Untitled Flashcard Set

Selective permeability

The property of cell membranes that allows certain molecules to pass through while blocking others.

Fluid mosaic model

A model that describes the structure of cell membranes, depicting a flexible layer made of lipid molecules with various proteins embedded in it.

Amphipathic

Molecules, such as phospholipids, that have both hydrophilic (water-loving) and hydrophobic (water-fearing) parts.

Phospholipid bilayer

A double layer of phospholipids that makes up the cell membrane, with hydrophilic heads facing outward and hydrophobic tails facing inward.

Hydrophilic

Substances that are attracted to water and can interact with water molecules.

Hydrophobic

Substances that repel water and do not mix with it.

Cholesterol

A type of lipid that helps to stabilize membrane fluidity at varying temperatures.

Integral protein

Proteins that penetrate the hydrophobic core of the lipid bilayer and often span the membrane.

Transmembrane protein

A type of integral protein that extends across the cell membrane.

Peripheral protein

Proteins that are loosely bound to the surface of the membrane, as opposed to embedding within it.

Glycoprotein

A protein with carbohydrate chains attached, important for cell recognition and signaling.

Lateral movement

The ability of lipids and proteins in the membrane to move sideways within the layer.

Passive transport

The movement of molecules across a cell membrane without the use of energy.

Diffusion

The passive movement of molecules from an area of higher concentration to an area of lower concentration.

Concentration gradient

A difference in the concentration of a substance across a space.

Osmosis

The diffusion of water across a selectively permeable membrane.

Tonicity

The ability of a surrounding solution to cause a cell to gain or lose water.

Hypotonic

A solution with a lower solute concentration compared to the cell, causing water to enter the cell.

Isotonic

A solution with the same solute concentration as the cell, resulting in no net movement of water.

Hypertonic

A solution with a higher solute concentration compared to the cell, causing water to exit the cell.

Turgor pressure

Pressure exerted by the fluid in the central vacuole of a plant cell that pushes the plasma membrane against the cell wall.

Plasmolysis

The process in which cells lose water in a hypertonic solution, causing the cell membrane to pull away from the cell wall.

Facilitated diffusion

The process of passive transport of molecules across the cell membrane via the aid of membrane proteins.

Channel protein

A protein that forms a pore or channel for specific molecules to cross the membrane.

Carrier protein

A protein that binds to molecules and changes shape to shuttle them across the membrane.

Active transport

The movement of molecules against their concentration gradient, requiring energy.

Sodium-potassium pump

An example of active transport that moves sodium ions out of cells and potassium ions into cells.

Cotransport

The coupled transport of one substance across a membrane via a protein that is energized by the movement of another substance.

Exocytosis

The process where cells expel materials in vesicles that fuse with the plasma membrane.

Endocytosis

The process by which a cell takes in materials by enveloping them in a lipid bilayer.

Autotroph

Organisms that produce their own food from inorganic substances, typically through photosynthesis.

Chloroplast

An organelle where photosynthesis takes place, containing the pigment chlorophyll.

Thylakoid

Membrane-bound structures within chloroplasts that house the machinery necessary for photosynthesis.

Granum

Stacks of thylakoids in chloroplasts where light-dependent reactions occur.

Stroma

The fluid-filled space in chloroplasts where the Calvin cycle takes place.

Chlorophyll a

The main pigment involved in photosynthesis that absorbs light energy.

Carotenoid

Accessory pigments that help capture light energy and appear yellow, orange, or red in color.

Absorption spectrum

The range of wavelengths of light that a pigment can absorb.

Photosystem II (P680)

The first photosystem in the light-dependent reactions of photosynthesis that absorbs light at 680 nm.

Photosystem I (P700)

The second photosystem in the light-dependent reactions of photosynthesis that absorbs light at 700 nm.

Photophosphorylation

The process of converting ADP to ATP using energy derived from light.

Chemiosmosis

The movement of ions across a selectively permeable membrane, down their electrochemical gradient.

NADPH

An electron carrier that provides the reducing power for the Calvin cycle.

Calvin cycle

The set of chemical reactions that take place in chloroplasts during photosynthesis, producing glucose.

Rubisco

The enzyme that catalyzes the first step of the Calvin cycle, fixing carbon dioxide.

Carbon fixation

The process of converting inorganic carbon into organic compounds during photosynthesis.

Photorespiration

A process that occurs when the enzyme Rubisco acts on oxygen instead of carbon dioxide, leading to decreased photosynthetic efficiency.

C4 plant

Plants that have evolved a mechanism to minimize photorespiration and efficiently fix carbon in hot environments.

CAM plant

Plants that fix carbon dioxide at night to reduce water loss in arid conditions.

Cellular respiration

The process by which cells convert glucose and oxygen into energy (ATP), carbon dioxide, and water.

Oxidation

The loss of electrons or increase in oxidation state by a molecule, atom, or ion.

Reduction

The gain of electrons or decrease in oxidation state by a molecule, atom, or ion.

NAD⁺ / NADH

NAD⁺ is an electron carrier that is reduced to NADH during glycolysis and the Krebs cycle.

FAD / FADH₂

FAD is another electron carrier that is reduced to FADH₂ during the Krebs cycle.

Glycolysis

The metabolic pathway that converts glucose into pyruvate, yielding a small amount of ATP and NADH.

Pyruvate

The end product of glycolysis, which can be further oxidized in cellular respiration.

Acetyl CoA

The entry molecule for the Krebs cycle, formed from pyruvate.

Krebs (citric acid) cycle

A series of enzymatic reactions in the mitochondrial matrix that generates electron carriers and ATP from Acetyl CoA.

Electron transport chain

A series of protein complexes and other molecules that transfer electrons from NADH and FADH₂ to oxygen, creating a proton gradient.

Chemiosmosis

The process of ATP production as protons flow back across the membrane through ATP synthase.

ATP synthase

An enzyme that synthesizes ATP from ADP and inorganic phosphate during chemiosmosis.

Oxidative phosphorylation

The production of ATP using the energy from the electron transport chain and chemiosmosis.

Substrate-level phosphorylation

The direct formation of ATP from ADP by the transfer of a phosphate group during glycolysis and the Krebs cycle.

Fermentation

The process of converting glucose to energy without using oxygen.

Lactic acid fermentation

A type of fermentation that produces lactic acid from glucose, occurring in muscle cells and some bacteria.

Alcohol fermentation

A type of fermentation that converts glucose to ethanol and carbon dioxide, performed by yeast.

Mitochondrial matrix

The innermost compartment of mitochondria where the Krebs cycle takes place.

Cristae

The folds of the inner mitochondrial membrane that increase surface area for ATP production.