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Untitled Flashcards Set
Microscope: An instrument used to view objects that are too small to be seen by the naked eye.
Light Microscope: Uses visible light and lenses to magnify small objects. It can view living cells but has limited resolution compared to electron microscopes.
Electron Microscope: Uses beams of electrons for much higher resolution imaging, allowing visualization of smaller structures like organelles and viruses.
Cell Theory: A fundamental theory in biology stating that all living organisms are made of cells, the cell is the basic unit of life, and all cells arise from pre-existing cells.
Ribosomes: Molecular machines made of RNA and proteins that synthesize proteins by translating messenger RNA (mRNA).
Cytosol: The fluid component of the cytoplasm where organelles are suspended and metabolic reactions occur.
Plasma Membrane: The biological membrane that separates the interior of the cell from the external environment, controlling the movement of substances in and out of the cell.
Prokaryote: Simple, single-celled organisms without a nucleus or membrane-bound organelles. Examples include bacteria and archaea.
Eukaryote: More complex cells that contain a nucleus and membrane-bound organelles. Examples include animal, plant, fungal, and protist cells.
Organelle: Specialized subunits within a eukaryotic cell that perform specific functions (e.g., nucleus, mitochondria, Golgi apparatus).
Nucleus: A membrane-bound organelle that contains the cell's DNA and controls gene expression and cell division.
Cytoskeleton: A network of protein fibers that maintain cell shape, enable cellular motion, and play roles in intracellular transport and cell division.
Microfilaments: The thinnest type of cytoskeletal fibers, made of actin, involved in cell movement and shape maintenance.
Actin: A protein that forms microfilaments, playing a key role in cell structure, movement, and division.
Intermediate Filaments: Cytoskeletal components that provide mechanical support and help maintain cell integrity.
Microtubules: Hollow tubes made of tubulin proteins that provide structural support, act as tracks for motor proteins, and are essential for cell division.
Tubulin: The protein that polymerizes to form microtubules.
Motor Proteins: Proteins that use energy (from ATP) to move along cytoskeletal filaments, transporting cellular cargo.
Myosin: A motor protein that interacts with actin filaments to facilitate muscle contraction and other cellular movements.
Kinesin: A motor protein that "walks" along microtubules, usually moving cargo toward the cell's periphery (plus-end).
Dynein: A motor protein that moves along microtubules, typically transporting materials toward the cell center (minus-end) and involved in the movement of cilia and flagella.
Phospholipid Bilayer: A double layer of phospholipids that forms the basic structure of cell membranes. Each phospholipid has a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails.
Amphipathic: Molecules that have both hydrophilic and hydrophobic regions. Phospholipids are amphipathic because their heads are hydrophilic, and their tails are hydrophobic.
Fluid Mosaic Model of the Plasma Membrane: A model describing the structure of the plasma membrane as a flexible (fluid) layer where lipids and proteins can move laterally. The membrane is a mosaic of phospholipids, proteins, and carbohydrates.
Hydrophobic Interactions: Nonpolar molecules tend to cluster together in aqueous environments to avoid contact with water, contributing to the stability of the membrane.
Lateral Movement: The side-to-side movement of phospholipids within the same layer of the bilayer. This is frequent and contributes to membrane fluidity.
Rotational Movement: The spinning of phospholipids around their axis, aiding membrane flexibility.
Flippase-Mediated Movement: The enzyme-catalyzed movement of phospholipids from one leaflet (side) of the bilayer to the other, which is otherwise energetically unfavorable.
Integral Proteins: Proteins that are embedded within the phospholipid bilayer and may span across it.
Transmembrane Proteins: A type of integral protein that extends across the entire bilayer, with parts exposed on both sides of the membrane.
Peripheral Proteins: Proteins that are loosely attached to the surface of the membrane, often interacting with integral proteins or the phospholipid heads.
Lipid-Anchored Proteins: Proteins that are covalently attached to lipids within the bilayer, anchoring them to the membrane.
Semifluid: Describes the flexible yet stable nature of the membrane, allowing lateral and rotational movement of its components but restricting some types of motion like flipping.
Unsaturated: Refers to fatty acids with one or more double bonds, causing kinks that prevent tight packing. This increases membrane fluidity.
Saturated: Fatty acids with no double bonds, resulting in straight chains that pack tightly, making the membrane less fluid.
Glycosylation: The process of attaching carbohydrates to proteins or lipids, important for cell recognition and signaling.
Glycolipid: A lipid molecule with a carbohydrate attached, found on the extracellular surface of the plasma membrane, contributing to cell recognition.
Glycoprotein: A protein with one or more carbohydrates attached, also involved in cell recognition, signaling, and structural integrity.
Transport Proteins: Proteins that assist in moving substances across the cell membrane.
Selective Permeability: The ability of the cell membrane to allow certain molecules to pass while blocking others.
Membrane Gradients: Differences in concentration, charge, or pressure across a membrane that drive the movement of substances.
Passive Transport: Movement of substances across the membrane without energy input, following the concentration gradient.
Active Transport: Movement of substances against their concentration gradient, requiring energy (usually from ATP).
Diffusion: The movement of particles from an area of high concentration to an area of low concentration.
Osmosis: The diffusion of water molecules across a selectively permeable membrane.
Passive Diffusion: Simple movement of small, nonpolar molecules across the membrane without assistance.
Facilitated Diffusion: Movement of substances across the membrane via transport proteins (channels or carriers).
Hypotonic: A solution with a lower concentration of solutes compared to the inside of the cell; water enters the cell, causing it to swell.
Isotonic: A solution with equal concentrations of solutes inside and outside the cell; no net water movement.
Hypertonic: A solution with a higher concentration of solutes compared to the inside of the cell; water exits the cell, causing it to shrink.
Crenation: Shrinking of animal cells in a hypertonic solution due to water loss.
Plasmolysis: Shrinking of the cytoplasm in plant cells as the cell membrane pulls away from the cell wall in a hypertonic solution.
Aquaporins: Specialized channel proteins that facilitate the transport of water across the cell membrane.
Channels: Pore-like proteins that allow specific molecules or ions to pass through the membrane.
Transporters/Carriers: Proteins that bind specific molecules and undergo shape changes to move them across the membrane.
Pumps: Active transport proteins that use energy to move substances against their concentration gradient.
Primary Active Transport: Direct use of energy (usually ATP) to move substances against their gradient.
Secondary Active Transport: Uses energy stored in the form of an ion gradient created by primary active transport.
Coupled Transporters: Proteins that transport two substances simultaneously.
Uniporter: Transports a single substance in one direction.
Symporter: Transports two substances in the same direction.
Antiporter: Transports two substances in opposite directions.
Bulk Transport: Movement of large particles or volumes of substances using vesicles.
Exocytosis: The process of vesicles fusing with the plasma membrane to release contents outside the cell.
Endocytosis: The process of the cell membrane engulfing substances to bring them into the cell.
Phagocytosis: A type of endocytosis where large particles, like bacteria, are engulfed ("cell eating").
Pinocytosis: A type of endocytosis where liquids or small particles are taken in ("cell drinking").
Receptor-Mediated Endocytosis: A selective form of endocytosis where cells absorb specific molecules by recognizing them with receptor proteins.
Equilibrium: A state where concentrations of substances are equal on both sides of the membrane, resulting in no net movement.
Energy: The capacity to do work or produce heat. It exists in various forms, such as kinetic, potential, thermal, and chemical energy.
Kinetic Energy: The energy an object possesses due to its motion.
Potential Energy: The stored energy an object has because of its position or structure.
First Law of Thermodynamics: Energy cannot be created or destroyed, only transferred or transformed. Also known as the law of energy conservation.
Second Law of Thermodynamics: In any energy transfer, some energy becomes unusable, often lost as heat, and the entropy (disorder) of the universe tends to increase.
Heat: A form of energy transfer between bodies due to a temperature difference.
Reactant: The starting substances in a chemical reaction that undergo change.
Product: The substances formed as a result of a chemical reaction.
Chemical Reaction: A process in which substances (reactants) are transformed into different substances (products) through breaking and forming chemical bonds.
Free Energy (Gibbs Free Energy): The energy in a system available to do work. It determines whether a reaction will occur spontaneously.
Equilibrium: The state in a reversible reaction where the rate of the forward reaction equals the rate of the reverse reaction, and the concentrations of reactants and products remain constant.
Endergonic Reaction: A chemical reaction that requires an input of energy, resulting in products with more free energy than the reactants.
Exergonic Reaction: A chemical reaction that releases energy, resulting in products with less free energy than the reactants.
Spontaneous Reaction: A reaction that occurs without needing external energy, typically releasing free energy (exergonic).
Activation Energy: The minimum energy required for a chemical reaction to occur.
Transition State: A high-energy, unstable arrangement of atoms during a chemical reaction that leads to the formation of products.
Catalyst: A substance that speeds up a chemical reaction by lowering the activation energy without being consumed in the process.
Enzyme: A biological catalyst, typically a protein, that accelerates chemical reactions in living organisms.
Substrate: The specific reactant that an enzyme acts upon.
Product (in enzymatic reactions): The substances formed after the enzyme catalyzes the conversion of substrates.
Catalyst: A substance that speeds up a chemical reaction without being consumed in the process.
Enzyme: A biological catalyst, typically a protein, that accelerates chemical reactions in living organisms.
Substrate: The specific reactant molecule that an enzyme acts upon during a chemical reaction.
Product: The resulting molecule(s) formed after an enzyme catalyzes a reaction with its substrate.
Active Site: The specific region of an enzyme where the substrate binds and the chemical reaction occurs.
Induced Fit: The concept that the enzyme's active site molds itself around the substrate for a better fit, enhancing catalytic efficiency.
Specificity: The property of an enzyme to selectively bind to a particular substrate due to the unique shape of its active site.
Conformational Change: A structural alteration in a protein (like an enzyme) that can affect its activity or interaction with other molecules.
Competitive Enzyme Inhibitor: A molecule that resembles the substrate and competes for binding at the enzyme's active site, blocking the actual substrate.
Noncompetitive Enzyme Inhibitor: A molecule that binds to an enzyme at a location other than the active site (allosteric site), altering the enzyme's shape and reducing its activity.
Allosteric: Refers to the regulation of an enzyme's activity through binding at a site other than the active site, which can change the enzyme's shape and function.
Activator: A molecule that increases the activity of an enzyme by enhancing its ability to bind to the substrate.
Coenzyme: A non-protein organic molecule (often a vitamin) that assists an enzyme in catalyzing a reaction.
Cofactor: A non-protein chemical compound (often a metal ion) that is required for an enzyme's activity.
Anabolic: Metabolic pathways that build larger molecules from smaller ones, requiring energy (e.g., protein synthesis).
Catabolic: Metabolic pathways that break down larger molecules into smaller ones, releasing energy (e.g., cellular respiration).
ATP (Adenosine Triphosphate): The main energy-carrying molecule in cells, used to power various biological processes.
ATP Hydrolysis: The process of breaking down ATP into ADP (adenosine diphosphate) and inorganic phosphate, releasing energy.
Inorganic Phosphate (Pi): A free phosphate group released during ATP hydrolysis, involved in energy transfer.
Metabolism: The sum of all chemical reactions in an organism, including both anabolic and catabolic processes.
Metabolic Pathway: A series of interconnected chemical reactions in a cell, where the product of one reaction becomes the substrate for the next.
Feedback Inhibition: A regulatory mechanism where the end product of a metabolic pathway inhibits an earlier step to prevent overproduction.
Cellular Respiration
A set of metabolic processes by which cells convert biochemical energy from nutrients (like glucose) into adenosine triphosphate (ATP), releasing waste products such as carbon dioxide and water.
Aerobic Respiration
A type of cellular respiration that requires oxygen to produce ATP. It involves glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation.
Redox Reactions
Chemical reactions involving the transfer of electrons from one molecule to another, encompassing two processes: reduction and oxidation.
Reduction
A chemical process where a molecule gains electrons, often accompanied by gaining hydrogen or losing oxygen.
Oxidation
A chemical process where a molecule loses electrons, often accompanied by losing hydrogen or gaining oxygen.
Energy Intermediates
Molecules that store energy and transfer it within cells, like ATP, NADH, and FADH₂, facilitating metabolic reactions.
NADH
Nicotinamide adenine dinucleotide (NAD⁺) in its reduced form, which carries electrons to the electron transport chain in cellular respiration.
FADH₂
Flavin adenine dinucleotide (FAD) in its reduced form, also an electron carrier that transports electrons to the electron transport chain.
Substrate-level Phosphorylation
A process of ATP production where a phosphate group is directly transferred from a substrate molecule to ADP, occurring during glycolysis and the citric acid cycle.
Oxidative Phosphorylation
The production of ATP using energy derived from the redox reactions of the electron transport chain, which creates a proton gradient to power ATP synthesis.
Glycolysis
The first stage of cellular respiration where glucose is broken down into two molecules of pyruvate, producing a small amount of ATP and NADH.
Pyruvate
A three-carbon compound formed from the breakdown of glucose during glycolysis, which enters the mitochondria for further processing.
Acetyl CoA
A molecule formed from the oxidation of pyruvate, which enters the citric acid cycle and contributes to the production of ATP, NADH, and FADH₂.
H⁺/Pyruvate Cotransporter
A transport protein located in the mitochondrial membrane that facilitates the import of pyruvate into the mitochondrial matrix along with protons (H⁺).
Mitochondrial Outer Membrane
The outer layer of the mitochondria that separates the organelle from the cytosol and is permeable to ions and small molecules.
Mitochondrial Inner Membrane
The membrane inside mitochondria that contains the electron transport chain and ATP synthase, essential for oxidative phosphorylation.
Mitochondrial Intermembrane Space
The space between the inner and outer mitochondrial membranes, where a high concentration of protons (H⁺) is built during the electron transport chain to drive ATP synthesis.
