Cell Biology and Domains of Life

Vocabulary flashcards covering cellular structures, organelles, and evolutionary concepts across the three domains of life.

Plasma membrane

An outer covering of a cell ranging from 5 to 10 nanometers in thickness that separates the cell interior from its surrounding environment and regulates the passage of molecules.

Cytoplasm

The material within a cell, consisting of a jelly-like liquid in prokaryotes, or the entire region between the plasma membrane and nuclear envelope in eukaryotes.

Ribosomes

Large enzymes composed of proteins and RNAs that synthesize proteins by translating messenger RNA (mRNA) instructions.

Phospholipids

Amphiphilic lipids that spontaneously form a lipid bilayer in water, serving as the major structural component of all cell membranes.

Fluid mosaic model

A structural model describing the plasma membrane as a fluid mixture of membrane components that can diffuse past each other within the membrane.

Integral proteins

Membrane proteins that are anchored directly within the cell membrane itself.

Peripheral proteins

Membrane proteins that interact only with the inner or outer surface of the cell membrane.

Nucleoid

The central region of a prokaryotic cell where a single circular DNA molecule is packaged around DNA-binding proteins.

Peptidoglycan

A network of large polysaccharides with attached amino acids that forms the cell wall of bacteria.

Conjugation

A form of reproduction in prokaryotes where two cells connect via pili to exchange genetic material, such as antibiotic resistance genes.

Nuclear envelope

A double-membrane structure surrounding the nucleus containing large pores that control the passage of DNA, RNA, and proteins.

Chromatin

The protein-DNA complexes composed mainly of histones and linear DNA that make up eukaryotic chromosomes.

Cytosol

The fluid portion of the cytoplasm excluding organelles and cytoskeleton filaments, containing water, dissolved molecules, and enzymes.

Nucleolus

A dark region within the eukaryotic nucleus where ribosomal RNA is produced and assembled with proteins into ribosome subunits.

Mitochondria

Oval-shaped double-membrane organelles responsible for making ATP via cellular respiration, possessing their own DNA genome and ribosomes.

Adenosine triphosphate (ATP)

A nucleotide that serves as the main short-term energy storage molecule of the cell.

Endomembrane network

A group of single-membrane eukaryotic organelles including the ER, Golgi apparatus, endosomes, and lysosomes that transport materials using vesicles.

Endocytosis

A transport process where the plasma membrane folds inward to form a transport vesicle, bringing extracellular fluid and particles into the cell.

Exocytosis

A transport process where a vesicle fuses with the plasma membrane to export materials out of the cell into extracellular space.

Endosome

An organelle that sorts material imported by endocytosis before directing it to its next cellular destination.

Lysosomes

Organelles containing hydrolytic enzymes that break down large organic molecules into smaller components.

Endoplasmic reticulum (ER)

A large eukaryotic organelle involved in membrane lipid synthesis and protein production via cytoplasmic-surface ribosomes.

Golgi apparatus

An organelle that receives proteins and lipids from the ER, sorts them, and packages them into transport vesicles for specific destinations.

Cellulose

A glucose-containing polysaccharide that forms the primary structural component of plant cell walls.

Chitin

A polysaccharide that makes up fungal cell walls and the exoskeletons of arthropods.

Pellicle

A flexible coat formed by interlocking protein strips that surrounds and protects certain protists without restricting mobility.

Chloroplasts

Photosynthetic organelles found in plants and algae featuring double membranes, thylakoid stacks called grana, stroma, and chlorophyll.

Central vacuole

A large organelle in plant cells that regulates water concentration and provides structural support to the cell wall.

Endosymbiotic Theory

The prevailing theory that eukaryotic organelles like mitochondria and chloroplasts originated from free-living prokaryotic cells engulfed by an ancestral host cell.