Nucleic Acids and Nucleotides Lecture Review

Vocabulary flashcards based on the lecture notes covering the biochemistry of nucleic acids, nucleotide structure, historical DNA models, and the different types of RNA involved in protein synthesis.

Nucleic acids

Large biomolecules which store, transmit and express genetic information of a cell; they include DNA and RNA.

DNA (deoxyribonucleic acid)

A type of nucleic acid that acts as the store of genetic information transmitted from one generation to the next in most cells.

RNA (ribonucleic acid)

A nucleic acid normally used as an intermediate in information transfer from DNA to proteins, though it acts as a genetic store in some viruses.

Nucleotides

The fundamental units of nucleic acids that consist of a pentose sugar, a nitrogenous base, and a phosphoric acid.

Polynucleotides

Extremely long molecules made up of multiple nucleotide units arranged together.

Purine

A nitrogenous base containing two rings; examples include adenine ($A$) and guanine ($G$).

Pyrimidine

A nitrogenous base containing one ring; examples include cytosine ($C$), thymine ($T$), and uracil ($U$).

Nucleoside

A molecule formed when a pentose sugar and a nitrogenous base combine through a condensation reaction resulting in a beta covalent glycosidic bond.

Phosphoester bond

The bond formed between the $OH$ group of carbon 5 ($C5$) of a nucleoside's pentose sugar and the $H$ of a phosphate.

Phosphodiester bridge

A bond formed during the creation of a dinucleotide between the $OH$ of carbon 3 ($C3$) of the first nucleotide and the $H$ of the phosphate on carbon 5 ($C5$) of the second nucleotide.

Chargaff’s rules

Chemical findings from 1949 stating that total purines $(A+G)$ equal total pyrimidines $(C+T)$, and the ratios of $A:T$ and $G:C$ both equal $1$.

X-ray crystallography

The technique used by Maurice Wilkins and Rosalind Franklin to find that DNA has a helical structure, a spacing of $3.4\,nm$, and a diameter of $20\,nm$.

Watson - Crick Model

The 1953 model describing DNA as a double helix of two complementary and anti-parallel polynucleotide chains held by hydrogen bonding.

Messenger RNA (mRNA)

A single-stranded molecule formed by transcription that carries the genetic code (codon) from the template DNA strand.

Ribosomal RNA (rRNA)

A single-stranded nucleic acid synthesized in the nucleolar organiser that combines with protein to form ribosomes.

Polyribosomes

Clusters of ribosomes linked together by a strand of $mRNA$.

70s Ribosome

The size of a prokaryotic ribosome, composed of $50s$ and $30s$ subunits.

80s Ribosome

The size of a eukaryotic ribosome, composed of $60s$ and $40s$ subunits.

Transfer RNA (tRNA)

An adaptor molecule described by the clover leaf model that transfers amino acids to the ribosomes during protein synthesis.

Anticodon

A triplet of bases on the $tRNA$ molecule that is specific to a particular amino acid.

CCA sequence

The base sequence that always appears at the $5'$ end of a $tRNA$ molecule.

Glycosidic bond (Beta covalent)

The specific bond formed between carbon 1 ($C1$) of a pentose sugar and a nitrogenous base during nucleoside formation.