Lab 5 – Chloroplasts and Mitochondria

Vocabulary flashcards covering key structures, processes, and techniques related to chloroplasts, mitochondria, and laboratory isolation methods discussed in Lab 5.

Photosynthesis

Process that converts light energy into stored chemical energy in the form of carbohydrates.

Cellular respiration

Catabolic pathway that transfers energy from carbohydrate bonds to ATP, usually aerobically in eukaryotes.

ATP (adenosine triphosphate)

Energy-carrying nucleotide whose high-energy phosphate bonds power cellular work.

Chloroplast

Double-membrane organelle in plants and algae where photosynthesis takes place.

Stroma

Fluid inside the chloroplast inner membrane containing enzymes for sugar synthesis and starch storage.

Thylakoid

Flattened membrane sac inside chloroplasts; its membrane houses the light-dependent reactions.

Thylakoid lumen

Aqueous space enclosed by a thylakoid membrane.

Granum (pl. grana)

Stack of interconnected thylakoid sacs in a chloroplast.

Light-dependent reactions

First stage of photosynthesis; occur in thylakoid membranes and produce ATP and NADPH.

Dark reactions (Calvin cycle)

Second stage of photosynthesis; occur in the stroma and assemble sugars from CO₂.

Pyrenoid

Specialized region within some chloroplasts that concentrates CO₂ and houses large amounts of RubisCO; often surrounded by starch.

RubisCO

Ribulose-1,5-bisphosphate carboxylase/oxygenase, the key but relatively inefficient CO₂-fixing enzyme.

Mitochondrion

Double-membrane organelle that carries out most steps of aerobic respiration and ATP synthesis.

Matrix (mitochondrial)

Compartment inside the inner mitochondrial membrane containing enzymes, circular DNA, and ribosomes.

Intermembrane space

Region between outer and inner mitochondrial membranes; chemically similar to cytosol.

Outer mitochondrial membrane

Smooth, relatively permeable membrane allowing many small molecules to pass.

Inner mitochondrial membrane

Selectively permeable, highly folded membrane that contains the electron transport chain and ATP synthase.

Cristae

Folds of the inner mitochondrial membrane that greatly increase its surface area.

Electron transport chain (ETC)

Series of protein complexes in the inner mitochondrial membrane that transfer electrons and pump protons.

Oxidative phosphorylation

ATP production that uses the proton gradient generated by the ETC to power ATP synthase.

Endosymbiotic Theory

Hypothesis that chloroplasts and mitochondria evolved from prokaryotes engulfed by ancestral eukaryotic cells.

Grana stacks

Large groups of thylakoids arranged one atop another, common in land-plant chloroplasts.

Stromal lamellae

Membranous connections linking grana stacks within a chloroplast.

Differential centrifugation

Method that separates cellular components by size/density through successive increases in centrifugal force.

Supernatant

Liquid fraction remaining above the pellet after centrifugation.

Pellet

Solid material collected at the bottom of a centrifuge tube after spinning.

Centrifugal force

Apparent force generated by rapid spinning that drives particles outward to aid separation.

Mitochondrial Isolation Buffer

Cold buffer containing 0.3 M D-mannitol and phosphate (pH 7.2) used to protect mitochondria during extraction.

Mitochondrial Assay Buffer

Isolation buffer supplemented with KCl and MgCl₂ for resuspending and storing isolated mitochondria.

Pyruvate oxidation

Conversion of pyruvate to acetyl-CoA in the mitochondrial matrix.

Citric acid cycle

Series of enzymatic reactions in the matrix that oxidize acetyl-CoA to CO₂ and reduce NAD⁺/FAD.

β-oxidation of fats

Matrix process that breaks fatty acids into two-carbon acetyl-CoA units.

Starch grain

Temporary carbohydrate storage granule often found in the stroma of plant chloroplasts.

Thylakoid membrane

Pigment-containing membrane within the chloroplast where photochemical reactions take place.