BIO 001: Cell Structure and Functions

Vocabulary flashcards covering prokaryotic and eukaryotic cellular structures, nuclear architecture, ribosomes, and the endomembranous system based on the lecture notes.

Cell

The basic structural and functional unit of a body; all living organisms are composed of cells, and living cells arise from previously living cells.

Cytosol

The semifluid, jelly-like material present within both prokaryotic and eukaryotic cells in which subcellular components are suspended.

Nucleoid

A specific, non-membrane-bound region in a prokaryotic cell where the genetic material (DNA) is located.

Nucleus

The most conspicuous membrane-bound organelle in a eukaryotic cell, containing the majority of the cell's genetic material and having an average diameter of $5\,\mu\text{m}$.

Nuclear Envelope

A double membrane enclosing the nucleus, composed of two phospholipid bilayers separated by a $20\text{--}40\,\text{nm}$ space and perforated by pores with an average diameter of $100\,\text{nm}$.

Nuclear Lamina

A net-like array of protein filaments lining the inner surface of the nuclear envelope (except at the pores) that mechanically supports the envelope and maintains nuclear shape.

Pore Complex

An intricate protein network lining each nuclear pore that regulates the entry and exit of RNA, proteins, and large macromolecular complexes.

Histones

Proteins associated with DNA in eukaryotic chromosomes that facilitate the coiling and packaging of DNA so that it fits inside the nucleus.

Chromatin

The complex of DNA molecules and associated proteins that appears dense and clumped in non-dividing eukaryotic cells.

Karyotyping

The diagnostic process used to determine the specific number of chromosomes present in a eukaryotic cell.

Nucleolus

A prominent structure in non-dividing nuclei where ribosomal RNA (rRNA) is synthesized and assembled with cytosolic proteins into large and small ribosomal subunits.

Transcription

The nuclear process wherein messenger RNA (mRNA) is synthesized from a DNA template prior to exiting via nuclear pores.

Translation

The cytosolic process in which mRNA is decoded by ribosomes to assemble specific polypeptide chains and proteins.

Ribosomes

Subcellular complexes made of rRNA and proteins that serve as the sites of protein synthesis according to instructions carried in genetic material.

Free Ribosomes

Ribosomes suspended in the cytosol that synthesize proteins functioning primarily within the cytosol, such as metabolic enzymes involved in glycolysis.

Bound Ribosomes

Ribosomes attached to the outer surface of the endoplasmic reticulum that produce proteins destined for insertion into membranes or for export.

Endomembranous System

A collection of eukaryotic membranes comprising the nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles, and the plasma membrane, functioning in protein synthesis, transport, lipid metabolism, and detoxification.

Endoplasmic Reticulum (ER)

An extensive network of membranous tubules and flattened sacs accounting for about half of the total membrane in a eukaryotic cell.

Cisternae

A network of flattened, membranous sacs and tubules that make up the internal architecture of the endoplasmic reticulum.

Rough Endoplasmic Reticulum

The segment of the endoplasmic reticulum that is studded with ribosomes on its outer cytosolic surface.

Smooth Endoplasmic Reticulum

The segment of the endoplasmic reticulum devoid of ribosomes, responsible for lipid synthesis (such as steroidal sex hormones), calcium ion storage, and drug detoxification.

ER Lumen

The internal fluid-filled space of the endoplasmic reticulum, which is directly continuous with the space between the two layers of the nuclear envelope.

Sarcoplasmic Reticulum

A specialized type of smooth endoplasmic reticulum found in muscle cells that stores calcium ions and releases them into the cytosol upon receiving nerve impulses to trigger muscle contraction.

Detoxification

A process mediated by the smooth ER in liver cells that converts drugs and toxic substances into more water-soluble molecules via the addition of a hydroxyl group, facilitating their excretion by the kidneys through urine.