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111 Cards in this Set
- Front
- Back
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Light microscope (LM)
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a device in which visible light is passed through the specimen and then through glass lenses, which refract the light and magnify the image of the specimen, which is projected to the eye
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Organelles
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Membrane-enclosed, subcellular compartments
Cannot be seen through a light microscope |
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Electron microscope (EM)
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Introduced in the 1950s
Focuses beam of electrons through the specimen or onto its surface. Reveals cell ultrastructure |
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Scanning electron microscope (SEM)
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Used for a detailed study of a specimen's surface
Electron beam scans surface of sample, which is coated with thin film of gold The beam excites electrons on the surface, and are detected by a device that translates the patterns into an electric signal, which is translated to a video screen |
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Transmission electron microscope (TEM)
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Used to study internal ultrastructure of cells
Sends electron beam thin part of specimen. Specimen has been stained with heavy metals that attach to several structures. Electrons concentrate in denser region, thus showing as darker Direction of electrons are guided by electromagnets |
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Cell fractionation
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Technique for studying cell structure and function
Takes cells apart and separates major organelles and other subcellular structures from one another Cells are homogenized and then placed in centrifuge to divide each structure type by density |
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Cytosol
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A semifluid, jellylike substance enclosed by the plasma membrane
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Eukaryotic cell
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Cell in which most of the DNA is in the nucleus
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Prokaryotic cell
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Cell in which DNA is not concentrated in a region that is not membrane-enclosed
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Nucleoid
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region in which DNA is concentrated within a prokaryotic cell. is not enclosed by a membrane
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Plasma membrane
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A selective barrier at the boundary of a cell that allows sufficient passage of oxygen, nutrients, and wastes to service the entire cell
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Nucleus
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Structure that contains most of the genes in the eukaryotic cell
General the most conspicuous organelle in the cell Averages about 5 micrometers in diameter |
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Nuclear envelope
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Structure enclosing the nucleus, separating its contents from the cytoplasm
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Nuclear lamina
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a netlike array of protein filaments maintaining the shape of the nucleus by mechanically supporting the nuclear envelope
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Chromosomes
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structures that carry the genetic information
structures DNA is organized into made up of chromatin |
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Chromatin
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a complex of protein and DNA
makes up chromosomes condenses during cell division |
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Nucleolus
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Structure in the nondividing nucleus
Location of synthesis of ribosomal RNA (rRNA), and where proteins imported from the cytoplasm are assembled with rRNA into ribosomal subunits |
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Ribosomes
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Complexes made up of ribosomal rRNA
the cellular components that create protein synthesis |
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Endomembrane system
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Carries out protein synthesis and transport, metabolism and movement of lipids, and detoxification of poisons
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Vesicles
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sacs made of protein
connect different parts of the endomembrane system |
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endoplasmic reticulum (ER)
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an extensive network of proteins, accounts for more than half of the cell's total membrane in many cells
consists of membraneous tubules and sacs called cisternae |
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Smooth ER
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region of the ER. Its surface lacks ribosomes
Processes: synthesis of metabolism, metabolism of carbohydrates, and detoxification of drugs and poisons |
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Rough ER
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region of the ER whose outer surface is covered with ribosomes
synthesizes proteins destined to be in the plasma membrane or transported outside the cell |
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Glycoproteins
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Are secretory proteins
Proteins that have carbohydrates covalently bonded to them by molecules built into the ER membrane |
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Transport vesicles
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Those that are in transit from one part of the cell to another
Contain secretory proteins, thus keeping them separate from the cytosol |
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Golgi apparatus
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Destination of many transport vesicles
Location in which the ER's products are manufactured, stored, sorted, and shipped Consists of flattened membraneous sacs called cisternae |
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Lysosome
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A membraneous sac of hydrolytic enzymes that an animal cell uses to digest macromolecules
Acidic environment inside this structure |
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Phagocytosis
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Engulfing of smaller organisms or other food particles by amoebas and many other protists
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Food vacuoles
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Formed by phagocytosis. The contents of it are eaten up by hydrolytic enzymes
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Contractile vacuoles
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Structure of many freshwater protists
Pump excess water out of the cell to maintain equilibrium inside the cell |
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Central vacuole
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Structure in most mature plant cells
Develops by the coalescence of smaller vacuoles |
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Mitochondria
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the sites of cellular respiration
about 1-10 micrometers long moves around the cell and divides has inner foldings of membrane called cristae |
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Chloroplasts
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sites of photosynthesis
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Peroxisome
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an organelle
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Cristae
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infoldings of the inner membrane of the mitochondria
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Mitochondrial matrix
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the space enclosed by the inner membrane of the mitochondria
contains a variety of enzymes, mitochondrial DNA, & ribosomes |
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Plastids
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A family of closely related plant organelles
Chloroplasts are a member Another subdivision: Amyloplasts (colorless plastids that store starch and chromoplasts, or flower pigments) |
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Thylakoids
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flattened, interconnected sacs inside a chloroplast
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Granum
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each stake of thylakoids
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Stroma
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the fluid outside the thylakoids, which contains the chloroplast DNA, ribosomes, and enzymes
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Cytoskeleton
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A network of fibers extending throughout the cytoplasm
Plays major role in organizing the structures and activities of the cell 3 types of molecular structures: microtubules, microfilaments, and intermediate filaments |
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Motor proteins
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Proteins that that allows several parts of the cell to move about the cell. These proteins attach to receptors on vesicles, and attach to a microtubule. Powered by ATP, they can move along the microtubule.
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Microtubules
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Hollow rods measuring about 25 nm in diameter and from 200 nm to 25 micrometers in length
Made of tubulin, a dimer (alpha tubulin and beta tubulin) one end of tubulin can dissemble/assemble more quickly than the other side Function: shape and support the cell, and serve as tracks for motor proteins |
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Centrosome
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a region located near the nucleus
"microtubule organizing center" microtubules grow out of it |
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Centrioles
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2 of them are in the centrosome
each has nine sets of triplet microtubules, arranged in a ring formation are not necessary to organize microtubule assembly in all eukaryotes |
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Flagella
Cilia |
microtubule-containing extensions that project from some cells
can work to move entire cell cilia working together can move fluid across a tissue |
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Basal body
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a structure similar to that of a centriole
it connects the flagellum or cilium to the cell |
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Dyneins
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large motor proteins that connect the double microtubules to each other || = || in a flagellum or cilium
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Microfilaments
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solid rods about 7 nm in diameter
also called actin filaments a twisted double chain of actin subunits function: bear tension, helps support cell shape |
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Actin
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a globular protein
makes up microfilaments |
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Cortex
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the outer cytoplasmic layer of a cell
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Cytoplasmic streaming
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contractions between actin and myosin leads to muscle contraction, which contributes to this
the circular flow of cytoplasm within cells |
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Intermediate filaments
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diameter: 8-12 nm
are a diverse group of cytoskeletal elements made up of keratin function: bear tension, reinforce shape of cell very durable |
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Cell wall
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extracellular structure of plant cells that distinguishes them from animal cells
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Primary cell wall
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The first secretion of the cell wall
Thin and flexible |
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Middle lamena
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between the primary walls of adjacent cells
a thin layer rich in sticky polysaccharides cll |
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tight junctions
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tightly pressed against one another bound by specific proteins, making seals
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Secondary cell wall
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Is between the plasma membrane and the primary wall
Has a strong and durable matrix --> cell protection and support Wood has this |
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Extracellular matrix (ECM)
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Outside of animal cell
Its main ingredients: glycoproteins secreted by the cells |
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Collagen
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the most abundant glycoprotein in the ECM
forms strong fibers outside the cells embedded in network of proteoglycans accounts for 40% of the total protein in the body |
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Proteoglycan
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molecule of core protein covalently attached to many carbohydrate chains
form a network surrounding collagen in the ECM |
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Fibronectin
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an ECM glycoprotein that attaches some cells to the ECM
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Integrins
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cell surface receptor proteins that bind to fibronectin
built into the plasma membrane |
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Plasmodesmata
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Channels that perforate the cell walls of plant cells
Cytosol passes through it and connects the chemical environments of adjacent cells Lined by the plasma membrane |
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Tight junctions
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When the plasma membranes of neighboring cells are very tightly pressed against one another by specific proteins
Forms seals, preventing leakage of extracellular fluid across layer of cells |
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Desmosomes
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Act like rivets, fastening cells together into strong sheets by intermediate filaments
Example of when used: muscle cells |
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Gap junctions
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Provide cytoplasmic channels from one cell to an adjacent cell
Similar in function to plasmodesmata Consist of membrane proteins surrounding a pore Necessary for communication between cells in many types of tissues |
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Selective permeability
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Exhibited by the plasma membrane
Allowance of some substances to cross it more easily than others |
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Amphipathic
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having both a hydrophilic region and a hydrophobic region
example: phospholipid |
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Fluid mosaic model
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Model for the arrangement of phospholipids and proteins in the membranes of cells in which the membrane is a fluid structure with a mosaic of various proteins embedded in or attached to a double layer (bilayer) of phospholipids
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Integral proteins
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one major population of membrane proteins
Penetrate the hydrophobic core of the lipid bilayer Some are transmembrane proteins, which span the membrane; others extend only partway into hydrophobic core Hydrophobic regions of it consist of at least one stretch of nonpolar amino aids, usually coiled into alpha helices |
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Peripheral proteins
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One of the major populations of membrane proteins
Are not embedded in the lipid bilayer Appendages loosely bound to the surface of the membrane, often to exposed parts of integral proteins |
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Glycolipids
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Membrane carbohydrates of fewer than 15 sugar units, covalently bonded to lipids
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Glycoproteins
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Membrane carbohydrates of fewer than 15 sugars units, covalently bonded to proteins
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Transport proteins
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Proteins in the plasma membrane that small, polar molecules pass through to enter or exit the cell
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Aquaporins
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Channel proteins that facilitate the transport of water molecules across the plasma membrane
Allows entry of up to 3 billion water molecules per second Is 10 water molecules wide |
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Diffusion
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A result of thermal motion
The movement of molecules of any substance so that they spread out evenly into the available space |
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Concentration gradient
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The way a substance will diffuse down to
The region along which the density of a chemical substance decreases |
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Passive transport
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The diffusion of a substance across a biological membrane
Requires no energy from the cell Its speed depends on the molecule |
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Osmosis
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The diffusion of water across a selectively permeable membrane
Is crucial to organisms |
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Tonicity
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the ability of a solution to cause a cell to gain or lose water
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Isotonic
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Quality of an environment in which no net movement of water across the plasma membrane will occur, if a cell is without a wall
Environment in which the volume of an animal cell is stable |
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Hypertonic
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A cell which has a higher concentration of water in its interior than its exterior
Will lose its water and shrivel up |
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Hypotonic
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A cell which has a higher concentration of water in its exterior than its interior
Will gain water quickly and burst (lyse) |
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Osmoregulation
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The control of water balance
Necessary for animals and other organisms without rigid cell walls that live in hypertonic or hypotonic environments |
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Turgid
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Condition of a plant cell that is hypotonic, but whose cell wall sends a back pressure to the outward pressure due to the swelling due to the input of water
Very firm The healthy state for most plant cells |
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Flaccid
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Limp
Condition of plant cells when they are isotonic, as there is no tendency for water to enter |
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Plasmolysis
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The event in which a hypertonic plant cell loses water to its surroundings, and shrinks, and the plasma membrane shrinks and pulls away from the cell wall
May lead to plant death |
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Facilitated diffusion
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The phenomenon in which many polar molecules and ions diffuse across the plasma membrane via the help of transport proteins
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Ion channels
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A type of transport protein
One major type of this type of transport protein: gated channels |
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Gated channels
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A type of ion channel
Open and close in response to an electrical or chemical (by a molecule other than one trying to be transported) stimulus |
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Active transport
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The type of membrane traffic that requires energy on the behalf of the cell
Done by proteins that move molecules against their concentration gradient |
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Sodium-potassium pump
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Exchanges Na+ for K+ across the plasma membrane of animal cells
Fueled by attachment of a phosphate group by ATP |
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Membrane potential
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The voltage (electrical potential energy: a separation of opposite charges) across a membrane
Ranges from about -50 to -200 millivolts (mV) |
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Electrochemical gradient
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The combination a chemical force (tendency of chemical to cross plasma membrane down its concentration gradient) and an electrical force (effect of membrane potential on the ion's movement)
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Electrogenic pump
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A transport protein that generates voltage across a membrane
Example: sodium-potassium pump |
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Proton pump
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The main electrogenic pump of plants, fungi, and bacteria
Actively transports H+ out of the cell Transfers charge positive charge from the cytoplasm to the extracellular solution |
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Cotransport
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A mechanism in which a single ATP-powered pump that transports a specific solute can indirectly drive the active transport of several other solutes in a mechanism
a specific solute that has been pumped against its concentration gradient travels back via diffusion, thus doing work, and brings a solute with it that moves against its concentration gradient (releases energy used by other solute to move against its concentration gradient) example: sucrose-H+ transport in plant cells |
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Exocytosis
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the fusion of vesicles with the plasma membrane, which allows for the secretion of certain biological molecules
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Endocytosis
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the formation of new vesicles from the plasma membrane, so that the cell can take in biological molecules and particulate matter
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Phagocytosis
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"cellular eating"
big-scale endocytosis: example is eating other cells the vesicle formed is as big as a vacuole type of endocytosis |
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Pinocytosis
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"cellular drinking"
type of endocytosis in which fluid from ECM enters vesicle, along with the needed molecules |
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Receptor-mediated endocytosis
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Type of endocytosis in which ligands bind to proteins with specific receptor proteins, and a vesicle is formed with the protein inside of it
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Ligands
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any molecule that binds specifically to a receptor site of another molecule
Are used in receptor-mediated endocytosis |
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Cotransport
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A mechanism in which a single ATP-powered pump that transports a specific solute can indirectly drive the active transport of several other solutes in a mechanism
a specific solute that has been pumped against its concentration gradient travels back via diffusion, thus doing work, and brings a solute with it that moves against its concentration gradient (releases energy used by other solute to move against its concentration gradient) example: sucrose-H+ transport in plant cells |
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Exocytosis
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the fusion of vesicles with the plasma membrane, which allows for the secretion of certain biological molecules
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Endocytosis
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the formation of new vesicles from the plasma membrane, so that the cell can take in biological molecules and particulate matter
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Phagocytosis
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"cellular eating"
big-scale endocytosis: example is eating other cells the vesicle formed is as big as a vacuole type of endocytosis |
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Pinocytosis
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"cellular drinking"
type of endocytosis in which fluid from ECM enters vesicle, along with the needed molecules |
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Receptor-mediated endocytosis
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Type of endocytosis in which ligands bind to proteins with specific receptor proteins, and a vesicle is formed with the protein inside of it
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Ligands
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any molecule that binds specifically to a receptor site of another molecule
Are used in receptor-mediated endocytosis |
