Cellular Respiration and Metabolism Vocabulary

Vocabulary flashcards defining key terms, enzymes, and metabolic pathways covered in the cellular respiration and metabolism lecture transcript.

Metabolism

All the chemical reactions in an organism.

Linking step

The step connecting glycolysis and cellular respiration where pyruvate is converted into acetyl CoA, producing one molecule of NADH and one molecule of carbon dioxide.

Krebs cycle

Also known as the citric acid cycle or TCA cycle; the first major part of cellular respiration where acetyl CoA combines with oxaloacetate to form citrate and proceeds through a series of reactions to produce NADH, $FADH_2$, ATP, and carbon dioxide.

FADH2

Flavin adenine dinucleotide; a nucleotide with a high-energy and low-energy form that yields two ATP molecules when donating electrons to the electron transport chain.

Electron transport chain

A series of membrane-bound cytochromes, ubiquinones, and quinones that pass electrons down a chain of oxidation-reduction reactions to power active transport of protons across a membrane.

Oxidized

The state of a molecule after it loses electrons, such as when high-energy NADH donates electrons to the first component of the electron transport chain.

Reduced

The state of a molecule after it gains electrons, such as when an electron transport chain component receives electrons handed off from NADH.

ATP synthase

A broccoli-shaped multiprotein complex in the membrane that acts as both an enzyme and a proton channel, using the mechanical energy of returning protons to synthesize ATP from ADP and phosphate.

Terminal electron acceptor

The final molecule that receives low-energy electrons at the end of the electron transport chain.

Aerobic cellular respiration

Cellular respiration that uses oxygen as the terminal electron acceptor, forming water as a safe waste product.

Anaerobic cellular respiration

Cellular respiration used by some bacteria that utilizes a terminal electron acceptor other than oxygen, such as carbonates, nitrates, or sulfates.

Lactic acid

The waste product created by human muscle cells when fermenting glucose during short-term strenuous exercise.

Lipases

Enzymes that break down lipids by severing fatty acid tails from the three-carbon glycerol backbone of a triglyceride.

Beta oxidation

A cyclic pathway that breaks down fatty acids two carbons at a time into molecules of acetyl CoA while generating NADH and $FADH_2$.

Deaminases

Enzymes that remove the amino group from specific amino acids so their carbon skeletons can enter the Krebs cycle.

Emden Meyerhoff pathway

The standard, universal glycolysis pathway that breaks down glucose into pyruvate.

Entner Duerdorff pathway

An alternative glycolysis pathway used by some bacteria that yields less ATP than the Emden Meyerhoff pathway but requires fewer enzymes to function.

Pentose phosphate pathway

A specialized glycolysis pathway that converts a six-carbon sugar into the five-carbon sugar ribose for nucleotide synthesis rather than primary energy harvesting.