Section 1
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Rough ER
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Section 1
(50 cards)
Rough ER
Region of the ER that has ribosomes on its outer surface. Acts as a membrane factory for the cell: it grows in place by adding membrane proteins and phospholipids to its own membrane. Parts of transported to other regions of the endomembrane system. Secretes many proteins. As a polypeptide chain grows from a bound ribosome, it is threaded into the ER lumen through a pore formed by a protein complex in the ER membrane. As the new protein enters the ER lumen, it folds into its conformation. Once these secretory proteins are formed, the ER membrane keeps them separate from those produced by free ribosomes, destined to stay in the cytosol. The secretory proteins, wrapped in the membrane of vesicles, debud from the transitional ER.
Amyloplasts
Colorless plastids that store starch (amylose)
Vacuoles
Mostly in plant and fungal cells. Similar to vacuoles in that they carry out hydrolysis but also carry out other functions as well. There are food vacuoles, contractile vacuoles, and the central vacuole found in mature plants.
Cisternal Space
Also known as the ER lumen The internal compartments of the RE
Transport Vesicles
Bud off from the transitional ER and often travel to the Golgi apparatus. Are vesicles in transit from one part of the cell to another.
Trans Face of the Golgi Apparatus
One side of the polar membrane of cisternae making up the Golgi. Functions in delivery from the Golgi by giving rise to vesicles which pinch off and travel to other sites of the cell.
Cell Sap
The solution found inside a large central vacuole in plants. Different composition than the cytosol, since it is made up of many solutes, selectively allowed through the tonoplast (membrane that encloses the vacuole)
Plastids
A family of closely related plant organelles. Consists of chloroplasts, amyloplasts, and Chromoplasts.
Mitochondria: Form
Enclosed by two membranes, each a phospholipid bilayer with a unique collection of embedded proteins. Outer membrane is smooth but the inner one divides the mitochondrion into two internal compartments: the intermembrane space and the mitochondrial matrix.
Nucleus-protein synthesis steps
Instructions provided by the DNA directions the synthesis of messenger RNA (mRNA), which then leaves the nucleus through the pore complex, entering the cytoplasm. Then ribosomes translates and transcribes the mRNA into the primary structures of specific polypeptides.
Endomembrane System
The different membranes of the eukaryotic cell that carries out a variety of tasks. Includes that nuclear envelope, ER, golgi apparatus, lysosomes, vacuoles, and the plasma membrane.
Ribosomes
Particles made of ribosomal RNA and protein; also, organelles that carry out protein synthesis Synthesized in the nucleoli Two types: Free ribosomes and bound ribosomes (the two types can alternate, depending on metabolic demand)
Food Vacuoles
Formed by phagocytosis and function like the lysosomes
Problem with lysosomes in Tay-Sachs disease
A person suffering from Tay-Sachs lack a functioning hydrolytic enzyme that is normally present in lysosomes. The lysosomes become engorged with indigestible substrates. In Tay-Sachs specifically, the enzyme is missing or inactive and the brain becomes impaired by an accumulations of lipids in the cells.
Thylakoids
Flattened and interconnected sacs found within the chloroplast, within the second membrane. Usually found in stacks called granum
Autophagy
In this, lysosomes use their hydrolytic enzymes to recycle the cell's own organic material. A damaged organelle or small amount of cytosol becomes surrounded by a membrane and a lysosome fuses with this vesicle. The lysosomal enzymes dismantle the enclosed material, and the organic monomers are returned to the cytosol to be used again. With this process, a cell is able to renew itself.
Sorting Vesicles at the trans face of the Golgi
At the trans face, the Golgi sorts the products and targets them for various part of the cell. Molecular identification tags, such as phosphate groups, that have been added to the Golgi products, aid in sorting by acting like shipping labels. Transports vesicles from the Golgi may also have external molecules on their membranes that recognize docking sites on the surface of specific organelles or on the plasma membrane.
Nucleoid
where the DNA is concentrated a prokaryotic cell. No membrane separates this from the rest of the cell, unlike the nucleus in eukaryotic cells
Chromosomes
Found within the nucleus. Units in which DNA is organized into. Made up of a material called chromatin which is a complex of proteins and DNA. Humans have 46 chromosomes
Nucleolus
Found within the nucleus Where ribosomal RNA (rRNA) is synthesized Proteins imported from the cytoplasm are assembled with rRNA into larger and small ribosomal subunits here.
Surface Area to Volume Ratio
The smaller the object, the great the ratio of surface area to volume. Cells that need to cover more surface area often have projections (microvilli), which keeps volume reasonably low.
Phagocytosis in Lysosomes (e.g. humans, amoebas and protists)
Amoebas (for example) and many other protists eat by engulfing smaller organisms or other food particles using phagocytosis. The food vacuole forms and fuses with the lysosome, whose enzymes digest the food. The digestion products (including amino acids, simple sugars and other monomers) pass into the cytosol and become nutrients for the cell. In humans, macrophages (a type of white blood cell) defends the body by engulfing and destroying invaders like bacteria.
Cristae
The folded surfaces of the innermembrane of mitochondria.
Contractile Vacuoles
Found in many freshwater protists They pump excess water out of the cell, maintaining the appropriate concentration of salts and other molecules.
Smooth ER
Region of the ER that lacks ribosomes on its outer surface. Involved in metabolic processes such as synthesis of lipids, metabolism of carbohydrates, and detoxification of drugs and poisons (which involves the addition of a hydroxyl group to the drugs, making them more soluble). Also involved in synthesis of lipids (oils, phospholipids, and steroids). Stores Ca ions (in muscle for example).
Chloroplast: Form
Contain the green pigment chlorophyll, among other enzymes and molecules that function in the photosynthetic production of sugar. Found in leaves and other green organs of plants and algae. Have an inner and outer membrane and a very narrow intermembrane space. Inside the chloroplast (within the second membrane) is another membranous system in the form of flattened and interconnected sacs called thylakoids Has three compartments: the intermembrane space, the stroma and the thylakoid space.
Cisternal Maturation Model
A new model of the Golgi apparatus structure. Previously, it was believed that the Golgi was a static structure, with its products in various stages of processing transferred from one cisternae to the next by vesicles. This new model show the dynamic nature of the Golgi: according to the model, the cisternae of the Golgi actually progress forward from the cis and the trans face of the Golgi, carrying and modifying their protein cargo as they move. So, the Golgi cisternae more in a cis-to-trans direction, which ultimately form vesicles at the end which bud off and move to new locations. The cis portion of the Golgi reforms by the vesicles coming from the ER then coalescing to the Golgi membrane.
Central Vacuole
Found in most mature plants. Enclosed by a membrane called the tonoplast. Develops from many small vacuoles coming together, which are originally derived from the ER and Golgi. Can hold reserves of important organic compounds such as proteins. Cell's main repository of inorganic ions like potassium and chloride. Often used as a disposal site for metabolic by-products that would otherwise endanger the cell. Some contain pigments that color the cells, like the red and blue pigments of petals that help attract pollinators. Can contain poisons that help the plant be protected from predators. Has a major role in the growth of the plant cells, which enlarge as their vacuoles absorb water, enabling the cell to become larger with minimal investment in new cytoplasm.
Definition: Cellular Respiration
The metabolic process that generates ATP by extracting energy from sugars, fats, and other fuels with the help of oxygen.
Cis Face of the Golgi Apparatus
One side of the polar membrane of cisternae making up the Golgi. Usually found near the ER, since it functions in receiving transport vesicles. These vesicles bud from the ER and add its membrane and contents of its lumen to the cis face by fusing with a Golgi membrane.
The Intermembrane Space of the Mitochondria
The narrow region between the inner and outer membranes. Proteins that function in respiration like the enzyme that makes ATP are built here.
Nuclear Envelope
Encloses the nucleus Made up of two lipid bilayers Contains protein structures making up a pore complex, regulating the entry and exit of particles
Bound Ribosomes
Ribosomes that are attached to the rough endoplasmic reticulum or nuclear envelope. Mostly make proteins that are destined for insertion into membranes, for packaging within certain organelles, or for secretion.
Tonoplast
The membrane that encloses the large central vacuole found in most mature plants. Selective in transporting solutes, and, as a result, the solution inside the vacuole (cell sap) differs in composition from the cytosol
Glycoproteins
A lot of secretory proteins are these. They are proteins that have covalently bonded carbohydrates which are attached to the protein in the ER by specialized molecules built into the ER membrane. Can be involved in cell-cell recognition.
Free Ribosomes
Ribosomes that are suspended in the cytosol. Most proteins made on these function with the cytosol.
Chromoplasts
Plastids that have pigments that give fruits and flowers their orange and yellow hues.
Definition: Mitochondria
Used to convert energy to forms that cells can use for work. The site of cellular respiration. Has at least two membranes separating the innermost space from the cytosol. Membrane proteins are not made by the ER, but by free ribosomes in the cytosol and ribosomes contained within themselves. Contains a small amount of DNA. Are semiautonomous, since they grow and reproduce within the cell. Can move around the cell with other organelles on networks of cytoskeleton.
Golgi Apparatus
Here, product of the ER are modified and stored and then sent to other destinations (is very extensive in cells specialized for secretion). Manufactures certain macromolecules by itself. Consists of flattened membranous sacs (cisternae). The membrane of each cisternae in a stack separates its internal space from the cytosol. A Golgi stack has a distinct polarity, with the membranes of the cisternae on opposite sides of the stack differing in thickness and molecular composition (the cis face and the trans face) and each function in either receiving or shipping.
Movement of proteins from the ER through the Golgi (e.g. glycoproteins)
Products of the ER are usually modified during their transit from the cis to the trans regions of the Golgi. For example, carbohydrates are first added to proteins in the rough ER, often during polypeptide synthesis. The carbohydrate on the resulting glycoprotein is then modified as it passes through the rest of the ER and the Golgi. The Golgi removes some of the sugar monomers and substitutes others, producing a large variety of carbohydrates.
Plasma Membrane
A selective barrier that allows sufficient passage of oxygen, nutrients and wastes
Lysosome
A membranous sac of hydrolytic enzymes that an animal cell uses to digest all kinds of macromolecules, which work best in the acidic environment of these sacs. The hydrolytic enzymes and the membrane of the sac are made by the rough ER and then transferred to the Golgi for further processing. They carry out intracellular digestion in a variety of circumstances including phagocytosis and autophagy.
The Mitochondrial Matrix
Enclosed by the inner membrane. Contains many different enzymes and mitochondrial DNA and ribosomes. Some of the metabolic steps of cellular respiration are catalyzed by enzymes here. Has highly folded surfaces (making up the cristae), giving the membrane a large surface area for the proteins, thus enhancing the productivity of cellular respiration.
Ribosomes
tiny organelles that make proteins according to instructions from the genes
Definition: Chloroplasts
Used to convert energy to forms that cells can use for work. Found only in plants and algae. Sites of photosynthesis. Convert solar energy to chemical energy by absorbing sunlight and using it to drive the synthesis of organic compounds such as sugars from CO2 and water. Has at least two membranes separating the innermost space from the cytosol. Membrane proteins are not made by the ER, but by free ribosomes in the cytosol and ribosomes contained within themselves. Contains a small amount of DNA. Are semiautonomous, since they grow and reproduce within the cell. Can move around the cell with other organelles on networks of cytoskeleton.
Cisternae
The network of membranous tubules and sacs that make up the endoplasmic reticulum, separated by the ER membrane
Nuclear Lamina
Lines the nuclear envelope, except at the pores. A netlike array of protein filaments that maintain the shape of the nucleus by supporting the envelope. Made up by intermediate filaments .
Endoplasmic Reticulum
Consists of a network of membranous tubules and sacs called cisternae. Two distinct regions: the smooth ER and the rough ER.
Cytosol
a semifluid substance in which organelles are found; within the cytoplasm
Mycoplasmas
Smallest cells known Bacterial cells
Section 2
(50 cards)
Cytoskeleton
A network of fibers extending through the cytoplasm. Plays a major role in organizing the structures and activities of the cell; gives mechanical support to the cell and helps maintain its shape. Three types of molecular structures: microtubules, microfilaments, and intermediate filaments. Can be dismantled and rebuilt in various areas within the cell; very dynamic.
Carrier Proteins
Type of transport protein. Hold onto their passengers and change shape in a way that shuttles them across the membrane.
Six Major Functions Performed by Proteins of the Plasma Membrane
Transport proteins Enzymatic activity-a protein built into the membrane may be an enzyme with its active sites exposed. Signal Transduction Cell-cell Recognition- some glycoproteins serve as identification tags that are specifically recognized by other cells. Intercellular Joining-at locations like gap junctions and tight junctions Attachment to the cytoskeleton and ECM
Extracellular Matrix
Mostly made up of glycoproteins secreted by the cells. (though animal cells lack walls, they have very elaborate ECMs)
Dynein
A motor protein. Found (for ex.) extending from one microtubule doublet to the next in cilium and flagellum and responsible for their bending movements. Composed of several polypeptides.
Basal Body
The anchor of the microtubule assemblage of cilium and flagellum. Structurally identical to a centriole.
Permeability of the Lipid Bilayer
Hydrophobic (nonpolar) molecules, such as hydrocarbons, carbon dioxide, and oxygen, can dissolve in the lipid bilayer of the membrane and cross it with ease and without aid. The direct passage of ions and polar molecules are impeded by the hydrophobic core; polar molecules such as glucose and other sugars, as well as water, pass through only slowly. Charged atoms and molecules have even more difficulty; proteins built into the membrane play roles in regulating transport of such things, ultimately making the membrane permeable to specific ions and a variety of polar molecules
Integral Proteins
One of two major populations of membrane proteins. Penetrate the hydrophobic core of the lipid bilayer Many are transmembrane proteins which span the membrane. The hydrophobic regions of an integral protein consist of one or more stretched of non-polar amino acids usually coiled into alpha-helices. Hydrophobic parts of the molecule are exposed to the aqueous solutions on either side of the membrane.
Primary Cell Wall
A young plant cell first secretes this relatively thin and flexible wall. Between the primary walls of adjacent cells is the middle lamella.
Channel Proteins
Type of transport protein. Have a hydrophilic channel that certain molecules or atomic ions use as a tunnel through the membrane.
Stroma
the fluid outside the thylakoids in a chloroplast, which contains the chloroplast DNA, ribosomes, and many other enzymes.
The Fluid Mosaic Model
A model of how phospholipids and proteins are arranged in the membranes of cells. In this model, the membrane is a fluid structure with a "mosaic" of carious proteins embedded in or attached to a double layer (bilayer) of phospholipids.
Secondary Cell Wall
What some plant cells add between the plasma membrane and the primary wall in order to strengthen the cell walls. Often deposited in several laminated layers, has a strong and durable matrix that affords the cell protection and support. For example, wood consists mainly of these walls.
Actin
A globular protein. Molecules of actin build micro- or actin filaments in a twisted double chain formation.
Fibronectin
Found in the ECM. A type of glycoprotein. Attaches cells to the ECM by binding to cell surface receptors called integrins.
Cell-cell Recognition
A cell's ability to distinguish one type of neighboring cell from another. Recognition is usually done through the binding of surface molecules, often carbohydrates, on the plasma membrane.
Gap Junctions
A type of intracellular junction found in animal cells. Provide cytoplasmic channels from one cell to an adjacent one. Consist of special membrane proteins that surround a pore through which ions, sugars, amino acids, and other small molecules may pass. Necessary for communication between cells in many types of tissues.
Cilia
Locomotor appendage that protrude from some cells. Held in place as part of a tissue layer. Usually occur in large numbers on the cell surface. Shorter than flagella. Differ from flagella in beating pattern: work like oars with alternating power and recovery strokes generating force in a direction perpendicular to the cilium's axis. Have 9+2 patterned structure.
Flagella
Locomotor appendage that protrude from some cells. Held in place as part of a tissue layer. Usually limited to one or a few per cell. Differ from cilia in beating pattern: moves in an undulating motion that generates force in the same direction as their axis. Have 9+2 patterned structure.
Intermediate Filaments
Type of cytoskeleton A fibrous protein supercoiled into thicker cables--subunits are one of several different proteins of the keratin family (depends on the cell). Functions in maintaining cell shape (tension-bearing), anchors nucleus and certain other organelles, involved in forming the nuclear lamina. More permanent fixtures than microfilaments and microtubules. The nucleus of a cell often sits within a cage made up by intermediate filaments, fixed in location by branches of the filaments that extend into the cytoplasm.
Peripheral Proteins
One of two major populations of membrane proteins. Not embedded in the lipid bilayer; they are appendages loosely bound to the surface of the membrane, often to the exposed part of integral membranes.
Unsaturated Hydrocarbon Tails of Phospholipids
Have kinks that keep the molecules from packing together, most of these enhances membrane fluidity.
The Three Types of Intercellular Junctions in Animal cells
Tight Junctions Desmosomes Gap Junctions Especially common in epithelial tissue, which lines the external and internal surfaces of the body.
Peroxisomes
A specialized metabolic compartment bounded by a single membrane. Contains enzymes that transfer hydrogen from various substrates to oxygen, producing hydrogen peroxide (H2O2) as a by-product. Some use oxygen to break down fatty acids into smaller molecules that can be then transported to mitochondria where they are used as guel for cellular respiration. Contains an enzyme that converts H2O2 to water, since peroxide itself is toxic. Do not bud, like lysosomes, from the endomembrane systems. They grow larger by incorporating proteins made primarily in the cytosol, lipids made in the ER, and lipids synthesized within the peroxisome itself. Can increase in number by splitting when they reach a certain size.
The Two Major Types of Membrane Proteins
Peripheral Proteins Integral Proteins
Collagen
The most abundant glycoprotein in the ECM of most animal cells. Forms strong fibers outside the cells. Accounts for about half of the total protein in the human body.
Motor Proteins
Required in order to enable cell motility along with use of the cytoskeleton. Vesicles that bud off from the ER travel to the Golgi along tracks built of cytoskeletal elements.
Transport Proteins
Facilitate movement of hydrophilic substances through the lipid bilayer. Span the membrane. Specific for the substance they translocate. Includes channel proteins and carrier proteins.
Centrioles
A pair of them can be found within centrosomes. Each composed of nine sets of triplet microtubules arranged in a ring. Replicate before a cell undergoes division.
Cell Cortex
The outer cytoplasmic layer of a cell.
Tight Junctions
A type of intracellular junction found in animal cells. At tight junctions, the membrane of neighboring cells are very tightly pressed against each other, bounded together by specific proteins. Forming continuous seals around the cells, they prevent leakage of extracellular fluid across a layer of epithelial cells.
Glyoxysomes
Specialized peroxisomes. Found in the fat-storing tissued of plant seeds. Contain enzymes that initiate the conversion of fatty acids to sugar, which in the emerging seedling can use as a source of energy and carbon until it is able to produce its own sugar by photosynthesis.
The Middle Lamella
The area between the primary cell walls of adjacent cells. A thin layer rich in sticky polysaccharides called pectins. Glues adjacent cells together.
Granum
stacks of thylakoids within a chloroplast.
Strengthening and remodeling of Plant's Primary Cell Walls
Some plant cells strengthen their walls simply by secreting hardening substances into the primary wall. Other cells add a secondary cell wall between the plasma membrane and the primary wall.
Microtubules
Thickest type of cytoskeleton Hollow tube Found in the cytoplasm or eukaryotic cells. Walls consist of 13 columns of tubulin molecules (alpha- and beta-tubulin subunits; dimer). Functions in maintaining cell shape (compression-resistant), cell motility (cilia, flagella), chromosome movements in cell division, and organell movements
Integrins
Cell surface receptors found in the ECM. Many ECM proteins bind this. Span the membrane and bind on their cytoplasmic side to associated proteins attached to microfilaments of the cytoskeleton. Can transmit stimuli between the cell's external environment and its interior and can result in changes in cell behavior.
Synthesis and Sidedness of Membranes
Membranes have distinct inside and outside faces; the two layers differ in lipid composition and each protein has a directional orientation in the membrane. When a vesicle fuses with the plasma membrane, the outside layer of the vesicle becomes continuous with the cytoplasmic layer of the plasma membrane (e.g. molecules that start out on the inside face of the ER, end up on the outside face of the plasma membrane).
Aquaporins
Channel proteins that play a major role in certain cells. Allow passage of water molecules through the membrane.
Desmosomes
A type of intracellular junction found in animal cells. Function by fastening cells together into strong sheets. Intermediate filaments made of sturdy keratin proteins anchor desmosomes into the cytoplasm.
Proteoglycans
Found in the ECM. A type of glycoprotein. Make up a woven network which has collagen fibers embedded within. Consists of a small core protein with many carbohydrate chains covalently attached. Large proteoglycan complexes can form when hundreds of proteoglycans become noncovalently attached to a single polysaccharide molecule.
Membrane Fluidity
A membrane is held together mostly by hydrophobic interactions, which are much weaker than covalent bonds; most of the lipids and some of the proteins can drift about laterally (i.e. in the plane of the membrane). Unsaturated hydrocarbon tail of phospholipids enhance fluidity, while saturated ones decrease it. Cholesterol reduces membrane fluidity at moderate temperatures by reducing phospholipid movement, but at low temperatures it hinders solidification by disrupting the regular packing of phospholipids.
Selective Permeability
Exhibited in the plasma membrane. Allowing some substances to cross more easily than others.
Structure of Cilia and Flagella
The 9+2 Pattern: Describes the structure of flagella and cilia: they have a core of microtubules sheathed in an extension of the plasma membrane Nine doublets of microtubules, the members of each pair sharing part of their walls, are arranged in a ring. In the center of the ring are two single microtubules. Flexible, cross-linking proteins, evenly spaced along the length of the cilia/flagella, connect the outer doublets to each other and the two central microtubules. Each outer doublet also has pairs of side-arms (the motor protein dynein) spaced along its length and reaching toward the neighboring doublet. The microtubule assembly of a cilium or flagellum is anchored by a basal body.
Centrosomes
In many cells, microtubules grow out from them. Often located near the nucleus. Has a pair of centrioles within them (not always in plants, though).
Plasmodesmata
Channels that perforate between adjacent cell walls in plants cells. Cytosol can pass through and connects the chemical environments of adjacent cells. Each channel is lined by the plasma membranes of adjacent cells and thus are continuous. Water and small solutes can pass freely from cell to cell as well as specific proteins and RNA molecules.
Amphipathic Molecule
a molecules that has both a hydrophobic and a hydrophilic region. Like phospholipids.
Glycolipids
Carbohydrates that are covalently bonded to lipids. Often membrane carbohydrates that play a role in cell-cell recognition.
Microfilaments (actin filaments)
Thinnest type of cytoskeleton Made of two intertwined strands of actin (each a polymer of actin subunits). Functions in maintaing cell shape (tension-bearing), involved in changing cell shape, muscle contraction, cytoplasmic streaming, cell motility, and cell division (specifically, cleavage furrow formation). Gives the cortex (outer cytoplasmic layer) of a cell the semisolid consistency of a gel, in contrast with the more fluid state of interior cytoplasm
Cell Wall
An extracellular structure of plant cells that distinguishes them from animals (also seen in prokaryotes, fungi, and some protists). Protects plant cells, maintain the shape, and prevents excessive uptake of water. Thicker than the plasma membrane. Microfibrils made of polysaccharide cellulose are embedded in a matrix o other polysaccharides and protein.
Section 3
(50 cards)
Catalyst
A chemical agent that speeds up a reaction without being consumed by the reaction
Activation Energy
The initial investment of energy for starting a reaction--the energy required to contort the reactant molecule so the bonds can change
Kinetic Energy
Energy associated with the relative motion of objects.
Thermal Energy
Kinetic energy associated with the random movement of atoms or molecules.
Electrochemical Gradient
The combination of forces acting on an ion. The two forces that drive diffusion of ions across a membrane: the chemical force and the electrical force.
ATP
Adenosine triphosphate. Contains the sugar ribose, with the nitrogenous base adenine and a chain of three phosphate groups bonded to it. Bonds between the phosphate groups can be broken by hydrolysis, which causes a molecule of inorganic phosphate to leave the ATP (becoming ADP) and is a exergonic reaction-->releases 7.3kcal of energy per mole of ATP hydrolyzed (^G=-7.3).
Hypotonic Solution
There is more solute in the cell than outside. Water will have a net movement into the cell. The cell will swell and lyse (burst).
Chemical Energy
Refers to the potential energy available for release in a chemical reaction. During a catabolic reaction, chemicals are rearranged and energy is released.
Enzyme
A catalytic protein.
Entropy
A measure of disorder, or randomness. The more randomly arranged a pattern is, the greater its entropy.
Ligands
A general term for any molecules that binds specifically to a receptor site of another molecule.
Phagocytosis
A type of endocytosis In this, a cell engulfs a particle by wrapping pseudopodia around it and packaging it within a membrane-enclosed sac large enough to be classified as a vacuole. The particle is digested after the vacuole fuses with a lysosome containing hydrolytic enzymes
Plasmolysis
If a plant cell (also seen in bacteria and fungi) is immersed in a hypertonic environment, this will occur. The cell will lose water to its surroundings and shrink; the cell will shrivel and the plasma membrane will pull away from the cell wall and the plant will wilt and possibly die.
Metabolism
The totality of an organism's chemical reactions. An emergent property of life that arises from interactions between molecules within the orderly environment of the cell.
Ion Channels
A group of channels that often function as gated channels where a stimulus (electrical or chemical) causes them to open or close.
Facilitated Diffusion
The movement of molecules with the help of transport proteins that span the membrane. Still passive transport since the substance is still moving down its concentration gradient.
Tonicity
Tonicity of a solution depends in part on its concentration of solutes that cannot cross a membrane, relative to that in the cell itself.
Exocytosis
The secretion of macromolecules by the fusion of vesicles with the plasma membrane.
Active Transport
The pumping of a molecules against its concentration gradient; requires work. All are carrier proteins. Allows cells to maintain internal concentrations of small molecules that differ from concentrations in its environment. ATP supplies the energy for most of this transport.
Osmoregulation
The control of water balance. Organisms that live in environments that are hyper- or hypotonic to them must have special adaptations to make this possible.
Potential Energy
Energy that is not kinetic. The energy that matter possesses because of its location of structure.
Thermodynamics
The study of the energy transformations that occur in a collection of matter. Organisms are open systems that transfer energy between their bodies and the environment and vice versa.
Catabolic Pathways
Degradative processes or breakdown pathways. E.g. cellular respiration.
Free Energy
Measures the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell. Defined by Gibbs (without considering the system's surroundings), symbolized by the letter G. Systems tend towards a state with lower free energy (more stable).
Anabolic Pathways
Consume energy to build complicated molecules from simpler one. Sometimes called biosynthetic pathways.
Pinocytosis
A type of endocytosis. In this, the cell "gulps" droplets of extracellular fluid into tiny vesicles. It is not the fluid itself that is needed by the cell, but the molecules dissolved in the droplet. Because any and all included solutes are taken into the cell, this is nonspecific in the substances it transports.
Flaccid
Or limp. Occurs in plant cells if their surroundings are isotonic and there is no tendency for water to enter.
Change in Free Energy (Rxn)
^G=^H-T^S (^=change in) H=system's enthalpy (total energy) S=change in systems entropy T=absolute temp in K Only systems with -^G are spontaneous.
Membrane Potential
The voltage across a membrane Voltage is electrical potential energy--a separation of opposite charges. The cytoplasm of a cell is negative in charge compared to the extracellular fluid because of an unequal distribution of anions and cations on opposite sides of the membrane-the membrane potential favors the passive transport of cations into the cell and anions out of the cell.
Thee Main Kinds of Work a Cell Does
Mechanical work, transport work, and chemical work.
First Law of Thermodynamics
The energy of the universe is constant. Energy can be transferred and transformed, but it cannot be created nor destroyed.
Exergonic Reaction
Proceeds with a net release of free energy. ^G is negative. Spontaneous.
Diffusion
The tendency for molecules of any substance to spread out evenly into the available space. Though molecules move randomly, diffusion of molecules may be directional (the net movement). A result of thermal motion which is a type of energy molecules have. Simple rule of diffusion: in the absence of other forces, a substance will diffuse from where it is more concentrated to where it is less concentrated: diffuse down the concentration gradient.
Proton Pump
The main electrogenic pump of plants, fungi, and bacteria. Actively transports hydrogen ions out of the cell transferring positive charge from the cytoplasm to the extracellular solution.
Electrogenic Pump
A transport protein that generates voltage across a membrane. The sodium-potassium pump is the major electrogenic pump of animal cells. By generating voltage across membranes, they store energy than can be tapped for cellular work, including a type of membrane traffic called cotransport.
A Metabolic Pathway
Begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product. Each step of the pathway is catalyzed by a specific enzyme.
Cotransport
A single ATP-powered pump that transports a specific solute can indirectly drive the active transport of several other solutes in this mechanism. A substance pumped across the membrane can do work as it moves back across the membrane by diffusion.
Turgid Fur
The healthy state of most plant cells. Occurs when the cell swells from entering water and the cell wall ultimately exerts opposing pressure.
Endergonic Reaction
One that absorbs free energy from its surroundings. ^G is positive. Non spontaneous.
Isotonic
The internal cell environment is the same as the solution surrounding it. There will be no net movement of water across the plasma membrane--water moves across the membrane but at the same rate in both directions.
Bioenergetics
Study of how organisms manage their energy resources.
Osmosis
The diffusion of water across a selectively permeable membrane.
Second Law of Thermodynamics
Every energy transfer or transformation increases the entropy of the universe. For a process to occur spontaneously, it must increase the entropy of the universe.
Passive Transport
The movement of a substance across a biological membrane that does not require the cell to expend any energy to make it happen. Diffusion of a substance across its concentration gradient, for example.
Energy Coupling
A key feature in the way cells manage their energy resources. The use of an exergonic process to drive an endergonic one. ATP is responsible for mediating most energy coupling in cells.
Phosphorylated
A recipient is said to be so when it receives a phosphate group from ATP, making the recipient more reactive.
Hypertonic Solution
There is more solute outside the cell than in. The cell will lose water to the environment, causing it to shrivel.
Energy
The capacity to cause change and can be used to do work (i.e. move matter against opposing forces, such as gravity or friction). There is kinetic, thermal, potential, and chemical energy.
Endocytosis
A mechanism by which a cell takes in macromolecules and particulate matter by forming new vesicles from the plasma membrane. 3 types: phagocytosis, pinocytosis, and receptor-mediated endocytosis.
Concentration Gradient
Substances diffuse down this. In the absence of other forces, a substance will diffuse from where it is more concentrated to where it is less concentrated. A substance moves down its own concentration gradient, unaffected by the concentration differences of other substances.
Section 4
(6 cards)