Biology Vocab

  1. Observation (Initial information): Gathering information through senses or instruments, which provides the basis for forming questions or hypotheses. 

  1. Scientific Question: A question based on observations that can be tested through experiments or further observations. 

  1. Hypothesis: A tentative explanation or prediction that can be tested by experiments or observations. 

  1. Prediction: A specific outcome expected if the hypothesis is correct. 

  1. Theory: A well-substantiated explanation of some aspect of the natural world that is based on a body of evidence. 

  1. Controlled Experiment: An experiment in which only one variable is changed while keeping all other variables constant. 

  1. Dependent (response) variable: The variable that is measured or observed in response to changes in the independent variable. 

  1. Independent (explanatory) variable: The variable that is changed or manipulated by the researcher to observe its effect on the dependent variable. 

  1. Valence electron: An electron in the outermost shell of an atom that can participate in chemical bonding. 

  1. Electronegativity: A measure of an atom's ability to attract electrons in a chemical bond. 

  1. Four types of bonds: Covalent, ionic, hydrogen, and Van der Waals bonds. 

  1. Covalent bond (polar & nonpolar): A bond where atoms share electrons; polar covalent bonds have unequal sharing, nonpolar bonds have equal sharing. 

  1. Ionic bond: A bond formed by the transfer of electrons from one atom to another, resulting in oppositely charged ions. 

  1. Hydrogen bond: A weak bond between a hydrogen atom and an electronegative atom like oxygen or nitrogen. 

  1. Van der Waals: Weak attractions between molecules due to temporary dipoles created by the movement of electrons. 

  1. pH: A measure of how acidic or basic a solution is, based on the concentration of hydrogen ions (H+). 

  1. Solute: The substance that is dissolved in a solvent to form a solution. 

  1. Solvent: The substance that dissolves the solute to form a solution. 

  1. Solution: A homogeneous mixture of solute and solvent. 

  1. Hydrophobic: Water-fearing; substances that do not dissolve in water. 

  1. Hydrophilic: Water-loving; substances that dissolve or interact well with water. 

 

  1. Biomolecule: A molecule that is essential for life, including carbohydrates, lipids, proteins, and nucleic acids. 

  1. Monomer: A small molecule that can bind to others to form a polymer. 

  1. Polymer: A large molecule made up of repeating monomer units. 

  1. Hydrolysis: A reaction where water breaks a bond in a polymer to separate it into monomers. 

  1. Dehydration Synthesis: A reaction where monomers are joined by removing water to form a polymer. 

  1. Enzyme: A biological catalyst that speeds up chemical reactions in cells. 

  1. Polypeptide: A chain of amino acids linked by peptide bonds. 

  1. Protein: A functional molecule made of one or more polypeptides folded into a specific structure. 

  1. Amino Acid: The building block of proteins, consisting of an amino group, carboxyl group, and side chain. 

  1. Hydrophobic: Repels water, commonly used to describe molecules that do not dissolve in water. 

  1. Hydrophilic: Attracts water, commonly used to describe molecules that dissolve in or interact with water. 

  1. Lipids: Hydrophobic molecules, including fats, oils, and phospholipids, that are used for energy storage and membrane structure. 

  1. Hydrophobic interaction: The tendency of nonpolar substances to avoid water and group together in aqueous environments. 

  1. Fatty acid: A long hydrocarbon chain with a carboxyl group, which is a component of fats. 

  1. Saturated fatty acid: A fatty acid with no double bonds, meaning it is fully saturated with hydrogen. 

  1. Unsaturated fatty acid: A fatty acid that contains one or more double bonds in its hydrocarbon chain. 

  1. Nucleic Acid: A polymer of nucleotides, such as DNA or RNA, that stores and transmits genetic information. 

  1. Adenine: A nitrogenous base in DNA and RNA; pairs with thymine in DNA and uracil in RNA. 

  1. Purine: A type of nitrogenous base, including adenine and guanine, characterized by a double-ring structure. 

  1. Cytosine: A nitrogenous base in DNA and RNA; pairs with guanine. 

  1. Uracil: A nitrogenous base found in RNA, replacing thymine. 

  1. Thymine: A nitrogenous base in DNA; pairs with adenine. 

  1. Guanine: A nitrogenous base in DNA and RNA; pairs with cytosine. 

  1. Complementary: Refers to the specific pairing of nitrogenous bases in DNA or RNA (A-T, G-C). 

  1. Pyrimidine: A type of nitrogenous base with a single-ring structure, including cytosine, thymine, and uracil. 

  1. Ribonucleic Acid (RNA): A nucleic acid involved in protein synthesis, consisting of a single strand of nucleotides. 

  1. Deoxyribonucleic Acid (DNA): A nucleic acid that carries genetic information, consisting of two strands in a double helix. 

  1. Nucleotide: The monomer of nucleic acids, consisting of a sugar, phosphate group, and nitrogenous base. 

  1. Polynucleotide: A polymer of nucleotides, forming either DNA or RNA. 

  1. Glucose (6C): A six-carbon sugar that serves as a primary energy source in cells. 

  1. Monosaccharide: The simplest type of carbohydrate, consisting of a single sugar molecule. 

  1. Polysaccharide: A carbohydrate polymer made of many monosaccharide units. 

  1. Starch vs Cellulose: Starch is a polysaccharide used for energy storage in plants; cellulose is a structural polysaccharide in plant cell walls. 

 

 

  1. Organelle: Specialized structures within a cell that perform specific functions, like the nucleus or mitochondria. 

  1. Chromosome: A thread-like structure made of DNA and proteins, carrying genetic information. 

  1. Cytoplasm: The fluid inside the cell, excluding the nucleus, that contains organelles and other cell components. 

  1. Cytosol: The liquid part of the cytoplasm, where metabolic reactions occur. 

  1. Plasma membrane: The semi-permeable membrane that surrounds the cell, controlling the movement of substances in and out. 

  1. Nucleus: The organelle that contains the cell’s genetic material (DNA) and controls cell activities. 

  1. Nuclear envelope: The double membrane surrounding the nucleus, containing nuclear pores for material exchange. 

  1. Nuclear pore: Openings in the nuclear envelope that allow for the transport of molecules between the nucleus and cytoplasm. 

  1. Endomembrane system: A group of organelles involved in modifying, packaging, and transporting proteins and lipids, including the ER and Golgi apparatus. 

  1. Vesicles: Small membrane-bound sacs that transport materials within or outside the cell. 

  1. Endoplasmic reticulum (ER): A network of membranes involved in protein and lipid synthesis. It comes in two types: 

  1. Smooth ER: Lacks ribosomes, involved in lipid synthesis and detoxification. 

  1. Rough ER: Studded with ribosomes, involved in protein synthesis. 

  1. Transport vesicle: A small membrane-bound sac that moves molecules between organelles in the cell. 

  1. Golgi apparatus: An organelle that modifies, sorts, and packages proteins and lipids for storage or transport out of the cell. 

  1. Vacuole: A large vesicle that stores nutrients, waste products, and helps maintain pressure within the plant cells. 

  1. Lysosome: An organelle that contains enzymes to break down and digest waste and cellular debris. 

  1. Cell wall: A rigid structure found in plant cells, providing support and protection; made of cellulose. 

  1. Ribosomes (bound and free): Small organelles that synthesize proteins; bound ribosomes are attached to the rough ER, while free ribosomes float in the cytoplasm. 

  1. Inner membrane/Outer membrane: Refers to the double membranes found in mitochondria and chloroplasts; the inner membrane often plays a role in energy production. 

  1. Intermembrane space: The space between the inner and outer membranes of mitochondria or chloroplasts, important for processes like oxidative phosphorylation. 

  1. Mitochondria: The powerhouse of the cell, where cellular respiration and energy (ATP) production occur. 

  1. Mitochondrial matrix: The innermost compartment of the mitochondria, where the citric acid cycle takes place. 

  1. Chloroplast: An organelle found in plant cells responsible for photosynthesis. 

  1. Stomata: Pores in plant leaves and stems that allow gas exchange. 

  1. Stroma: The fluid-filled space inside chloroplasts where the Calvin cycle of photosynthesis occurs. 

 

  1. Phospholipid: A lipid with a hydrophilic head and hydrophobic tails, forming the main structure of cell membranes. 

  1. Semi-permeability: The ability of a membrane to allow some substances to pass through while blocking others. 

  1. Amphipathic: A molecule with both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions, like phospholipids. 

  1. Fluid mosaic model: A model describing the dynamic, flexible nature of the cell membrane, where proteins float in or on a fluid lipid bilayer. 

  1. Integral proteins: Proteins embedded in the lipid bilayer that can span the membrane and facilitate transport. 

  1. Peripheral proteins: Proteins attached to the surface of the membrane, involved in signaling and maintaining structure. 

  1. Transport protein: Proteins that help move substances across the cell membrane, either by facilitated diffusion or active transport. 

  1. Aquaporin: A transport protein specifically for water, allowing water to move through the cell membrane. 

  1. Active transport: The movement of substances across a membrane against their concentration gradient, requiring energy (ATP). 

  1. Cotransport: The coupled transport of two substances across a membrane, where one substance moves down its concentration gradient and the other moves against it. 

  1. Concentration gradient: A difference in the concentration of a substance across a space, driving diffusion. 

  1. Diffusion: The passive movement of molecules from a region of high concentration to low concentration. 

  1. Dynamic Equilibrium: When the concentration of molecules is the same throughout a space, but molecules continue to move randomly. 

  1. Facilitated diffusion: The passive movement of molecules across a membrane via transport proteins. 

  1. Exocytosis: The process by which cells expel materials in vesicles by fusing them with the cell membrane. 

  1. Endocytosis: The process by which cells take in materials by engulfing them in vesicles. 

  1. Hypo/Hyper/Iso Osmotic: Refers to the relative concentrations of solutes outside versus inside the cell: 

  1. Hypoosmotic: Lower solute concentration outside the cell. 

  1. Hyperosmotic: Higher solute concentration outside the cell. 

  1. Isoosmotic: Equal solute concentration inside and outside the cell. 

  1. Ion pumps (Sodium-potassium pump; proton pump): Transport proteins that use energy to move ions across the membrane against their concentration gradients. 

  1. Membrane Potential: The voltage difference across a cell membrane, caused by the distribution of ions. 

  1. Osmosis: The passive movement of water molecules across a semi-permeable membrane from an area of lower solute concentration to higher solute concentration. 

  1. Osmolarity: The concentration of solutes in a solution, affecting water movement. 

  1. Osmoregulation: The process by which cells or organisms regulate water balance to maintain homeostasis. 

  1. Passive transport: The movement of substances across a membrane without the use of energy, including diffusion and facilitated diffusion. 

  1. Adenosine diphosphate (ADP): A molecule that, when combined with a phosphate group, forms ATP, the energy currency of the cell. 

  1. Adenosine triphosphate (ATP): The main energy carrier in cells, used to power many cellular processes. 

  1. Potential energy: Stored energy due to position or structure. 

  1. Kinetic energy: Energy of motion. 

  1. Energy Coupling: The process of using energy released from exergonic reactions to drive endergonic reactions. 

  1. Entropy: A measure of disorder or randomness in a system. 

  1. Equilibrium: A state in which the forward and reverse reactions occur at the same rate, with no net change in the system. 

  1. Exergonic: Reactions that release energy. 

  1. Endergonic: Reactions that require energy input. 

  1. First Law: Energy cannot be created or destroyed, only transformed. 

  1. Second Law: The entropy of the universe always increases over time. 

  1. Gibbs Free Energy: The amount of energy available to do work in a system. 

  1. Inorganic Phosphate: A free phosphate group released during ATP hydrolysis, often involved in energy transfer. 

  1. Anabolism: Metabolic pathways that build molecules and require energy. 

  1. Catabolism: Metabolic pathways that break down molecules and release energy. 

  1. Phosphorylation: The addition of a phosphate group to a molecule, often to activate or deactivate enzymes. 

  1. Spontaneous: Reactions that occur without energy input (negative Gibbs free energy). 

  1. Nonspontaneous: Reactions that require energy input (positive Gibbs free energy). 

  1. Activation Energy: The energy required to start a chemical reaction. 

  1. Active Site: The region on an enzyme where the substrate binds. 

  1. Competitive Inhibitor: Binds to the active site, preventing substrate binding. 

  1. Noncompetitive Inhibitor: Binds to a different part of the enzyme, changing its shape and function. 

  1. Enzyme: A protein that speeds up chemical reactions by lowering activation energy. 

  1. Feedback Inhibition: A regulatory mechanism where the product of a pathway inhibits an earlier step, preventing overproduction. 

  1. Induced Fit: A model describing how enzyme binding causes a change in the shape of the active site, optimizing substrate interaction. 

  1. Optimal Conditions: The most favorable conditions for enzyme activity, including temperature and pH. 

  1. Substrate: The molecule on which an enzyme acts. 

 

  1. Acetyl CoA (2C): A two-carbon molecule formed from pyruvate that enters the citric acid (Krebs) cycle in cellular respiration. 

  1. Chemiosmosis: The movement of ions (usually H⁺) across a membrane to generate ATP, driven by a proton gradient. 

  1. Oxidative phosphorylation: The process of producing ATP through the transfer of electrons along the electron transport chain, coupled with chemiosmosis. 

  1. Aerobic cellular respiration: The process of producing ATP by breaking down glucose in the presence of oxygen. 

  1. Glycolysis: The breakdown of glucose (6C) into two molecules of pyruvate (3C), producing a small amount of ATP and NADH. 

  1. Mitochondrial Matrix: The innermost part of the mitochondria where the citric acid cycle occurs. 

  1. ATP (Adenosine triphosphate): The energy currency of the cell that stores and transfers energy for cellular activities. 

  1. G3P (3C): Glyceraldehyde-3-phosphate, an intermediate in glycolysis and the Calvin cycle. 

  1. Pyruvate (3C): A three-carbon molecule produced at the end of glycolysis, which is converted into acetyl CoA during cellular respiration. 

  1. ATP synthase: An enzyme that synthesizes ATP from ADP and inorganic phosphate during chemiosmosis, using the energy from a proton gradient. 

  1. Inner/Outer Membrane (mitochondria): The two membranes that surround the mitochondria; the inner membrane houses the electron transport chain and ATP synthase. 

  1. Pyruvate oxidation: The conversion of pyruvate into acetyl CoA, releasing carbon dioxide (CO₂) and generating NADH. 

  1. Carbon Dioxide (1C): A waste product of cellular respiration, released during pyruvate oxidation and the citric acid cycle. 

  1. Intermembrane Space: The space between the inner and outer mitochondrial membranes, where protons accumulate during chemiosmosis. 

  1. Substrate-level phosphorylation: The direct formation of ATP by transferring a phosphate group to ADP from a high-energy substrate during glycolysis or the citric acid cycle. 

  1. Citric acid (Krebs) cycle: A series of chemical reactions that further break down acetyl CoA, producing ATP, NADH, FADH₂, and releasing CO₂. 

  1. Mitochondrion: The organelle where aerobic cellular respiration occurs, producing the majority of ATP in eukaryotic cells. 

  1. Proton (H⁺) Gradient: The buildup of protons (H⁺ ions) across a membrane, driving ATP production in chemiosmosis. 

  1. Fermentation: An anaerobic process that allows glycolysis to continue by regenerating NAD⁺, producing lactic acid or ethanol as by-products. 

  1. NAD⁺/NADH: Nicotinamide adenine dinucleotide, a coenzyme involved in redox reactions. NAD⁺ accepts electrons to form NADH, which carries electrons to the electron transport chain. 

  1. Oxaloacetate (4C): A four-carbon molecule that combines with acetyl CoA to start the citric acid cycle. 

  1. FAD/FADH₂: Flavin adenine dinucleotide, a coenzyme involved in redox reactions. FAD is reduced to FADH₂ during the citric acid cycle, carrying electrons to the electron transport chain. 

  1. Oxidation-reduction (Redox): Reactions where one molecule loses electrons (oxidation) and another gains electrons (reduction). 

  1. Anaerobic cellular respiration: A form of respiration that occurs without oxygen, using alternative electron acceptors to produce ATP. 

  1. Electron transport chain: A series of protein complexes located in the inner mitochondrial membrane that transfer electrons, releasing energy used to pump protons and generate ATP. 

  1. ATP synthase Chemiosmosis: The production of ATP through the movement of protons across a membrane via ATP synthase, driven by the proton gradient established by the electron transport chain.