3.1.8.1 = THE GENETIC CODE DNA IS UNIVERSAL, NON-OVERLAPPING & DEGENERATE: nature of genetic code

Genetic code

The sequence of DNA triplet bases (or mRNA codons) that codes for a specific amino acid.

Triplet

Refers to a sequence of three DNA bases coding for a specific amino acid.

Codon

A sequence of three RNA bases (triplet) that corresponds to a specific amino acid.

Universal

The concept that the same specific DNA base triplets code for the same amino acids in all living organisms.

Non-overlapping

Each DNA triplet or mRNA codon is discrete and can only be used once, coding for a unique amino acid.

Degenerate

A feature of the genetic code where the same amino acid can be coded for by more than one base triplet.

Transcription

The process of producing mRNA from DNA in the nucleus.

Translation

The process of producing polypeptides from the sequence of codons carried by mRNA in the cytoplasm.

Messenger RNA (mRNA)

RNA made by transcription that acts as a template for translation.

Transfer RNA (tRNA)

RNA involved in translation that carries specific amino acids and has an anticodon complementary to mRNA codon.

ATP's role in translation

ATP provides energy for bonding amino acids to tRNA and for forming peptide bonds between amino acids.

Ribosomes

Cellular structures that attach to mRNA and facilitate the pairing of tRNA anticodons with mRNA codons, allowing for peptide bond formation.

Eukaryotic transcription

In eukaryotes, DNA is transcribed to premRNA which then undergoes splicing to remove introns and form mRNA.

Prokaryotic transcription

In prokaryotes, mRNA is produced directly from DNA without introns or splicing.

Chaperone proteins

Specialized proteins that assist in the folding of polypeptides into their correct three-dimensional structures.

Primary structure of protein

The linear sequence of amino acids in a polypeptide.

Secondary structure of protein

The coiling or folding of a polypeptide into structures such as alpha helices or beta sheets.

Tertiary structure of protein

The three-dimensional shape of a polypeptide determined by interactions between R-groups.

Quaternary structure of protein

A structure formed by the association of multiple polypeptide chains and non-protein groups.

Hydrophobic interactions

Interventions that occur in proteins when non-polar R groups aggregate together, affecting protein folding.

Disulfide bonds

Covalent bonds that can form between cysteine residues in proteins, contributing to tertiary and quaternary structure.

Ionic bonds in proteins

Interactions between acidic and basic R groups that can stabilize protein structure.

HSP 70

A type of chaperone protein that prevents incorrect interactions during the synthesis of polypeptides.

HSP 60

Chaperonins that provide a protective environment for polypeptides to fold correctly away from other molecules.