DNA – Structure, Function, and Replication

Vocabulary flashcards covering structural components, chemical properties, functional concepts, and laboratory techniques related to DNA.

DNA (Deoxyribonucleic Acid)

Double-stranded polymer of nucleotides that stores genetic instructions for all living organisms.

Nucleotide

Monomer of DNA composed of a phosphate group, deoxyribose sugar, and nitrogenous base.

Sugar-Phosphate Backbone

The repeating chain of deoxyribose sugars linked by phosphate groups that forms DNA’s structural framework.

Nitrogenous Base

Adenine, thymine, cytosine, or guanine—molecules that encode genetic information via specific pairing.

Purine

Two-ring nitrogenous base (adenine or guanine) found in DNA.

Pyrimidine

Single-ring nitrogenous base (cytosine or thymine in DNA; uracil in RNA).

Antiparallel

Orientation of the two DNA strands running 5'→3' in opposite directions.

Double Helix

Right-handed, twisted ladder structure of DNA formed by two antiparallel strands held by hydrogen bonds.

Hydrogen Bond

Weak attraction between complementary bases (A–T with 2 bonds, G–C with 3) that stabilizes DNA.

Chromosome

Discrete DNA molecule packaged with proteins; circular in prokaryotes, linear in eukaryotes.

Prokaryotic Chromosome

Single circular DNA molecule attached to the cell membrane of bacteria and archaea.

Eukaryotic Chromosome

Linear DNA molecule wrapped around histones and stored inside the nucleus.

Histone

Basic protein that DNA coils around to form chromatin in eukaryotes.

Genome

Complete set of genetic material in an organism or virus.

Gene

Specific nucleotide sequence that contains instructions to build a protein or functional RNA.

Central Dogma

Flow of genetic information: DNA → RNA → Protein (storage, carrier, function).

Transcription

Process of copying DNA information into complementary RNA by RNA polymerase.

Translation

Decoding of mRNA into a specific amino-acid sequence to build a protein.

DNA Replication

Cellular process that produces an identical copy of the entire genome before cell division.

Watson–Crick Base Pairing

Specific pairing of A with T and G with C that provides a template for replication.

Polymerase Chain Reaction (PCR)

Laboratory technique that uses primers, heat, and DNA polymerase to exponentially amplify a selected DNA region.

Primer (PCR)

Short, synthetic DNA oligonucleotide that provides a 3' end for DNA polymerase to extend during PCR.

Cycle (PCR)

One round of denaturation, primer annealing, and extension; doubles target DNA each time.

dATP, dTTP, dCTP, dGTP

Deoxyribonucleotide triphosphates that serve as building blocks for new DNA strands.

Phosphate Group

Acidic, negatively charged component of nucleotides that allows DNA isolation via charge interactions.

Deoxyribose

Five-carbon sugar lacking an oxygen at the 2' position; distinguishes DNA from RNA.

DNA Isolation (Salt Precipitation)

Technique using detergent to lyse cells and salt to aggregate proteins, leaving DNA in solution.

Silica Binding (Column Purification)

Method where salted DNA adheres to silica, enabling wash steps and pure DNA elution.

Genome Analogy

Nucleotides : Genes : Genome :: Letters : Sentences : Book—illustrates DNA’s hierarchical organization.