3.1 ATP and Chemiosmosis Vocabulary Flashcards

Vocabulary flashcards reviewing key terms, enzymes, coenzymes, and processes related to ATP synthesis, respiration, and photosynthesis.

Phosphorylation

The addition of an inorganic phosphate group ($PO_4^{3-}$ or $P_i$) to a molecule, such as ADP to form ATP.

Photophosphorylation

The synthesis of ATP from ADP and $P_i$ using light energy, taking place on the thylakoid membranes inside chloroplasts.

Substrate-level phosphorylation

The direct transfer of a phosphate group from a donor substrate molecule to ADP to form ATP, occurring without the need for a membrane, electron transport chain, oxygen, or light.

Oxidative phosphorylation

The formation of ATP driven by energy released from electron transport along electron carriers to oxygen on the inner mitochondrial membrane during aerobic respiration.

Universal energy currency

A term for ATP because it serves as the common, immediate energy source for energy-requiring reactions across all living species.

ATP synthetase

An enzyme protein complex in membranes that synthesizes ATP from ADP and $P_i$ using the energy provided by protons ($H^+$) flowing down their electrochemical gradient.

ATPase

The enzyme responsible for hydrolysing ATP into ADP and $P_i$, releasing energy in small, controlled amounts ($30.6\,kJ\,mol^{-1}$).

Coenzymes

Molecules such as NAD, FAD, and NADP that assist enzymes by binding hydrogen atoms or electrons and transporting them during metabolic processes.

NAD

A coenzyme involved in respiration (glycolysis, link reaction, Krebs cycle) that collects hydrogen atoms and delivers them to the inner mitochondrial membrane.

FAD

A respiratory coenzyme that carries hydrogen atoms removed from respiratory substrates to the electron transport chain on the inner mitochondrial membrane.

NADP

A coenzyme in chloroplasts that acts as the final electron acceptor in photosynthesis, combining with protons and electrons in the stroma to form reduced NADP.

Electron carrier

A protein arranged within membranes that accepts and passes along electrons sequentially, utilizing their loss of energy to power proton transport.

Electrochemical gradient

A difference in proton ($H^+$) concentration and charge built up across a biological membrane, storing potential energy.

Chemiosmosis

The process where protons ($H^+$) diffuse down their electrochemical gradient across a membrane through ATP synthetase, driving ATP production.

Proton pump

A membrane protein that uses potential energy released from excited/moving electrons to actively pump protons ($H^+$) across a membrane against their concentration gradient.

Oxidation

A chemical process involving the loss of electrons or hydrogen atoms (e.g., reduced NAD being converted back to NAD).

Reduction

A chemical process involving the gain of electrons or hydrogen atoms (e.g., NADP picking up protons and electrons to become reduced NADP).

Dehydrogenase

An enzyme that catalyzes the removal of hydrogen atoms from substrate molecules and transfers them to coenzymes.

Photolysis

The light-driven reaction in chloroplasts that splits water into protons ($H^+$), electrons ($e^-$), and oxygen ($\frac{1}{2}O_2$).

Brown adipose tissue (BAT)

Fat tissue found in the neck, shoulders, and chest of humans containing mitochondrial membrane proteins that allow proton leakage, generating heat instead of ATP.

Capsaicin

A chemical compound in red chili peppers that makes the inner mitochondrial membrane of brown adipose tissue cells more permeable to protons, lowering ATP production and increasing heat production.

DNP (2,4-Dinitrophenol)

An agent that transports protons across biological membranes, uncoupling chemiosmosis by decreasing the proton gradient and causing energy to be lost as heat rather than producing ATP.