Chapter 4 (copy)

Argrose gel

A gel matrix used for electrophoresis

Allele

A different form of a gene. Alleles of a gene have different DNA sequence, sometimes resulting in different forms of a phenotype

Annealing

In PCR, a process of joining separate strands of DNA together as a result of hydrogen bonds pairing; occurs when the temperature is lowered

Bacteria competence

The ability of bacterial cell to alter its genome by taking DNA from other cells or the environment

Bacteriophage

A virus that infects bacteria

Blunt-end restriction enzyme

A restriction enzyme that leaves clean-cut ends because it cuts both strands of the DNA molecule at the same location with the recognition site

cas9

an endonuclease enzyme found in bacteria that is used to cut specific sequences of invading viral DNA

Complementary DNA (cDNA)

Double-stranded DNA that contains no introns; copied from mRNA by the enzyme reverse transcriptase

cRNA

CRISPR RNA

CRISPR cas9

A gene editing technique that uses guide DNA (gRNA) to guide a cas9 enzyme to a target DNA site where the enzyme cuts the DNA.

CRISPR

clustered regularly interspaced short palindromic repeats’ segments of DNA with short repetitive sequences that are interspersed with unique DNA sequences

DNA amplification

The process of creating millions of identical copies of a DNA sample using the polymerase chain reaction (PCR)

DNA ladder

A set of DNA molecules known size used as a ‘molecular ruler’ on gel electrophoresis to determine the size of other DNA molecules

DNA ligase

An enzyme that joins together fragments of DNA by forming a phosphodiester bond between adjacent nucleotides

DNA polymerase

An enzyme that catalyses the formation of pi=olymers of DNA by linking nucleotides into a chain by complementary base pairing with a template strand

DNA profiling

A technique used to produce an individual’s unique pattern of DNA bands on a gel. Produced by analysing short tandem repeat (STR) regions of a genome

DNA sequencing

A technique used to determine the sequence of bases in DNA. DNA sequencing can be used to determine relationships between individuals of a species and for determining the entire genome of an organism

DNA thermocycler

The machine used in the polymerase chain reaction that alters the temperature in the pre-programmed steps

Endonucleases

An enzymes (also called a reaction enzyme) that occurs naturally in bacteria and can cut DNA at a particular site (a recognition site); used in genetic engineering. Cuts the sugar-phosphate bond between nucleotides.

Gel electrophoresis

A technique used for separating fragments of DNA, or different proteins, based on the molecular weight (or length). Fragments migrate through a gel at rates that are dependent on weight and charge

Gene cloning

The production of a identical copies of a gene

gene editing

The modification of genes by removal, substitution or alteration of by mutation, without necessarily introducing a foreign gene

genetic transformation

The process of cells incorporating foreign DNA. This process can be natural or artificial

Genetically modified organism (GMO)

An organism with genetic modification (GM) made by transfer of specific genes from another organism (transgenic) or by gene editing techniques

Guide RNA (gRNA)

A short, synthetic RNA composed of a scaffold sequence necessary for the Binding of the Cas9 enzyme. Guide RNA guides the Cas9 enzyme to DNA target sites and the enzyme cuts the DNA in the editing technique CRISPR-Cas9

hydrolase

breaking a bond by adding water

inducer

A molecule that regulates gene expression

Ligation

The process of joining two fragments of DNA using a DNA ligation enzyme

palindromic sequence

A DNA or RNA sequence that is the same when read from 5’ to 3’ on one strand and 5’ to 3’ on the complementary strand

plasmid

Small, circular pieces of double stranded DNA found in bacterial cells. Plasmids, replicate independently of the bacteria’s chromosomal DNA and are used in genetic engineering for recombinant DNA

polymerase

A group of enzymes that catalyse the formation of polymers, in particular the formation of nucleic acid polymers by complementary base pairing with a template strand

polymorphism

Genetic variation within a population. The least common allele has to have a frequency in a population of 1% or more to  be considered polymorphism rather than mutation

primer

A short strand of DNA or RNA that is able to bind oe anneal to single-stranded DNA to create a region where DNA polymerase can join and initiate DNA synthesis

Recognition (restriction) site

 The short sequence of DNA bases recognised and cut by a restriction enzyme

recombinant DNA

DNA that has been genetically engineered forming fragment of DNA from two or more different organisms

Recombinant plasmid

A plasmid containing a foreign gene that has been inserted by the use of restriction enzymes and DNA ligase

regulatory gene

A gene that codes for transcription factors (which turn control gene expression at the transcription stage)

reverse transcriptise

A type of polymerase enzyme used by retroviruses to copy their RNA genome into DNA; used in genetic engineering to copy messenger RNA (mRNA) into complementary DNA (cDNA)

RNA polymerase

An enzyme that catalyses the synthesis of RNA, using an existing strand of DNA as a template

Short tandem repeat (STR)

A region of non-coding DNA with 4-6 base pair repeated sequences. Used in DNA profiling

Spacer region

DNA from bacteriophages that have infected the cell in the past

Sticky-end restriction enzyme

A type of restriction enzyme that makes a staggered cut in DNA to leave fragments with overhanging (or ‘sticky’) ends. The exposed bases of the sticky ends are then able to form complementary base pairs with nucleotides of other DNA molecules that have been cut with the same restriction enzyme

Taq polymerase

A  type of heat-resistant DNA polymerase that is widely used in PCR

Target DNA

A particular region of DNA molecule that a scientist intends to study or manipulate

Transgene

A gene or genetic material that has been transferred naturally or by genetic engineering techniques from one organism to another

Transgenic organism

A genetically modified organism (GMO) that has has a gene from another species inserted into its genome

Vector

A vehicle used to transfer foreign DNA into a cell (e.g a plasmid, virus or liposome).

X-gal

A synthetic compound that contains a galactose connected to an indole. When connected it is white. When broken off the galactose, the indole turns bright blue