Cellular Organelles and Structures Practice Flashcards

These flashcards cover the structure and function of cellular organelles, the components of the cytoskeleton, energy production, and mechanisms of cellular damage and detoxification as described in the Sophia Learning lecture notes.

Cytosol

The jelly-like substance within the cell that provides the fluid medium necessary for biochemical reactions.

Organelle

Meaning “little organ,” it is one of several different types of structures in the cell, each performing a unique function.

Cytoplasm

The combination of the cell's organelles and cytosol.

Nucleus

A cell’s central organelle which contains the cell’s DNA (genetic code).

Cytoskeleton

A group of fibrous proteins providing structural support, cell motility, cell reproduction, and internal transport of substances.

Microtubule

The thickest cytoskeletal filament, composed of tubulin, which maintains cell shape, resists compression, and creates pathways for internal transport.

Tubulin

The protein subunits that compose microtubules.

Centrosome

A pair of two short, identical microtubule structures (centrioles) that serve as the origin point for microtubules during cell division.

Microfilament

A thin type of cytoskeletal filament primarily composed of actin that anchors the cytoskeleton to membrane proteins and forms extensions like microvilli.

Actin

The protein that forms the long chains of single subunits making up microfilaments.

Intermediate Filament

A middle-thickness cytoskeletal filament made of keratin that maintains cell shape and resists tension (pulling forces).

Keratin

The long fibrous protein subunits wound together to compose intermediate filaments.

Ribosome

A non-membranous organelle composed of RNA subunits and proteins that serves as the site of protein synthesis.

Free Ribosomes

Ribosomes that float in the cytosol unattached to any other structure.

Attached Ribosomes

Ribosomes connected to the external surface of the endoplasmic reticulum.

Endoplasmic Reticulum (ER)

A system of channels continuous with the nuclear membrane composed of lipid bilayer material.

Rough Endoplasmic Reticulum (RER)

A form of ER dotted with ribosomes that functions in the synthesis and modification of proteins.

Smooth Endoplasmic Reticulum (SER)

A form of ER lacking ribosomes that synthesizes lipids, sequesters $Ca^{2+}$, and detoxifies certain toxins.

Golgi Apparatus

A membranous organelle shaped like a stack of flattened discs responsible for sorting, modifying, and shipping products from the RER.

Lysosome

A membranous organelle containing enzymes that break down unneeded cellular components or foreign material like bacteria.

Autophagy

The process of a cell digesting its own structures, often facilitated by lysosomes.

Autolysis

A controlled cell death mechanism where lysosomes release digestive enzymes into the cytoplasm; associated with apoptosis.

Peroxisome

A membrane-bound organelle containing enzymes for lipid metabolism and chemical detoxification that produces and then neutralizes $H_2O_2$.

Reactive Oxygen Species (ROS)

Highly reactive products of cellular processes (e.g., peroxides, free radicals) that can cause oxidative damage to lipids, proteins, and DNA.

Oxidative Stress

Damage to cellular components caused by reactive oxygen species (ROS) that accumulate beyond the capacity of cellular defenses.

Mutation

A change in the nucleotide sequence in a gene within a cell’s DNA, potentially altering the protein coded by that gene.

Antioxidants

Substances that work by being oxidized themselves to halt destructive reaction cascades initiated by free radicals.

Mitochondria

The membranous, bean-shaped “powerhouse of the cell” that produces the majority of the body’s ATP.

Cristae

The highly folded winding structures of the inner mitochondrial membrane that provide surface area for cellular respiration.

Adenosine Triphosphate (ATP)

The cell’s major energy currency produced by mitochondria through the conversion of nutrient molecules like glucose.

Free Radical Theory of Aging

The theory suggesting that accumulated cellular damage from oxidative stress contributes to the physiological effects of aging.