Untitled Flashcard Set

Aerobic Respiration

The process of turning food into energy (ATP) that uses oxygen and produces a high yield of ATP.

ATP (Adenosine Triphosphate)

The main activated energy carrier molecule used by cells to store and transfer energy.

Glycolysis

The first stage of cellular respiration, occurring in the cytoplasm, which breaks down one glucose molecule into two molecules of pyruvate.

Pyruvate

A 3-carbon molecule produced by the breakdown of glucose during glycolysis.

Fermentation

The anaerobic pathway pyruvate undergoes when oxygen is not available, resulting in products like lactic acid or ethanol.

Mitochondria

The "powerhouse" of the cell where the later stages of respiration occur, consisting of the matrix, inner membrane, outer membrane, and intermembrane space.

Cristae

The highly folded structures of the inner mitochondrial membrane which increase its surface area.

Acetyl CoA

An activated carrier molecule that carries a 2-carbon acetyl group into the citric acid cycle.

Citric Acid Cycle (Krebs Cycle)

The stage occurring in the mitochondrial matrix that completes the breakdown of the remaining components of glucose to CO2, generating ATP/GTP, NADH, and FADH2.

NADH and FADH2

Activated energy carriers that harvest and store energy in the form of high-energy electrons and hydrogens.

Glycogen & Starch

Branched polysaccharides used for energy storage in animals (glycogen) and plants (starch).

Photosynthesis

The complementary process to cellular respiration where plants use light energy, CO2, and water to manufacture sugars and oxygen.

Chloroplast

The organelle in plant cells where photosynthesis takes place, containing an inner membrane, outer membrane, stroma, and thylakoids.

Stroma

The fluid-filled space surrounding the thylakoids inside the chloroplast where the light-independent reactions occur.

Thylakoid

Membrane-bound structures inside the chloroplast that contain chlorophyll and are the site of the light-dependent reactions.

Granum (plural Grana)

A stack of thylakoid membranes inside the chloroplast.

Chlorophyll

The green pigment in land plants that absorbs photons of light to excite electrons and drive photosynthesis.

Light-Dependent Reactions

The first stage of photosynthesis occurring on the thylakoid membrane that requires light and water to produce O2, ATP, and NADPH.

Photosystems (I and II)

Protein clusters in the thylakoid membrane that contain chlorophyll molecules and harvest light energy.

Calvin Cycle (Light-Independent Reactions)

The second stage of photosynthesis occurring in the stroma that uses ATP, NADPH, and CO2 to manufacture sugars.

Rubisco

The highly abundant enzyme that catalyzes carbon fixation by combining CO2 with a 5-carbon sugar in the Calvin Cycle.

G3P (Glyceraldehyde 3-phosphate)

The 3-carbon sugar product of the Calvin cycle that is used to build other sugars.

Oxidative Phosphorylation

The final stage of cellular respiration that converts the energy from NADH and FADH2 into ATP.

Electron Transport Chain (ETC)

A series of transmembrane protein complexes on the mitochondrial cristae that pass high-energy electrons down a chain, using the released energy to pump H+ ions.

ATP Synthase

A protein complex that uses the proton (H+) gradient created by the electron transport chain to synthesize ATP from ADP and inorganic phosphate.

Golgi Apparatus

The "post office" of the cell consisting of stacks of flattened sacs (cisternae) that modifies, sorts, and packages proteins and lipids.

Glycosylation

The process of adding carbohydrate (sugar) residues to specific amino acids on proteins, which occurs in the ER and Golgi.

Exocytosis

The process where vesicles bud off the Golgi and fuse with the plasma membrane to dump their contents outside the cell.

Endocytosis

The process of creating vesicles from the plasma membrane to bring substances into the cell.

Phagocytosis

"Cellular eating"—the endocytosis of large particles, debris, or bacteria.

Pinocytosis

"Cellular drinking"—the non-specific endocytosis of fluids and small dissolved solutes.

Receptor-Mediated Endocytosis

A highly specific form of endocytosis where target ligands must bind to specific receptors to trigger vesicle formation.

Clathrin

A protein with a triskelion shape that frequently coats vesicles as they bud off from the membrane.

Endosomes & Lysosomes

Endosomes are sorting vesicles that bring contents to Lysosomes, which are organelles filled with hydrolytic enzymes used for cellular digestion.

Autophagy

A biological recycling system where a cell breaks down its own damaged organelles or unneeded structures using lysosomes.

Lipoproteins (HDL & LDL)

Complexes of protein and cholesterol used to circulate lipids in aqueous fluids; HDL is "High Density" and LDL is "Low Density."

Signal Transduction

The process where an extracellular signal molecule is converted into an intracellular signaling molecule that alters cell behavior.

Endocrine Signaling

Long-distance communication where cells produce hormones that travel through the bloodstream to reach target cells.

Kinase & Phosphatase

A kinase is an enzyme that adds a phosphate group to a protein, while a phosphatase removes a phosphate group.

Ion-channel-coupled Receptors

Receptors that open to change the permeability of the plasma membrane in response to an extracellular signal.

G-Protein-Coupled Receptors (GPCRs)

A massive family of 7-transmembrane domain receptors that activate an associated heterotrimeric G-protein upon binding a ligand.

Second Messengers

Small, short-lived molecules generated inside the cell that help amplify and distribute a signal.

Entropy

A measure of the lack of order in a system; the entropy of the universe is always increasing.

Catabolism

Metabolic pathways that break down larger molecules into smaller ones, releasing energy.

Anabolism

Metabolic pathways that synthesize larger molecules from smaller ones, requiring an input of energy.

Exergonic Reaction

A spontaneous 'downhill' reaction that proceeds with a net release of free energy (ΔG < 0).

Endergonic Reaction

A non-spontaneous 'uphill' reaction that absorbs free energy from its surroundings (ΔG > 0).

Activation Energy (E_A)

The initial energy required to break stable bonds and start a chemical reaction.

Catalyst / Enzyme

A chemical agent that speeds up a chemical reaction by lowering the activation energy barrier.

Coupled Reactions

A mechanism where cells use the energy released by an exergonic reaction to drive an unfavorable endergonic reaction.

Oxidation & Reduction

Oxidation is the loss of electrons, while reduction is the gain of electrons.