Lecture Notes: Cell Structure, RNA World, and Early Evolution

Vocabulary flashcards covering liposomes, membranes, RNA world concepts, DNA/RNA/protein roles, ribosome components, and early evolution ideas discussed in the lecture.

Liposome

A small vesicle with a lipid bilayer that forms a primitive cell-like compartment.

Lipid bilayer

A two-layer sheet of phospholipids forming the boundary of a liposome or cell; hydrophobic tails inward, hydrophilic heads outward.

Self-assembly

Phospholipids spontaneously organizing into a bilayer in water without external energy input.

Clay/mineral-assisted compartments

Experimental observation that compartments can form spontaneously in the presence of clay/minerals and can grow/divide.

Phospholipids

Molecules that form lipid bilayers and drive membrane structure in water.

DNA

The molecule that stores genetic information in modern cells.

Proteins / enzymes

Molecules that catalyze most chemical reactions in modern cells.

RNA

Nucleic acid capable of storing information and, in early stages, catalyzing reactions; central to the RNA world.

Ribozymes

RNA molecules with catalytic activity capable of accelerating chemical reactions.

RNA world

Hypothetical early stage where RNA carried both information storage and catalysis.

Chemical selection

Process by which RNA molecules with favorable traits become more abundant within a population of molecules.

Chemical evolution

Change over time in a population of molecules due to replication, selection, and mutation.

Mutation

A change in a molecule that can increase its copying ability and abundance.

Complementary base pairing

Rules by which bases pair (A-U/T and C-G) enabling replication and stable base pairing.

Copying / Replication (RNA)

RNA’s capacity to duplicate itself through base pairing, producing more copies.

DNA vs RNA stability

DNA is double-stranded and more stable for long-term storage; RNA is usually single-stranded and less stable.

Ribosome

A ribonucleoprotein complex that builds proteins; composed of protein and ribosomal RNA, with the RNA part catalyzing peptide bond formation.

Ribosomal RNA (rRNA)

The RNA component of the ribosome that catalyzes peptide bond formation during protein synthesis.

Peptide bond formation

The chemical reaction catalyzed by the ribosome’s RNA component that links amino acids.

Cell boundary

The boundary separating the inside from the outside of a cell, enabling controlled exchange.