VCE BIOLOGY GLOSSARY:
Terms used in biotechnology.
This list of terms is not exhaustive. It is derived from terms used in the Interviews with Scientists at the VCE Biology Students' Site.
Students should consult their textbook or a good biology dictionary for meanings of other biological terms not listed here.
Particular forms of a gene. Alleles usually occur in pairs, at the same gene locus, on an organisms homologous chromosomes. If both alleles are the same, the organism is homozygous, if they are different, the organism is heterozygous.
antibody
An immunologically active protein made by B cells in response to a specific antigen.
antigen
A foreign substance, such as a virus, bacteria or protein, that triggers an immune response.
autosomes
A type of chromosome, found in all cells, that is NOT concerned with sex determination. In humans there are 44 autosomes and two sex chromosomes in all body cells.
bacteriophage
A virus that infects bacteria, used in biotechnology for transfer of DNA into a bacterium also called phage .
biotechnology
The scientific manipulation of living things to produce useful products - especially involving the manipulation of DNA.
bottleneck effect
A period in the history of a population during which the population number is severely depleted, perhaps by disease or changed environmental conditions. During this time, the gene pool may also become depleted, leading to reduced genetic variability within the surviving population.
callus
A mass of immature plant cells growing in laboratory tissue culture. Can be stimulated to develop into an entire plant with appropriate treatment with plant hormones.
The use of chemical substances to treat people suffering from malignant cancers. The chenotherapeutic agents are usually designed to interfere with mitosis in some way, thus slowing the rate of division of the malignant cell mass.
chimera
(chimaera in UK English) An organism, usually a plant, with a genotype containing genes from two different species.
chromosome crossover
During meiosis, when DNA replication has occurred and homologous chromosomes are paired, the chromatids my intertwine and break. This process is known as crossing over. Enzymes repair these breaks, but not always in the correct manner to restore each chromatid to its previous location. Chromatids, therefore, can 'swap' between different DNA strands. The breaking and repair of chromosomes in this way can lead to chromosomal mutations.
chromosomal mutations
Changes to the chromosome number or structure. Chromosomal mutations may result in whole chromosomes being absent or extra chromosomes being present (as in Trisomy 21), or to sizeable portions of a chromosome being absent or in the wrong location.
cell cycle
The ordered sequence of events in the life of eukaryotic cells including cell growth and division phases.
cell differentiation
The, generally irreversible, process by which a cell or group of cells adopt a specialised function - controlled at the level of genes by regulatory proteins.
cell fractionation
The technique of separating the components of cells, membranes, nucleus, cytoplasm, mitochondria and the like, so that each may be examined as needed.
cell membrane
Structure forming outer cell covering and found inside cells, a lipid bilayer with proteins on or within the bilayer, refer to the diagram in notes for cell structure and function.
cell structure
The total type and arrangement of components in a cell - varies depending on species and specialised function.
clone
(noun) A population of cells, arising by mitosis, which are genetically identical to the parent cell; (verb) see cloning below.
cloning
Process of growing a large number of genetically identical cells from a single cell.
common ancestor
An ancestor, often only known from fossil remains, from which two or more different species or lines of species are thought to have evolved.
constructs
New arrangements of genes produced by genetically modifying DNA.
A type of mutation where a section of a gene or of a chromosome is missing. Deletions may or may not have a phenotypic consequence, depending on the normal role of the DNA which is absent.
DNA gun
Any one of several methods of inserting a transformed plasmid into a cell. See also gene transfer techniques.
DNA ligase
An enzyme that catalyses the reaction which links together two DNA molecules - used in linking DNA fragments together at their sticky ends formed previously with a restriction enzyme.
DNA polymerase
An enzyme that catalyses the synthesis of double stranded DNA using a primer and DNA as a template - used in PCR.
DNA probe synthesis
The production of a single stranded DNA molecule with base sequence designed to be complimentary to DNA it is intended to bind to - may contain radioactively labelled bases which help with location of the probe later.
DNA replication
A normal process in cells which are about to divide - DNA double strands dissociate and the enzyme DNA polymerase catalyses the addition of complimentary bases to each strand. Two identical DNA molecules are formed.
DNA sequencing
The process of determining the sequence of the bases in a length of DNA - this uses chemical methods and can be done with a machine.
DNA structure
The three-dimensional double helix as determined by Watson and Crick. Complimentary base pairing (adenine with thymine and cytosine with guanine) enables many hydrogen bonds to form between the two strands, holding the strands together.>
Edman reaction
A chemical reaction used to remove and analyse amino acids one by one from a protein, used in determining the primary structure of a protein, this can be done with a machine.
electrophoresis
A method of separation of molecules in a mixture; an electric current is passed through the mixture which has been loaded on a support medium, usually a gel or sometimes paper, the molecules move through the support - the extent of each molecule's movement is related to its size and its charge.
entomology
The study of the biology of insects.
evolution
An explanation of the way present-day and past organisms have been produced. Current evolutionary theory explains this process on the basis of mutations being the starting point for Natural Selection to choose the best varients in a population. Over time, the mutations which are passed on to succeeding generations, accumulate so that speciation occurs. This is the evolution of new species.
evolutionary distance
A measure of the time since two distinct, or similar species shared a common ancestor. May also be used as a measure of time since reproductively isolated populations of a species were one breeding population.
exons
The portion of a gene which is eventually expressed in a protein product. (See also introns.)
A short length of a chromosome, made of DNA, which carries the information for a particular characteristic.
gene data bank
A file of information concerning the chromosome location and the base sequences of the genes of a particular species, used to compare newly isolated genes with those reported by other workers. This information is usually stored as computer data, much of which is available on the Internet.
gene library
A collection of organisms, usually viruses, bacteria or yeast, which have been transformed by the addition of extra genes from another species. The library can be screened to find a gene of particular interest to researchers.
gene locus
The position of a gene along a chromosome.
gene pool
All of the genes, including all of their alleles, in a population.
gene transfer techniques
Any one of a number of methods of transferring genes from one organism (species) to another (usually different species). May involve a vector such as a virus or a plasmid, or may use chemical carriers such as liposomes. The method used depends on the nature of the cell which is to receive the genetic information.
genome
The complete set of genes in a cell, or in the cells of an individual.
genotype
The genetic makeup of an individual. This may refer to just one trait or it may refer to the combination of many or all of the traits of the individual.
Human Genome Project
A cooperative effort to map and sequence all of the genome of the human species.
inbreeding
Mating between closely related individuals. This can lead to a loss of vability in the population due to accumulation of undesirable alleles passed on from a common ancestor.
introns
A piece or number of pieces of the DNA of a gene, which after transcription into mRNA is/are cut out of the mRNA. Therefore, introns do not contribute to the translation of the mRNA into the protein product of the gene.
in vitro
In a test tube, or other laboratory apparatus. Used to describe biological processes happening outside a living organism.
A chemical technique used to investigate aspects of the structure of molecules.
meiosis
The type of nuclear division involved in sexual reproduction. The diploid starting cell gives rise to four haploid gametes.
minisatellite
An oligonucleotide, used as a gene probe, which is produced to reflect the repeats of nucleotide base sequences seen in many eukaryotic genes. Minisatellites are typically between 13 -19 nucleotides in length.
mitochondrial DNA
The DNA in the mitochondria of eukaryotes. This DNA codes for many of the organelles functions and is replicated indepently of the nuclear DNA. Mitochondrial DNA (mtDNA) appears to contain no introns.
mitosis
A type of nuclear division which leads to two identical daughter nuclei in the resulting daughter cells. Occurs in eukaryotes constantly during the processes of growth and repair. Asexual cell reproduction.
monoclones - monoclonal antibodies
A monoclone is a line of cells grown up from a single selected cell. All are genetically identical. If such cells produce an antibody, the resulting monoclonal antibody is exteremely pure.
Agents which increase the rate mutations in DNA. Examples are X-rays, UV light and many chemicals.
mutations
Changes in the genetic material of an organism. These changes may or may not alter the function of a gene or genes, but if genotype is altered there is a chance that this will lead to an accompanying change in phenotype.
The mechanism, proposed by Charles Darwin, by which gradual evolutionary change takes place. Organisms which are better adapted to the environment at any particular time are more likely to pass their alleles to the next generation. The alleles which confer a selection advantage have been 'selected' by 'nature'. So over time, and in the face of environmental changes, a gradual shift in the population's gene pool may occur. This in turn may lead to the evolution of new species.
Noah's Ark Blot
This is a species screening Southern Blotting technique. DNA samples from males and females of the species to be investigated are separated by electrophoresis and probed with the DNA of interest. This technique is useful in gene mapping and in the estimation of evolutionary distance between species.
nucleoside
A chemical structure where a nitrogenous base is attaches to a sugar. In nucleic acids (RNA and DNA), nucleosides are joined together with phosphate residues to form a long chain.
A chemical structure where a nucleoside is attached to a phosphate residue. The sugar molecule is in the 'middle' of the structure, having both the nitrogenous base and the phosphate attached to it.
A short sequence of nucleotides which is needed for the functioning of the enzyme polymerase. In PCR, this sequence is chosen so that it initiates the polymerase chain reaction.
panning
A selection method by which a transgenic virus expressing a desired protein may be selected from a mixture of viruses.
parasitology
The study of the biology of parasites. For example, the study of the biology of the parasite that causes malaria, Plasmodium falciparum.
passive immunity
Immunisation, usually of relatively short duration, induced by the introduction of preformed antibodies into an individual. This may occur naturally, as with the transfer of antibodies between mother and baby, either via the placenta or via breast milk. Or the antibodies may be acquired via injection.
patent
A legal document, protecting the inventor/discoverer of a new process which is deemed to be 'novel, inventive and innovative' from having her/his work copied and sold by others for a profit.
PCR
Polymerase Chain Reaction. A method for amplifying specific DNA sequences in a laboratory. Many millions of copies of the DNA can be produced in just a few hours. The details of how PCR occurs can be found in any good Biology textbook. We've put our version of a PCR diagram on another page.
peptide
A chemical compound that consists of two or more amino acids linked by chemical bonds (peptide bonds).
phage
Short for bacteriophage. (See bacteriophage in this glossary.)
phenotype
The observable features of an individual as they reflect the genotype of that individual and the effect of the indivual's environment.
plasma cells
Antibody secreting cells that develop from B-cells in response to the sequence of events occurring in the humoral immune system upon detection of certain types of antigens.
plasmid
DNA, or sometimes RNA, molecules which occur in cells separately to the chromosal DNA. They occur in both prokaryotic and eukaryotic organisms, often in the cytoplasm. Plasmids are important in genetic engineering, as they can , with appropriate treatment of the cells, be inserted into cells from different species to that from which the plasmid was isolated. Plasmids are easily manipulated to have pieces of DNA inserted and/or removed using modern techniques of biotechnology.
population
The total number of individuals of a particular species in a particular, defined, locality or region.
population genetics
The study of hereditary at the population level. This may include measurement of allele frequencies and the genetic relationships between members of the group.
probes
Particular nucleic acid (DNA or RNA) molecules which can be used to detect specific nucleic acid sequences that are complimentary to the probes. The probes are labelled in some way so that, when hybridised with the complimentary nucleic acid, the probe can be detected. Probes are often labelled with either radioactive isotopes or fluorescent chemicals.
promotor
A particular nucleotide sequence in the DNA of a gene that promotes the initiation of transcription by allowing the enzyme RNA polymerase to bind to the DNA.
protein primary structure
The linear sequence of amino acids in a polypeptide or protein. This is the amino acid sequence for which the triplet code of bases in the mRNA codes.
protein purification
Chemical methods, usually based on a combination of chemical properties and physical properties, by which a desired protein is isolated from the other proteins with which it normally occurs.
protein sequencing
The determination of the primary structure of a protein. This is usually done using a machanised version of the Edman reaction, a chemical process which sequentially removes amino acids from the protein and identifies the amino acid which is removed.
protein trafficking
The movement of proteins around a cell or within organelles so that they reach the correct place to carry out their activity. See also targeting.
In biotechnology, this is DNA formed by combining DNA from two different sources. The sources may or may not be from different species, but the recombinant DNA so formed has genetic information considered to be more useful than it was in the two separate sources.
regulatory genes
Segments of a gene which regulate the switching on (expression) of the gene or nor (repression). There are several different types of genes involved in this, and the details are beyond the scope of a secondary Biology course. Interested students may read further about the Operon model of the gene in more advanced texts.
reproductive isolation
A form of genetic isolation where gene transfer between different populations of a species is prevented. The isolating mechanisms may be ecological (such as water barriers), seasonal ( eg breeding seasons at different times of the year), behavioural ( eg different courtship behaviours in each group) or physiological (some aspect of body form or function prevents mating between individuals from each group). In time, reproductive isolation may lead to the evolution of new sub-species or new species.
restriction enzymes
Enzymes produced by bacteria that break 'foreign' DNA into segments, acting at specific base sequences to do this. Different restriction endonucleases have different base-sequence sites at which they act. Many of them produce sticky ends on the products of their activity. These enzymes are sometimes known as "gene shears" and are represented in diagrams as scissors.
restriction fragments
Lengths of DNA remaining after the action of restriction enzymes (see above) on a longer piece of DNA. These fragments may or may not have sticky ends, depending on the nature of the restriction enzyme used in their formation.
reverse transcriptase
An enzyme, originally found in retroviruses, that catalyses the formation of cDNA from an RNA template.
RNA polymerase
An enzyme that catalyses the formation of RNA from a DNA template.
selective breeding
The breeding of selected plants or animals to enhance the probability of desirable characteristics in the offspring.
sex chromosomes
These chromosomes, called X and Y in humans, are the chromosomes that carry the genetic information that controls sex determination. Not all of the information needed for sex development is on these chromosomes, but the vital regulatory genes that initiate the sequence of events that leads to sex development are on these chromosomes. The human female has 44 autosomes and XX, the human male has 44 autosomes and XY.
Southern blotting
A method of transfer of bands of DNA, separated on a gel electrophoresis, onto a membrane, from which the bands may be treated with chemicals to enable them to be seen. {Named after the inventor of the process, E.M Southern. Related methods have been named 'Northern Blotting' (RNA blotting from electrophoresis gels) and 'Western Blotting' (protein blotting) by scientists with a sense of humour!}
species
A population or series of populations of closely related and similar organisms. The individuals within a species are able to interbreed freely with each other, producing healthy, fertile offspring. Members of a species are not able to interbreed successfully with members of other species.
sticky ends
On the ends of a restriction fragment of double stranded DNA, there may be a short, single stranded piece of DNA . This is known as a sticky end, since it may be used to join two or more different restriction fragments together where they have complimentary sticky ends. This is very useful in the formation of recombinant DNA molecules.
targeting
The movement of proteins around a cell or within organelles so that they reach the correct place to carry out their activity.
terminator
A particular nucleotide sequence in the DNA of a gene that signals the termination of transcription.
transcription
The formation of RNA from a DNA template. The RNA may be ribosomal (rRNA), transfer (tRNA) or messsenger (mRNA). The code for the RNA production is revealed when the section of DNA double helix unwinds and one strand (the sense strand) is used as the template for the RNA production.
transfection
A method of introduction of purified viral DNA into cells.
transfection cassette
The carrier of the DNA used in transfection. Usually the virus itself.
transformation
The acquisition of genetic material (DNA) by a recipient cell.
transgenic
An organism carrying genetic material that it would not normally contain.
translation
The formation of a defined polypeptide chain on a ribosome according to the triplet code of bases of the mRNA which codes for the process at the time. (Students should be familiar with the details of this process which will be explained in any Biology text.)
translocation
A type of chromosomal mutation where a piece of a chromosome is moved to an abnormal position on the same or a different (usually) chromosome. This type of mutation may or may not have phenotypic consequences depending on whether or not the genetic material in the moved DNA is able to function normally.
triplet code
A group of three nucleotides in a DNA molecule that codes for a specific amino acid in the protein product of that DNA. Also called a codon. (Students should be familiar with the relationships between the triplet code on DNA, the corresponding bases on mRNA and the eventual translation of this code into an amino acid in a polypeptide chain. This information will be found in any Biology text.)
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