Nucleic Acids and the Origin of Life

This set of vocabulary flashcards covers the chemical structures of nucleic acids (DNA and RNA), their biological functions, and the scientific theories regarding the origin of small molecules, large molecules, and the first cells.

Nucleotides

The monomeric building blocks of nucleic acids specialized for the storage, transmission, and use of genetic information.

Deoxyribonucleic acid (DNA)

A type of nucleic acid that carries hereditary information between generations and consists of a pentose sugar (deoxyribose), a phosphate group, and nitrogenous bases.

Ribonucleic acid (RNA)

A type of nucleic acid that uses genetic information to determine the sequence of amino acids in proteins, typically consisting of a single polynucleotide chain.

Pentose sugar

A five-carbon sugar found in nucleotides; it is deoxyribose in DNA and ribose in RNA.

Nucleoside

A molecule consisting of a pentose sugar and a nitrogenous base, but containing no phosphate group.

Pyrimidine

A nitrogen-containing base with a single ring structure, including Cytosine (C), Thymine (T), and Uracil (U).

Purine

A nitrogen-containing base with a fused ring structure, including Adenine (A) and Guanine (G).

Phosphodiester linkages

The bonds forming the backbone of DNA and RNA that link carbon $3'$ in one sugar to carbon $5'$ in another sugar.

Antiparallel

The orientation of the two strands of DNA, which run in opposite directions.

Complementary base pairing

The specific hydrogen bonding between purines and pyrimidines: Adenine pairs with Thymine (A—T) and Cytosine pairs with Guanine (C—G).

Double helix

The structural shape formed by the two strands of a DNA molecule.

Genome

The complete set of DNA in a living organism.

Genes

Specific sequences of DNA that code for proteins and are transcribed into RNA.

DNA replication

The function of DNA that allowing it to reproduce itself exactly.

Transcription

The process by which DNA copies its information into RNA.

Translation

The process by which RNA specifies an amino acid sequence based on DNA information.

ATP (Adenosine triphosphate)

A nucleotide that serves as an energy transducer in biochemical reactions.

GTP (Guanosine triphosphate)

A nucleotide that serves as an energy source in protein synthesis.

cAMP (Cyclic adenosine monophosphate)

A nucleotide essential to the action of hormones and the transmission of information in the nervous system.

Spontaneous generation

The disproved theory that life could originate from inanimate or decaying matter.

Extraterrestrial source theory

The proposal that life originated from molecules brought to Earth by meteorites, such as those from Mars containing water and magnetite.

Chemical evolution

The theory that conditions on primitive Earth led to the formation of simple molecules, which then led to the formation of life forms.

Miller and Urey experiment

An experiment that simulated Earth's early atmosphere using hydrogen gas, ammonia ($NH_3$), methane ($CH_4$), and water vapor to produce purines, pyrimidines, and amino acids.

Ribozymes

Folded RNA molecules that act as catalysts and can catalyze their own replication.

Protocells

Enclosed compartments formed by fatty acid bilayers in water that permit the maintenance of an internal chemical environment.

Early Cell Fossils

Imprints found in ancient rocks that are approximately $3.5 \text{ billion years}$ old.