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Comprehensive vocabulary flashcards covering key terms and concepts from Chapters 5 through 8 for BIO 201 Exam 2.

Phospholipid bilayer

Two layers of phospholipids forming the cell membrane, where hydrophilic heads face water and hydrophobic tails face inward.

Glycolipids

Lipids with carbohydrates attached, important for cell recognition.

Cholesterol

A lipid component that helps stabilize membrane fluidity in animal cell membranes.

Glycoproteins

Proteins with carbohydrates attached, important for cell recognition and communication.

Extracellular Matrix (ECM)

Material outside animal cells that supports, connects, and organizes cells.

Aquaporin

A membrane protein channel specifically for water movement across the membrane.

Cell-recognition proteins

Membrane proteins that act as molecular ID tags for the cell.

Channel proteins

Membrane proteins that form passages allowing specific molecules or ions to cross.

Carrier proteins

Membrane proteins that bind a specific substance and change shape to move it across the membrane.

Enzymatic proteins

Membrane proteins that catalyze specific chemical reactions directly at the membrane.

Receptor proteins

Membrane proteins that bind specific signaling molecules to trigger a cellular response.

Junction proteins

Membrane proteins that connect cells to one another or allow direct cell-to-cell communication.

Selectively permeable

A property of cellular membranes that allows some substances to cross more easily than others.

Concentration gradient

A difference in the concentration of a substance between two adjacent areas.

Diffusion

The movement of a solute down its concentration gradient from high to low concentration without ATP.

Facilitated diffusion

The movement of a solute down its concentration gradient through a channel or carrier protein without requiring ATP.

Active transport

The movement of a solute against its concentration gradient from low to high concentration, requiring energy (ATP) and a transport protein.

Solute

The substance that is dissolved in a liquid to form a solution.

Solvent

The dissolving agent of a solution; water is the primary biological solvent.

Bulk transport

The movement of large particles or large quantities of substances across the membrane using vesicles.

Endocytosis

A cellular process that brings materials into the cell by forming vesicles from the plasma membrane.

Exocytosis

A cellular process that releases materials out of the cell by fusing vesicles with the plasma membrane.

Phagocytosis

A type of endocytosis in which a cell engulfs large particles or whole cells ('cell eating').

Pinocytosis

A type of endocytosis in which a cell takes in extracellular fluid and dissolved solutes ('cell drinking').

Osmosis

The net movement of water across a selectively permeable membrane toward the side with higher solute concentration.

Plasmolysis

The shrinking/pulling away of the plant cell membrane from its cell wall following water loss.

Isotonic

A solution environment with an equal solute concentration compared to inside the cell, resulting in no net water movement.

Turgor pressure

The internal water pressure exerted against the plant cell wall when in a hypotonic environment.

Hypotonic

A solution environment with a lower solute concentration than the cell, causing net water entry into the cell.

Lysis

The bursting of an animal cell caused by excessive water influx.

Hypertonic

A solution environment with a higher solute concentration than the cell, causing net water exit from the cell.

Crenation

The shrinking of an animal cell resulting from net water loss in a hypertonic environment.

Passive transport

The movement of substances across a membrane down their concentration gradient without consuming ATP.

Collagen

A structural protein component of the extracellular matrix that provides strength.

Proteoglycans

Components of the extracellular matrix that provide water retention and compression support.

Fibronectin

An ECM protein involved in cell attachment and matrix organization.

Integrins

Membrane proteins that connect the extracellular matrix to the cell interior and mediate cell signaling.

Adhesion junctions

Cell junctions that mechanically attach or anchor neighboring cells together.

Tight junctions

Intercellular junctions that seal the spaces between animal cells to prevent fluid leakage.

Gap junctions

Channels between adjacent animal cells that allow small molecules and ions to pass directly between them.

Plasmodesmata

Microscopic channels passing through plant cell walls that allow direct intercellular transport and communication.

Autocrine signaling

A form of cell signaling in which a chemical signal acts on the very same cell that secreted it.

Paracrine signaling

A form of cell signaling where local signaling molecules act on nearby target cells.

Endocrine signaling

Long-distance signaling involving hormones released into the bloodstream to act on distant target cells.

Reception

The first stage of cell signaling in which a signaling molecule binds to a specific receptor protein.

Transduction

The second stage of cell signaling where the signal is converted into a form that can bring about a specific cellular response.

Response

The final stage of cell signaling in which the transduced signal triggers a specific cellular activity.

Energy

The capacity to do work or cause change.

Potential energy

Stored energy available to do work.

Kinetic energy

The energy associated with objects or particles in motion.

Chemical energy

Potential energy stored in the chemical bonds of molecules.

First law of thermodynamics

The principle that energy cannot be created or destroyed, only transferred or transformed.

Second law of thermodynamics

The principle that every energy transfer increases the total entropy of the universe, releasing usable energy as heat.

Entropy

A quantitative measure of energy dispersal or disorder in a system.

Open system

A system that continuously exchanges both energy and matter with its surroundings.

Closed system

A system that does not exchange matter with its surroundings.

Metabolism

The sum total of all chemical reactions occurring within a cell or organism.

Exergonic reaction

A spontaneous chemical reaction that releases free energy, characterized by $ΔG < 0$.

Endergonic reaction

A non-spontaneous chemical reaction that requires free energy input, characterized by $ΔG > 0$.

Free energy

The portion of a system's energy that is available to perform work at constant temperature and pressure ($ΔG$).

Coupled reaction

A pair of reactions where an energy-releasing (exergonic) reaction directly drives an energy-requiring (endergonic) reaction.

Enzymes

Biological catalysts (typically proteins) that speed up chemical reactions by lowering activation energy.

Ribozymes

RNA molecules that function as biological catalysts.

Activation energy

The minimum energy barrier required to initiate a chemical reaction.

Metabolic pathway

A sequence of linked, enzyme-catalyzed chemical reactions leading from reactants to products.

Substrate

The specific reactant molecule upon which an enzyme acts.

Active site

The specific region of an enzyme where the substrate binds and catalysis occurs.

Induced fit model

Model of enzyme activity stating that an enzyme changes its shape slightly to fit tightly around the substrate upon binding.

Cofactor

A non-protein helper required for proper enzyme function, often an inorganic ion.

Coenzyme

An organic non-protein helper molecule required for an enzyme to function.

Vitamins

Essential organic nutrients required in small amounts, often serving as precursors to coenzymes.

Competitive inhibitor

A molecule that reduces enzyme activity by directly binding to the active site in competition with the substrate.

Noncompetitive (allosteric) inhibitor

A molecule that binds to an allosteric site away from the active site, altering the enzyme shape and activity.

Oxidation

The loss of electrons from a substance during a redox reaction (OIL).

Reduction

The gain of electrons by a substance during a redox reaction (RIG).

Autotrophs

Organisms that produce their own organic nutrients from inorganic carbon using energy sources such as sunlight.

Heterotrophs

Organisms that obtain organic energy molecules by consuming other organisms or organic matter.

Stomata

Microscopic pores on the surface of leaves that regulate gas exchange.

Grana

Stacks of thylakoid membranes within a chloroplast.

Stroma

The dense fluid region surrounding the thylakoid membranes inside a chloroplast where the Calvin cycle occurs.

Thylakoids

Sac-like photosynthetic membranes inside chloroplasts where the light-dependent reactions take place.

Chlorophyll

The primary photosynthetic pigment in plants that absorbs light energy.

Palisade mesophyll

Tightly packed leaf tissue layer beneath the upper epidermis containing abundant chloroplasts where most photosynthesis occurs.

Spongy mesophyll

Loosely packed leaf tissue layer with internal air spaces that conducts photosynthesis and facilitates gas exchange.

Absorption spectrum

A graph showing the specific wavelengths of light absorbed by a given pigment.

Carotenoids

Accessory photosynthetic pigments that absorb additional light wavelengths and provide photoprotection.

Photosystem

A light-capturing unit located in the thylakoid membrane consisting of a reaction center surrounded by light-harvesting antenna complexes.

P680

The special chlorophyll a molecule at the reaction center of Photosystem II (PSII).

P700

The special chlorophyll a molecule at the reaction center of Photosystem I (PSI).

Rubisco

The primary enzyme that catalyzes carbon fixation by attaching $CO_2$ to RuBP during the Calvin cycle.

RuBP

Ribulose 1,5-bisphosphate; the 5-carbon molecule that acts as the initial $CO_2$ acceptor in the Calvin cycle.

C3 plants

Plants that form a 3-carbon compound (3-PGA) as the first stable product of carbon fixation.

Photorespiration

A metabolic pathway occurring in C3 plants under hot, dry conditions when Rubisco binds $O_2$ instead of $CO_2$, consuming energy and wasting photosynthetic productivity.

C4 plants

Plants that initially fix $CO_2$ into a 4-carbon compound using PEP carboxylase in mesophyll cells before delivering $CO_2$ to bundle-sheath cells for the Calvin cycle.

CAM plants

Plants adapted to arid environments that open stomata at night to fix $CO_2$ into organic acids and run the Calvin cycle during the day.

Cellular respiration

A metabolic process that breaks down fuel molecules to release energy and synthesize ATP.

Glycolysis

A cytosolic pathway that breaks down one glucose molecule into two pyruvate molecules, producing net $2\text{ ATP}$ and $2\text{ NADH}$.

Prep reaction

A mitochondrial matrix process where pyruvate is oxidized into acetyl-CoA, releasing $CO_2$ and producing NADH.

Krebs cycle

A pathway in the mitochondrial matrix that completes the breakdown of acetyl-CoA, releasing $CO_2$ and generating NADH, $FADH_2$, and ATP/GTP.

Substrate-level phosphorylation

The direct transfer of a phosphate group from a phosphorylated substrate molecule to ADP to form ATP.