| Question | Answer |
| Feedback inhibition | Regulate metabolism. Molecule is altered in a series of steps, each catalyzed by a specific enzyme to form final product. More product than needed, then inhibitor may block production |
| Uses of inhibitors | Drugs, pesticides and poisons |
| Noncompetitive inhibitor | Does not enter active site. Binds to enzyme somewhere else, changing shape of enzyme so that active site no longer fits substrate |
| Competitive inhibitor | Compete for active site. Reduces enzyme's productivity by blocking substrates from entering the active site. Can be overcome by increasing concentration of substrate, making it more likely that a substrate molecule will be nearby when an active site becomes vacant |
| Inhibitor | Chemical that interferes with enzyme's activity. Attaches to enzyme by covalent bonds. Usually irreversible. Reversible when weak attractions bind inhibitor and enzyme |
| Coenzymes | Nonprotein helpers, organic |
| Cofactors | Nonprotein helpers, inorganic |
| Optimal conditions for enzymes | Specific temperature and pH for each enzyme |
| Induced fit | Active site changes shape so embraces substrate more snugly |
| Steps of enzymes working | 1. Start with empty active site. 2. Substrate enters active site, attaching by weak bonds. Induced Fit. Active site in position to catalyze reaction. 3. Strained bonds of substrate react with water (hydrolyze). 4. Enzyme released products and returns to original shape |
| Active site | Region of enzyme. Formed by only a few of enzyme's amino acids. Only fits specific substrate molecules |
| Substrate | Reactant that enzyme acts on |
| Enzymes | Proteins that function as biological catalysts. Increase rate of reaction without being consumed by reaction. Lower EA barrier. Unique, 3D shape. Catalyze specific reaction. Names end in -ase, many named for substrate. |
| How can break break energy of activation? | Add heat, cannot in cell, though, because would speed up all reaction or kill the cell. Enzymes |
| Energy of activation (EA) | Nothing spontaneously decomposes because of energy barrier that must be overcome before chemical reaction can begin. Energy must be absorbed to contort or weaken bonds in reactants so that they can break and new bonds can form. Amount of energy needed to push reactants over energy barrier |
| Transport work | Solutes across membrane against concentration gradient |
| Mechanical work | Transfer phosphate groups |
| Chemical work | Energy drives endergonic synthesis of products |
| Phosphorylation | Uses energy to transfer P group to another molecule, creating an endergonic reaction. Most cellular work depends on ATP energizing molecules by phosphorylating them |
| Structure of ATP | Nitrogenous base, ribose (5-carbon sugar) and 3 phosphate groups (negatively charged) |
| ATP | Powers nearly all forms of cellular work. Adenosine triphosphate. Bonds connecting phosphate groups unstable, readily broken by hydrolysis, Becomes ADP and energy released. Work can be sustained because ATP renewable resource that cells regenerate. Uses ATP continuously. |
| Energy coupling | Use of energy released from exergonic reactions to drive endergonic reactions |
| Metabolic pathways | Series of chemical reactions that either builds a complex molecule or breaks down a complex molecule into simpler compounds |
| Metabolism | Total of an organism's chemical reactions |
| Endergonic reactions | Gain energy. Starts with little potential energy, ends with more potential energy stored in covalent bonds. Amount of additional energy equals difference in potential energy between reactants and produces. Photosynthesis |
| Cellular respiration | Uses oxygen to convert chemical energy stored in fuel molecules to form chemical energy ATP |
| Exergonic reactions | Releases energy. Reactants whose covalent bonds contain more energy than those in products. eg. Burning, Cellular respiration |
| Entropy | Measure of disorder |
| Second law of thermodynamics | Some energy unusable/unavailable to do work. Heat = disordered form of energy. Energy conversions increase entropy of universe |
| First law of thermodynamics | Law of energy conservation. Energy in universe is constant. Can be transferred and transformed but cannot be created or destroyed |
| Surroundings | Everything outside system |
| System | Matter under study |
| Thermodynamics | Study of energy transformations that occur in collection of matter |
| Chemical energy | Due to arrangement of atoms. Available for release in chemical reaction. ATP. Can power work of cell |
| Potential energy | Stored energy. Possesses energy as result from location or structure |
| Heat | Thermal energy. Form of kinetic energy. Random movement of atoms of molecules |
| Kinetic energy | Energy of motion. Perform work by transferring motion to other matter |
| Energy | Capacity to perform work. Object moved against an opposing force. 2 basic forms: kinetic and potential |
| Receptor-mediated endocytosis | Contrasts to pinocytosis. Receptor proteins line membranes. Pick up particular molecules from surroundings |
| Pinocytosis | "Cellular drinking." "Gulps" droplets of fluid into tiny vesicles. Takes in any and all solutes dissolved in droplets. Becomes vesicles |
| Phagocytosis | "Cellular eating." Cell engulfs a particle by wrapping pseudopodia around it and packaging it. Forms food vacuoles -- large |
| 3 types of endocytosis | Phagocytosis, pinocytosis, receptor-mediated endocytosis |
| Endocytosis | Cell takes in substances. Plasma membrane pinches in and forms vesicle enclosing material from outside |
| Exocytosis | Exports bulky materials such as proteins or polysaccharides. Transport vesicle from Golgi apparatus moves to plasma membrane, fuses, and spills out of cell while vesicle becomes part of plasma membrane |
| Steps of active transport | 1. Solute attaches to specific binding site of transport protein. 2. ATP transfers one phosphate group to transport protein. 3. Causes it to change shape and solute released. 4. Phosphate group detaches, returning protein to its original shape |
| Active transport | Cell must expend energy. Move solute against concentration gradient. ATP supplies energy. Allows cells to maintain concentrations |
| Aquaporins | Make very rapid diffusion of water into and out of a cell, type of transport proteins |
| Transport proteins | Proteins provide hydrophilic channel. Proteins bind to passenger, change shape and release passenger. Transport proteins specific to substance it helps. Greater number of transport proteins, faster solute's rate of diffusion |
| Facilitated Diffusion | Proteins make it possible for substance to move across membrane. Polar substances cannot diffuse across cell membrane. Need the help of transport proteins. Does not require energy. Type of passive transport. Driven by concentration gradient |
| Plasmolysis | Plant cell loses water and shrivels. Plasma membrane pulls away from cell wall |
| Osmoregulation | Control of water balance. Must have ways to prevent excessive uptake or loss of water |
| Hypertonic to cell | Higher solute concentration. Both plant and animal cells shrivel |
| Hypotonic to cell | Solution has lower concentration than cell. Water flows into cell. Animal cells lyse, plant cells remain turgid |
| Isotonic to the cell | Solute concentration of cell is equal to its environment. Cell gains H2O at same rate it loses it. Animal cells are normal, plant cells are flaccid |
| Tonicity | Ability of a solution to cause a cell to gain or lose water. Depends on its concentration of solutes that cannot cross the plasma membrane relative to concentration of solutes in the cell |
| Osmosis | Diffusion of water across a selectively permeable membrane. If membrane permeable to H2O and not a solute, then the H2O will move to create equal concentration. Different water levels. If solution less concentrated, most H2O are free from being attached to polar molecule. Net movement of H2O down its own water concentration gradient. Water diffuses due to total solute concentration, not by nature of solutes |
| Passive transport | When cell does not perform work when molecules diffuse across a membrane. Ions and polar molecules can move by passive transport with transport proteins |
| Diffusion | Tendency for particles of any kind to spread out evenly in available space. Move from where they are most concentrated to where they are least concentrated. Move randomly due to thermal motion. Requires no work. Net movement from more to less concentrated. Diffuses down concentration gradient. No net change in concentration of either side |
| Selectively permeable | Allow some substances to cross more easily than others. Hydrophobic interior. Nonpolar easily pass. Polar cannot, require Transport proteins |
| Signal transduction | Message-transfer process |
| Receptors | For chemical messages. Shape that fits a specific messenger |
| Glycoproteins | Cell-cell recognition. Carbohydrates bonded to proteins or lipids. Used by immune system |
| Integrins | Give membrane strong framework. Types of proteins |
| Fluid mosaic | Bilayer of cell. Diverse protein molecules embedded in framework of phospholipids. Membrane 'fluid.' Most molecules can drift around. Double bonds in phospholipids prevent it from being solid. Cholesterol stabilizes membrane. 'Mosaic:' Many different types and functions of proteins, Each cell unique blend |
| Plasmodesmata | Channels between adjacent plant cells. Form a circulatory and communication system |
| Layered arrangement of cell wall | Primary wall: Thin and flexible, Allows growing cell to continue to enlarge. Secondary wall: Deposited in laminated layers. Layer of sticky polysaccharides: Hold cells together |
| Cell wall | Protects cell. Provides skeletal support that keeps plants upright on land. Made of fibers of cellulose embedded in matrix of other polysaccharides and proteins. Layered arrangement. |
| Gap junctions | Channels that allow small molecules to flow through protein-lined pores in neighboring cells |
| Anchoring junctions | Rivets. Fasten cells together into strong sheets. Keratin proteins. Common in tissues subject to stretching or mechanical stress |
| Tight junctions | Very tightly pressed against each other. Knit together by proteins. Form continuous seals around cells. Prevent leakage of extracellular fluid. In digestive tract |
| 4 types of junctions | Animals - Tight, anchoring and gap. Plants - Plasmodesmata |
| Integrins | ECM may attach to cell through integrins. Glycoproteins. Bind to membrane proteins. Span the membrane, attaching on other side to proteins connected to microfilaments of cytoskeleton. Transmit information between ECM and cytoskeleton, integrating changes occurring outside and inside the cell |
| Extracellular matrix (ECM) | Layer helps hold cell together. Protects and supports plasma membrane. Composed of glycoproteins. Collagen forms fibers outside of cell. Embedded in network woven from other types of glycoproteins. Can regulate cell's behavior. May help coordinate behavior of all cells in that tissue. Direct connections between cells also do this |
| How does bending of locomotor appendages happen? | Dynein arms. Motor proteins. Attached to each outer microtubule doublet. Grab adjacent doublet and exerts sliding force as 'walks' along it |
| Basal body | Anchoring structure. Microtubule extend to it. Pattern of 9 microtubule triplets arranged in a ring. Foundation for microtubule assembly. Very similar to centrioles |
| 9 + 2 pattern | Structure of cilia and flagella. Both composed of microtubules wrapped in extension of plasma membrane. Ring of 9 microtubule doublets surround pair of central microtubules |
| Flagella | Longer, limited to 1 or 2, in protists and human sperm cells |
| Cilia | Short, numerous, in lungs |
| 2 types of locomotion appendages | Cilia and flagella |
| Centrioles | Inside centrosome. 2 of them. |
| Centrosome | Microtubule-organizing center |
| Microtubules | Straight, hollow tubes. Globular proteins. Readily disassembled in reverse manner- Tublin subunits can be reused. Grow out from centrosome. Shape and support the cell. Guide movement of chromosomes. Main components of cilia and flagella |
| Intermediate Filaments | Various fibrous proteins. Ropelike structure. Reinforce cell shape. Anchor organelles, eg. hold nucleus in place. Permanent fixtures |
| Microfilaments | AKA Actin filaments. Solid rods. Globular proteins-- actin. Inside plasma membrane. Helps support cell's shape. Also in cell movements, cause contraction of muscle cells. Can be disassembled and reassembled |
| 3 types of fibers | Microfilaments, intermediate filaments and microtubules |
| Cytoskeleton | Network of protein fibers. Extend throughout cytoplasm of cell. Provide structure and support and cell motility--Motor proteins, Both internal movement and locomotion |
| Endosymbiosis | Mitochondria and Chloroplasts contain DNA and ribosomes. Single, circular DNA molecule. Ribosomes similar to prokaryotes. Reproduce by splitting process similar to prokaryotes. Double membranes: Similar to prokaryotes. Mitochondria and chloroplasts were formerly small prokaryotes that began living within larger cells. May have gained entry to larger cell as undigested prey or internal parasites. Host would have benefited from endosymbionts because they would release large amounts of energy in cellular respiration. Became increasingly interdependent and became single organism. Mitochondria evolved before chloroplasts |
| Granum | Each stack or thylakoids. Chloroplast's solar power packs |
| Thylakoids | Inter-connected sacs. Compartment inside sacs is thylakoid space |
| Stroma | Thick fluid. Contains chloroplast DNA and ribosomes and enzymes |
| Chloroplasts | Conversion of light energy from sun to sugar molecules (chemical energy). Photosynthesizes. Internal membranes partition into compartments. Enclosed by inner and outer membranes. Thin intermembrane space |
| Cristae | Folds in mitochondrial matrix. Increases surface area, so can produce more ATP |
| Mitochonrial matrix | Enclosed by intermembrane. Highly folded. contains mitochondrial DNA and ribosomes and enzymes. |
| Intermembrane space | Narrow region between inner and outer membranes in mitochondria |
| Mitochondria | Carry out cellular respiration. In all eukaryotic cells. Converting chemical energy of foods to ATP. Phospholipid bilayer w/ embedded proteins |
| Peroxisome | Organelle involved in various metabolic functions including break down of fatty acids and detoxification of alcohol. Not part of endomembrane system |
| Contractile vacuoles | In Protists. Collect excess water and expel it |
| Central vacuole | Plant cells. Helps cell grow in size. Stores vital chemicals/wastes. Contain pigments, Poisons |
| Food vacuoles | Work with lysosomes in digestion |
| Vacuoles | Membranous sacs, Variety of functions |
| Several types of digestive functions by lysosomes | Engulf food particles into food vacuoles. Fuse with food vacuoles. White blood cells use lysosomes to break down viruses or bacteria. Recycling centers, Damaged organelles can be broken down within |
| Lysosomes | Consist of digestive enzymes enclosed in membranous sac. Enzymes made my rough ER through Golgi. Encloses compartment in which digestive enzymes are provided with acidic environment and safely isolated from rest of cell |
| Maturation model | Entire sacs 'mature' as they move from receiving to shipping end |
| Golgi Apparatus | Membranous organelle Flattened sacs on top of each other Not interconnected like ER sacs Number of Golgi stacks correlate with how active the cell is in secreting proteins Functions in partnership with ER Receives and modifies products manufactured in ER During transit through Golgi Modify carbohydrate part of glycoproteins, add phosphate groups Vesicles join and form new Golgi sac |
| Steps of ribosomes | 1. Polypeptide synthesized, threaded into cavity of rough ER through pore. Protein folds into 3D shapes 2. Becomes glycoprotein. Chains of sugars often linked to polypeptide 3. Transport vesicle moves molecule when ready for export 4. Vesicles buds off ER and goes to Golgi |
| Rough Endoplasmic Reticulum | Makes more membrane. Makes phospholipids. Bound ribosomes make proteins. Inserted into ER membrane and transported |
| Smooth Endoplasmic Reticulum | Diverse metabolic processes. Enzymes important in synthesis of lipids. Help process drugs (Tolerance increases because cells exposed to more of a certain toxin and duplicate) Storage of calcium ions in Muscle cells |
| Endoplasmic reticulum (ER) | Membranes continuous with nuclear envelope |
| Vesicles | Sacs made of membrane |
| Endomembrane system | Physically connected. Sometimes related by transfer or membrane sgements. Includes nuclear envelope, ER, Golgi, lysosomes, vacuoles, and plasma membrane. Work together in synthesis, storage, and export of molecules. |
| Bound Ribosomes | Attached to outside of endoplasmic reticulum or nuclear envelope. Inserted into membranes or exported to other cells |
| Free ribosomes | Suspended in fluid of cytoplasm. Mostly function in cytoplasm |
| Ribosomes | Cellular components that carry out protein synthesis. Large number in cell. Cells active in protein synthesis have lots of ribosomes as well as a prominent nucleolus. All ribosomes structurally identical: Large and small subunits. |
| Nucleolus | Prominent structure in the nucleus. Site where ribosomal RNA is synthesized according to DNA. Proteins assembled with rRNA in nucleolus |
| Nuclear Envelope | Encloses nucleus. Double membrane perforated with protein-lined pores. Controls flow of materials into and out of nucleus. Connects with ER |
| Chromatin | Makes up eukaryote's chromosomes. Mixture of proteins + DNA |
| Membrane structure | Amazingly thin. Performs diverse functions that depend on structure. Phospholipids main components. Polar, hydrophilic head = Phosphate group. Nonpolar, hydrophobic tail = 2 fatty acids. Proteins embedded. Interior hydrophobic, exterior hydrophilic. Nonpolar molecules pass easily through. Polar molecules need passages through proteins |
| Differences between Animal and Plant cells | Almost all the same. Plants: Cell wall (Protection and maintain shape, Made of cellulose) Chloroplasts (Photosynthesis) Central vacuole (Compartment that stores water and variety of chemicals). Animals: Lysosomes, centrioles |
| Cellular metabolism | Chemical activities within a cell. Much happens with organelles. Can maintain specific conditions for chemical reactions. |
| 4 function groups of organelles | 1. Manufacturing: Nucleus, ribosomes, ER, Golgi. 2. Breakdown or hydrolysis of molecules: Lysosomes, vacuoles, peroxisomes. 3. Energy processing: Mitochondria, chloroplasts. 4. Structural support, movement and communication among cells: Cytoskeleton, plasma membrane, cell wall |
| Organelles | Membrane-bound. Perform specific functions in the cell |
| Nucleus | Membrane-bound. Multiple chromosomes. Nucleolus: Houses RNA. Contains most DNA. Controls activities by directing protein synthesis. Creates messenger RNA (mRNA) to send to ribosomes |
| Ribosomes | Tiny structures that make proteins according to DNA instructions |
| Chromosomes | Carry genes of DNA |
| Plasma membrane | Binds cells, cell boundary |
| Cytoplasm | Region between nucleus and plasma membrane |
| Eukaryotic cells | Membrane-enclosed nucleus, Cytoplasm, Membrane-enclosed organelles, Cell's common features: Plasma membrane, Chromosomes, Ribosomes |
| Pili | Attach prokaryotes to surfaces |
| Nucleoid | Nucleus-like. Where DNA is coiled |
| Prokaryotic cells | Bacteria and Archaea. Lacks nucleus. Nucleoid (nucleus-like). Smaller ribosomes. Rigid cell wall: Protects and maintains shape. Capsule. Some surface projections. Pili. |
| Why are cells the size they are? | Cells must carry out certain functions: Must be able to house DNA, proteins and organelles to survive. Max size of cells = Enough surface area to obtain adequate nutrient and oxygen from environment and dispose of wastes. Distance materials have to diffuse in cell. Smallest cells have the most surface area : volume ratio |
| Problems with electron microscopes | Must kills cells to see, cannot see movement |
| Transmission electron microscope (TEM) | Details of internal structure. Thin sections stained with atoms of metals |
| Scanning Electron Microscope (SEM) | Study details of architecture of cell surfaces. Scan surface covered by metal film |
| Electron microscope (EM) | Beam of electrons, much greater resolution. Distinguish biological structures 2nms. Cellular ultrastructure. Internal anatomy of a cell |
| Cell theory | All living things composed of cells and all cells come from other cells. Cells discovered with microscopes |
| resolution | Measure of the clarity of an image. Ability of an optical instrument to show two close objects as separate. Every optical device, limit to resolution |
| magnification | Increase in the apparent size of an object |
| light microscopes (LM) | First microscopes to be used. Shine light through specimen. Lenses bend light to magnify it. Effectively magnify only 1000 x |
139 cards - created sep 27, 11:48am