Histology Wk 6 Flashcards
what is the function of mitochondria
organelles with arrays of enzymes spe- cialized for aerobic respiration and production of adenosine triphosphate (ATP), with high-energy phosphate bonds, which supplies energy for most cellular activities.
membranes of the mitochondria
create two compartments: the innermost matrix and a narrow intermembrane space Both mitochondrial membranes contain a higher density of protein molecules than other membranes in the cell and have reduced fluidity.
The outer membrane is sieve-like, contain- ing many transmembrane proteins called porins that form channels through which small molecules such as pyruvate and other metabolites readily pass from the cytoplasm to the intermembrane space.
describe the inner membrane
The inner membrane has many long folds called cristae, which project into the matrix and greatly increase the membrane’s surface area
Formation of ATP by oxidative phosphorylation enzymes occurs by a chemiosmotic process. Membrane proteins guide the small electron carrier molecules through closely packed enzyme complexes so that the electrons move sequentially along the chain.
Formation of ATP by oxidative phosphorylation enzymes occurs by a chemiosmotic process. Membrane proteins guide the small electron carrier molecules through closely packed enzyme complexes so that the electrons move sequentially along the chain.
Electron transfer is coupled with oriented proton uptake and release, with protons accumulat- ing in the intermembrane space (Figure 2–20) and producing an electrochemical gradient across the inner membrane. Membrane-associated proteins of the ATP synthase
describe another role of mitochondria
occurs at times of cell stress when the protein cytochrome c is released from the inner membrane’s electron-transport chain. In the cytoplasm, this protein activates sets of proteases that degrade all cellular components in a regulated process called apoptosis which results in rapid cell death
what are peroxisomes
Oxidases located here oxidize substrates by removing hydrogen atoms that are transferred to molecular oxygen (O2), producing H2O2. Peroxidases such as catalase immediately break down H2O2, which is potentially damaging to the cell.
what are lipid droplets
accumulations of lipid-filling adipocytes (fat cells) and present in various other cells.
abundant in cells of the adrenal cortex
glycogen granules
aggregates of the carbohydrate polymer in which glucose is stored, visible as irregu- lar clumps of periodic acid–Schiff (PAS)—positive or electron-dense material in several cell types, notably liver cells.
Glycogen is a ready source of energy, and such granules are often abundant in cells with high metabolic activity.
