GRE-Cellular Structure and Function

GRE-Cellular Structure and Function

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Section 1

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Rough ER

Front

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Cards (156)

Section 1

(50 cards)

Rough ER

Front

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.

Back

Amyloplasts

Front

Colorless plastids that store starch (amylose)

Back

Vacuoles

Front

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.

Back

Cisternal Space

Front

Also known as the ER lumen The internal compartments of the RE

Back

Transport Vesicles

Front

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.

Back

Trans Face of the Golgi Apparatus

Front

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.

Back

Cell Sap

Front

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)

Back

Plastids

Front

A family of closely related plant organelles. Consists of chloroplasts, amyloplasts, and Chromoplasts.

Back

Mitochondria: Form

Front

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.

Back

Nucleus-protein synthesis steps

Front

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.

Back

Endomembrane System

Front

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.

Back

Ribosomes

Front

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)

Back

Food Vacuoles

Front

Formed by phagocytosis and function like the lysosomes

Back

Problem with lysosomes in Tay-Sachs disease

Front

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.

Back

Thylakoids

Front

Flattened and interconnected sacs found within the chloroplast, within the second membrane. Usually found in stacks called granum

Back

Autophagy

Front

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.

Back

Sorting Vesicles at the trans face of the Golgi

Front

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.

Back

Nucleoid

Front

where the DNA is concentrated a prokaryotic cell. No membrane separates this from the rest of the cell, unlike the nucleus in eukaryotic cells

Back

Chromosomes

Front

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

Back

Nucleolus

Front

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.

Back

Surface Area to Volume Ratio

Front

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.

Back

Phagocytosis in Lysosomes (e.g. humans, amoebas and protists)

Front

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.

Back

Cristae

Front

The folded surfaces of the innermembrane of mitochondria.

Back

Contractile Vacuoles

Front

Found in many freshwater protists They pump excess water out of the cell, maintaining the appropriate concentration of salts and other molecules.

Back

Smooth ER

Front

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).

Back

Chloroplast: Form

Front

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.

Back

Cisternal Maturation Model

Front

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.

Back

Central Vacuole

Front

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.

Back

Definition: Cellular Respiration

Front

The metabolic process that generates ATP by extracting energy from sugars, fats, and other fuels with the help of oxygen.

Back

Cis Face of the Golgi Apparatus

Front

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.

Back

The Intermembrane Space of the Mitochondria

Front

The narrow region between the inner and outer membranes. Proteins that function in respiration like the enzyme that makes ATP are built here.

Back

Nuclear Envelope

Front

Encloses the nucleus Made up of two lipid bilayers Contains protein structures making up a pore complex, regulating the entry and exit of particles

Back

Bound Ribosomes

Front

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.

Back

Tonoplast

Front

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

Back

Glycoproteins

Front

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.

Back

Free Ribosomes

Front

Ribosomes that are suspended in the cytosol. Most proteins made on these function with the cytosol.

Back

Chromoplasts

Front

Plastids that have pigments that give fruits and flowers their orange and yellow hues.

Back

Definition: Mitochondria

Front

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.

Back

Golgi Apparatus

Front

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.

Back

Movement of proteins from the ER through the Golgi (e.g. glycoproteins)

Front

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.

Back

Plasma Membrane

Front

A selective barrier that allows sufficient passage of oxygen, nutrients and wastes

Back

Lysosome

Front

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.

Back

The Mitochondrial Matrix

Front

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.

Back

Ribosomes

Front

tiny organelles that make proteins according to instructions from the genes

Back

Definition: Chloroplasts

Front

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.

Back

Cisternae

Front

The network of membranous tubules and sacs that make up the endoplasmic reticulum, separated by the ER membrane

Back

Nuclear Lamina

Front

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 .

Back

Endoplasmic Reticulum

Front

Consists of a network of membranous tubules and sacs called cisternae. Two distinct regions: the smooth ER and the rough ER.

Back

Cytosol

Front

a semifluid substance in which organelles are found; within the cytoplasm

Back

Mycoplasmas

Front

Smallest cells known Bacterial cells

Back

Section 2

(50 cards)

Cytoskeleton

Front

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.

Back

Carrier Proteins

Front

Type of transport protein. Hold onto their passengers and change shape in a way that shuttles them across the membrane.

Back

Six Major Functions Performed by Proteins of the Plasma Membrane

Front

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

Back

Extracellular Matrix

Front

Mostly made up of glycoproteins secreted by the cells. (though animal cells lack walls, they have very elaborate ECMs)

Back

Dynein

Front

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.

Back

Basal Body

Front

The anchor of the microtubule assemblage of cilium and flagellum. Structurally identical to a centriole.

Back

Permeability of the Lipid Bilayer

Front

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

Back

Integral Proteins

Front

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.

Back

Primary Cell Wall

Front

A young plant cell first secretes this relatively thin and flexible wall. Between the primary walls of adjacent cells is the middle lamella.

Back

Channel Proteins

Front

Type of transport protein. Have a hydrophilic channel that certain molecules or atomic ions use as a tunnel through the membrane.

Back

Stroma

Front

the fluid outside the thylakoids in a chloroplast, which contains the chloroplast DNA, ribosomes, and many other enzymes.

Back

The Fluid Mosaic Model

Front

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.

Back

Secondary Cell Wall

Front

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.

Back

Actin

Front

A globular protein. Molecules of actin build micro- or actin filaments in a twisted double chain formation.

Back

Fibronectin

Front

Found in the ECM. A type of glycoprotein. Attaches cells to the ECM by binding to cell surface receptors called integrins.

Back

Cell-cell Recognition

Front

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.

Back

Gap Junctions

Front

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.

Back

Cilia

Front

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.

Back

Flagella

Front

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.

Back

Intermediate Filaments

Front

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.

Back

Peripheral Proteins

Front

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.

Back

Unsaturated Hydrocarbon Tails of Phospholipids

Front

Have kinks that keep the molecules from packing together, most of these enhances membrane fluidity.

Back

The Three Types of Intercellular Junctions in Animal cells

Front

Tight Junctions Desmosomes Gap Junctions Especially common in epithelial tissue, which lines the external and internal surfaces of the body.

Back

Peroxisomes

Front

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.

Back

The Two Major Types of Membrane Proteins

Front

Peripheral Proteins Integral Proteins

Back

Collagen

Front

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.

Back

Motor Proteins

Front

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.

Back

Transport Proteins

Front

Facilitate movement of hydrophilic substances through the lipid bilayer. Span the membrane. Specific for the substance they translocate. Includes channel proteins and carrier proteins.

Back

Centrioles

Front

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.

Back

Cell Cortex

Front

The outer cytoplasmic layer of a cell.

Back

Tight Junctions

Front

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.

Back

Glyoxysomes

Front

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.

Back

The Middle Lamella

Front

The area between the primary cell walls of adjacent cells. A thin layer rich in sticky polysaccharides called pectins. Glues adjacent cells together.

Back

Granum

Front

stacks of thylakoids within a chloroplast.

Back

Strengthening and remodeling of Plant's Primary Cell Walls

Front

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.

Back

Microtubules

Front

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

Back

Integrins

Front

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.

Back

Synthesis and Sidedness of Membranes

Front

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).

Back

Aquaporins

Front

Channel proteins that play a major role in certain cells. Allow passage of water molecules through the membrane.

Back

Desmosomes

Front

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.

Back

Proteoglycans

Front

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.

Back

Membrane Fluidity

Front

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.

Back

Selective Permeability

Front

Exhibited in the plasma membrane. Allowing some substances to cross more easily than others.

Back

Structure of Cilia and Flagella

Front

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.

Back

Centrosomes

Front

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).

Back

Plasmodesmata

Front

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.

Back

Amphipathic Molecule

Front

a molecules that has both a hydrophobic and a hydrophilic region. Like phospholipids.

Back

Glycolipids

Front

Carbohydrates that are covalently bonded to lipids. Often membrane carbohydrates that play a role in cell-cell recognition.

Back

Microfilaments (actin filaments)

Front

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

Back

Cell Wall

Front

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.

Back

Section 3

(50 cards)

Catalyst

Front

A chemical agent that speeds up a reaction without being consumed by the reaction

Back

Activation Energy

Front

The initial investment of energy for starting a reaction--the energy required to contort the reactant molecule so the bonds can change

Back

Kinetic Energy

Front

Energy associated with the relative motion of objects.

Back

Thermal Energy

Front

Kinetic energy associated with the random movement of atoms or molecules.

Back

Electrochemical Gradient

Front

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.

Back

ATP

Front

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).

Back

Hypotonic Solution

Front

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).

Back

Chemical Energy

Front

Refers to the potential energy available for release in a chemical reaction. During a catabolic reaction, chemicals are rearranged and energy is released.

Back

Enzyme

Front

A catalytic protein.

Back

Entropy

Front

A measure of disorder, or randomness. The more randomly arranged a pattern is, the greater its entropy.

Back

Ligands

Front

A general term for any molecules that binds specifically to a receptor site of another molecule.

Back

Phagocytosis

Front

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

Back

Plasmolysis

Front

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.

Back

Metabolism

Front

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.

Back

Ion Channels

Front

A group of channels that often function as gated channels where a stimulus (electrical or chemical) causes them to open or close.

Back

Facilitated Diffusion

Front

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.

Back

Tonicity

Front

Tonicity of a solution depends in part on its concentration of solutes that cannot cross a membrane, relative to that in the cell itself.

Back

Exocytosis

Front

The secretion of macromolecules by the fusion of vesicles with the plasma membrane.

Back

Active Transport

Front

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.

Back

Osmoregulation

Front

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.

Back

Potential Energy

Front

Energy that is not kinetic. The energy that matter possesses because of its location of structure.

Back

Thermodynamics

Front

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.

Back

Catabolic Pathways

Front

Degradative processes or breakdown pathways. E.g. cellular respiration.

Back

Free Energy

Front

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).

Back

Anabolic Pathways

Front

Consume energy to build complicated molecules from simpler one. Sometimes called biosynthetic pathways.

Back

Pinocytosis

Front

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.

Back

Flaccid

Front

Or limp. Occurs in plant cells if their surroundings are isotonic and there is no tendency for water to enter.

Back

Change in Free Energy (Rxn)

Front

^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.

Back

Membrane Potential

Front

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.

Back

Thee Main Kinds of Work a Cell Does

Front

Mechanical work, transport work, and chemical work.

Back

First Law of Thermodynamics

Front

The energy of the universe is constant. Energy can be transferred and transformed, but it cannot be created nor destroyed.

Back

Exergonic Reaction

Front

Proceeds with a net release of free energy. ^G is negative. Spontaneous.

Back

Diffusion

Front

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.

Back

Proton Pump

Front

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.

Back

Electrogenic Pump

Front

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.

Back

A Metabolic Pathway

Front

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.

Back

Cotransport

Front

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.

Back

Turgid Fur

Front

The healthy state of most plant cells. Occurs when the cell swells from entering water and the cell wall ultimately exerts opposing pressure.

Back

Endergonic Reaction

Front

One that absorbs free energy from its surroundings. ^G is positive. Non spontaneous.

Back

Isotonic

Front

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.

Back

Bioenergetics

Front

Study of how organisms manage their energy resources.

Back

Osmosis

Front

The diffusion of water across a selectively permeable membrane.

Back

Second Law of Thermodynamics

Front

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.

Back

Passive Transport

Front

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.

Back

Energy Coupling

Front

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.

Back

Phosphorylated

Front

A recipient is said to be so when it receives a phosphate group from ATP, making the recipient more reactive.

Back

Hypertonic Solution

Front

There is more solute outside the cell than in. The cell will lose water to the environment, causing it to shrivel.

Back

Energy

Front

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.

Back

Endocytosis

Front

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.

Back

Concentration Gradient

Front

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.

Back

Section 4

(6 cards)

Competitive Inhibitors

Front

Chemicals that selectively inhibit an enzyme. Reduce the productivity of enzymes by blocking substances from entering active sites.

Back

Feedback Inhibition

Front

A common method of metabolic control in which a metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway.

Back

Substrate

Front

The reactant an enzyme acts on. When they bind (at the enzyme's active site), the enzyme-substrate complex is formed.

Back

Allosteric Regulation

Front

Describes any case in which a protein's function at one site is affected by the binding of a regulatory molecule to a separate site. May result in either inhibition or stimulation of an enzyme's activity.

Back

Noncompetitive Inhibitors

Front

Bind a separate part of an enzyme than its active site. Still impedes enzymatic reactions.

Back

Cofactors

Front

Nonprotein enzyme helpers for catalytic activity. May be bound permanently or may bind loosely and reversibly along with the substrate. If it is an organic molecule, it is more specifically called a coenzyme.

Back