Cell Biology and SDH Activity Review

Vocabulary flashcards covering cellular fractionation, SDH activity, cellular organelles, the cytoskeleton, cell junctions, and plasma membrane transport based on the lecture transcript.

Succinate Dehydrogenase (SDH)

An enzyme embedded in the inner mitochondrial membrane of eukaryotes that converts succinate into fumarate in the Krebs cycle, generating FADH2.

Complex II

The electron transport chain complex where SDH resides, converting succinate to fumarate and passing electrons from FADH2 to ubiquinone (coenzyme Q).

DCIP (DCPIP)

A blue redox indicator dye in its oxidized state that becomes colorless upon being reduced by accepting electrons during the SDH activity assay.

Differential Centrifugation

A laboratory procedure using repeated centrifugation steps up to $25000\text{ RPM}$ to isolate the mitochondrial fraction containing SDH activity.

Cristae

Shelf-like regular inward foldings of the inner mitochondrial membrane that significantly increase its surface area compared to the outer membrane.

Thylakoids

Individual flattened membrane sacs within chloroplasts that are arranged in stacks called grana to harvest energy for photosynthesis.

Stroma

The fluid surrounding the grana stacks inside a chloroplast.

Endosymbiont Theory

The theory that mitochondria and chloroplasts originated when an ancestral eukaryotic cell ingested an independent prokaryotic cell without digesting it.

Motor Proteins

Proteins that utilize cellular energy in the form of ATP to change shape and generate physical movement along cytoskeletal tracks.

Microtubules

The thickest cytoskeletal components, composed of hollow rods of tubulin protein dimers that support cell shape, guide organelle movement, separate chromosomes, and form a $9+2$ pattern in cilia and flagella.

Centrosome

A structure located near the nucleus in animal cells that acts as the microtubule-organizing center, containing a pair of centrioles with nine triplets of microtubules arranged in a ring.

Microfilaments (Actin Filaments)

The thinnest cytoskeletal components, consisting of solid rods made of actin subunits that assist in cell movement, muscle contraction with myosin, amoeboid movement, and cytoplasmic streaming.

Intermediate Filaments

Cytoskeletal fibers with middle-range diameters that serve as permanent structural support in certain animal cells, including vertebrates.

Extracellular Matrix (ECM)

An external network in animal cells made of collagen, proteoglycans, and fibronectin that assists in cell adhesion, tissue formation, filtering, and chemical signaling.

Integrins

Cell-surface receptor proteins embedded in the plasma membrane that attach to extracellular matrix proteins.

Plasmodesmata

Channels passing through plant cell walls that allow water, ions, small solutes, RNA, and proteins to transfer between neighboring cells.

Tight Junctions

Intercellular junctions in animal epithelial cells that encircle cells like a belt to prevent fluid and substances from leaking through intercellular spaces.

Desmosomes

Anchoring junctions in animal tissues that bind adjacent cells to the cytoskeleton, providing mechanical strength to prevent tissues like cardiac muscle from tearing apart.

Gap Junctions

Protein channels running between adjacent animal cells that allow direct cytoplasmic communication and passage of materials.

Fluid Mosaic Model

A structural model depicting the plasma membrane as a dynamic mosaic of a phospholipid bilayer, carbohydrates for recognition, and embedded transport and signaling proteins.