kk2 glossary

agarose gel

A special type of porous gel used in gel electrophoresis, which allows for DNA to be separated by fragment size.

annealing

The second stage in PCR, in which primers attach to the single-stranded DNA.

bacterial transformation

Process in which bacterial cells take up segments of foreign DNA that become part of their genetic make-up.

blunt ends

Ends of a DNA fragment with no overhanging bases after being cut by an endonuclease.

complementary DNA (cDNA)

A strand of DNA that has complementary bases to the opposite strand and is usually produced through reverse transcription.

CRISPR-Cas9

A tool for precise and targeted genome editing that uses specific RNA sequences to guide an endonuclease, Cas9, to cut DNA at the required positions.

denaturing

The first stage in PCR, in which a double-stranded piece of DNA is heated and separated into single-stranded DNA.

DNA fingerprinting

Technique for identifying DNA from different individuals based on variable numbers of tandem repeats of short DNA segments near the ends of chromosomes.

DNA profiling

Technique for identifying DNA from different individuals based on variable regions known as short tandem repeats (STRs) or microsatellites.

DNA sequencing

Identification of the order or sequence of bases along a DNA strand.

electroporation

A technique that uses brief exposure of host cells to an electric field to enable the entry of segments of foreign DNA into the cells.

endonucleases

Enzymes, also known as restriction enzymes, that cut at specific sites within DNA molecules.

ethidium bromide

A dye that binds to DNA and illuminates under UV light.

extension

The third stage in PCR, in which the Taq polymerase enzyme synthesises a new strand of DNA by adding free nucleotides.

gel electrophoresis

A technique for sorting a mixture of DNA fragments (and other molecules with a net charge) through an electric field on the basis of different fragment lengths.

genetically modified organisms (GMOs)

Organisms whose genomes are altered through the use of genetic engineering technology.

genome editing

A process by which changes are made to the nucleic acid sequence of genes; also termed gene editing.

heat shock

A technique to transform bacteria in which cells are suspended in an ice cold solution and then moved into a warm solution to increase plasma membrane fluidity.

hypervariable regions

Regions in DNA that are highly polymorphic.

insulin

A hormone that allows for glucose to enter cells, reducing blood glucose levels.

ligase

An enzyme that catalyses the joining of two double-stranded DNA fragments.

origin of replication (ORI)

A DNA base sequence in a plasmid in which DNA replication begins.

plasmid

A small circular piece of double-stranded DNA that is able to reproduce independently and may be taken up by cells (usually bacteria) in addition to chromosomal DNA.

polymerase

Enzyme involved in synthesising nucleic acids.

polymerase chain reaction

A technique used to amplify a segment of DNA.

recombinant plasmids

Plasmids that carry foreign DNA.

restriction enzyme

Enzymes, also known as endonucleases, that cut at specific sites within DNA molecules.

reverse transcriptase

Enzyme that directs the formation of copy DNA from a messenger RNA template through reverse transcription.

selectable marker

Genes carried by plasmids for certain traits, often for antibiotic resistance.

short tandem repeats (STRs)

Chromosomal sites where many copies of a short DNA sequence are joined end-to-end; the number of repeats is variable between unrelated people.

sticky ends

Ends of a DNA fragment with overhanging bases after being cut by an endonuclease.

Taq polymerase

An enzyme used in PCR that adds free nucleotides to the single stranded DNA in order to synthesise a new strand.

transgenic organisms

Organisms that carry in their genomes one or more genes artificially introduced from another species.

vector

An agent or vehicle used to transfer pathogens or genes between cells and organisms.

probe

Single-stranded segment of DNA (or RNA) carrying a radioactive or fluorescent label with a base sequence complementary to that in a target strand of DNA.