Cell Biology Test 1

Front 1

G-Actin

Back 1

monomer of microfilaments

Front 2

F-Actin

Back 2

helical polymer of microfilaments

Hint 2

None

Front 3

lag phase of actin polymerization

Back 3

formation of actin trimer (nucleation site)

Front 4

Actin-binding proteins

Back 4

versatile family of proteins that crosslink actin filaments into loose gels, bind them into stiff bundles, attach to PM, or move them

Hint 4

None

Front 5

minimyosin (myosin 1)

Back 5

motor protein of actin filaments in non-muscle cells

Front 6

filamin

Back 6

protein that crosslinks actin filaments into gel

Front 7

spectrin

Back 7

protein that crosslinks filaments to PM by their sides

Front 8

fimbrin

Back 8

protein that bundles actin filaments

Front 9

α actinin

Back 9

protein that bundles actin filaments and links actin filament to viniculin at focal contacts

Front 10

gel solin

Back 10

calcium dependent protein that severs or fragments actin filaments

Front 11

cap-Z

Back 11

protein that caps the positive end of actin

Front 12

profilin

Back 12

protein that binds actin monomers and inhibits polymerization

Front 13

Cytochalasins

Back 13

drug that blocks cell movement by binding to + end of actin to block polymerization and inhibit motility, phagocytosis, organelle and vesicle trafficking and production of lamellipodia and filopodia

Front 14

Focal contacts

Back 14

place that actin attaches the cell PM to extracellular matrix

Front 15

Integrins

Back 15

family of transmembrane proteins that link ECM's fibronectin w/ cytoplasmic actin filaments of stress fibers with attachment proteins

Front 16

talin

Back 16

protein that links viniculin to integrin at focal contacts

Front 17

viniculin

Back 17

protein that links α actinin to talin at focal contacts

Front 18

integrins linkage at focal contacts

Back 18

transmembrane protein that links talin to fibronectin

Front 19

ankyrin

Back 19

protein mainly responsible for attaching the spectrin cytoskeleton to red cell PM

Front 20

filopodia

Back 20

thin stiff protrusions of the cell surface that form and reform quickly and contain a bundle of actin filaments

Front 21

lamellipodia

Back 21

thin sheetlike processes of cell surface made of actin filament involved in cell movement

Front 22

tubulin

Back 22

dimer of α and β tubulin. The subunit of microtubules

Front 23

protofilaments

Back 23

long parallel rows into which tubulin molecules align; 13 make a microtubule

Front 24

kinesins

Back 24

motor protein family that move along microtubules. Associated with ER

Front 25

dyneins

Back 25

motor protein family that move toward the α end of microtubules. Ciliary and cytoplasmic varietys exist and are associated with the golgi

Front 26

colchicine

Back 26

antimitotic drug which binds to free tubulin and prevents polymerization

Front 27

taxol

Back 27

antimitotic drug which binds to microtubules and prevents depolymerization

Front 28

γ-tubulin

Back 28

ring shaped structure of centrosome which acts as the nucleation-site of a microtubule

Front 29

dynamic instability

Back 29

property of microtubules based on rapid polymerization and depolymerization (if GTP of plus end is hydrolyzed before the next tubulin is added)

Front 30

centrioles

Back 30

pair of cylindrical microtubule structures in the centrosome

Front 31

arrangement of microtubules in centrioles

Back 31

9 + 0

Front 32

arrangement of microtubules in cilia

Back 32

9 + 2

Front 33

basal bodies

Back 33

accumulation of centrioles beneath the PM which initiate tubulin polymerization to form the axoneme of cilia or flagella

Front 34

arrangement of microtubules in basal bodies

Back 34

9 + 0

Front 35

axoneme

Back 35

core of each cilium with 9 microtubule doublets around a pair of unjoined mt's

Front 36

ciliary dynein

Back 36

protein that forms the arms that extend from subfiber A and hydrolyze ATP to generate a sliding force that moves cilia

Front 37

nexin

Back 37

protein that forms bridges to link adjacent doublets in axonemes

Front 38

radial spokes

Back 38

link the doublets to the sheath in axonemes

Front 39

sheath

Back 39

surrounds the central microtubule pair of axonemes

Front 40

effective stroke

Back 40

stiff rapid forward stroke of cilia

Front 41

recovery stroke

Back 41

slower bending stroke of cilia

Front 42

keratins

Back 42

cytoplasmic IF in epithelial cells and their derivatives

Front 43

vimentin

Back 43

IF in cytoplasm of cells of mesenchymal origin

Front 44

neurofilaments

Back 44

IF in cytoplasm of neurons

Front 45

lamins

Back 45

IF in nucleus

Front 46

filaggrin

Back 46

protein in epidermis of skin that bundles keratin IF into tonofilaments

Front 47

tonofilaments

Back 47

bundles of keratin IF

Front 48

Gated Transport

Back 48

Type of protein transport from the cytosol to the nucleus

Front 49

TransmembraneTransport

Back 49

Type of transport from the cytosol to the ER, Mitochondria, or peroxisomes

Front 50

Vesicular Transport

Back 50

Type of transport from the ER to the Lysosomes, golgi and cell curface

Front 51

Proteolysis

Back 51

enzymatically break down proteins into constituent amino acids

Front 52

Proteasomes

Back 52

large complexes of proteolytic enzymes

Front 53

Ubiquitin

Back 53

small protein that covalently attaches to proteins to mark them for destruction and to be recognized by proteasomes

Front 54

Cristae

Back 54

folds of the inner mitochondrial membrane

Front 55

Porins

Back 55

transport proteins which form large aqueous channels through the lipid bilayer of the mitochondria's outer membrane. Form a Beta barrel

Front 56

Inner Mitochondrial membrane components:

Back 56

ETC enzymes (FMN, coenzyme Q, cytochrome a,b,c), succinate dehydrogenase, ATP synthase

Front 57

Matrix Comparment contents:

Back 57

TCA enzymes, fatty acid β-oxidation enzymes, DNA, mRNA, tRNA, rRNA, Ca and Mg granules

Hint 57

None

Front 58

Peroxisomes

Back 58

spherical to ovoid membrane bound organelles w/ 50 oxidative enzymes

Front 59

catalase

Back 59

uses H2O2 to oxidize other substrates like alcohols, formaldehydes and formic acid (H2O2 + R'H2 --> R' + 2 H2O)

Front 60

Superoxide dismutase

Back 60

naturally occuring enzyme in peroxisome that disposes of free radicals

Front 61

transporter

Back 61

proteinaceous ring that occupies center of Nuclear pore complex and is supported by the scaffold

Front 62

Cage

Back 62

on the nuclear side of the NPC fibrils converge to form this structure

Front 63

Exportins

Back 63

transport macromolecules (RNA) from the nucleus to cytoplasm

Front 64

Importins

Back 64

transport cargo (like protein subunits of ribosomes) from the cytosol to the nucleus

Front 65

Contact sites

Back 65

Sites of adhesion between the inner and outer mitochondrial membranes through which unfolded proteins are translocated into the matrix from the cytosol

Front 66

Signal for protein to enter the mitochondria

Back 66

a positive charge on the N- terminus; 20-80 amino acids in length with an α helix; removed by signal peptidase once in destination

Front 67

Signal for protein to enter the nucleus; NLS

Back 67

short signal located anywhere within the polypeptide which is not removed and binds to the nuclear import receptors which direct it to the NPC; unidirectional transport only

Hint 67

None

Front 68

Signal for protein to enter peroxisomes:

Back 68

3 amino acid sequence on the C-terminal that remains on protein

Front 69

cistern

Back 69

lumen of the endoplasmic reticulum

Front 70

Signal recognition particles (SRP)

Back 70

particles in the cytosol that recognize protein ER signal sequence that attach to the P site and halts translation of the protein and migrates to the rough ER with the protein

Front 71

SRP receptor, docking protein

Back 71

Contacts the SRP and with ribosomal receptors attaches the polysome to the cytoplasmic surface of the ER; the SRP is released and translation resumed

Hint 71

None

Front 72

protein translocation channel

Back 72

channel in ER membrane through which the growing polypeptide chain inserts into a pore in the ER membrane

Hint 72

None

Front 73

Stop transfer sequence

Back 73

sequence of hydrophobic amino acids that releases the polypeptide chain from the protein translocation channel so it will drift into the bilayer of the ER forming an α-helix of the transmembrane protein (N-terminal in the lumen)

Hint 73

None

Front 74

start transfer sequence

Back 74

er signal sequence in the middle of the polypeptide and ends up forming a transmembrane protein that passes multiple times through the PM

Front 75

core region

Back 75

5 sugars (3 are mannose) of the 14 oligosaccaride to glycosylate proteins

Front 76

KDEL @ C-Terminal

Back 76

sorting signal on proteins that directs them away from the Golgi apparatus (or to stay in the ER)

Front 77

Exocytosis

Back 77

process of discharging large cellular products through plasma membrane

Front 78

acid phosphatase

Back 78

enzyme in all lysosomes

Front 79

primary lysosomes

Back 79

lysosomes that haven't entered a digestive event

Front 80

mannose-6-phosphate

Back 80

tag for lysosomal proteins; tagged in the CGN then sorted into clathrin coated transport vesicles

Hint 80

None

Front 81

KFERQ

Back 81

signal on protein to be taken up by lysosomes

Front 82

heterophagy

Back 82

process whereby lysosomes digest materials taken into cells from its environment by endocytosis

Front 83

Residual body

Back 83

any undigested materials in the phagosome or secondary lysosome which are released back into the extracellular fluid by exocytosis

Front 84

profesional phagocytes

Back 84

macrophages and neutrophils

Front 85

Autophagy

Back 85

process by which worn out organelles are digested

Front 86

autolysis

Back 86

process by which lysosomal enzymes destroy their own cell

Front 87

COP-I

Back 87

mediated transport vesicle from CGN to ER in retrograde transport

Hint 87

None

Front 88

COP-II

Back 88

involved in anterograde transport from the ER to CGN

Front 89

SNAREs

Back 89

family of transmembrane proteins involved in vesicle docking with unique recognition to ensure that transport vesicles fuse with only the correct membrane

Hint 89

None

Front 90

NSF and SNAPs

Back 90

fusion proteins which catalyze membrane fusions and form fusion complex that provide the means to cross this energy barrier

Front 91

apical domain

Back 91

region of PM that borders luminal space

Front 92

Basolateral domain

Back 92

region of PM in contact with extracellular matrix

Front 93

microvilli

Back 93

nonmotile rigid bundle of microfilaments bound by villin with + end at the tip

Front 94

terminal web

Back 94

dense network of actin filaments, spectrin and cytokeratin (IF)

Front 95

striated border microvilli

Back 95

shortest microvilli uniform in length and found on intestinal epithelium

Front 96

brush border

Back 96

microvilli that are longer and less uniform and found in proximal tubules of nephrons

Front 97

stereocilia

Back 97

long, nonmotile microvilli found in epididymal epithelium and hair cells in the inner ear

Front 98

intercellular secretory canaliculi

Back 98

increase surface area between cells for exocytosis in glands and terminate blindly above basal lamina

Front 99

basal infoldings

Back 99

invaginations of basal PM to increase basal contact SA with ECM; form labrynth that creates basal striations with mitochondria between

Front 100

What confine transport proteins to their appropriate domains by acting as a diffusion barrier?

Back 100

tight junctions (zonula occludens)

Front 101

zonula occludens (tight junction)

Back 101

junction between cells composed of strands of long rows of specific transmembrane proteins in each cells PMs which join directly to occlude intercellular space

Front 102

claudin

Back 102

protein in tight junctions that form linear fibrils to create diffusion barriers for solutes, ions and water

Hint 102

None

Front 103

occludin

Back 103

transmembrane protein found in tight junctions that interacts with 4 major intracellular peripheral proteins

Hint 103

None

Front 104

fascia occludens

Back 104

junction found between capillary endothelial cells

Front 105

zonula adherens

Back 105

encircles each cell near apex just below tight junction. Calcium dependent

Hint 105

None

Front 106

e-cadherin

Back 106

transmembrane linker protein that mediates zonula adherens between epithelial cells

Front 107

desmosomes

Back 107

anchoring sites for IF to form a continuous structure throughout the tissue

Front 108

basal lamina

Back 108

specialized mat of ECM @ the interface between epithelium and connective tissue

Front 109

α6β4

Back 109

integrin found in hemidesmosomes and is the only integrin to connect intermediate filament

Front 110

Junctional complex

Back 110

tight junction + zonula adherens + desmosome

Front 111

connexons

Back 111

transmembrane proteins that align to form a hydrophilic channel between two cells in gap junctions

Front 112

paracrine communication

Back 112

uses local chemical mediators which are rapidly taken up and destroyed or immobilized and can only act on immediate environment

Front 113

endocrine communication

Back 113

specialized cells secrete hormones (steroids and water soluble hormones) that travel trough vasculature to influence cells over greater distances.

Front 114

synaptic signalling

Back 114

cells secrete neurotransmitters at specialized junctions (synapses)

Front 115

syncytium

Back 115

secondary union of originally separate cells and the precursors are nonfunctional

Front 116

perinuclear cisterna

Back 116

space that separates inner and outer nuclear membrane

Front 117

nuclear lamina

Back 117

layer made of IF (lamin) that separates the nuclear envelope from regions of peripheral heterochromatin

Front 118

snRNPs- small nuclear ribonucleoprotein particles

Back 118

proteins that assist in splicing to produce mRNA

Front 119

Fibrillar region

Back 119

nucleolar region made of ribosomal DNA that codes for the production of rRNA that is actively being transcribed

Front 120

Granular region

Back 120

nucleolar region made of maturing preribosomal subunit particles

Front 121

Nucleolar-orgainizing regions

Back 121

parts of chromosomes 13, 14, 15, 21,and 22 gene loci that encode rRNA and are located in the Nucleolus

Front 122

heterochromatin

Back 122

highly condensed, transcriptionally inactive chromatin

Front 123

euchromatin

Back 123

extended, dispersed transcriptionally active chromatin

Front 124

constituitive heterochromatin

Back 124

heterochromatin that is never uncoiled

Front 125

facultative heterochromatin

Back 125

packed chromatin that contains coding sequences and may or man not be unfolded

Front 126

barr body

Back 126

type of facultative heterochromatin that is never uncoiled

Front 127

generation time

Back 127

time of one cell cycle and dependent mainly on the G1

Front 128

G1

Back 128

phase of cell cycle of synthesis of proteins and specialized functions of the cell

Front 129

S

Back 129

phase of cell cycle when DNA is duplicated and histones are produced

Front 130

G2

Back 130

phase of cell cycle when the cell is prepared for mitosis

Front 131

G0

Back 131

phase of cells that have left the cell cycle, called end cells

Front 132

stem cells

Back 132

cells of same type that haven't become sufficiently specialized and can undergo mitosis and continue to cycle.

Front 133

progenitor cells

Back 133

cells that can proliferate but usually lose capacity for self reneal and become committed to roduce a sigle type of end cell

Front 134

Cyclin-dependent kinases

Back 134

proteins that for a complex with cyclins and then phosphorylate other proteins to initiate or block activities crucial to progress through cell cycle

Front 135

p53

Back 135

tumor suppressor protein that is a Cdk inhibitor and is absent in many cancers

Front 136

D-type Cyclins

Back 136

cyclins needed at the G1 checkpoint to activate Cdk 4 and 6 and allow cells to progress to the S phase

Front 137

MPF- M phase promoting factor

Back 137

a cyclin B-Cdc 2 complex with kinase activity that is the command to enter mitosis that accumulates in G2 at the checkpoint

Front 138

kinetochore

Back 138

protein structure that links centromere of chromosomes to spindle microtubules during mitosis

Front 139

telomerase

Back 139

enzyme that elongates existing telomere making cells 'immortal'. Only activated in cancer

Front 140

satellites

Back 140

DNA attached to short arms of chormosomes 13, 14, 15, 21 and 22 bye secondary constriction and contains rRNA genes. These fuse to form the nucleolus after mitosis

Front 141

apoptosis

Back 141

active form of cell death initiated by the cell. Programmed elimination of the cell

Front 142

caspases

Back 142

enzymes which degrade regulatory and structural proteins in nucleus and cytoplasm.

Front 143

pyknosis

Back 143

chromatin condensation that occurs in apoptosis

Front 144

Starlings law of capillaries

Back 144

the volume of fluid and solutes reabsorbed is approximately the volume filtered

Front 145

glycosaminoglycans (GAGs)

Back 145

long, inflexible, unbranched polysaccharides w/ amino sugar which are negative and have a slippery texture

Front 146

aggrecan

Back 146

proteoglycan expressed in cartilage with keratan sulfate and chondroitin sulfate as the GAGs

Front 147

perlecan

Back 147

proteoglycan found with all cells making basal lamina that is made with heparan sulfate

Front 148

RGD sequence

Back 148

simple 3-peptide sequence that is the integrin binding sites of many adhesive proteins

Front 149

fibronectin

Back 149

large plycoprotein dimer with binding sites for extracellular components and integrins. The main product of fibroblasts. Involved in adhesion of cells to ECM

Front 150

laminin

Back 150

large glycoprotein composed of 3 large polypeptide chains with binding sites for heparan sulfate, type IV collagen, entactin and PM. Located in the Basal Lamina

Front 151

Entactin

Back 151

glycoprotein that binds to laminin and type IV collagen in the basal lamina

Front 152

Type I Collagen

Back 152

most common collagen; secreted by fibroblasts and provides tensile strenth in connective tissues

Front 153

Type II Collagen

Back 153

fill the extracellular matrix of cartilage

Front 154

Type III Collagen

Back 154

called reticular fibers; highly glycosylated collagen that forms thin fibers

Front 155

Type IV Collagen

Back 155

Sheets that surround organs and epithelia. Found in the basal lamina and external lamina for support and filtration

Front 156

Type VII collagen

Back 156

anchoring collagen found in epidermal-dermal junctions that links type IV collagen of the basal lamina to underlying connective tissue

Front 157

procollagen peptidase

Back 157

protein on E-surface of PM that cleaves registration peptides from procollagen to form tropocollagen

Front 158

propeptides or registration peptides

Back 158

guide the formation of triple helical structure and prevent intracellular formation of collagen fibers

Front 159

lysyl oxidase

Back 159

forms covalent crosslinks between tropocollagen molecules and tropoelastin molecules

Front 160

fibrillin

Back 160

glycoprotein distributed mainly as microfibrils on the elastic fiber surface

Front 161

basal laminae

Back 161

mats of specialized ECM (mostly type IV collagen) that underlie all epithelial cell cheets and tubes and surround individual muscle, fat and schwann cells

Front 162

lamina rara

Back 162

layer of basal lamina adjacent to basal PM and made of heparan sulfate (perlecan)

Front 163

lamina densa

Back 163

electron dense layer of basal lamina just beneath the lamina rara. Made mostly of type IV collagen

Front 164

lamina reticularis

Back 164

3rd layer of basal lamina that isn't always present. Connects the basal lamina to connective tissue below and composed of type III collagen

Front 165

Function of Na+ channels

Back 165

generating and propagating action potentials in excitable cells

Front 166

function of K+ channels

Back 166

control of excitability and shaping of electrical signals

Front 167

Function of Ca++ channels

Back 167

neurotransmitter release, muscle contraction and intracellular signalling pathways

Front 168

hyperkalemic periodic paralysis

Back 168

an Na+ chanenelopathy revealed when extracellular K+ is raised. Channel doesn't inactivate properly and action potential can't develop.

Front 169

tetrodotoxin (TTX)

Back 169

neurotoxin that is highly specific blocker of voltage-gated Na+ channels. Leads to respiratory paralysis and is found in puffer fish

Front 170

local anesthetics- novacain, lidocain

Back 170

block voltage gated Na channels in axon and prevent conduction of nerve impulses

Front 171

Lamber-eaton Myasthenic Syndrome (LEMS_

Back 171

autoimmune disease that impairs calcium influx and reduces transmitter relase at neuromuscular junction resulting in muscle weakness

Front 172

halothan

Back 172

anestheic that opens the leak K+ channels

Front 173

nifedipin and verapamil

Back 173

drugs used in the treatment of cardiovascular disease by blocking Ca++ channels

Front 174

3,4 Diaminopyridine

Back 174

drug used to treat LEMS by blocking K+ channel and prolongs the action potential

Front 175

acetylcholine receptors

Back 175

ligand gated channels at neuromuscular junction involved in excitatory neurotransmission

Front 176

glutamate receptors

Back 176

ligand gated channels at CA3-CA1 hippocampal synapse

Front 177

GABA receptors

Back 177

ligand gated channels at hippocampal synapses

Front 178

Nicotinic acetylcholine receptor

Back 178

ligand gated channel at neuromuscular junction that bind Ach and allows Na+ and K+ flux and induces depolarization which increases Ca++ and results in muscle contraction

Front 179

hyperpolarized

Back 179

a membrane potential which becomes more negative

Front 180

depolarized

Back 180

a membrane potential which becomes less negative

Front 181

acetylcholinesterase

Back 181

breaks Ach into acetate and choline and terminates signal

Front 182

congenital myasthenic syndrome

Back 182

this is a slow channel syndrome present at birth that is caused by mutations on Ach receptors causing weakness, rapid fatigue, and muscle atrophy

Front 183

D-Tubocurarine

Back 183

competetive inhibitor of Ach that causes paralysis and death by asphyxiation

Front 184

Vercoronium, Pancuronium, and Rocuronium

Back 184

synthetic chemicals that cause parlaysis by competitively inhibiting Ach receptors. Used in surgical procedures

Front 185

α bungarotoxin

Back 185

snake toxin that binds competetively and irriversibly to Ach receptors

Front 186

Succinycholine

Back 186

Ach R agonist that binds and causes depolarization and is used as a muscle relaxant

Front 187

Nicotine

Back 187

Ach R agonist that binds at same sites as ACh and can cause muscle contraction

Front 188

Myasthenia Gravis

Back 188

autoimmune neuromuscular disease caused by the destruction of peripheral NACh receptors causing muscle weakness, movement deficit and fatigue

Hint 188

None

Front 189

Picrotoxin

Back 189

noncompetetive blocker of GABA

Front 190

Benzodiazapine

Back 190

anxiolytic drug that increases GABA activity and is used for anxiety disorders and insomnia

Front 191

Barbituates

Back 191

anticonvulsant and sedative drug that increases GABA activity. Used for epilepsy, anesthesia and anxiety

Front 192

Hormone response elements

Back 192

DNA sequences where steroid receptor complexes bind and regulate rate of transcription

Front 193

Gs

Back 193

G-protein that stimulates AC and activates protein kinase A

Front 194

Gi

Back 194

G-protein that inhibits AC and inhibits protein kinase A

Front 195

Gq

Back 195

G-protein that is coupled to Phospholipase C which increases DAG, and in turn IP3 and Ca++ and activates protein kinase C

Front 196

Cholera toxin

Back 196

bacterial toxin that stimulates Gs and causes and excess production of cAMP

Front 197

Pertussis Toxin

Back 197

bacterial toxin that inhibits Gi and cases excess cAMP

Front 198

Sos

Back 198

guanine nucleotide exchange factor for Ras that is attracted by Grb2 in the signaling event of tyrosine kinase receptor

Front 199

GTPase activating proteint (GAP)

Back 199

hydrolyzes GTP and inactivates Ras

Front 200

Restriction Point

Back 200

the point in G1 when the cell cycle stops being GF dependent

Front 201

Oncogene

Back 201

a mutated protein of the cell cycle control system that is constituitively activated, Ras, myc, fos, jun

Front 202

Tumor supressor gene

Back 202

protein that inhibits cell cycle progression- Rb, p53

Front 203

Akt pathway

Back 203

signaling effect of neurotrophins binding to receptor tyrosine kinase that prevents cell death