Cells: Parts & Functions

A set of vocabulary flashcards covering the definitions of cell types, cellular organelles, membrane transport mechanisms, and structural components based on the lecture notes.

Cells

The basic unit of life that is responsible for all life's processes and acts as the building blocks of life.

Prokaryotes

The oldest cell type that is small, simple, and lacks a nucleus and organelles; the name literally means "before nucleus" ("Pro"=before; "Kary"=Nucleus).

Eukaryotes

Larger, more complex cells that evolved from prokaryotes and contain a nucleus and organelles; the name means "true nucleus" ("Eu"= true; "Kary"=Nucleus).

Cell Differentiation

The process during which young, immature unspecialized cells (stem cells) take on individual characteristics and reach their mature (specialized) form and function.

Homeostasis

The maintenance of the internal environment of the body in a relatively constant state.

Cell Membrane

Also known as the Plasma Membrane, it is a semipermeable phospholipid bilayer with integrated proteins and carbohydrates that separates the cell interior from the outside environment.

Fluid Mosaic Model

A model describing the plasma membrane as a mosaic of components—primarily phospholipids, cholesterol, and proteins—that move freely and fluidly in the plane of the membrane.

Amphipathic

Having both hydrophilic ("water-loving") heads and hydrophobic ("water-fearing") fatty acid tails, a characteristic of phospholipids.

Simple Diffusion

A process where small noncharged molecules or lipid soluble molecules pass between phospholipids from areas of high concentration to areas of low concentration.

Protein Carrier / Transporter

A protein that transports specific substances through intracellular compartments, into the extracellular fluid, or across cells.

Protein Channel

A type of facilitated diffusion where molecules move across the membrane through a protein without using energy.

Pumps

Transmembrane proteins that actively move ions and/or solutes across biological membranes against a concentration or electrochemical gradient.

Endocytosis

A cellular process in which substances are brought into the cell.

Phagocytosis

A form of endocytosis meaning "cell eating" ("Phago"- to eat) that results in the production of a phagosome.

Phagosome

A vesicle formed around a particle engulfed by a phagocyte.

Pinocytosis

A form of endocytosis meaning "cell drinking" ("Pino"- to drink) that results in the production of a vesicle.

Receptor-Mediated Endocytosis

A process through which bulk amounts of specific molecules are imported into a cell after binding to cell surface receptors.

Clathrin

A structural protein that coats the coated pit of the budding vesicle and gives it its round form during receptor-mediated endocytosis.

Exocytosis

A process for moving large molecules out of the cell to the cell exterior via vesicles formed by the Golgi apparatus.

Constitutive Exocytosis

A type of exocytosis used for products that are released from cells continuously as soon as synthesis is complete, such as collagen.

Regulated-Secretion Exocytosis

A type of exocytosis occurring in specialized cells (like neurons or endocrine cells) where release occurs in response to a specific stimulus, such as insulin release.

Cytoplasm

The part of the cell including all organelles except the Nucleus, involved in protein synthesis, energy production, and structural support.

Cytosol

The liquid part of the cytoplasm which contains a lot of enzymes.

Organelles

The "tiny organs" of the cell.

Mitochondria

The "powerhouse of the cell" where chemical energy is produced and stored in the molecule adenosine triphosphate (ATP).

Endoplasmic Reticulum (ER)

An organelle involved in the synthesis, folding, modification, and transport of proteins.

Rough ER

ER that has a rough appearance due to attached ribosomes and is responsible for protein synthesis and signaling the nucleus if folding problems occur.

Apoptosis

Programmed cell death, which can be triggered if protein synthesis and folding in the Rough ER fails.

Smooth ER

ER involved in detoxification and the synthesis of lipids, including cholesterol and phospholipids for cellular membranes.

Ribosomes

The site of protein synthesis, consisting of a smaller subunit for mRNA decoding and a larger subunit where amino acids are added.

Lysosomes

Membrane-bound organelles containing digestive enzymes used to break down excess cell parts or destroy invading viruses and bacteria.

Golgi Apparatus

An organelle named after Camillo Golgi that processes and packages proteins and lipid molecules, appearing as a series of stacked membranes.

Cis Face

The part of the Golgi apparatus facing the ER where proteins enter for processing.

Trans Face

The part of the Golgi apparatus where processed glycoproteins move out to the rest of the cell.

Cisternae

The folded membrane structures of the Golgi apparatus.

Cytoskeleton

A structure that helps cells maintain shape and internal organization while providing mechanical support for division and movement.

Microtubules

The largest type of cytoskeletal filament, composed of the protein tubulin.

Intermediate Filaments

Mid-sized cytoskeletal filaments with a diameter of about $10\,nm$ that are generally strong and ropelike.

Microfilament

Also known as Actin Filament, these are mid-sized ($10\,nm$) filaments found beneath the cell cortex involved in cytokinesis and cell movement.

Cytokinesis

The process of cell division, such as Meiosis or Mitosis.

Centrosome

A cellular structure involved in cell division that contains two centrioles and moves to opposite ends of the cell during division.

Centromere

A highly constricted region on the chromosome.

Nucleus

A double-membraned eukaryotic organelle containing genetic material and serving as the home for protein synthesis and cell division.

Nuclear Envelope

The double membrane (inner and outer) surrounding the nucleus, perforated by nuclear pores.

Nucleolus

The site within the nucleus for ribosome and ribosomal RNA (rRNA) production.