Genetic Traceability and DNA Analysis in Food Science

These flashcards cover genetic traceability in food, DNA structure and chemical properties, laboratory techniques like PCR, RFLP, and electrophoresis, and specific applications in meat, oil, and wheat authenticity.

Forensic Genetics

A branch of science that utilizes DNA analysis for judicial purposes, transforming biological traces into legal evidence.

Traceability (Regulation EC 178/2002)

The ability to track and follow food and ingredients through all stages of the supply chain.

One step back - one step forward

A traceability principle requiring each operator to identify their immediate supplier and the subsequent recipient.

Authentic Food

An item that conforms to the producer's description, has a verifiable geographic origin, and is of the correctly identified species or variety.

DOP, IGP, and STG

European quality markings: Denominazione di Origine Protetta, Indicazione Geografica Protetta, and Specialità Tradizionale Garantita.

Nucleotides

The basic units of nucleic acids, demonstrated by Levene in 1931 to be composed of a pentose sugar, a nitrogenous base, and a phosphate group.

Pyrimidines

The class of nitrogenous bases that includes uracil, cytosine, and thymine.

Purines

The class of nitrogenous bases that includes adenine and guanine.

DNA Base Spacing

The constant distance between bases in DNA, which is $0.34\,nm$.

DNA Helix Turn

A complete $360^{\circ}C$ turn of the helix involving $10$ nucleotides, with a total length of $3.4\,nm$.

Restriction Enzymes (Endonucleases)

Enzymes that cut double-stranded DNA at specific palindromic target sequences.

Electrophoresis

A technique that separates DNA fragments in a gel (agarose or polyacrylamide) based on their molecular size and negative charge.

Molecular Probes

Short DNA or RNA sequences complementary to a target sequence used for identification via hybridization.

Hot Probes

Molecular probes marked with radioactive isotopes, such as phosphorus-$^{32}P$, detected through autoradiography.

Cold Probes

Molecular probes marked with dyes, enzymes, or fluorochromes, often visible under UV light.

RFLP (Restriction Fragment Length Polymorphism)

A genetic analysis technique based on variation in the length of DNA fragments produced by restriction enzymes.

Southern Blotting

The process of transferring DNA fragments from a gel to a nitrocellulose or nylon membrane using capillary action.

PCR (Polymerase Chain Reaction)

A DNA replication technique using cycles of temperature changes to exponentially amplify a target sequence.

PCR Denaturation

The first step of PCR occurring at $94-95^{\circ}C$ to separate the DNA strands.

Anneling (Annealing)

The step in PCR occurring at $55-65^{\circ}C$ where primers bind to the single-stranded DNA template.

PCR Extension

The phase at $72^{\circ}C$ where Taq polymerase synthesizes the new DNA strand.

Multiplex PCR

An advanced PCR method involving the simultaneous amplification of multiple DNA targets to save time.

Deterministic Approach

A method of identification looking for specific alleles (presence or absence) to identify a variety with certainty.

Probabilistic Approach

A method that compares global genetic profiles with databases to assign a sample to a variety based on allele frequency.

Cytochrome b

A mitochondrial DNA target used in PCR-RFLP to screen very different animal species.

Myostatin (MSTN)

A protein that regulates muscle growth; mutations in its gene lead to the double muscling phenotype in cattle like the Piemontese.

Extension and Spotted Loci

Two genetic markers that must be combined to accurately distinguish between cattle breeds like Bruna, Reggiana, and Frisona.

Plastid DNA (matK, rbcL, trnL-trnF)

DNA from chloroplasts used for oil traceability because it is more abundant and resistant to degradation than nuclear DNA.

Triticum durum

Tetraploid wheat ($2n = 4x = 28$) with the genomic formula AABB, used for pasta production.

Triticum aestivum

Hexaploid wheat ($2n = 6x = 42$) with the genomic formula AABBDD, containing the D genome used to detect flour fraud.

DNA Fingerprinting

A technique for creating a global genetic map or 'digital footprint' of a sample using molecular markers.