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Cell Biology Exam 1
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74
Biology
Graduate
10/24/2012

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Term
How many cells are in the human body?
Definition
100 trillion
Term
25 trillion cells are this type
Definition
Erythrocytes
Term
What does each cell contain?
Definition
Organelles
Inclusions
Cytoplasmic matric
Term
Organells
Definition
Little Organs
Structural elements that confer functional attributes to the cell and may be membranous or non-membranous.
Term
Cell mitochondrial levels
Definition
May be 35% of a cardiac muscle cell but is totally absent in erythrocytes.
Term
Cytoplasm v Cytoplasmic matrix
Definition
Cytoplasm - Part of cell external to the nucleus that suspends organelles and inclusions
Cytoplasmic matrix (cytosol) - The portion of the cytoplasm devoid of organelles and inclusions. Contains numerous molecules and electrolytes.
Term
Creatine Kinase (CK)
Definition
Found in the cytosol of various cell types where it functions to transport fuel in cells exhibiting high energy requirements (cardiac and skeletal muscle cells and nerve cells). In response to insult, damaged cells release CK into the blood where it can then be assayed as a diagnostic marker, for example, of myocardial infarction, muscular dystrophy, and muscle inflammation.
Term
Cytoplasmic Inclusions
Definition
Discrete accumulations of end products of metabolic activity and are considered nonliving.
Stored foods, Pigments, and crytalline in composition.
Term
Stored Foods
Definition
Glycogen Lipid Droplets
Term
Glycogen
Definition
In cytoplasm as clusters or discrete electron-dense particles in electron micrographs.
Abundant in hepatocytes and striated muscle cells.
Depot of energy reserve that can be deployed to meet energy shortage.
Term
Glycogen: Light microscopic level
Definition
Demonstrated by presence of magenta granulations in the cytoplasm as a result of employing the PAS reaction.
Term
Glycogen Storage diseases
Definition
Result in accumulation polysaccharides in the cytoplasmic matrix.
Term
Glycogen synthase deficiency (type 0)
Definition
Storage disorder that decreases cellular glycogen stores.
Term
Fat (lipid) droplets
Definition
Non-membrane buond and found in relative abundance in adipocytes, hepatocytes, muscle and steroid-secreting cells. Function as depots of energy and precursor molecules for synthesis of steroid hormones.
Term
Type 1a (Von Gierke Disease)
Definition
Enzyme Defect: Glucose-6-phosphatase
Structural Changes: Liver enlargement, glycogen accumulation in cytoplasm and nucleus, kidney enlargement, glycogen accumulation in epithelial tubular cells
Clinical Features: Stunted growth, failure to thrive, hypoglycemia (may lead to convulsions), metabolic acidosis due to increased lactate, hyperlipidemia, elevated uric acid leading to gout in many patients, liver neoplasms, renal disfunction.
Term
Type II (Pompe Disease)
Definition
Enzyme Defect: Lysosomal alpha-1,4-glucosidase
Structural Changes: Liver and heart enlargement, Liver lysosomes expand with glycogen; in heart glycogen accumulates in sarcoplasm and lysosomes; skeletal muscle changes similar to that observed in heart
Clinical Features: Muscle weakness and decreased tone; cardiac failure; skeletal muscle atrophy; respiratory muscle weakness
Term
Type V (McArdle Syndrome)
Definition
Enzyme Defect: Muscle phosphorylae
Structural Changes: Specific to skeletal muscle, subsarcolemmal accumulations of glycogen
Clinical Features: Cramping with strenuous exercise; exercise intolerance; myoglobin elevated with strenuous exercise; CK elevated; venous lactate does not increase with exercise.
Term
Lipid accumulation derangements
Definition
Fatty liver change as a result of alcohol abuse or nonalcoholic fatty liver disease
Term
Pigments
Definition
Colored chemical substances that are found in the cytosol. Except melanin, not bound by a membrane. Non-membrane pigments include hemosiderin and lipofuscin.
Term
Hemosiderin
Definition
Yellow-brown pigment that serves to store iron.
Normally found in small amounts in the macrophages of the spleen, liver, and red bone marrow as these professional phagocytic cells degrade erythrocytes. This degradation releases iron from Hb and binds to apoferritin (protein) in cytosol. Iron-apoferritin complex then forms ferritin micells that aggregate into hemosiderin granules.
Term
Hemosiderosis
Definition
Iron load elevation that causes increased deposition of hemosiderin in tissues and organs. Seen with increased absorption of iron in diet, impaired use of iron by the body, hemolytic anemias, and repeated transfusions of blood.
Term
Hemochromatosis
Definition
Disorder characterzed by a more severe accretion of iron due to a genetic defect causing excessive iron absorption or transfusion reaction
Term
Heart failure Cells (Damming of blood in pulmonary circulation)
Definition
Results in extravasation of blood into the alveoli where alveolar macrophages degrade the erythrocytes and accumulate iron as hemosiderin. Fluid accumulation in lungs and patient coughs sputum laden with macrophages well endowed with hemosiderin. When Prussin blue is applied to sputum sample, the iron is well demonstrated by appearing blue. Pathological observation is consistent with heart failure diagnosis.
Term
Three types of pigment melanin found in humans.
Definition
Eumelanin
Phaeomelanin
Neuromelanin
Term
Eumelanin
Definition
Brown-black pigment found in membrane-limited granules in the epidermiis and eye as the pigment layer of retina and pigmented epithelium of the ciliary body and iris. In skin, eumelanin occupies a supranuclear position (think of nuclear hat of eumelanin) in keratinocytes (principle cell type of epithilium). Protects genetic apparatus from potentially mutagenic effects of ultra-violet radiation.
Term
Eumelanin: Clinical
Definition
Elevated in response to UV radiation.
Increased in Addison' disease in response to elevated adrenocorticotropin hormone.
Absent in albinos due to lack of tyrosinase, necessary enzyme for eumalanin and phaeomelanin production.
Term
Phaeomelanin.
Definition
Yellow to red pigment. Found in skin and hair.
Responsible for tinting a pinkish red color, specifically responsible for red hair.
Not protective against ultraviolet radiation and may even become carcinogenesis in response to UV light.
Term
Neuromelanin.
Definition
Brown-black in color, limited by a membrane, and found in igmented, catecholaminergic neurons of four deep nuclei of brain.
Found in substantia nigra (black substance), locus coeruleus, dorsal motor nucleus of the vagus nerve, and the median raphe of the pons.
Substantia nigra and locus coeruleus are most pigmented.
Function may be neuroprotective against toxic metals and reactive oxygen species.
Term
Parkinson disease
Definition
Loss of neuromelanin-containing catecholaminergic neurons from the substantia nigra leads to depigmention of this deep brain structure.
Term
Lipofuscin (lipochrome or wear-and-tear pigment)
Definition
Brownish-yellow pigment that is an amalgam of lipids, metals, and organic molecules. Accumulates in long-lived cells, such as neurons and cardiac muscle cells, and hepatocytes.
Term
Increased lipofuscin.
Definition
Measure of cellular stress (free radical injury and lipid peroxidation)
Increased cellular deposition is seen in severe malnutrition and cachexic states associated with cancer.
Term
Crystalline inclusions
Definition
Discernible with light microscopy in specific cell types, such as Sertoli cells and interstitial cells (of Leydig) found in the testis). Inclusions not specifically confined to the cytoplasm as electron microscopy has revealed their presence in organelles.
Term
Cause of crystalline inclusions in organelles.
Definition
May be due to viral infections and mitochondrial myopathy.
Term
Organelles
Definition
Structural elements that confer functional attributes to the cell and may be membranous and non-membranous.
Term
Plasmalemma
Definition
Plasma membrane
Only visible as a trilaminar structure with electron microscopy.
Contains ampiphilic phospholipids, cholesterol, Lipid rafts, and proteins.
Term
Lipid rafts
Definition
Microdomains in membrane where sphingolipids and cholesterol and chiefly concentrated. Raft region is thick and unique causing certain proteins to aggregate. Raft microdomain is signalling platform.
Term
Lipid rafts: Clinical Relevance
Definition
Cancer cell types exhibit greater concentrations of cholesterol which correlates with more lipid rafts.
Simvastatin has been shown to induce apoptosis of cancer cells by reducing raft formation. Down regulates cell survival signaling molecule, Akt.
Term
Proteins in plasmalemma
Definition
Pheripheral: Attached ionically to extra-or cyto-side of plasmalemma. Can be removed with salt (ionic) solutions.
Integral: Partially embedded in membrane or extend across entire thickness.
Term
Creutzeldt-Jacob Disease
Definition
Occurs when normal prion protein (PrP) located on outer surface of plasmalemma of neurons is converted to abnormal variant. Cross-linked filaments resistant to proteolysis. Accelerates conversion of normal PrP to same form. Normal prion proteins have antioxidant function and may serve to establish long-term memory.
Term
Beta-amyloid precursor protein.
Definition
Transmembrane protein altered in Alzheimer's disease. Forms protein aggregate resistant to proteolysis. Important in neuronal migration during development, synaptic formation and repair,cell signaling, long-term potentiation of memory, and cell adhesion.
Term
Six Categories of integral proteins
Definition
Receptors
Transporters
Pores or channels
Enzymes
Linkers
Junctional Proteins
Term
Receptors
Definition
Allow a cell to respond to external signal.
Term
Atropine Eye drops.
Definition
Administered to dilate the pupil to aid in examining the fundus and retina.
Blocks acetylcholine from binding to its muscarinic cholinergic receptor on the sphincter muscle of the pupil causing it to dilate.
Term
Atenolol
Definition
Beta1-adrenergic antagonist. Dampens sympathetic drive to heart. Lowers arterial pressure by decreasing heart rate and contractility of the cardiac muscle.
Term
Transport proteins
Definition
Uniporters, symporters, or antiporters.
Passive or active
Term
Low ATP Effects
Definition
K/Na pump is unable to maintain gradient across the cell membrane. increase in intracellular ionic concentrain pulls water into the cell by the process of osmosis resulting in cytoplasmic and organellar swelling.
Term
Multidrug resistance protein (type 1 and 2)
Definition
Found in various cell types (intestinal epithelial cell, hepatocytes, renal proximal convoluted tubule cells, and endothelial constituting blood-brain and blood-testis barrier) Transports substrates across the plasmalemma.
Term
Multidrug-resistance protein (MDR-1) and Clinical Correlations
Definition
MDR-1 causes some cancer cells to be resistant to cytotoxic drugs. Overexpression of of MDR-1 transport proteins that pump cytotoxic agents out.
Drug avaiability. Overexpression in intestinal epihelial cells diminishes the absorption of pharmacological agents that are substrates for the transporter. Bioavailability may not reach therapeutic level.
Underexpresion enhances absorption of pharmacological agents that are substrates. Supratherapeutic plasma level of the drug may also be toxic.
Possible therapy in gene silencing through RNA interference and inhibitors of the protein.
Term
MDR-2 Protein: Clinical Correlations
Definition
Transports conjugated bilirubin into passageways called canaliculi. Protein defective in Dubin-Johnson syndrome. Affected have mildly elevated levels of direct bilirubin in blood. Microscopy reveals coarse pigment granules of epinephrine metabolites in the lysosomes of hepatocytes. Disease has a benign course and no treatment required.
Term
Pores
Definition
Allow passage of chemical substances across plasmalemma.
Term
Aquaportins
Definition
Protein channels for water and 12 isoforms exist. Aquaporin-2 expresed by renal collecting tubule cells for water reabsorption.
Vasopressin causes translocation of aquaorin protein channels into plsma membrane of tubule cell increasing movement of water across apical domain of tubule cells and into blood vascular system (reabsorption).
Nephrogenic Diabetes insipidus results when both aquaporin-2 genes are inactivated by mutations causing water to not be reabsorbed and eliminated excessively in urin.
Term
Cystic Fibrosis
Definition
Autosomal recessive disease from mutation in CFTR. Channel for Cl- and other ion channels disrupted. Affected epithilial tissues in the airways, gi tract, and sweat gland have organ specific abnormal ion transport. Sweat glands secrete elevated Na+ and Cl- ions, Excess transport in lungs results in movement of water from mucus into cell creating thicker mucus that is harder to clear.
Term
Enzymes in plasmalemma of small intestine
Definition
Hydrolyze oligopeptides to amino acids and oligosaccharides into monosaccharides
Term
Lactase deficiency
Definition
Unable to adequately digest lactose and may suffer from diarrhea, cramping, and gas when they ingest dairy products.
Term
GGTP or GGT (gamma-glutamyl transpeptidase)
Definition
Released into blood from plasmalemmae of epithelial cells lining the bile duct in response to cellular injury caused by cholestasis (obstruction to bile flow)
GGTP found in other tissues so additional tests needed to confirm diagnosis
Term
Linker proteins of plasmalemma
Definition
Adds structural support and allows response
Integrins, sarcoglycans, dystroglycans.
Term
Dystrophin
Definition
Links protein complex of sarcoglycans and dystroglycans to the actin cytoskeleton in muscle cells.
Mutated in DMD leading to degeration and loss of myocytes.
Term
Sarcoglycan mutations
Definition
Implicated in four different forms of limb-girdle muscular dystrophies. Mutations similary disrupt the interface leading to a severe course of Duchenne-like features.
Term
Junctional proteins
Definition
Form connections between one cell and other cells.
Occludins, claudins, E-cadherin, desmocollin, desmoglein
Term
Carbohydrates of plasmalemma
Definition
In the form of oligosaccharides and attached to membrane lipids and proteins forming glycolipids (only in cyto monolayer) and glycoproteins.
React with regulatory molecules, repel other negatively charged substances, and protection as some carbohydrate components participate in immune reactions.
Term
Ganglioside GM1
Definition
Glycolipid that serves as a cell receptor for the cholera toxin. Receptor concentrated on lipid rafts, Toxin bind to ganglioside GM1 and then ramps of cAMP synthesis leading to efflux of sodium and water into intestine. Diarrhea
Term
What to five distinct pathways of endocytosis require?
Definition
Expenditure or energy
Ca 2+
Term
Five distinct pathways of endocytosis
Definition
Macropinocytosis
Clathrin-mediate endocytosis
Caveolae-mediated endocytosis
Nonclathrin/noncaveolin endocytosis
Phagocytosis
Term
Macropinocytosis
Definition
GTP fueled process that allows many cell types to uptake large volumes of extracellular fluid and solid cargo in large endocytotic vesicles called macropinosomes.
Created due to actin assembly causing protrusions of plasmalemma enriched with lipid rafts. Protrusions bend around extracellular fluid to form macropinosomes. General nutrient uptake.
Thyroid gland -> ingest thyroglobulin from colloid, internalize, and ingest in lysosome to release thyroid hormones.
Dendritic cells: immune surveillance
Pathogenic Bacteria: Stimulate macropinocytosis through release of toxins to escape targeting by phagocytic cells.
Term
Clathrin-mediated endocytosis
Definition
Specific sites called coated pits. Pits coated with clathrin and associated proteins. Most stimulated by ligand-receptor interaction.
Also referred to as receptor-mediated endocytosis.
Term
Clathrin-mediated endocytosis: Purpose
Definition
Ingest specific nutrients and regulate receptor density on the plasmalemma.
LDL: LDL's bind to LDL-receptors that aggregate in coated pit, cytoplasmic portion possesses a coated-pit binding site which anchors intermediary protein called daptin Ligand-receptor complex is formed, clathrin promotes invagination of plasmalemma and vesicle is pinched off by dynamin, a GTP-ase Results in formation of cytoplasmic clathrin-coated vesicle that sheds its clathrin coat and then fuses with other vesicles or is delivered to the endosomal compartment o fthe cell while disassembled clathrin is recyled to cytoplasmic side of the plasmalemma.
Term
Dominant intermediate Charcot-Tooth-Marie Neuropathy type B
Definition
Dynamin 2 Mutations leads to defects in clathrin-mediated endocytosis. Myelination of axons is dependent on dynamin 2 and clathrinmediated endocytosis perturbations impairs myelination. Disease is characterized by muscular atrophy, loss ot touch sensation predominately in the distal lower limbs, and foot drop.
Term
Familial Cholesterolemia
Definition
AD disorder of absent or defective LDL receptors.
Complete Absence of LDL receptors
Defective transport between ER and Golgi apparatus. Transport may be completely or partially locked
Defective binding of LDL to recepto
Deficiency of LDL receptors ni coated pits.
Defective uncoupling of LDL from its receptor following internalization so recycling is abated.
Total cholesterol levels will range from 30 mg/dl to greater than 500 mg/dl.
Elevated levels accelerate development of atherosclerosis, subjecting patients to revascularization procedures.
Term
Clathrin-mediated endocytosis: Independent of ligand-receptor interaction
Definition
Synaptic transmission. Synaptic vesicles dock with plasmalemma and release neurotransmitter via exocytosis. Adds membrane to presynaptic terminal. Synaptic vesical discharges it contents and membrane is recycled to prevent accretion. Clathrin molecules will then cat the membrane to be retrieved through endocytosis. Once vesicle is internalized, it will be recharged with neurotransmitter.
Term
Caveolae-mediated endocytosis
Definition
In microdomains of plasmalemma. Enriched with cholesterol along with caveolin, a protein. caveolin binds to cholesterol and forms and stabilizes regions of plasmalemma. Cavelae gets flask-shaped invaginations and are numerous in endothelial cells (lining vascular structures) where they shuttle proteins and nutrients from blood to tissues. Endocytosis of caveolae requires actin microfilaments and the GTPase dynamin. Once internalized, the vesicles, termed caveosomes retain their caveolin coat unlike clathrin coated vesicles which become uncoated.
Term
Simian Virus 40
Definition
Enters cells through endocytosis mediated by caveolae. SV 40 found in monkey species and used in polio vaccines. Exposed to US individuals and some tumor cells contain virus
Term
Nonclathrin/noncaveolin endocytosis
Definition
Occurs on lipid rafts May function to direct the secretory pathway. Sphingolipids are added to the lipid bilayer of secretory vesicle formed y Golgi.Sphingolipids then direct secretory vesicle to plasmalemma for exocytosis. Spingolipid-enriched bilayer of vesicle is incorporated into the plasmalemma. New lipid raft microdomains are determinant sites for nonclathrin/noncaveolin endocytosis as a means to recycle sphingolipids back to Golgi.
Term
Toxins that enter cells through the nonclathrin/noncaveolin pathway
Definition
Chorea and Shiga
Toxins are also internalized by clathrin-mediated endocytosis. Only have ill effect through nonclathrin noncaveolin endocytosis
Term
Phagocytosis
Definition
Internalization of large particles, pathogenic invaders, foregin objects, mediated by receptors. Activation of receptors -> rearrangement of cytoskeleton causing protrusions of plasmalemma to extend and engulf the offending agent.
Membrane-limited structure has been internalized, referred to as phagosome. Fated to lysosomal compartment of cell.
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