Cell Biology: Organelles and Structures

Comprehensive vocabulary flashcards covering cell organelles, nuclear structure, cytoplasm, and the cell membrane based on the lecture transcript.

Organelle

A structure within a cell that performs a specific function, such as the nucleus, mitochondria, or ribosome.

Uninucleated (Mononucleated) cells

Cells that contain only one nucleus, with examples including sperm cells and cardiac muscle cells.

Anucleated cell

A cell that lacks a nucleus, such as matured red blood cells of animals, sieve tubes of phloem, and platelets.

Binucleated cell

A cell containing two nuclei, for which the paramecium is a cited example.

Multinucleated cell

A cell containing more than two nuclei, such as skeletal muscle cells or osteoclasts (bone destruction cells).

Protoplasm

The collective term for the nucleus and the cytoplasm, a word coined by J. E. Purkinje.

Cytoblast

The name given to the nucleus by Mathais Schleiden in 1838, referring to its role as a 'cell builder'.

Nuclear Envelope

Also called the nuclear membrane or karyotheca, this double membrane delimits the nucleoplasm and contains nuclear pores for material exchange.

Perinuclear space

The fluid-filled space that separates the outer and inner layers of the nuclear membrane.

Nucleoplasm

Also known as karyoplasm, karyolymph, or nucleus sap, it is the transparent, granular, and jelly-like fluid of the nucleus surrounded by the nuclear membrane.

Nucleolus

A thick dark region in the nucleoplasm that lacks a membrane and is responsible for synthesizing ribosomal RNA ($rRNA$), known as the 'ribosome factory'.

Chromatin

A thin thread-like structure composed of DNA and histone protein that packages DNA into a smaller volume to fit within the cell.

Ribosomes

The smallest and most numerous organelles, these membraneless granules composed of proteins and $rRNA$ serve as the site of protein synthesis.

Endoplasmic Reticulum (ER)

A network of membranous channels or sacs called cisternae that transport molecules and extend from the nuclear membrane to the plasma membrane.

Smooth ER

Also called agranular ER, it lacks ribosomes and is the site for synthesis of lipids (phospholipids), cholesterol, and steroid hormones like testosterone.

Rough ER

Also called granular ER, it has many ribosomes on its surface, continues with the nuclear membrane, and is involved in protein synthesis.

Amphipathic (Amphiphilic)

A property of molecules, like phospholipids, that contain both polar (hydrophilic) and non-polar (hydrophobic) parts.

Fluid-Mosaic Model

A description of the cell membrane where the phospholipids represent the fluid and the embedded proteins represent the mosaic.

Cell Wall

A rigid, metabolically inactive, and non-living structure made of cellulose in plants, peptidoglycan in bacteria, or chitin in fungi.

Cytoplasm

The translucent, colloidal, and jelly-like substance inside the cell that holds organelles, a term coined by Albert Von Kolliker in 1862.

Cytosol

The aqueous part of the cytoplasm, making up approximately $70\%$ of the cell volume, where proteins and cytoskeleton filaments are suspended.

Cyclosis

Also known as cytoplasmic streaming or protoplasmic streaming, it is the circular movement of the cytoplasm used to distribute substances.

Hyaloplasm

The portion of the cytoplasm that includes the cytosol and cell inclusions but excludes the organelles.

Perikaryon

The technical name for the cytoplasm within the body of a nerve (neuron) cell.

Cell Inclusions

Also called ergastic or paraplastic substances, these are non-living, non-membrane-bound cytoplasmic substances such as stored nutrients or pigments.

Cystolith

The specific term for crystals of calcium carbonate found within cells.

Raphides

The specific term for crystals of calcium oxalate found within cells.

Mitochondria

Sausage-shaped or rod-shaped organelles surrounded by a double membrane that are involved in cellular respiration.