Cellular Component & Organelle Cards

Vocabulary practice flashcards covering cell types, cellular components, and organelle structures and functions from the BIOL 115 Principles of Biology lecture.

Prokaryotic cells (prokaryotes)

Single-celled organisms, such as Bacteria and Archaea, that lack a membrane-bound nucleus, store circular DNA in a nucleoid, and typically possess a cell wall rich in peptidoglycan.

Eukaryotic cells (eukaryotes)

Organisms (including Plants, Animals, Fungi, and Protists) that are mostly multicellular, containing linear DNA compacted into chromosomes and enclosed within a membrane-bound nucleus.

Peptidoglycan

A carbohydrate that enriches the cell wall of most prokaryotic organisms.

Cytosol

The jelly-like fluid residing inside the plasma membrane but outside all organelles; it consists of $70\%$ water, ions, salts, and polar molecules (such as enzymes) to sustain cellular metabolism and store nutrients.

Nucleoid

An irregularly shaped, non-membrane-bound cytoplasmic region in prokaryotes where circular DNA is compacted.

Loop domains

Loop structures formed by circular chromosomal DNA with associated proteins that compact prokaryotic DNA about $10\text{-fold}$.

Nucleus

A membrane-bound organelle that encapsulates and protects eukaryotic DNA, serving as the site of DNA replication and transcription to RNA.

Nuclear envelope

A double-phospholipid bilayer membrane that encases and isolates the nucleus.

Nuclear pores

Protein-lined openings in the nuclear envelope that act as gateways allowing molecules such as RNA to exit into the cytoplasm.

Nucleolus

A darkly stained internal subregion of the nucleus where ribosomal RNA (rRNA) is synthesized and ribosomal subunits assemble.

Ribosomes

Macromolecular complexes made of proteins and rRNA (ribosomal RNA), arranged into a large and small subunit, responsible for translating single-stranded RNA into functional proteins.

Rough Endoplasmic Reticulum (Rough ER)

A system of flattened membrane stacks continuous with the nucleus and studded with ribosomes; serves as the primary site for protein synthesis, packaging, and export.

Lumen (Rough ER)

The internal center cavity of the rough endoplasmic reticulum into which ribosomes deposit newly formed proteins.

Smooth Endoplasmic Reticulum (Smooth ER)

A network of flattened membrane stacks located outside the rough ER that lacks ribosomes and contains enzymes for carbohydrate and lipid synthesis and/or degradation.

Vesicles

Small membrane-bound bubbles that transport packaged molecules produced in the endoplasmic reticulum and Golgi apparatus to other destinations in the cell.

Golgi apparatus

An organelle made of flattened membrane stacks that receives incoming transport vesicles, sorts their cargo by size and chemical properties, and repackages them for distribution.

Cis face (Golgi apparatus)

The receiving side of the Golgi apparatus facing the endoplasmic reticulum, where incoming vesicles fuse and deposit their contents.

Trans face (Golgi apparatus)

The shipping side of the Golgi apparatus facing the plasma membrane, where sorted materials are released in newly formed vesicles.

Cisternae (Golgi apparatus)

The individual flattened membrane layers of the Golgi apparatus through which vesicle contents pass and are sorted.

Lysosomes

Golgi-derived digestive vesicles containing up to $40$ different acid-activated enzymes used to break down food particles, ingested bacteria, and worn-out or non-functional organelles.

Acid hydrolases

Digestive enzymes located within lysosomes that function optimally in acidic conditions ($\sim\text{pH } 5$).

Central vacuoles

Large, membrane-bound plant organelles that can occupy $80\%$ or more of a cell's volume, storing water, enzymes, nutrients, salts, minerals, proteins, and pigments while providing internal turgor support.

Peroxisomes

Membrane-bound organelles containing oxidizing enzymes synthesized on free-floating ribosomes; they detoxify harmful substances (e.g., drugs and alcohol) and produce hydrogen peroxide ($H_2O_2$) as a byproduct.

Catalase

A peroxisomal enzyme that converts toxic hydrogen peroxide ($H_2O_2$) into harmless water and oxygen ($2H_2O + O_2$).

Mitochondria

Double-membraned organelles that produce cellular energy ($\text{ATP}$); they contain their own circular DNA and ribosomes and replicate independently of the host cell.

Cristae

The internal folds of the inner mitochondrial membrane that extend into the matrix.

Mitochondrial matrix

The fluid-filled space enclosed within the inner mitochondrial membrane, situated between the cristae.

Chloroplasts

Double-membraned organelles that carry out photosynthesis in plant cells; they possess their own genetic material, internal thylakoid systems, and divide independently of the cell.

Stroma

The fluid-filled internal space surrounding the thylakoid membranes within a chloroplast.

Thylakoids

Flattened, disc-like membrane sacs within a chloroplast whose internal hollow compartment is called the lumen.

Granum

A coin-like stack of flattened thylakoid membranes situated within the chloroplast stroma.