Membranes & Transport, Metabolism & Enzymes, Cellular Respiration, Photosynthesis, and Cell Signaling

These flashcards cover key concepts related to membranes and transport, metabolism and enzymes, cellular respiration, photosynthesis, and cell signaling.

Integral membrane proteins

Proteins embedded in the lipid bilayer, often spanning it, with hydrophobic and hydrophilic regions.

Membrane fluidity

Determined by temperature, fatty acid saturation (unsaturated = more fluid), and cholesterol.

Simple diffusion

Movement of molecules directly through the membrane down their gradient.

Facilitated diffusion

Passive movement through membrane proteins.

Active transport

Movement against a gradient using energy (ATP).

Osmosis

Movement of water toward higher solute concentration.

Hypertonic solution

A solution where the cell shrinks as water leaves.

Hypotonic solution

A solution where the cell swells as water enters.

Electrochemical gradient

Combined effect of concentration and electrical gradients.

Catabolic pathway

Pathway that breaks down molecules and releases energy.

Anabolic pathway

Pathway that builds molecules and requires energy.

Exergonic reaction

A reaction that releases energy.

Endergonic reaction

A reaction that requires energy.

Activation energy

Energy required to start a reaction.

Enzymes

Molecules that lower activation energy and speed up reactions.

Competitive inhibition

Inhibition where an inhibitor competes for the active site.

Noncompetitive (allosteric) inhibition

Inhibition where an inhibitor binds elsewhere and changes enzyme shape.

Feedback inhibition

Process where an end product shuts down an earlier step in a pathway.

Electron transport chain

Location where most ATP is produced in respiration.

NADH and FADH₂

Molecules where energy is stored before ATP is made.

Proton-motive force

H⁺ gradient across a membrane.

Chemiosmosis

Use of H⁺ gradient to make ATP via ATP synthase.

Oxygen in respiration

Final electron acceptor in the electron transport chain.

Fermentation

Process to regenerate NAD⁺ so glycolysis can continue.

Excitation of electrons

Process where electrons are excited by light in photosynthesis.

Products of the light reactions

ATP and NADPH.

Source of oxygen in photosynthesis

Oxygen comes from splitting water (H₂O).

Cell-surface receptors

Receptors used for binding polar molecules that cannot cross the membrane.

Intracellular receptors

Receptors used for binding nonpolar molecules (like steroids).

G protein-coupled receptor (GPCR)

A receptor that activates a G protein when a ligand binds.

Phosphorylation cascade

A series of kinases activating each other by adding phosphate groups.

Protein kinases

Enzymes that add phosphate groups to proteins to regulate activity.

Direction of ion movement

Ions move down the electrochemical gradient (toward opposite charge and lower concentration).

Main purpose of ATP in cells

To provide energy for cellular work.