Plasma Membrane and Cellular Processes

This set of flashcards covers key vocabulary and concepts related to cell membranes, transport mechanisms, cellular respiration, energy transformation, and metabolic pathways, essential for understanding biological processes.

Plasma membrane

A dynamic, fluid structure composed of a phospholipid bilayer.

Fluid mosaic model

The model describing the plasma membrane as flexible with mobile phospholipids and proteins.

Phospholipid bilayer

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

Selective permeability

The ability of the plasma membrane to allow certain substances to cross more easily than others.

Transport

The movement of substances across the plasma membrane.

Diffusion

The movement of molecules from an area of higher concentration to lower concentration until equilibrium is reached.

Osmosis

The diffusion of water across a selectively permeable membrane.

Hypertonic solution

A solution that has a higher solute concentration compared to another solution.

Hypotonic solution

A solution that has a lower solute concentration compared to another solution.

Isotonic solution

A solution that has an equal solute concentration compared to another solution.

Passive transport

Movement of substances across a membrane without the use of energy.

Active transport

Movement of molecules across a membrane against their concentration gradient requiring energy.

Endocytosis

The process of taking substances into the cell by forming a vesicle.

Exocytosis

The process in which an intracellular vesicle fuses with the plasma membrane to release contents outside the cell.

Sodium-potassium pump

A protein pump that moves sodium out and potassium into the cell, requiring ATP.

Membrane-spanning proteins

Proteins that extend across the plasma membrane and regulate transport.

Perfume diffusion

An analogy for diffusion where scent molecules spread out from higher concentration to lower concentration.

Concentration gradient

A difference in concentration of a substance across a distance.

Facilitated diffusion

The process of spontaneous passive transport of molecules or ions across a membrane via specific transmembrane proteins.

Active transport vs Passive transport

Active transport uses energy and moves substances against their gradient, while passive transport does not require energy and moves substances down their gradient.

Resting potential

The state of a neuron when it is ready to fire, typically between -55mV to -70mV.

Action potential

An electric signal that neurons send along their axons, characterized by depolarization and repolarization.

Depolarization

The process where the membrane potential becomes more positive during an action potential.

Repolarization

The process where the membrane potential returns to a negative value after depolarization.

Summation

The process of combining all incoming signals at a neuron to determine if a threshold is reached.

Signal transduction pathways

The series of intracellular events triggered by receptor activation.

Neuron

A specialized cell transmitting nerve impulses.

Soma

The cell body of a neuron containing the nucleus.

Dendrites

Branch-like structures of a neuron that receive signals.

Axon

The long, tail-like structure of a neuron that transmits signals away from the cell body.

Myelin sheath

Fatty encasings around axons that increase the speed of impulse transmission.

Membrane potential

The difference in electrical charge inside and outside a neuron.

NAD+

A coenzyme that acts as an electron carrier in cellular respiration.

FAD

A coenzyme that serves as a redox partner in cellular metabolism.

Electron transport chain

A series of complexes that transfer electrons to generate ATP.

Glycolysis

The process of breaking down glucose into pyruvate, producing a small amount of ATP and NADH.

Citric acid cycle

A series of chemical reactions used by all aerobic organisms to generate energy.

Fermentation

A metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen.

Potential energy

Stored energy that can be converted to kinetic energy.

Kinetic energy

The energy of motion.

Exergonic reactions

Chemical reactions that release energy.

Endergonic reactions

Chemical reactions that require energy input.

ATP

Adenosine triphosphate, the primary energy carrier in cells.

Activation energy

The minimum energy required to start a chemical reaction.

Enzyme specificity

The ability of an enzyme to choose exact substrate from a group of similar chemical molecules.

Allosteric site

A site on an enzyme where a molecule can bind to regulate the enzyme's activity.

Competitive inhibition

When a substance mimics a substrate and competes for active site binding.

Noncompetitive inhibition

When a substance binds to an enzyme at a site other than the active site, altering its shape.

Feedback inhibition

A regulatory mechanism where the end product of a metabolic pathway inhibits an upstream process.

Thermodynamics

The branch of physical science that deals with the relations between heat and other forms of energy.

Covalent bonds

Chemical bonds formed by the sharing of electrons between atoms.

G3P

Glyceraldehyde 3-phosphate, an intermediate in glycolysis.

ATP cycle

The continuous regeneration of ATP from ADP and inorganic phosphate.

Oxidation-reduction reactions

Reactions where electrons are transferred between substances.

Cellular respiration

The process of converting biochemical energy from nutrients into ATP.

Photosynthesis

The process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll.

Chloroplasts

Organelles in plant cells where photosynthesis occurs.

Mitochondria

Organelles responsible for energy production in eukaryotic cells.

NADH

The reduced form of NAD+, which carries high-energy electrons.

FADH₂

The reduced form of FAD, another electron carrier.

Proton gradient

A gradient formed by the difference in proton concentration across a membrane.

Chemiosmosis

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

ATP synthase

An enzyme that synthesizes ATP from ADP and inorganic phosphate using energy from the proton gradient.

Oxidative phosphorylation

A metabolic pathway that uses energy released by the oxidation of nutrients to produce ATP.

ATP production

The process by which cells generate ATP, primarily through glycolysis, citric acid cycle, and oxidative phosphorylation.

End products of fermentation

Lactic acid or ethanol, produced in anaerobic conditions.

Cellular respiration inputs

Glucose and oxygen, needed for energy production.

Cellular respiration outputs

Carbon dioxide, water, and ATP, released as waste products.

Pyruvate

The end product of glycolysis; a key intermediate in cellular respiration.

Acetyl-CoA

A crucial intermediate in the citric acid cycle, derived from pyruvate.

CoA

Coenzyme A, involved in the synthesis and oxidation of fatty acids.

Energy investment phase

The phase of glycolysis where ATP is consumed to break down glucose.

Energy harvesting phase

The phase of glycolysis where ATP and NADH are produced.

ATP input and output in glycolysis

ATP is used to initiate glycolysis but also produced during the process.

Lactate

The end product of lactic acid fermentation in muscle cells.

Alcohol fermentation

The process where pyruvate is converted into alcohol and carbon dioxide.

Regeneration of NAD+

The process during fermentation that allows glycolysis to continue by converting NADH back to NAD+.

Entropic principle

The principle that energy transfer increases disorder, often seen in thermodynamics.

Link between glycolysis and aerobic respiration

Glycolysis can proceed anaerobically, but for full ATP yield, it links to aerobic pathways in mitochondria.

Aerobic respiration stages

Includes glycolysis, citric acid cycle, and electron transport chain.

Substrate-level phosphorylation

The direct production of ATP from ADP during glycolysis and citric acid cycle.

Oxidation of glucose

The process where glucose loses electrons, producing carbon dioxide.

Reduction of oxygen

The process where oxygen gains electrons, forming water.

Glycolysis net ATP

Produces a net of 2 ATP per glucose molecule processed.

Energy yield of cellular respiration

Cells extract energy from glucose stored in ATP during respiration.

Mitochondrial function

Mitochondria are sites for ATP production and energy metabolism.

Electron carriers role

Transport electrons to the electron transport chain for ATP generation.

Proton motive force

The force generated by the proton gradient that drives ATP production.

Coupled reaction concept

Connecting exergonic and endergonic processes via ATP synthesis.

Overall cellular respiration reaction

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP.

Photosynthesis vs Cellular respiration

Photosynthesis stores energy while respiration releases it.

Human uses of fermentation

Used in yogurt and cheese production.

ATP synthase function

Catalyzes ATP synthesis driven by the proton gradient.

Critical cellular processes

Include energy production, cell signaling, and membrane transport.

Energy transformations in cells

Cells convert chemical potential into kinetic energy.

Phosphorylation process

The addition of a phosphate group to a molecule, usually enhancing energy.

Reaction coordinate diagrams

Graphical representations that depict energy changes during reactions.

Acid-base nature of enzymes

Enzymes can be affected by pH and alter their structure at extremes.

Metabolic pathways

A linked series of chemical reactions that transform a substance.

Cytoplasm vs Mitochondria

Cytoplasm: glycolysis occurs; mitochondria: citric acid cycle and oxidative phosphorylation.