Exam 1: Cell Flashcards
3 Cellular consituents
Organelles
Inclusions
Cytoplasmic matrix (cytosol)
Cytoplasm
part of cell external to nucleus
suspends organelles and inclusions
Cytoplasmic matrix (cytosol)
cytoplasm devoid of organelles and inclusions
Inclusions
nonliving entities found in cytoplasm and nucleus
Stored food, pigments, and crystalline not bound by membrane
Stored foods
Glycogen - abundent in liver and skeletal and cardiac muscle cells
Lipid droplets - found in adipocytes, hepatocytes, muscle, and steroid secreting cells
Glycogen demonstrated by
PAS reaction
McArdle disease
genetic defect in skeletal muscle phosphorylase
Accumulations of glycogen under sarcolemma
Cramping, exercise intolerance, elevated myoglobin, creatine kinase elevated, venous lactate level does not increase with exercise
Exogenous Pigments
Carotene - yellow orange color
Carbon particles
Tattoo pigments - stored in macrophages of dermis
Anthracosis
accumulation of carbon particles in lungs and regional lymph nodes
Harmless
Endogenous pigments
Hemoglobin - cyanosis and myoglobin Hemosiderin Bilirubin Melanin Lipofuscin
Hemosiderin
Iron containing pigment
brown
spleen & liver
Hemosiderosis & Hemochromatosis - accumulation of iron
Melanin
Eumelanin - brown/black found in epidermis
Neuromelanin - found in neurons - substantia nigra
Parkinson’s disease depigmentation
Phaemelanin - red pigment of skin/hair
Plasmalemma (plasma membrane)
separates internal and external environment lipid bilayer (contains phospholipids, glycolipids, cholesterol) Cholesterol strengthens bilayer
Lipid rafts
areas in membrane where sphingolipids and cholesterol concentrated
Thicker
involved in cell signaling
simvastatin
cholesterol inhibitor that induces apoptosis by reduction in raft formation
down regulates cell survival signaling molecule, Akt
Integral proteins
some partially embedded, other extend across entire plasma membrane
Creutzfeldt-Jakob disease
normal prion protein is converted to abnormal variant.
Forms cross-linked filaments - resistant to proteolysis
Functions of proteins
Receptors, transporters, enzymatic control of chemical rxns, linker protein for structural support, cellular identification tags, anchor cell to extracellular matrix, intercellular junctional complexes
Carrier transport proteins
transport one or more chemicals in one direction or two chemicals in opposite direction without direct expenditure of energy
Pump transport proteins
require direct expenditure of energy
Na/K pump
cleaves ATP to transport 3 Na ions out of cell and 2 K ions into cell
regulate intracellular volume
Digoxin
partially inhibits Na/K pump
decrease in Ca/Na transporter = increase in sarcoplasmic Ca ion concentrations - improves cardiac pump performance
Na/K pump and cotransport of glucose and Na
secondary active transport
Na and glucose enter cell as Na moves down its concentration gradient
To maintain gradient Na is pumped out of cell by Na/K pump
Multidrug resistant transporters
primary transporter proteins that are ATPases
MDR-1 expressed in kidney, intestine, liver, and blood-brain barrier - Transports drugs
Overexpression can cause cancer cells to become resistant to cytotoxic drugs
MDR-2 transports conjugated bilirubin
MDR-3 expressed in liver, flippase of phosphatidylcholine
Pores
Aquaporins - channels for water
Vesopressin
causes translocation of aquaporin receptors to plasma membrane of collecting tubule cells
Dystrophin
provides structural ingetrigy
link plasma membrane to underlying cytoskeleton
brown ring
Role of carbohydrates in membrane
attach to lipids and proteins forming glycolipids and glycoproteins, net negative charge repels other negatively charged substances, react with regulatory molecules, play role in cell to cell and cell to matrix recognition, protection
Glycolipids
exclusively on noncytosolic lipid monolayer
Endocytosis
transport into cell
energy ATP and Ca required
Macropinocytosis
Actin-based, nonspecific ingestion
occurs in thyroid cells as they take up thyroglobulin and dendritic cells for immune surveillance
Clathrin-mediated endocytosis
occurs in clathrin coated pits
Dynamin (GTPase) is required to pinch of vesicle
receptor mediated - cholesterol, protein hormones
Phagocytosis
ingestion of large particles (cell eating) mediated by receptors dependent on actin Phagosomes fuse with lysosomes
Exocytosis (bulk secretion)
secretion of cellular synthetic products with secretory vesicles
Secretory vesicles
formed in Golgi complex
fuse with plasma membrane
intracellular trafficking orchestrated by COPs
Consitutive exocytosis
continuous secretory process
secretory product not stored in secretory granules
Regulated exocytosis
secretory product stored in secretory vesicles until signal causes product to be secreted
Porocytosis
quantal release of neurotransmitters
Ribosome
basophilic
small electron dense particles
subunits exported from nucleus to cytoplasm where assemeble when actively synthesizing proteins
Polyribosomes free in cytoplasm
create proteins to be used in cell
Polyriosomes attached to endoplasmic reticulum
create proteins to be secreted
rER
membranous organelle, basophilic
continuous with outer membrane of nuclear envelope
ER stress
accumulation of unfolded/misfolded proteins in ER cisterna
Chaperone synthesis increases, decreased protein synthesis, caspases activated, misfolded proteins tagged for degradation
Targeting signals
sequences of amino acids in protein
direct proteins to their target compartments by binding to receptors specific for the organelles
sER
lacks polyribosomes acidophilic continuous with rER Cisternae more tubular Cholesterol homeostasis, steroid synthesis, phospholipid synthesis, detoxification of drugs, storage & release of Ca in muscle
van Gierke disease
defect in glucose 6 phosphatase or transporter; sER unable to transport glycogen - glycogen accumulation in cytoplasm and nucleus
liver enlargement, hypoglycemia, increased lactate
Cholera toxin gains entry into the cell by using
a glycolipid
Non-coated mediated endocytosis
Cholera and Shiga toxins
Caveolae mediated endocytosis
Simian virus 40
cytochrome p450 and alcohol detoxification takes place in
sER
Synthesis of phospholipids occurs in the lipid monolayer in the
sER and rER
Alastin
involved in shaping the ER
Deficiency leads to fragmented ER & spastic paraplegia
Spastic paraplegia caused by
deficienty in atlastin (ER fragmented)
stiff leg & gait disturbances
Proteasomes
large complex protease
Proteolysis of regulating proteins, damaged proteins, and antigenic proteins (initiate immune response)
Proteasomes are dependent on
ubiquitin for degredation
Abnormal prion proteins inhibit
proteasomes
Defective ubiquination of proteins is implicated in
Parkinson’s disease, as well as a form of cystic fibrosis
Bortezomib
partially inhibits proteasomes
effective against multiple myeloma - promotes apoptosis of cancer cells