Introduction to Cell Biology and Organelles

Vocabulary flashcards covering primordial origin theories, prokaryotic and eukaryotic distinctions, cell size limitations, and cellular organelles derived from Chapters 1 through 8 lecture transcript.

Primordial soup

The concept that early oceans were home to organic compounds formed via atmospheric electrical discharges (Miller's experiment) and underwater hydrothermal vents before life existed on land.

Miller's experiment

An experiment demonstrating that electrical discharges in an atmospheric gas mixture cause molecules to form organic compounds.

RNA world hypothesis

The theory that single-stranded RNA, rather than double-stranded DNA, was the first informational molecule due to its ability to store information and perform enzymatic reactions.

Ribozymes

RNA molecules capable of catalyzing enzymatic reactions, such as inducing peptide bond formation during protein translation.

Liposomes

Hollow membrane-bound lipid vesicles considered primitive protocells that could spontaneously form in primordial oceans and trap RNAs.

Domains of life

The three primary high-level branches of biological organization: Bacteria, Archaea, and Eukaryotes.

Prokaryotes

Simpler, smaller single-celled organisms lacking a membrane-bounded nucleus, comprising Bacteria and Archaea.

Eukaryotes

Complex unicellular or multicellular organisms (including plants, animals, algae, and protozoa) defined by the presence of a membrane-bounded nucleus.

Membrane-bounded nucleus

The key structural feature distinguishing eukaryotic cells from prokaryotic cells (Bacteria and Archaea).

Archaea

Single-celled prokaryotic organisms, originally termed archaebacteria, that diverged from a common ancestor shared with eukaryotes and frequently inhabit extreme environments.

Methanogens

A group of Archaea that generate energy by converting hydrogen and $CO_2$ into methane.

Halophiles

Archaea adapted to live in extremely salty environments.

Thermoacidophiles

Archaea that thrive in acidic, high-temperature environments such as hot springs.

Surface area to volume ratio

A critical geometric factor limiting maximum cell size because surface area determines cellular exchange capability while volume determines required exchange capacity.

Villi

Three-dimensional finger-like protrusions in the intestinal tract that maximize surface area for nutrient absorption.

Cytoplasm

The internal volume of a cell (excluding the nucleus) containing a liquid matrix, organelles, and cytoskeletal fibers.

Diffusion

The passive movement of a substance from an area of high concentration to an area of low concentration, which decreases in rate as molecular size increases.

Subcellular compartmentalization

The structural separation of specific cellular functions into distinct membrane-bound organelles to concentrate necessary enzymes and substrates.

Nucleoid

The compact structure in bacterial or archaeal cells where circular genetic material is folded and attached to the cell membrane without a nuclear envelope.

Cyanobacteria

A group of photosynthetic bacteria containing extensive internal membrane systems where photosynthetic reactions occur.

Exocytosis

The cellular process of transporting materials from intracellular compartments to the outside of the cell.

Endocytosis

The cellular process of bringing materials into or moving them within the cell.

Binary fission

The process of cell replication and division used by bacteria and archaea to distribute replicated DNA into daughter cells.

Mitosis

The eukaryotic process of nuclear division where replicated chromosomes are systematically distributed into daughter cells.

Cell wall

A rigid outer structural layer surrounding the plasma membrane in plant and fungal cells, providing mechanical stiffness.

Nuclear envelope

The double-membrane structure surrounding the nucleus of a eukaryotic cell that contains nuclear pores.

Nuclear pores

Transport channels spanning the nuclear envelope that regulate the passage of molecules such as RNA between the nucleus and cytoplasm.

Nucleolus

A specialized structure within the eukaryotic nucleus responsible for synthesizing ribosomal RNA and initiating ribosome assembly.

Mitochondria

Eukaryotic double-membrane organelles responsible for aerobic respiration, sugar degradation, and generating cellular ATP energy.

Chloroplasts

Plant cell organelles that harvest solar energy and convert $CO_2$ into chemical energy via photosynthesis.

Thylakoids

Coin-like inner membrane structures stacked into grana inside chloroplasts where solar energy-dependent photosynthetic reactions take place.

Stroma

The semi-fluid internal matrix of a chloroplast where the reduction of $CO_2$ to sugar occurs during photosynthesis.

Plastids

A group of plant organelles that includes chloroplasts, chromoplasts (pigment storage), and amyloplasts (starch storage).

Endosymbiotic theory

The scientific theory proposing that mitochondria and chloroplasts evolved from ancient prokaryotes that established a symbiotic relationship inside primitive host cells.