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58 Cards in this Set
- Front
- Back
Cell |
Smallest structural and functional living unit |
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Plasma Membrane |
Flexible outer boundary of cell; Biomolecular layer of phospholipids, some cholesterol, and variously positioned proteins in a constantly changing fluid mosaic; Plays dynamic role in cellular activity; Separates intracelluar fluid (ICF) from extracellular fluid (ECF) |
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Cytoplasm |
Intracellular fluid containing organelles |
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Nuclues |
Control center of cell |
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Interstitial Fluid (IF) |
Extracellular fluid that surrounds cells |
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Phospholipids (Cytoplasm) |
Most abundant lipid; Phosphate heads are polar and hydrophilic; Fatty acid tails are nonpolar and hydrophobic |
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Glycolipids (Cytoplasm) |
Lipids with polar sugar groups on outer membrane surface |
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Cholesterol (Cytoplasm) |
Increases membrane stability and fluidity |
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Integral Proteins (Cytoplasm) |
Firmly inserted into the membrane (transmembrane) |
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Peripheral Proteins (Cytoplasm) |
Include filaments on intracellular surface and glycoproteins on extracellular surface |
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Functions of Membrane Proteins |
Transport; Receptors for signal transduction; Attachment to cytoskeleton and extracellular matrix; Enzymatic activity; Intercellular joining; Cell to cell recognition |
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Membrane Junctions |
Tight Junction, Desmosomes, Gap Junction |
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Tight Junction |
Impermeable junction prevents molecules from passing through the intercellular space |
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Desmosomes |
Anchoring junctions bind adjacent cells together and help form an internal tension-reducing network of fibers |
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Gap Junctions |
Communicating junctions allow ions and small molecules to pass from one cell to the next for intercellular communication |
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Membrane Transport Permeability |
Plasma membranes are selectively permeable (some molecules easily pass through membrane, others do not) |
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Membrane Transport: Passive Processes |
No cellular energy (ATP) required; Substance moves down concentration gradient; Lipid solubility of substance, appropriately sized channels, and carrier proteins determine whether or not a substance can passively permeate a membrane |
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Passive Processes: Simple Diffusion |
Nonpolar lipid-soluble (hydrophobic) substances diffuse directly through phospholipid bilayer |
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Passive Processes: Facilitated Diffusion |
Certain lipophobic molecules (glucose, amino acids, ions, etc.) use carrier proteins or channel proteins that exhibit specificity, are saturable, and can be regulated in terms of activity/quantity |
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Carrier Protein Process |
Transmembrane integral proteins transport specific polar molecules (sugars and amino acids) and the binding of the agent causes carrier shape change |
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Channel Protein Process |
Aqueous channels formed by transmembrane proteins selectively transport ions or water; Leakage channels are always open; Gated channels are controlled by chemical/electrical signals |
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Passive Processes: Osmosis |
Movement of solvent (water) across selectively permeable membrane; Concentration gradient based on presence of solute, low solute concentration means high water concentration; Water diffuses through plasma membranes through lipid bilayer (nominal) and aquaporins (AQPs) |
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Membrane Transport: Active Processes |
Energy (ATP) required; Substance moves against concentration gradient; Occurs only in living cell membranes; Requires carrier proteins that serve as pumps |
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Primary Active Transport |
Energy from hydrolysis of ATP causes shape change in transport protein so bound solutes (ions) are "pumped" across membrane |
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Sodium-Potassium Pump (Na+ -K+ ATPase) |
Located in all plasma membranes; Involved in primary and secondary active transport; Maintains electrochemical gradients essential for functions of muscle and nerve tissue |
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Sodium Potassium Pump Process |
Cytoplasmic Na+ binds to pump protein; Binding Na+ promotes phosphorylation of protein by ATP; Phosphorylation causes protein shape change, which expels Na+ to the outside; Extracellular K+ binds to pump; K+ binding triggers phosphate release, pump returns to original config.; K+ is released from pump and Na+ sites are ready to bind Na+ again. |
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Phagocytosis |
Pseudopods engulf solids and bring them into cell interior (Macrophages and some white blood cells); Combines with lysosome; Undigested contents remain in vesicle (now a residual body) or are ejected by exocytosis |
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Fluid-Phase Endocytosis (Pinocytosis) |
Plasma membrane infolds, bringing extracellular fluid and solutes into cell interior; Nutrient absorption in small intestine |
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Exocytosis |
Bulk release of substance that is controlled (hormone secretion, neurotransmitter release, mucus secretion, waste ejection, etc.) |
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Exocytosis Process |
Membrane bound vesicle migrates to plasma membrane; Proteins at vesicle surface (v-SNAREs) bind with plasma membrane proteins (t-SNAREs); Vesicle and plasma membrane fuse and a pore opens up; Vesicle contents are released to cell exterior |
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Membrane Potential |
Separation of oppositely charged particles (ions) across a membrane l (potential energy measured as voltage) |
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Resting Membrane Potential (RMP) |
Voltage measured in resting state in all cells; Ranges from –50 to –100 mV in different cells; Results from outward diffusion (mainly K+) |
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RMP Generation/Maintenance |
Na+ -K+ pump continuously ejects Na+ from cell and carries K+ back in; Some K+ continually diffuses down it concentration gradient out of cell through leakage channels; Membrane interior becomes negative (relative to exterior) because of large anions trapped inside cell; Electrochemical gradient begins to attract K+ back into cell; RMP is established at point where the electrical gradient balances the K+ concentration gradient; Steady state it maintained because the rate of active transport is equal to and depends on the rate of Na+diffusion into cell |
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Cytoplasm |
Located between plasma membrane and nucleus |
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Cytosol |
Water with solutes (proteins, salts, sugars, etc._ |
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Cytoplasmic Organelles |
Metabolic machinery of cell |
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Inclusions |
Granules of glycogen or pigments, lipid droplets, vacuoles, and crystals |
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Mitochondria |
Double membrane structure with shelf-like crystae; Provide most of cell's ATP via aerobic cellular respiration; Contain own DNA and RNA |
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Ribosomes |
Granules containing protein and RNA; Site of protein synthesis; Free ribosomes synthesize soluble proteins; Membrane-bound ribosomes (on rough ER) synthesize proteins to be incorporated into membranes or exported from the cell |
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Endoplasmic Reticulum |
Interconnected tubes and parallel membranes |
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Rough ER |
external surface has ribosomes; Manufactures secreted proteins and synthesizes membrane integral proteins and phospholipids |
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Smooth ER |
In liver - lipid and cholesterol metabolism, breakdown of glycogen, detoxification of drugs, pesticides, carcinogens; In intestinal cells - absorption, synthesis, and transport of fats; In skeletal and cardiac muscle - storage and release of calcium |
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Golgi Apparatus |
Stacked and flattened membranous sacs; Modifies, concentrates, and packages proteins and lipids; Transport vessels from ER fuse with convex cis face of GA; Proteins then pass through GA to trans face; Secretory vesicles leave trans face of GA stack and move to designated parts of cell |
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Lysosomes |
Spherical membranous bags containing digestive enzymes (acid hydrolases); Digest ingested bacteria, viruses, toxins; Degrade nonfunctional organelles; Break down and release glycogen; Break down bone to release Ca2+; Destroy cells in injured or non-useful tissue (autolysis) |
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Cytoskeleton |
Elaborate series of rods through cytosol |
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Microtubules (tubulin) |
Dynamic hollow tubes that determine overall shape of cell and distribution of organelles |
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Microfilaments (actin) |
Dynamic strands involved in cell motility, change in shape, endocytosis and exocytosis |
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Intermediate filaments (variety of proteins) |
Tough insoluble rope-like protein fibers that resist pulling forces on the cell and attach to desmosomes |
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Motor Molecules |
Protein complexes that function in motility (movement of organelles and contraction); powered by ATP; Facilitate movement of vesicles and organelles along cytoskeleton |
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Cilia and Flagella |
Motile extensions on surfaces of certain cells; Contain microtubules and motor molecules; Cilia moves substances across cell surfaces; Longer flagella propel whole cells (eg. tail of sperm) |
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Microvilli |
Fingerlike extensions of plasma membrane; Increase surface area for absorption; Core of actin filaments for stiffening |
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Nucleus |
Genetic library with blueprints for nearly all cellular proteins; Responds to signals and dictates protein synthesis; Most cells are uninucleate; Red blood cells are anucleate; Skeletal muscle cells, bone destruction cells, and some liver cells are multinucleate |
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Cell Cycle |
Defines changes from formation of the cell until it reproduces; Includes Interphase and Cell Division (Mitotic Phase) |
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Interphase |
Period from cell formation to cell division; Nuclear material called chromatin; Four subphases |
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G1 (Gap 1) |
Vigorous growth and metabolism |
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G0 |
Gap phase in cells that permanently cease dividing |
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S (Synthetic) |
DNA Replication |
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G2 (Gap 2) |
Preparation for cell division |