified by _________________.

processive

Movement of kinesin is __________________: motor protein moves in a hand-over-hand model along an individual microtubule for a long distance without falling off

I-IV, V

Of the 5 classes of intermediate filaments, type(s) ___________ is/are cytoplasmic, while type(s) ___________ is/are present in the inner lining of the nuclear envelope

independent, actin microfilaments

Phagocytosis is clathrin (dependent/independent), driven by __________________ extending pseudopods around extracellular material to form a phagosome.

retention, retrieval

Proteins are kept in the ER by one of two mechanisms: ________________ of resident molecules based on physical properties like solubility or association with large portion complexes. ________________ of "escaped" molecules back to the compartment where they reside (via the identification of "retrieval signals" in the amino acid sequence).

dissociation

Sar-mediated hydrolysis of GTP to GDP causes a conformation change and _________________ of the COPII protein lattice from vesicles.

early endosomes, late endosomes

Signaling receptors are kept within the ____________ which fuse and mature into _____________ (which have an even lower pH). After fusion, these units fuse with lysosomes and their products are degraded and either exocytosed or used as building blocks for metabolic processes.

plus-end

The _____________ of the microtubule terminates with beta-subunits and is the dynamic end where growth and disassembly occurs.

minus-end

The _______________ of the microtubule terminates with alpha-subunits and is static; it does not experience growth or disassembly.

actin

The dynamic cytoskeletal element of microfilaments is a polymer of _______________ monomers, arranged in a consistent, polar fashion into two-stranded, helical, rope-like structures

v-SNAREs, t-SNAREs

______________ (which attach to the vesicle membrane) and ______________ (which attach to the target membrane) have complementary domains that promote fusion of the two lipid bilayers.

dynamin

a G-protein required for release of clathrin-coated vesicles from the membrane; polymerizes around the neck of the budding vesicle, GTP hydrolysis cause conformation change that twists the neck, pinching it free of the plasma membrane

RNA interference

a genetic technique that blocks translation of a specific mRNA (generates a loss of function phenotype for the associated gene), can be used as a rapid screening approach to identify genes required for a specific process

green fluorescent protein (GFP)

a small protein isolated from a jellyfish that can be attached to different intracellular proteins to reveal their movement within a living cell

Golgi complex

a system of flattened, disk-like cisternae with dilated rims and associated vesicles and tubules

microfilaments

actin-based filament group that coordinates most animal cell motility, aspects of intercellular transport, muscle contraction, and cell division; polymerization is ATP dependent and monomers are ATPases

excitation-contraction coupling

action potential spreads to T tubules and travels down into the cell, causing the muscles to contract

inside-out signaling

activation of a number of cytoplasmic ligands binds the cytoplasmic tails and separates the alpha and beta chains; this induces a conformation change that allows integral to bind ECM ligands

ubiquitin ligases

add long chains of the protein ubiquitin to aberrant proteins as part of ERAD

O-linked glycosylation

addition of NAG sugar to the -OH group of specific serine and threonine residues of certain proteins, occurs exclusively in the Golgi

laminin

along with fibronectin, this protein plays an essential role as a road map for migrating cells during animal development

constitutive secretion

always occurring, functions to maintain the extracellular matrix and plasma membrane

extracellular matrix (ECM)

an organized network beyond the plasma membrane that plays key regulatory roles in determining cell shape and activities; extensively involved in cell signaling as it regulates diffusion of ligands and their interactions with receptors

centrosome

animal specific structures that initiate microtubule nucleation and regulate their dynamics, each contains two barrel-shaped centrioles

treadmilling

at low ATP-actin concentrations, filaments reach a steady state where addition to the plus end equals loss from the minus end (likely plays an important role at the leading edge of migrating cells to push the membrane forward)

centriole

barrel-shaped molecule that comprises centrosomes, composed of 9 triples of microtubules arranged in a pinwheel orientation (1 full and 2 incomplete microtubules in each triplet set)

signaling receptors

bind to extracellular molecules and initiate a cellular response (ex. divide, stop dividing, migrate, etc.)

troponin

binds and links actin and tropomyosin in the sarcomere

Sar1-GTP

binds the ER outer membrane and extends an alpha-helix into the outer leaflet, expanding the leaflet and initiating curvature

protofilaments

building blocks of microtubules, assembled from heterodimers of non-identical alpha- and beta-tubulin subunits

pinocytosis

category of endocytosis, aka bulk-phase endocytosis, nonspecific uptake of extracellular fluids that does not involve receptors or clathrin vesicles

glycocalyx

cell coat, a glycolprotein-polysaccharide covering that surrounds the cell membrane of epithelial cells, mediates cell-cell and cell-substratum interactions and provides mechanical protection to cells and inhibits the movement of extracellular material towards the plasma membrane, also helps facilitate the bind of important signaling molecules to the cell surface

mesenchymal cell

cells able to dissociate from an epithelium and migrate independently

axoneme

central microtubule core of both cilia and flagella, consist of microtubules in a 9+2 arrangement (9 doublets of microtubules surrounding a pari of central microtubules), nucleated by basal bodies and the plus-ends extend into the membrane surrounded cilia or flagella

subcellular fractionation

centrifugation that separates organelles based on density, buoyancy, or mass

BiP

chaperone proteins that inactivate membrane associated protein sensors (when gone, the sensors will relay information about misfolded proteins to activate UPR); if this molecule is accumulated as a result of an extended UPR, the loss of it activates apoptosis

unconventional myosins

class of myosin; can carry vesicles to sites within the cell, function cooperatively with microtubule motors to deliver targets to correct locations, often handing off or accepting cargo from dynein or kinesin motors

conventional myosin II

class of myosin; principal motor proteins that promote muscle contraction, migrate toward the plus end of microfilaments, also assist in cell division, tensile strength of focal adhesions, cell migration, and the direction of axonal growth cone movement; composed of 4 light chains and 2 heavy chains

receptor-mediated endocytosis

clathrin dependent uptake of specific extracellular ligands following their binding to specific transmembrane receptors

signal peptidase

cleaves the signal sequence once the ribosome-bound mRNA is in the RER lumen

fibrosis

common disease of many tissues caused by excessive production of collagen-containing connective tissue

TOM complex

complex found on the outer mitochondrial membrane that includes a pre-sequence receptors and channel to move unfolded protein into inter membrane space

ribosomes

complexes that translate mRNAs into protein

glycosylation

composition and arrangement of sugars for a protein; ultimately it is both cell-type and organelle specific (meaning that in different cell types, the same protein can be distinct); modifications can alter protein conformation or solubility, participate in inter- and intracellular signaling, protein-protein interaction, and cell-cell recognition

connective tissues

consist mostly of extracellular material secreted by the resident cells

neuromuscular junction

contact between nerve and muscle

plectin

cross-bridging protein that establishes connections between intermediate filaments (IFs) and other components of the cytoskeleton, organelles, and the nucleus

myofibrils

cylindrical actin-myosin rich strands that comprise skeletal muscle fibers, consists of a repeating array of sarcomeres

plasmodesmata

cytoplasmic channels passing through cell walls of adjacent plant cells

glycosyltransferase

destination-specify enzyme that catalyzes modification of ER synthesized proteins to produce species-, individual-, and cell-specific patterns

proteasomes

digests ubiquitin-tagged proteins as part of ERAD

Riemann-Pick disease

disease in which cholesterol cannot be transported out of the lysosomes, leading to neuronal degeneration and early childhood death

scurvy

disease resulting from vitamin C deficiency that prevents proline hydroxylation and collagen processing

desmosomes

disk-shaped adhesive junctions between cells, contain cadherins that link the two cells across a narrow gap

TIM complex

distinct inner membrane complex that directs the nascent protein to either the mitochondrial matrix (where the protein's N-terminal pre-sequence is removed) or as an integral inner membrane protein (pre-sequence is internal and not removed)

G-proteins

diverse family of small regulatory proteins that control function/activity of many proteins/enzymes; bind GTP and contain an intrinsic GTPase activity (hydrolyze GTP to GDP) that controls its on/off state

actin-binding proteins

diverse group of proteins that affect localized assembly/disassembly of actin filaments for the purpose of promoting crawling and phagocytosis, and as such their expression/activity are tightly regulated in response to stimuli

microtubule associated proteins (MAPs)

diverse group of proteins that attach to microtubules and function to increase or decrease stability by promoting either polymerization or disassembly

focal adhesions

docking sites were cells adhere to their substratum and send signals to the cell interior

epithelial-mesenchymal transition (EMT)

driven by cadherins, mediates many of the changes in adhesive contacts during embryonic development

endomembrane system

encompasses all membranes of the organelles; nucleus, endoplasmic reticulum, Golgi complex, endosomes, lysosomes, and vacuoles functioning as an interconnected but discontinuous coordinated unit

GTP

energy storage required molecule for microtubule assembly, form dimers to create a stabilizing cap for the plus-end

oligosaccharyltransferase

enzyme responsible for the transfer of multiple sugar groups to proteins (namely, proteins produced in the ER and modified in the Golgi)

oligosaccharyltransferase

enzyme that transfers glycan to specific asparagine residues within the sequence Asp-X-Ser/Thr

acid hydrolases

enzymes contained in lysosomes that can collectively digest every type of biological molecule, require a low pH (maintained by a proton pump) for activity

matrix metalloproteinases (MMPs)

enzymes secreted by migrating fibroblast cells that degrade ECM materials

glucosidases

enzymes which cleave 2 of the 3 terminal glucose monomers

UGGT

enzymes which inspects the new protein for proper folding

scramblases

evenly distribute lipids to both sides of the membrane, non-specific, do not require input of energy, help to establish the asymmetry of the membrane

outside-in signaling

extracellular ECM ligands (primarily collagen and fibronectin) can bind sites in some integral dimers inducing conformational change Such signaling leads to cytoplasmic interactions with diverse proteins that may affect: cytoskeletal dynamics, change in cell shape, cytoplasmic signaling cascades that lead to gene activation or inactivation, secretion of signaling molecules from other cells)

cis

face of the Golgi complex closest to the ER

trans

face of the Golgi complex closest to the outside of the cell

selectins

family of integral membrane glycoproteins that recognize and bind specific gylcosylation patterns on cell surface proteins; calcium-dependent; contain a small cytoplasmic domain, a single membrane-spanning domain, and a large extracellular segment; mediate transient interaction between migrating white blood cells (leukocytes) and blood vessel walls at sites of inflammation

collagens

fibrous glycoproteins found only in the ECM, most abundant proteins in the human body, provide high tensile strength, tetramer of helical polypeptide chains wound around each other

actin filaments

filaments that make up the cytoskeleton and are attached to the cytoplasmic domains of cadherin molecules via linking proteins like beta-catenin

ERGIC (ER-Golgi intermediate complex)

formed by the fusion of transport vesicles with each other, acts as a shuttle system that delivers proteins and newly synthesized lipids to the Golgi complex for further processing and sorting

alpha

gamma-tubulin only associates with ___________-tubulin, thus establishing microtubule polarity

intermediate filaments

heterogeneous group of proteins that assemble as strong, flexible, rope-like fibers that provide mechanical strength; less dynamic, highly stable; basic building block is a rod-like tetramer formed by two antiparallel dimers via spontaneous assembly

microtubules

hollow, cylindrical, rod-like structures that each contain an array of 13 protofilaments aligned longitudinally along its length

axonemal dynein

hydrolyzes ATP, providing the mechanical forces that promote both cilia and flagellar movement

actin, tropomyosin, troponin

identify in order, separated by commas

ER-associated degradation (ERAD)

improperly folded proteins are transferred to membrane associated ubiquitin ligases, such tagged proteins are exported to the cytoplasm where they are digested by proteasomes (ex: this is the fate of the CFTR proteins that fail to fold properly in people with cystic fibrosis)

collagen type IV

instead of forming fibrils, this type of collagen is non-fibrillar and is restricted to the basement membrane

intraflagellar transport

kinesin and dynein transport materials into and out of both growing and mature cellular movement structures, promoting growth and maintenance

cadherins

large family of glycoproteins that mediate Ca2+-dependent cell-cell adhesion; join cells of similar types to one another; also involved in transmitting signals from the ECM to the cytoplasm

fibroblasts

largely autonomous, non-connected, motile cells that secrete materials of the connective tissues (ex. dermis of skin, cartilage)

beta-catenin

linking protein that assists in connecting the cytoplasmic domains of cadherin molecules to the actin filaments of the cytoskeleton

keratin

major structural proteins of epithelial cells establishing a protective barrier in such tissues

neurofilaments

major supporting network in neuronal axons, type of intermediate filament

coated vesicles

membraneous sacs surrounded by specific protein networks, used to carry materials between endomembrane compartments

endoplasmic reticulum

membranous network, continuous with the outer nuclear membrane, that penetrates into much of the cytoplasm, highly dynamic

vesicular transport model

model of movement through Golgi complex (combined with competing model to give our current model) in which cargo is shuttled from the CGN toward the TGN in vesicles; the actual stacks remain relatively unchanged

cisternal maturation model

model of movement through Golgi complex (combined with competing model to give our current model) in which each cisternae "matures" as it moves from the cis face to the trans face; cis face forms from fusion of vesicles arriving from her ER and cisternae mature as they progress toward the trans face

myosins

molecular motors of actin filaments, divided into two groups: conventional (type II) and unconventional (types I, III-XVIII)

immunoglobulin superfamily (IgSF)

most are involved in immune function, however some mediate calcium-independent cell-cell interactions; includes VCAM (vascular cell-adhesion molecule), NCAM (neural cell-adhesion molecule), and L1 (neural development)

myosin

motor protein that moves along microfilament tracks

dynein

motor protein that moves towards the minus-end of microtubules (towards the nucleus), also responsible for the movement of cilia and flagella, moves like a "drunken sailor" due to large head size

kinesin

motor protein that moves towards the plus-end of microtubules (away from the nucleus), heterotetramer of two heavy chains and two light chains, moves in a hand-over-hand model due to smaller head unit

clathrin-coated vesicles

move materials from TGN to endosomes, lysosomes, and become secretory granules destined for plasma membrane (anterograde); also import proteins from the plasma membrane (retrograde).

retrograde

movement "backward" from the ERGIC and Golgi back to the ER, or from the trans Golgi to the cis Golgi cisternae

anterograde

movement "forward" from the ER to the ERGIC and Golgi, or from the cis Golgi to the trans Golgi cisternae

skeletal muscle fibers

multinucleate cells resulting from embryonic fusion of myoblasts and are associated as sheathed muscle bundles within skeletal muscles, each fiber contains hundreds of myofibrils

sarcomeres

muscle contractile units with a stereotypical arrangement of actin and myosin fibers, each has a distinct banding pattern due to the overlap of thick filaments and thin filaments

basal bodies

name given to centrioles found at the base of eukaryotic cilia and flagella, they coordinate growth and organization of the microtubules in these motility structures

medial network

name given to the area of the Golgi complex between the cis face and trans face

Sec proteins

name of the 4 structural proteins that compose the COPII vesicle coat; on the cytoplasmic surface of the ER, these Sec proteins recognize and bind soluble cargo receptors and ER export signal sequences of TM (transmembrane) proteins

signal recognition particle (SRP)

name of the protein that recognizes an N-terminus signal sequence on a piece of mRNA

lamins

name of type V intermediate filaments which are present in the nuclear envelope

TOC and TIC

names of both protein complexes that import chloroplast targeted proteins

pericentriolar material (PCM)

nebulous load of various accessory proteins that surrounds centrioles

cisternae

network of flattened sacs that composes the endoplasmic reticulum (both RER and SER)

cytonemes

new type of cell-cell communication, also called "tunneling nanotubes", protrusions that extend from the plasma membrane that enable different animal cells to touch over long distances

tropomyosin

occupies the gap between the two actin strands of the sarcomere, inhibits myosin from binding to the actin filaments

gap junction

open channels between animal cells that allow cytoplasmic sharing and intercellular communication, play an important role in ion passage (allowing muscle cells to contract synchronously)

trans-Golgi network

packaging station where proteins are segregated into different types of membrane enclosed vesicles for delivery to the plasma membrane or organelles

protein coats

part of a coated vesicle, they have 2 functions: to curve the membrane, forming spherical vesicles that detach from cisternae, and to select components to be carried by the vesicle, cargo (proteins/lipids) as well as targeting and docking proteins

Z line

part of sarcomere; anchor proteins that form the boundaries between sarcomeres; where actin filament plus ends are bound; minus ends extend toward sarcomere center

H zone

part of sarcomere; myosin tails only (center of sarcomere)

M line

part of sarcomere; the middle of the sacromere where tails of antiparallel myosin fibers overlap

A band

part of sarcomere; thick filaments, myosin filaments engaging with actin filaments

I band

part of sarcomere; thin filament, actin filaments only

cortex

plasma membrane under which the majority of actin is restricted

smooth endoplasmic reticulum (SER)

primary site of lipid synthesis, detoxifies various organic compounds (liver), synthesizes steroid hormones in endocrine cells, sequesters calcium ions from cytoplasm of muscle cells (highly regulated), continuous with the RER

endocytosis

process by which material (cell surface receptors and bound extracellular ligands) is taken up by the cell

exocytosis

process by which material leaves the cell

N-linked glycosylation

process by which new covalent bonds are formed between a sugar and the nitrogen within the side chain of asparagine, plays a critical role in evaluating proper folding of proteins as they are translated and processed in the ER

autophagy

process in which an organelle is surrounded by a double membrane forming an autophagosome, which fuses with lysosomes allowing compartmentalized digestion; while some material is exocytosed, a large amount is recycled as metabolites for cellular activities

ER quality control (ERQC) system

process that ensures proper folding of ER synthesized proteins

titin

protein (giant, long, elastic fiber) that extends from the Z line to the M band - providing elasticity, resting tension, and preventing the sarcomere from being pulled apart during muscle stretching

fibronectin

protein that facilitates interactions between ECM components, transmits mechanical force as signals to attached cells which relay this information to the cell interior for responses via the integrin receptors

translocon complex

protein that mediates RER protein translocation, mRNA is bound and delivered here by SRP

proteoglycans

protein-polysaccharide complex with a core protein attached to glycosaminoglycans (GAGs) - each GAG chain has a repeating disaccharide structure, extremely acidic due to the presence of both sulfate and carboxyl groups

WASP proteins

proteins that are activated via stimulus at the cell surface and, upon activation, recruit and activate Arp2/3 G protein complex

SNAREs

proteins that promote fusion of the vesicle and target membrane

lipid-transfer proteins

proteins which bind and transport lipids without the use of vesicle transport

lamellipodium

protruding leading edge formed along a substrate as a result of force generated by the receipt of a chemotactic extracellular signal

adapter proteins

recruited by activated Sar-GTP, finds and binds appropriate cargo receptors and transmembrane proteins, aggregating them into a confined space, this recruitment continues to curve the ER membrane; aka sec 23/24 proteins

housekeeping receptors

responsible for continuous uptake of material necessary for general activities (like LDL receptors); after internalization, these are recycled back to the membrane for reuse

gamma-TURKS (gamma-tubulin ring complexes)

ring structures formed by gamma-tubulin in the pericentiolar material, same diameter as a microtubule, serves as the seed site for polymerization of the alpha- or beta-tubulin dimers, can be assembled on established microtubules to promote branching

hemidesmosomes

rivets that promote basal attachment of epithelial cells to the basement membrane

regulated secretion

secretion occurs only in response to a specific stimulus (ex: digestive enzymes of pancreatic cells, neurotransmitters, hormones)

epithelial

sheets of closely packed cells tightly connected to one another and a defined extracellular material (the basement membrane), form a protective barrier that line both the external surface and internal cavities and lumina of tissues

transport vesicles

shuttle materials (mainly proteins and lipids) back and forth, most materials end up leaving the cell

ER export signal

signal in peptide sequence of proteins bound for deliver to the Golgi, faces the cytoplasm, (in soluble proteins) this signal is recognized and bound by specific COPII cargo receptor proteins

cis-Golgi network

sorting station, distinguishes proteins that need to be shipped back to ER from those that will be distributed throughout the endomembrane system

endosomes

sorting stations formed by the fusion of vesicles with other vesicles and tubules after internalization

basement membrane (basal lamina)

specialized ECM under the basal surface of epithelia, a continuous sheet that maintains cell attachment, provides signals for cell survival (survival of most cells is contact dependent), separate distinct tissues within an organ, serves as substratum for cell migration, forms a barrier to macromolecules

tight junctions

specialized contacts between epithelial cells, prevent H2O and solutes from squeezing in-between cells, located apical to junctional complex between cells composed of the two TM proteins occludins and claudins, some are permeable to specific ions or solutes

microtubule-organizing centers (MTOCs)

specialized structures for nucleation and assembly of microtubules

RGD

specific ligand squence possessed by extracellular proteins that interact with integrins

dynamic instability

spontaneous disassembly of microtubules, occurs when the incorporation of new GTP-bound dimers is slower than the rate of GTP-hydrolysis

clathrin coated pits

substances that enter the cell through clathrin-mediated RME (receptor-mediated endocytosis) become bound to _________________ on the plasma membrane; these regions invaginate and then pinch free into the cytoplasm

situs inversus

syndrome that often results from mutations in genes encoding ciliary proteins, inability to circulate signaling molecules during early animal embryogenesis, results in left-right body symmetry is reversed compared to the normal state

biosynthetic or secretory pathway

synthesis, modification, and transport of proteins and lipids through the endomembrane system for ultimate release from secretory cells

rough endoplasmic reticulum (RER)

synthesizes proteins to be part of the endomembrane system or exocytosed from the cell, covered in ribosomes on cytosolic surface, continuous with the outer membrane of the nuclear envelope

pre-sequence

targeting sequence found on the unfolded proteins that are destined for the mitochondria or chloroplasts

metastasis

the ability of some cancer cells to spread beyond their original site due to changes in their cell-adhesion properties (are less adhesive (cadherins), no longer anchorage dependent (interns), are able to penetrate several barriers (MMPs), are able to invade normal tissues (MMPs, EMT)

occludins and claudins

the two transmembrane proteins that make up a tight junction

triskelion

three heavy and three light chains of clathrin linked together

microtubules, microfilaments, and intermediate filaments

three types of filamentous protein structures that make up the cytoskeleton, polymers of protein subunits held together by weak, non-covalent interactions, highly dynamic

growth cones

tip of migrating neuronal axons

sliding-microtubule mechanism

tubules are fixed in position by radial spokes and the basal body; therefore, when dynein hydrolyzes ATP and attempts to "walk" towards the minus ends of associated beta-tubules, this causes adjacent microtubules to slide past one another; by precisely controlling when and which dynes hydrolyze ATP, distinct patterns of ciliary and flagellar movements are coordinated

calnezin and calreticulin

two chaperones that are part of the ERQC system and promote proper folding of the monoglucosylated polypeptide by preventing aggregation and premature export from the ER

E-selectin

type of selectin on endothelial cells

P-selectin

type of selectin on platelets and endothelial cells

L-selectin

type of selectin on white blood cells

gamma-tubulin

type of tubulin which is localized to the PCM and is critical for MT (microtubule) nucleation, serves as a protective cap for the minus-end, preventing it from being disassembled

phagocytosis

uptake of particulate matter

autoradiography

uses radioactive labeled materials and exposure to photographic film to analyze diverse biological processes

COPI-coated vesicles

vesicles that move materials in a retrograde fashion

COPII-coated vesicles

vesicles that move materials in an anterograde fashion