IBDP HL Biology - Cell Origins, Early Earth Conditions, and Spontaneous Generation

Vocabulary flashcards focusing on cell origins, early Earth conditions, historical experiments disproving spontaneous generation, early genetic material hypotheses, cell membranes, and virus characteristics.

Cell

The smallest unit of self-sustaining life, composed of intracellular structures and cytosol working together as a living system.

Spontaneous Generation

The disproved theory that living organisms originate spontaneously from non-living matter or a vital principle in the air.

Miller-Urey Experiment

A $1953$ experiment by Stanley Miller and Harold Urey that passed a continuous $60000\,\text{volt}$ electrical current through simulated primitive gases ($CH_4$, $NH_3$, $H_2$, $H_2O$) to form amino acids and organic biomolecules.

Swan-Neck Flask

An apparatus designed by Louis Pasteur in $1862$ that allowed sterile broth to be exposed to air while preventing dust and bacteria from entering, disproving spontaneous generation.

Blender Experiment

A $1952$ experiment by Alfred Hershey and Martha Chase using bacteriophages, radioactive markers, and E. coli to demonstrate that genetic information is stored in DNA rather than protein.

RNA World Hypothesis

The concept that RNA was the first genetic material because of its catalytic enzymatic role, simpler ribose sugar, and ability to self-replicate without separate enzymes.

LUCA

Last Universal Common Ancestor; the simple single-celled organism from which all domains and kingdoms of life are thought to have evolved.

Archaea

A domain of organisms similar to bacteria that inhabit extreme environments, such as conditions of high heat, high salinity, or high acidity.

Cyanobacteria

Early photosynthetic organisms whose evolution introduced oxygen into the Earth's atmosphere.

Chemoautotrophic Organism

The simple unicellular metabolic type hypothesized to be the first cell form on Earth prior to photoautotrophs.

Phospholipid Bilayer

A biological membrane structure composed of polar, hydrophilic phosphate heads facing outward toward water and non-polar, hydrophobic fatty acid tails facing inward.

Low Density Lipoprotein (LDL)

A complex that transports lipids through the bloodstream surrounded by a membrane, often referred to as bad cholesterol when elevated.

Virus

A non-living structure containing genetic material (RNA or DNA) enclosed in a protein coat that lacks cytoplasm, organelles, independent metabolism, and homeostasis.

Francesco Redi's Experiment

A $1668$ experiment demonstrating that maggots arise from fly eggs rather than decaying meat, providing an early disproof of spontaneous generation.

Lazzaro Spallanzani's Experiment

An experiment showing that boiling meat broth and sealing it completely from the air prevented bacterial growth.

John Needham's Experiment

A $1748$ experiment observing microorganisms in boiled meat broth, which he incorrectly interpreted as evidence for spontaneous generation.

Cotton Plug Experiment

An $1850$ experiment by George Friedrich Müller and Theodore von Beth that filtered air passing into a flask through a sterile cotton plug to trap airborne microbes.