Cell Fractionation, Ultracentrifugation, and Organelle Function

Flashcards reviewing cell fractionation techniques, ultracentrifugation steps, solution properties, organelle isolation methods, and protein synthesis pathways in pancreatic cells.

pH Buffered Solution (Cell Fractionation)

A solution with a constant pH used during cell fractionation to prevent proteins, enzymes, and cell structures from denaturing, thereby protecting delicate internal membranes and active enzymes within organelles such as mitochondria.

Isotonic Solution (Cell Fractionation)

A solution that has the same water potential as the cell, preventing organelles from bursting or shrinking as a result of osmosis.

Ice-Cold Solution (Cell Fractionation)

A solution kept at low temperatures to slow down or prevent destructive enzyme activity that might digest cellular components or damage cell structures.

Homogenisation

The process of grinding or blending tissue in a cold, isotonic, pH-buffered solution to physically break open cells and release internal cell components into a liquid called the homogenate.

Filtration (Cell Fractionation)

The step where the homogenate is passed through a gauze to separate large, unbroken cell debris from the cell organelles.

Ultracentrifugation

A process where filtered homogenate is spun in a centrifuge at increasing speeds to separate organelles by size and density into distinct pellets.

Pellet

The solid sediment containing cellular components that settles at the bottom of a centrifuge tube after spinning at a specific speed.

Supernatant

The liquid remaining above the pellet after centrifugation, which is poured off into a new tube and spun at a higher speed to isolate lighter organelles.

Chloroplast Isolation Procedure

Grind plant tissue in prepared solution, filter the liquid through gauze to remove cell debris, centrifuge the homogenate at low speed to pellet nuclei, pour the supernatant into a new tube, and spin at a higher speed to obtain chloroplasts in the pellet.

Mitochondria Isolation Procedure

Blend animal cells in an ice-cold, isotonic, pH-buffered solution, filter through gauze to isolate cell structures from debris, centrifuge at low speed to pellet nuclei, and centrifuge the supernatant at a higher speed to collect mitochondria in the pellet.

Peptide Bond

The type of chemical bond that joins amino acids together in a polypeptide chain.

Protein Secretion Pathway

The sequential pathway $F \rightarrow H \rightarrow J \rightarrow E \rightarrow K$ taken by amino acids from the cytoplasm ($F$), synthesizing into proteins, modifying in the Golgi apparatus ($J$), transporting in vesicles ($E$), and secreting out of the cell ($K$).

Organelle G (Mitochondria in Pancreatic Cells)

An organelle that produces $\text{ATP}$ for energy, which pancreatic cells require to break down blood glucose, trigger insulin release, and perform exocytosis.