Carbohydrates, Biomolecules, and Origin-of-Life Theories

Vocabulary flashcards covering carbohydrates, lipids, proteins, and major hypotheses about the origin of life, derived from the lecture notes.

Carbohydrate

Organic macromolecule composed of carbon, hydrogen, and oxygen (≈CH₂O) that provides energy.

Monosaccharide

Single sugar molecule; monomer of carbohydrates.

Disaccharide

Carbohydrate made of two bonded monosaccharides.

Polysaccharide

Complex carbohydrate consisting of many monosaccharide units; a polymer.

Monomer

Individual repeating unit within a polymer (e.g., a single glucose in starch).

Polymer

Large molecule composed of repeating monomers (e.g., polysaccharide).

Simple carbohydrate

Carbohydrate composed of one or two sugar units (mono- or disaccharide).

Complex carbohydrate

Long-chain carbohydrate; synonymous with polysaccharide.

Glucose

Monosaccharide that supplies the quickest form of energy.

Fructose

Fruit sugar monosaccharide; combines with glucose to form sucrose.

Galactose

Monosaccharide commonly found in milk; simple sugar.

Sucrose

Table sugar; disaccharide of glucose + fructose.

Cellulose

Structural polysaccharide in plant cell walls.

Starch

Storage polysaccharide in plants; dietary carbohydrate broken down into glucose.

Glycogen

Animal storage polysaccharide; excess glucose stored in liver and muscles.

Lipid

Hydrophobic biomolecule used mainly for long-term energy storage.

Glycerol

Three-carbon backbone of many lipids.

Fatty acid

Hydrocarbon chain with a carboxyl group; lipid building block.

Triglyceride

Lipid of glycerol bonded to three fatty acids; major energy reserve.

Phospholipid

Lipid with glycerol, two fatty acids, and phosphate; forms cell membranes.

Steroid

Lipid with four fused carbon rings; includes hormones like cholesterol.

Hydrophobic

Water-repelling property characteristic of most lipids.

Protein

Macromolecule of amino acid chains; performs structural and functional roles.

Amino acid

Monomer unit of proteins containing amino and carboxyl groups.

Enzyme

Protein that acts as a biological catalyst, speeding up reactions.

Biomolecule

Any molecule produced by living organisms, such as carbohydrates, lipids, or proteins.

Panspermia

Hypothesis that life originated in space and was seeded on Earth.

Svante Arrhenius

Scientist who formally proposed modern panspermia.

Chemosynthesis

Production of food using chemical energy (e.g., hydrogen sulfide) instead of sunlight.

Iron-sulfur world hypothesis

Günter Wächtershäuser’s idea that life began at hydrothermal vents via iron-sulfur chemistry.

Günter Wächtershäuser

Proposer of the iron-sulfur world hypothesis for life’s origin.

RNA World Hypothesis

Theory that RNA was the first self-replicating molecule before DNA and proteins.

Walter Gilbert

Scientist who coined the term “RNA World” in 1986.

Hydrothermal vent theory

Proposal that life originated at deep-sea volcanic vents through chemosynthesis.

Clay hypothesis

Idea that clay minerals provided templates for forming complex organic molecules on early Earth.

Alexander Graham Cairns-Smith

Scientist who formulated the clay hypothesis.

Electrical Spark (Miller-Urey) experiment

Simulation of early Earth lightning that produced organic compounds, supporting abiogenesis.

Abiogenesis

Concept that life arose from non-living matter via gradual chemical evolution.

Oparin-Haldane theory

Early proposal that organic molecules formed in a primordial soup, leading to life.