Cell Biology: Cytoskeleton and Organelles

Vocabulary flashcards reviewing cellular structures, cytoskeleton, and organelles based on lecture notes.

Microfilaments

Cytoskeletal structures composed of the protein actin that support the membrane and microvilli, and produce cell movement.

Intermediate filaments

Cytoskeletal elements thicker and stiffer than microfilaments that participate in tight junctions and provide strength in epidermal cells for hair and nails.

Microtubules

Cytoskeletal components composed of the protein tubulin that hold organelles in place, maintain cell shape, form the axoneme core inside cilia and flagellum, produce beating movement, manage chromosome movement during cell division, and move cargo such as organelles and macromolecules.

Nucleus

The largest organelle and genetic control center of the cell containing chromosomes; typically one per cell, though some cells are anuclear (RBCs) or multinucleate (skeletal muscle cells).

Nuclear envelope

Membranes surrounding the nucleus that contain nuclear pores.

Nucleolus

A structure located inside the nucleus responsible for ribosome synthesis.

Endoplasmic Reticulum

A system of interconnected channels called cisternae within the cell.

Rough ER

Endoplasmic reticulum composed of parallel, flattened sacs covered with ribosomes; continuous with the outer membrane of the nuclear envelope and functions in protein synthesis.

Smooth ER

Endoplasmic reticulum composed of tubular and more branched cisternae lacking ribosomes; functions in steroid (+ other lipids) synthesis and detoxifies alcohol and drugs.

Ribosomes

Small granules of protein and RNA that 'read' coded genetic messages (messenger RNA) to assemble amino acids into proteins during translation and protein synthesis.

Golgi Complex

A system of cisternae that synthesizes carbohydrates, modifies proteins, performs glycoprotein synthesis, receives newly synthesized proteins from the rough ER, and packages proteins into Golgi vesicles.

Lysosomes

Membrane-bound packages of catabolic enzymes that carry out intracellular hydrolytic digestion, autophagy, autolysis, and glucose mobilization through glycogen breakdown in liver cells.

Autophagy

The lysosomal digestion of worn-out organelles or phagocytized bacteria.

Autolysis

Programmed cell death ('cell suicide') mediated by lysosomes, such as in the uterus and neutrophils.

Peroxisomes

Organelles resembling lysosomes that use $O_2$ to oxidize organic molecules, neutralize free radicals, detoxify alcohol, drugs, and toxins, break down fatty acids into acetyl groups for mitochondrial ATP synthesis, and produce hydrogen peroxide ($H_2O_2$); abundant in liver and kidney cells.

Proteasomes

Protein disposal structures that break down damaged, nonfunctional, and foreign (viral) proteins into short peptides and free amino acids, handling human cell protein disposal for $>80\%$ of cell proteins.

Mitochondria

Double unit membrane-bound organelle known as the powerhouse of the cell that synthesizes ATP by extracting energy from organic molecules like glucose.

Cristae

Folds in the inner membrane of mitochondria where enzymes transfer extracted energy to ATP.

Matrix (Mitochondrial)

The space between mitochondrial cristae that contains ribosomes, enzymes for ATP synthesis, and small circular mitochondrial DNA molecules.

Centrioles

Structures composed of an assembly of microtubules arranged in $9$ groups of $3$ microtubules each that organize chromosomes during cell division and form the basal body of a cilium or flagellum.

Inclusions

Various nutrients, pigments, or pathological materials within the cell, categorized into stored cellular products (glycogen granules, pigments, oil droplets) and disease markings or pathological protein aggregates (phagocytized viruses, bacteria, tau proteins).