Human Anatomy and Physiology: Cells - The Living Units (Part B)

This set of vocabulary flashcards covers the organelles, cytoskeletal structures, cellular extensions, and nuclear features of human cells as described in Chapter 03 Part B.

Cytoplasm

The cellular material located between the plasma membrane and the nucleus, composed of cytosol, inclusions, and organelles.

Cytosol

A gel-like solution within the cytoplasm made up of water and soluble molecules such as proteins, salts, and sugars.

Inclusions

Insoluble molecules in the cytoplasm that vary with cell type, such as glycogen granules, pigments, lipid droplets, and melanin.

Mitochondria

The "power plant" of the cell that produces most ATP via aerobic cellular respiration; they contain their own DNA, RNA, and ribosomes.

Cristae

The many folds of the inner mitochondrial membrane which are embedded with proteins that play a role in cellular respiration.

Fission

The type of cell division used by mitochondria that resembles the division process of bacteria.

Ribosomes

Nonmembranous organelles made of protein and ribosomal RNA (rRNA) that serve as the site of protein synthesis.

Free Ribosomes

Floating ribosomes that synthesize soluble proteins that function in the cytosol or other organelles.

Membrane-bound Ribosomes

Ribosomes attached to the endoplasmic reticulum (ER) that synthesize proteins for membranes, lysosomes, or export from the cell.

Endoplasmic Reticulum (ER)

A series of parallel, interconnected cisterns continuous with the outer nuclear membrane.

Cisterns

Flattened membranous tubes within the endoplasmic reticulum that enclose fluid-filled interiors.

Rough ER

The portion of the endoplasmic reticulum studded with ribosomes that functions specifically in protein synthesis.

Smooth ER

The portion of the endoplasmic reticulum used for lipid metabolism, detoxification, calcium storage, and steroid-based hormone synthesis.

Golgi Apparatus

Stacked and flattened membranous sacs that modify, concentrate, and package proteins and lipids received from the rough ER.

Peroxisomes

Membranous sacs containing oxidases and catalases used to neutralize toxins like free radicals.

Free Radicals

Highly reactive, toxic molecules produced as natural by-products of cellular metabolism.

Catalase

An enzyme in peroxisomes that converts toxic hydrogen peroxide ($H_2O_2$) into harmless water.

Lysosomes

Spherical membranous bags containing acid hydrolases (digestive enzymes) that degrade nonfunctional organelles and ingested bacteria.

Autolysis

The process where a cell digests itself due to the intracellular release of lysosomal enzymes in injured cells.

Tay-Sachs Disease

A lysosomal storage disease resulting from a lack of an enzyme needed to break down glycolipids in brain cells, often resulting in death before age $5$.

Cytoskeleton

An elaborate network of rods in the cytosol, including microfilaments, intermediate filaments, and microtubules, acting as the cell’s "bones and muscles."

Microfilaments

The thinnest cytoskeletal elements composed of actin, involved in cell motility and changes in cell shape.

Intermediate Filaments

Tough, insoluble protein fibers in the cytoskeleton that help the cell resist pulling forces.

Microtubules

Hollow tubes composed of tubulin that determine the overall shape of the cell and distribution of organelles.

Centrosome

Located near the nucleus, it serves as the microtubule organizing center and contains the centrioles.

Centrioles

A pair of barrel-shaped organelles at right angles that organize the mitotic spindle and form the basis of cilia and flagella.

Cilia

Whiplike, motile extensions that work together to move substances, such as mucus, across cell surfaces in one direction.

Flagella

Longer cellular extensions, such as the tail of a sperm, that propel the entire cell.

Microvilli

Fingerlike projections of the plasma membrane that increase surface area for absorption; they have a core of actin microfilaments.

Uninucleate

The condition of a cell having only one nucleus, which is the case for most cells.

Anucleate

The condition of a cell having no nucleus, such as red blood cells.

Apoptosis

Programmed cell death where caspases cause the degradation of DNA and the cytoskeleton, leading the cell to shrink and be phagocytized.

Caspases

Enzymes activated during apoptosis that cause the degradation of a cell's DNA and cytoskeleton.