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167 Cards in this Set
- Front
- Back
Cells |
Smallest living units in the human body |
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Microscopy |
Study of objects using a microscope |
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Cytology |
Study of cellular structure & function |
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Somatic Cells |
Body cells |
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Sex Cells |
Germ cells, reproductive cells Sperm in males Oocytes in females |
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Plasma Membrane |
Cell membrane, the cell's outer boundary consists of a phospholipid bilayer |
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Phospholipid Bilayer |
The cell membrane - phospholipid molecules in two layers with the hydrophilic heads at the membrane surface and the hydrophobic tails on the inside, account for most of the surface area of the plasma membrane but only 42% of the weight, Proteins ~55% of weight, Carbohydrates ~3% of weight
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Integral Proteins |
Proteins embedded within the plasma membrane |
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Transmembrane Proteins |
Proteins that span the width of the plasma membrane one or more times |
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Peripheral Proteins |
Bound to inner or outer surface of plasma membrane |
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Anchoring Proteins |
Proteins that attach the plasma membrane to other structures and stabilize its position |
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Recognition Proteins |
Identifiers - often glycoproteins, cells of the immune system recognize other cells as normal or abnormal based on these proteins |
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Enzymes |
Proteins that catalyze reactions in extracellular fluid or cytosol |
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Receptor Proteins |
Proteins sensitive to the presence of ligands, may trigger changes in cell activity |
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Carrier Proteins |
Bind solute and transport them across the plasma membrane (may require ATP) |
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Channel Proteins |
Integral proteins containing a channel/pore that forms a passageway completely through the plasma membrane |
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Gated Channels |
Channel proteins that can open or close to regulate the passage of substances |
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Rafts |
Areas where certain integral and peripheral proteins are always confined |
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Glycocalyx |
Layer of carbohydrate portions of complex molecules that extends beyond the outer surface of the plasma membrane Functions in lubrication and protection, anchoring and locomotion, specificity in binding, and recognition |
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Cytoplasm |
The material between the plasma membrane and membrane that surrounds the nucleus Contains the cytosol, organelles, inclusions |
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Cytosol |
The intracellular fluid, a mixture of water and various dissolved and insoluble materials in which organelles and inclusions are suspended |
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Organelles |
Internal structures of cells that perform most of the tasks that keep a cell alive and functioning normally |
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Non-Membranous Organelles |
Not completely enclosed by membranes Cytoskeleton, centrosome (centrioles), ribosomes, proteasomes, cellular extensions (microvilli, cilia, flagella) |
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Membranous Organelles |
Organelles that are isolated from the cytosol by phospholipid membranes Endoplasmic reticulum, Golgi apparatus, lysosomes, peroxisomes, mitochondria |
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Inclusions |
Masses of insoluble materials in the cytoplasm Stored nutrients (glycogen, lipid droplets) Pigment granules (melanin) |
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Sodium/Potassium Concentrations in Cytosol vs. Extracellular Fluid |
Higher sodium concentration in extracellular fluid Higher potassium concentration in cytosol |
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Cytoskeleton |
Serves as the cell's skeleton Internal protein framework that gives the cytosol strength & flexibility |
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Microfilaments |
Smallest cytoskeletal structure (~5nm diameter) made up of the protein actin Anchor the cytoskeleton to integral proteins of the plasma membrane Determine consistency of cytosol |
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Intermediate Filaments |
Intermediate in size between microfilaments and microtubules (~9 to 11nm diameter) Protein composition varies among cell types, insoluble in watery medium Most durable of the cytoskeletal elements, strengthens the cell, helps maintain its shape, stabilizes the position of organelles, stabilizes the position of the cell |
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Microtubules |
Largest of the cytoskeletal components (~25nm in diameter) Hollow tubes built from the globular protein tubulin, extend outward into the periphery of the cell from the centrosome Forms from aggregation of tubulin molecules growing out from centrosome, persists for a while then disassembles Forms the main portion of the cytoskeleton, gives cell strength, maintains its shape, anchors the positions of major organelles, assists in cell movement, monorail system for movement of materials in the cell, distribute duplicated chromosomes during cell division by forming the spindle apparatus |
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Microvilli |
Small, non-motile, finger-like projections of the plasma membrane that greatly increase the surface area of the cell Found in cells that are actively absorbing materials such as cells lining the digestive tract Have extensive connections with the cytoskeleton Core of microfilaments stiffens each microvillus and anchors it to the terminal web |
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Centrosome |
A region of cytoplasm located next to the nucleus, the microtubule-organizing center of animal cells, the heart of the cytoskeletal system, surrounds a pair of cylindrical structures called centrioles which lie perpendicular to each other, with microtubules forming 9 groups with three in each group, with no central microtubules, called 9 + 0 array |
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Cilia |
Fairly long, slender extensions of the plasma membrane, can be motile or nonmotile |
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Primary Cilium |
Single, non-motile cilium found in cells in a variety of tissues, similar to 9+0 array organization of centrioles Acts as a signal sensor, detecting environmental stimuli and coordinating activities such as embryonic development and homeostasis at the tissue level |
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Motile Cilia |
Multiple motile cilia found on cells lining the respiratory tract & reproductive tracts Nine pairs of microtubules surround a central pair (9+2 array) Anchored to central basal body just beneath the cell surface (9+0 array) Beat rhythmically to move fluids or secretions across the cell surface, move oocytes and sperm through reproductive tract |
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Flagellum |
A whip-like extension of the plasma membrane Same 9+2 microtubule organization as motile cilia but are much longer Only human cell with a flagellum is sperm (only 1 per cell) |
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Ribosome |
Organelle responsible for protein synthesis, made of proteins and rRNA Two subunits: small ribosomal subunit and large ribosomal subunit |
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Free Ribosomes |
Scattered throughout cytoplasm, proteins they manufacture directly enter cytosol |
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Fixed Ribosomes |
Temporarily bound to rough endoplasmic reticulum, proteins they manufacture enter the ER where they are modified and packaged for use or secreted from the cell |
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Proteasomes |
Organelles that contain protein-digesting (proteolytic) enzymes called proteases |
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Endoplasmic Reticulum |
Network of intracellular membranes continuous with the nuclear envelope |
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Smooth Endoplasmic Reticulum |
No fixed ribosomes, involving in synthesis of lipids, fatty acids, carbohydrates, absorbs and stores ions, detoxifies or inactivated drugs |
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Rough Endoplasmic Reticulum |
Contains fixed ribosomes, synthesizes, modifies, and packages proteins |
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Golgi Apparatus |
Organelle typically consisting of 5 or 6 flattened membranous discs called cisternae Modifies and packages secretions such as hormones or enzymes for release from the cell, adds or removes carbohydrates to or from proteins, renews or modifies the plasma membrane, packages special enzymes with vesicles (lysosomes) for use in the cytoplasm |
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Lysosomes |
Vesicles produced by the Golgi Apparatus that provide an isolated environment for potentially dangerous chemical reactions Contain digestive enzymes that break organic polymers into monomers |
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Peroxisomes |
Smaller than lysosomes and carry different enzymes Creates by the growth and subdivision of existing peroxisomes Generates hydrogen peroxide (potentially dangerous free radical) from breakdown of fatty acids and other organic compounds Catalan breaks down the hydrogen peroxide into oxygen and water |
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Mitochondria |
Produce energy in the form of ATP molecules Double membrane, outer membrane surrounds the organelle, inner membrane contains numerous folds called cristae surrounding the fluid contents (matrix) Contain their own DNA (mtDNA) |
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Glycolysis |
Break down of glucose molecule into two molecules of pyruvate in the cytosol |
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Citric Acid Cycle |
AKA Krebs Cycles or Tricarboxylic Acid Cycle - breaks down pyruvate after it is absorbed into mitochondria into CO2 and H |
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Aerobic Respiration |
AKA Cellular Respiration - type of ATP production in the mitochondria that requires oxygen Produces about 95% of ATP needed in cell |
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Membrane Flow |
AKA membrane trafficking, continuous movement and exchange of membrane segments |
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Nucleus |
Usually largest and most conspicuous structure in cell, stores all information needed to direct protein synthesis in DNA Most cells only contain one nucleus but skeletal muscle cells contain many and red blood cells do not have a nucleus |
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Nuclear Envelope |
Double membrane that encloses contents of nucleus separating them from the cytosol, layers separated by narrow perinuclear space, nuclear envelope continuous with ER |
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Nuclear Pores |
Openings in the nuclear envelope that regulate transport of material such as RNA and proteins |
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Nucleoplasm |
AKA Karyolymph - the fluid portion of the nucleus |
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Nuclear Matrix |
Network of fine filaments that provides structural support to the Nucleus and may be involved in regulation of genetic activity |
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Nucleoli |
Dark-staining areas of the nucleus, transient organelles that synthesize ribosomal RNA (rRNA) and assemble ribosomal subunits which enter the cytoplasm through the nuclear pores Composed of RNA, enzymes, and histones, form around portions of DNA that contain instructions for producing ribosomal proteins and RNA when those instructions are being carried out |
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Nucleosome |
DNA strands wound around histones that allow for large amounts of DNA to be packaged into a small space Determine which information is available |
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Chromatin |
Fine filaments of nucleosome chains that are loosely coiled in cells that are not dividing |
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Chromosomes |
Distinct structures resulting from tightly coiled nucleosome chains in cells preparing to divide |
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Triplet Code |
Sequence of three nitrogenous bases that code for a single amino acid |
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Gene |
Functional unit of heredity, sequence of nucleotides in a DNA strand that specifies which amino acids are needed to produce a specific protein |
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Protein Synthesis |
Assembling of functional polypeptides in the cytoplasm |
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Gene Activation |
Portion of DNA molecule containing the gene is uncoiled and the histones are temporarily removed allowing the gene to be read |
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Promotor |
Special region of DNA at the start of each gene signaling the start of the gene |
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Transcription |
The synthesis of RNA from a DNA template |
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Messenger RNA (mRNA) |
RNA transcribed from DNA that carries the information needed to synthesize proteins |
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Coding Strand |
DNA strand that contains the triplets that specify the sequence of alibi acids in the polypeptide |
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Template Strand |
DNA strand that contains the complementary triplets that will be used as a template for mRNA production |
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RNA Polymerase |
Enzyme that binds to the promoter of a gene on the template strand that promotes hydrogen bonding between nitrogenous bases between the nucleotides on the template strand and nucleotides in the nucleoplasm, and strings together nucleotides by covalent bonding |
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Codon |
Three nucleotide sequence that codes for a specific amino acid in DNA and RNA |
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RNA Processing |
Immature mRNA (pre-mRNA) contains many triplets not needed in protein synthesis Noncoding introns get snipped out, Coding exons are spliced together, creating a much shorter, functional mRNA strand |
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Intron |
Noncoding intervening segments of mRNA |
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Exon |
Coding segments of mRNA |
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Translation |
The formation of a linear chain of amino acids (a polypeptide) using the information from an mRNA strand |
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Transfer RNA (tRNA) |
Binds and delivers a specific type of amino acid during translation |
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Anticodon |
Base sequence complementary to the mRNA codon that indicates the type of amino acid carried by the tRNA |
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Initiation |
Translation begins as mRNA binds to small ribosomal subunit at the start codon, tRNA binds to mRNA, then a large ribosomal subunit binds to create a functional ribosome |
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Elongation |
Translation continues as amino acids are added one by one as ribosome moves along mRNA strand |
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Termination |
End of Translation - Elongation ends when the ribosome reaches the stop codon, the polypeptide chain is release, the ribosomal subunits separate, the mRNA strand is freed. |
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Permeability |
The property of the plasma membrane that determines precisely which substances can enter or leave the cytoplasm |
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Impermeable |
A membrane through which nothing can pass |
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Freely Permeable |
A membrane through which any substance can pass |
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Selectively Permeable |
Permeability permits the free passage of some materials and restricts the passage of others |
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Diffusion |
Net movement of a substance from an area of higher concentration to an area of lower concentration |
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Concentration Gradient |
Difference between high and low concentrations if a substance Potential energy gradient |
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Electrochemical Gradient |
Net result of the chemical and electrical forces acting on an ion |
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Membrane Channels |
Small passageways through the plasma membrane created by transmembrane proteins |
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Leak Channels |
Membrane channels that are always open and allow ions to pass across the plasma membrane |
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Osmosis |
The net diffusion of water across a membrane |
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Osmotic Pressure |
An indication of the force with which pure water moves into a solution as a result of its solute concentration |
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Hydrostatic Pressure |
Pressure resulting from pushing against a fluid |
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Aquaporins |
Membrane channels allowing the free passage of water molecules |
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Osmolarity |
Osmotic concentration - the total solute concentration in an aqueous solution |
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Tonicity |
The effects of various osmotic solutions on a cell |
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Isotonic |
Equal solute (osmotic) concentration Does not cause an osmotic flow of water into or out of a cell |
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Hypotonic |
Lower solute (osmotic) concentration Water flows into a cell, causing it to swell up and eventually burst |
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Hypertonic |
Higher solute (osmotic) concentration Water flows out of the cell, causing it to shrivel up |
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Crenation |
The shrinking of cells due to a hypertonic solution |
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Carrier-Mediated Transport |
Integral proteins bind specific ions or organic substrates and carry them across the plasma membrane Can be active or passive |
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Vesicular Transport |
Involves moving materials within small membranous sacs (vesicles) Always an active process |
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Symport Mechanisms |
Cotransport, common carrier protein (symporter) transports two different molecules or ions through a membrane in the same direction |
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Antiport Mechanism |
Countertransport, carrier protein (antiporter) transports two different molecules or ions through a membrane in opposite directions |
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Facilitated Diffusion |
Passive transport across the plasma membrane through a carrier protein |
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Active Transport |
A high-energy bond (ATP) provides energy needed to move ions or molecules across the membrane |
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Ion Pumps |
Actively transports the cations sodium, potassium, calcium, and magnesium across the plasma membrane Some cells also transport iodide, chlorine, and iron ions |
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Exchange Pump |
Occurs when a countertransport (antiporter) mechanism moves ions |
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Primary Active Transport |
Process of pumping solute against a concentration gradient using the energy from ATP |
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Sodium-Potassium Exchange Pump |
Exchanges intracellular sodium ions for extracellular potassium ions Maintains high extracellular sodium concentration and high intracellular potassium concentrations 1 ATP --> 3 sodium ejected from cell, 2 potassium absorbed into cell |
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Secondary Active Transport |
Transport mechanism itself does not require energy, but the cell often needs to expend ATP at a later time to preserve homeostasis. Concentration gradient for one substance provides the driving force needed by the carrier protein to transport the second substance |
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Endocytosis |
Extracellular materials packaged in vesicles at the cell surface and imported into the cell |
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Endosomes |
Vesicles created during endocytosis |
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Receptor-Mediated Endocytosis |
Produces vesicles that contain a specific target molecule in high concentrations |
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Clathrin-Coated Pits |
Inwardly depressed areas of the plasma membrane that contain receptors and high concentrations of the protein clathrin on their cytoplasmic surface |
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Caveolae |
Small flask-shaped indentations in the plasma membrane |
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Pinocytosis |
Cell drinking, formation of endosomes filled with extracellular fluid No receptors involved, not very selective |
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Phagocytosis |
Cell eating, produces endosomes called phagosomes containing solid objects that may be as large as the cell itself Performed only by specialized cells (such as macrophages) such as macrophages that protect tissues by engulfing bacteria, cell debris, or other abnormal materials |
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Pseudopodia |
Cellular extensions that surround an object and their membranes fuse to form a phagosome |
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Exocytosis |
A vesicle formed inside the cell fuses with the plasma membrane, releasing its contents into the extracellular fluid |
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Transcytosis |
Endocytosis produces vesicles on one side of the cell that are discharged through exocytosis on the opposite side of the cell |
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Membrane Potential |
Positive and negative charges are held apart by the plasma membrane, causing a potential difference across a plasma membrane |
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Resting Membrane Potential |
The membrane potential in an unstimulated, undisturbed cell Ranges from about -10mV to -100mV |
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Cell Division |
Form of cellular reproduction, a single cell divides to produce a pair of daughter cells |
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Apoptosis |
The genetically controlled death of cells |
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Interphase |
The stage of the cell life cycle between mitotic divisions where a cell performs its normal functions |
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DNA Replication |
Duplication of DNA |
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DNA Helicase |
Enzyme that unwinds the DNA strands and disrupts the hydrogen bonds between the bases |
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DNA Polymerase |
Enzyme that promotes bonding between nitrogenous bases of the DNA strand and the complementary DNA nucleotides and links the nucleotides with covalent bonds |
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DNA Ligase |
Splice together DNA segments on the lagging strand of DNA |
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M Phase |
Includes mitosis and cytokinesis |
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Mitosis |
Duplication of the chromosomes in the nucleus and their separation into two identical sets in the process of somatic division |
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Cytokinesis |
The division of the cytoplasm during mitosis producing two daughter cells |
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G0 Phase |
Cell in this phase is not preparing for division and is performing all of the other functions appropriate for that cell type |
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G1 Phase |
A cell that is ready to divide first enters this phase during which the cell makes enough mitochondria, cytoskeletal elements, endoplasmic reticula, Golgi apparatus membranes, and cytosol for two functional cells |
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G2 Phase |
Phase devoted to last-minute protein synthesis and to the completion of centriole replication |
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Prophase |
Phase begins when the chromatin condenses, and chromosomes become visible as single structures under a light microscope |
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Spindle Fibers |
Array of microtubules that extend between centriole pairs |
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Astral Rays |
Smaller microtubules that radiate into cytoplasm |
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S Phase |
DNA replication takes places during this phase |
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Chromatid |
Each copy of a chromosome |
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Centromere |
Each chromatid is connected to its duplicate copy at this point |
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Kinetochores |
Protein-bound areas of the centromere that attach to spindle fibers forming chromosomal microtubules |
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Metaphase |
Begins as the chromatids move to a narrow central zone called the metaphase plate, ends when all the chromatids are aligned in the plane of the metaphase plate |
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Anaphase |
Begins when the centromere of each chromatids pair splits and the chromatids separate, two daughter chromatids are pulled toward opposite ends of the cell along the chromosomal microtubules |
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Telophase |
Each new cell prepares to return to the interphase state, nuclear membranes reform, nuclei enlarge, chromosomes gradually uncoil |
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Cytokinesis |
The division of the cytoplasm into two daughter cells, beginning with the formation of the cleavage furrow |
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Mitotic Rate |
Frequency of cell division can be estimated by the number of cells in mitosis at any time |
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Stem Cells |
Undifferentiated cells that maintain cell populations through repeated cycles of cell division |
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M-Phase Promoting Factor (MPF) |
Also known as maturation-promoting factor Internal trigger that promotes cell division |
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Cyclin |
Levels climb as cell life cycle proceeds, when levels get high enough, MPF appears in the cytoplasm and mitosis starts |
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Growth Factors |
Natural body substances derived from food that can stimulate the division of specific types of cells
Hormones, peptides, nutrients |
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Repressor Genes |
Genes that inhibit cell division |
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p53 |
Protein that binds to DNA that activates a gene that directs the production of growth-inhibiting factors in the cell |
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Telomeres |
Terminal segments of DNA that protect the ends of the chromosome from damage during mitosis |
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Telomerase |
Enzyme that repairs telomeres that is active in early life but becomes active by adulthood Activating telomerase is a key step in the development of cancer |
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Tumor |
Neoplasm, a mass or swelling produced by abnormal cell growth and division |
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Benign Tumor |
Cells usually remain within the tissue where it originated and seldom threatens the individual's life |
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Malignant Tumor |
Cells no longer respond to normal controls and do not remain confined within the epithelium or a connective tissue capsule and spread to surrounding tissues |
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Invasion |
Spreading of tumor cells to other tissues |
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Cancer |
An illness that results from the abnormal proliferation of any of the cells in the body characterized by mutations that disrupt normal cell regulatory controls and produce potentially malignant cells |
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Oncogenes |
Mutated genes involved in cell growth, differentiation, or division |
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Mutagens |
Agents that cause a mutation (change in DNA) |
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Carcinogens |
Cancer-causing agents |
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Metastasis |
The spread of the cancer to other areas, malignant cells break out of the primary tumor and invade the surrounding tissue |
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Angiogenesis |
The growth of new blood vessels |
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Cellular Differentiation |
Development of specific cellular characteristics and functions that are different from the original cell |
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Induced Pluripotent Stem (iPS) Cells |
Ability to take a person's stem or somatic cells and create new cells or neurons to treat disease such as Parkinsin's |