A1.2 Nucleic Acids Practice Flashcards

Vocabulary terms and definitions based on the IBO Biology syllabus for Nucleic Acids, covering DNA/RNA structure, replication, transcription, translation, and historical experiments.

DNA (Deoxyribonucleic acid)

The genetic material of all living organisms that stores information for protein production and is passed between generations through replication.

RNA (Ribonucleic acid)

A nucleic acid polymer involved in protein synthesis that may also serve as the genetic material for certain viruses like Coronavirus and HIV.

Nucleotide

The monomer unit of nucleic acids consisting of a five-carbon sugar, a negatively charged phosphate group ($PO_4^-$), and a nitrogenous base.

Pentose

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

Sugar-phosphate backbone

The structural frame of DNA and RNA formed by alternating sugar and phosphate groups linked by covalent bonds through condensation reactions.

Condensation reaction

The type of chemical reaction that links nucleotides together to form a polymer chain, releasing a water molecule as a by-product.

5' end

The end of a nucleic acid strand that terminates with a phosphate group attached to the fifth carbon of the pentose sugar.

3' end

The end of a nucleic acid strand that terminates with the third carbon of the pentose sugar.

Antiparallel

The arrangement of the two strands in a DNA double helix, where they run in opposite directions relative to their $5'$ and $3'$ ends.

Purines

Nitrogenous bases with a double-ring structure, which include Adenine (A) and Guanine (G).

Pyrimidines

Nitrogenous bases with a single-ring structure, which include Cytosine (C), Thymine (T), and Uracil (U).

Complementary base pairing

The specific hydrogen bonding between nitrogenous bases where Adenine pairs with Thymine (or Uracil in RNA) and Guanine pairs with Cytosine.

Semiconservative replication

The process of DNA duplication where each original strand acts as a template for a new strand, resulting in two identical molecules each containing one original and one new strand.

Transcription

The synthesis of RNA using a DNA template, catalyzed by the enzyme RNA polymerase in a $5'$ to $3'$ direction.

Translation

The synthesis of a polypeptide from mRNA where a ribosome reads the code from the $5'$ end towards the $3'$ end.

Universal genetic code

The system used by nearly all living organisms to decode genetic information into proteins, serving as evidence of universal common ancestry.

LUCA

The Last Universal Common Ancestor of life, believed to have carried the universal genetic code passed to all descendants.

Nucleosome

The basic structural unit of DNA packaging in eukaryotic cells, consisting of DNA coiled around a core of eight histone proteins.

Histones

A family of small, positively charged proteins that attract negatively charged DNA to facilitate packaging into nucleosomes.

Naked DNA

DNA found in prokaryotic cells that is not associated with or wrapped around histone proteins.

Hershey–Chase experiment

A 1952 study using bacteriophages and radioactive isotopes ($^{32}P$ and $^{35}S$) that provided evidence that DNA, not protein, is the genetic material.

Chargaff’s data

Evidence collected in 1948 showing that in DNA, the amount of Guanine is roughly equal to Cytosine and Adenine is roughly equal to Thymine.

Bacteriophage

A type of virus used in the Hershey-Chase experiment that specifically infects bacteria by injecting its genetic material into the host cell.