Stručný slovník biotechnologických pojmů a výrazů

A

actin

a peptide forming a cytoskeleton filamens

acyl-CoA

coenzyme A carrying a activated acyl-group

acylation

substitution a molecule by an acid group

adenine

(A) – 6-aminopurine, one of the five most important bases in nucleic acids. Represents a letter in the genetic code. Adenine is also a component of the ATP and several coenzymes (coenzyme).

aerobic

a (biological) process or organism using oxygen

aflatoxins

another name for mycotoxins (mycotoxine) - substances produced by moulds, viz. Aspergillus flavus. Cancerogenic substances. Very serious contaminant of food and feed. Due to lipophilic nature pass from feed into animal fat and milk.

Agrobacterium tumefaciens

soil bacterium capable of transfer its own plasmid to plant cell. The plasmid carrying genes for the formation of plant growth hormone induces multiplication of plant cells, thus resulting in the formation of a structure resembling tumour.

alfa-helix

secondary coiled structure of polypeptide

allele

alternative form of certain gene

allergen

a substance in sensitive person inducing the formation of antibodies (antibody) (immunoglobulin E) that cause an oversensitivity to this particular substance (e.g., pollen).

allergy

oversensitivity to particular substance due to formation of antibody against it.

amino acid

organic compound bearing both acid group –COOH and amino group –NH2; the stereoisomers with the configuration ??are building blocks of proteins. There are 20 main amino acids in proteins.

amylase

an enzyme hydrolysing starch

amylopectin

component of starch with branched polysaccharide chain

amylose

component of starch with linear polysaccharide chain

anaerobic

a (biological) process or organism going or living in the absence of air

anthocyan

plant coloured substances soluble in water; localised in vacuoles (vacuole)

antibody

a glycoprotein molecule formed by the immunity system as a response to the antigen and specifically reacts with it.

anticodon

sequence of three bases in the tRNA molecule specifically binding to codon in the mRNA molecule

antigen

a macromolecule, usually a protein or glycoprotein, capable of inducing immunology response, i.e. formation of antibodies (antibody) and specifically reacting with them

apoptosis

programmed process of cell death that proceeds as natural regulated decomposition of cell structures

archea

a kingdom of organisms with the morphology of bacteria (they were called also “archebacteria”) but different from bacteria on molecular bases. In some respects close to eukaryota. They are anaerobic organisms, some of them living in extreme conditions (e.g., at high temperature).

ATP

adenosine triphosphate; a molecule that performs a function of a universal storage unit of chemical energy in living systems

autochthonous

naturally occurring

autosome

any chromosome except for sex-specific chromosomes (gonosome)

autotrophic

organism generating energy independent on organic substances

auxin

plant hormone | ??indolylacetic acid

auxotrophic mutation

mutation causing auxotrophy, i.e., inability to synthesise certain essential component for life, therefore this component must be present in the medium

B

Bacillus thuringiensis

microorganism common in the nature. During the formation of spores it synthesises a protein in a crystalline form that is toxic for specific groups of insects.

bacteriophage

a virus infecting bacteria

base

general name for alkaline molecules, but in biotechnology means two purines (A and G) and three pyrimidines (C, T and U), which occur in nucleic acid and play the role of letters in the genetic code.

Basta

commercial name of the herbicide gluphosinate

beta-sheet

a sheet-like secondary structure of polypeptide chains

biodiversity

spectrum of biological species

biolistic method

the way of introduction of foreign DNA in a plant cell consisting in the bombardment of the cell with gold or tungsten microspheres with adsorbed that DNA

biom

characteristic community of plants formed on large scale by climatic conditions, e.g. desert, rain forest, ocean, forest, etc.

bioremediation

removal of pollutants by the activity of organisms

biotechnology

usually defined as any processing method based on live organisms or their parts for the human needs using also modification of organisms´ traits

biotop

the area of life of certain community of organisms or species determined by environmental conditions

bp

abbreviation for base pair

Bt crops

(e.g., Bt corn, Bt cotton, Bt potato, etc.) – are genetically modified crops with introduced gene from Bacillus thuringiensis coding for the protein toxic for specific group of insects; the toxin after ingestion binds to specific receptor in the intestine of given insect and destroys the intestinal epithelia cells.

C

C

usually means cytosine

C-3-plants

plants performing direct binding of carbon dioxide

C-4-plants

plants performing indirect binding of carbon dioxide; their photosynthesis is more effective. E.g., corn and sugar cane

callus

a structure formed by plant cells that did not pass differentiation but are able to divide

carotene

a lipophillic red compound with conjugated bonds found in plant cells

cassava

plant with starch tubers -?Manihot esculenta (Euphorbiaceae) growing wild in American continent (Amazonia to Mexico). Next to potato most common source of starch

cell culture

cells grown in vitro

cell membrane

bilayer of phospholipides (phospholipids) that surrounds the cell content (cytoplasma)

cell wall

a solid structure of plants and fungi covering the cell; composed from cellulose, pectin and chitin (in fungi)

chimerical

an organism or gene composed of parts of different origin

chitin

an aminopolysaccharide present in the cell wall of fungi and forming solid external skeleton of insects and crustacea

chlorophyll

chemical substance in plants and certain bacteria that absorbs light in the red region (therefore has green colour) converting the light energy into chemical energy

chloroplast

an organelle in plant cell composed of a membrane system (thylacoid) and containing chlorophyll; the site of photosynthesis. See plastids.

chromatin

a complex of DNA and histones

chromosome

distinct structure the nuclear content (i.e., DNA and histones) is organised in during nuclear division (mitosis); the number of chromosomes is constant in species.

clone

a set of organisms or cells with identical genome usually originating through vegetative reproduction

cloning

in general vegetative reproduction (e.g., using potato tubers for planting potato); in molecular biology multiplication of a gene using bacterial plasmides; in animal reproduction the introduciton of a body cell nucleus into the enucleated oocyte and transfer of the developing embryo into an uterus of a surrogate mother. This is called reproductive cloning. If the embryo is used as a source of stem cells (cell) (and is destroyed in this way) such method is called therapeutic cloning.

CoA

coenzyme A – carries acyl groups during synthesis processes in the cell

code

see genetic code

codon

triplet of bases determining particular amino acid

coenzyme

non-protein part of an enzyme (usually can be separated from the protein part) that executes the chemical reaction of the enzyme

collagen

protein forming the extracellular matrix

complementary

in molecular genetics a sequence of bases that reflect a sequence of a master chain obeying a pairing rule A-T(U) and G-C

conjugation

natural association of two organisms accompanied with the transfer of genetic material

construct

a part of a DNA molecule prepared in vitro to be transferred into the receptor DNA in genetic engineering

crossingover

an exchange of corresponding segments between parent chromosomes (chromosome) during meiosis

cry-protein

see ?-endotoxine

cytoplasma

general name for the content of the cell harbouring organells (organelle), i.e., structures separated by a membrane

cytosine

2-oxy-4-aminopyrimidine, a base of nucleic acid pairing with guanine

cytoskeleton

a network of protein filaments and tubuli in the cytoplasma of eukaryotic cells; fixing organells (organelle), modifying the shape of the cell (e.g., executing endocytosis) and directing the cellulose molecules during the cell wall synthesis in plants

D

denaturation

change to unnatural not active form (proteins by heat); in connection with nucleic acid means the separation of strands from double helix

deoxynucleoside

a nucleic acid base (A, G, C, T, U) substituted by deoxyribose

deoxynucleotide

a phosphate ester of deoxynucleoside

deoxyribonucleic acid

see DNA

destruents

organisms decomposing dead organisms or their debris

detritus

particles of organic mater resulting from dead organisms that accumulate on the soil surface

dicotyledones

plants with two storage leafs (cotyledons) upon germination

diploid

organism (cell) with two sets of chromosomes (chromosome), containing one pair of each

DNA

deoxyribonucleic acid. Linear polymer composed from four monomeric units called nucleotides (nucleotide). They are connected by ester bond between phosphoric acid and hydroxyl of the sugar deoxyribose. Stable form is represented by double helix where two opposite running chains are bond through base pairing adenine with thymine (A-T) and guanine with cytosine (G-C). The sequence of bases forms a genetic code.

DNA polymerase

an enzyme catalysing the synthesis of DNA

dominant allele

the allele from two or more present in a genome that is expressed and determines the trait(s), the other is recessive allele

donor organism

in genetic engineering the source of introduced gene

E

E. coli

stays for Escherichia coli bacteria normally common in human intestine as a commensal or symbiont, however certain strains may be pathogenic. Most common laboratory object in molecular biology and biochemistry.

ecosystem

holistic unity of organisms and inorganic factors forming at certain biotop a network of mutual interactions

electrophoresis

separation of molecules by the electric field in certain medium; the movement of molecules is the result of two opposite forces: the driving force (depending on the charge of the molecule) and the medium resistance (depending on the size of the molecule). Therefore it is used for sorting molecules according to size.

electroporation

distortion the cell membrane by an electric pulse that makes possible the intracellular transfer of DNA molecule

endocytosis

engulfing of particles or liquid droplets from surrounding medium inside the cell; the process is performed by cytoskeleton making inverse sac of cellular membrane.

endonuclease

enzyme hydrolysing the ester bonds along the strand of nucleic acid; enzymes hydrolysing the bond at ends of the polynucleotide chain are exonucleases

endoplasmatic reticulum

intracellular tubular membrane structure in eukaryotic cells. The place of synthesis and shape formation of most proteins

enzyme

a protein with catalytic function

epithel

type of tissue forming the lining of body cavities or envelope of body internal organs

epitop

a characteristic part of the molecule exposed on its surface that is recognised by the immunity system

erythrocyte

red blood cell

ethylene

unsaturated hydrocarbon with the function of a plant hormone

eukaryonts

organisms having DNA inclosed in a cell nucleus separated from cytoplasma by a membrane

eukaryotic cell

a cell with nucleus separated from cytoplasma by a membrane

exon

segment of the gene (DNA) carrying genetic information. When transcribed in the mRNA corresponding part of the mRNA molecules is released from the nucleus and takes part in the synthesis of proteins. The segment giving the part of mRNA remaining in the nucleus is called intron.

exonuclease

see endonuclease

expression of the gene

synthesis of a protein coded by the gene that results in occurring of the particular trait

extracellular matrix

secreted proteins and polysaccharides outside cells and binding them together

F

F1 , F2

fírst and second generation resulting from sexual hybridisation

fenotype

sum of all genetically determined traits of an organism

fermentation

process driven by microorganisms or enzymes chemically changing organic substances; originally was limited to anaerobic processes, recently covers all processes.

fingerprinting

in molecular biology means sorting the fragments of DNA according to their size by electrophoresis. The fragments are obtained by splitting the DNA by restrictases. Therefore the molecule is broken at specific sequences and the size distribution of fragments in facts indicates the frequency of these particular sequences along he chain. This is typical for an individual and therefore compared to fingerprints.

flavin

a substance of yellow colour found in several coenzymes n the electron transfer chain

fusion of protoplasts

protoplasts prepared by removing the cell wall from the plant cell are treated by chemicals (e.g., polyethylene glycol) or electric field. This causes disturbances in cellular membranes resulting in joining the content of two protoplasts in one membrane envelope.

G

G

usually stands for guanine, a purine base of nucleic acid

gama-endotoxine

protein formed by Bacillus thuringiensis toxic for specific groups of insects; another name cry-protein

gamete

sexual cell, e.g., ovum, sperm cell, pollen; macrogamete means female gamete, mictogamete male gamete

gene

a segment of linear DNA molecule carrying specific information; either determines the composition of protein, of RNA (structural genes), or executing a regulatory function (regulatory genes); most of genes are located in chromosomes (nucleus), but mitochondria, plastids in plants and plasmids in bacteria contain own genes.

genetic code

the rule determining particular amino acid by particular triplet of nucleic acid bases

genetic engineering

changing the chemical composition of DNA in a way that changes the traits of the organism

genetic information

sum of the information stored in genes

genetically modified organism (GMO)

in common sense means hereditary changed organisms, but by convention of legislation this means an organism whose DNA was changed by genetic engineering, i.e., by addition of gene(s) from other organism or by removal of particular native gene. The introduced gene is equipped by regulatory signals so that it exhibits its own function.

genofond

the sum of all genes carried by all members of particular species

genome

the sum of chromosomal genes of particular organism (individual)

gluphosinate

synonymum phosphinotricine; common name for 4-(hydroxymethyl)-phosphinoyl-D,L-homoalanine. It is produced by soil aktinomycetes (e.g., Streptomyces hygroscopicus). Produced by synthesis as a commercial broad-spectrum herbicide under names Liberty, Basta, Finale, Radicale and others.

glycogen

storage polysaccharide in animals composed from glucose units

glycoprotein

protein with saccharide units in side chains

glyphosate

common name for ??phosphinomethyl-glycin, total herbicide, commercially produced under the name Roundup

GMM

abbreviation for “genetically modified microorganism”

GMO

abbreviation for “genetically modified organism” *

Golgi system| cellular organelle*, site of modification and separation of proteins and lipids; in plants also a site of cellulose synthesis

gonosome

a chromosome determining sex; in mammals female is determined by two X gonosomes, male by X and Y pair

guanine

2-amino-6-oxypurine, base of nucleic acids; as a rule in base-pairing makes pair with cytosine

H

haploid

cell or organism with simple set of chromosomes containing one of each

herbicide

a pesticide, i.e., chemical suppressing the growth of plants

heterosis

vitality of hybrids with different alleles from parents that is higher than vitality of either parent

histones

basic proteins that binds to DNA forming with it a regular structural complex (chromatin) in nucleus and chromosomes

homology

corresponding nature of organs (e.g., wing of birds and leg of mammals), in polynucleotides corresponding sequence of bases

homozygote

an organism having identical alleles of a gene

hormones

chemical substances executing information function by regulating certain processes

hybridisation

in general crossing of female and male individual; in polynucleotides formation of a complex of two chains by pairing of bases A-T (or A-U) and G-C.

hydrophilic

a substance with affinity to water

hydrophobic

a substance with no affinity to water or repelling water

I

immunoglobulin

glycoprotein with a function of an antibody

in vitro

a process going outside from a living organism (“in a testube”)

insecticides

chemical substances suppressing insect pests, usually toxic to insects

insert

a fragment of DNA chain introduced by genetic engineering into the DNA molecule; usually a construct harbouring a transgene.

integration

in genetic engineering means the joining of an insert with the DNA it was introduced to

intron

the segment of a gene (DNA) without genetic information. After transcription the corresponding part of the mRNA is excised and stays inside the nucleus; see exon.

K

kb

kilobase, means thousand of bases in sequence of a polynucleotide (nucleic acid)

L

Liberty

commercial name for the herbicide gluphosinate

ligase

an enzyme joining polynucleotide chains by forming sugar-phosphate bonds

lipophilic

substance having high affinity to fat (oils)

LMO

abbreviation for “Living Modified Organisms”; equivalent to GMO

locus

position of an allele in the sequence of genes (genetic map) in the genome

lymphocyte

white blood cell producing amtibodies

lysosome

a cellular organelle (vacuole) containing digestive enzymes

M

macrophage

white blood cell with a phagocytosis activity

meiosis

the division of cell nucleus during the formation of gametes reducing the diploid number of chromosome in a haploid set

mitochondria

a organelle of all aerobic eukaryoticcells generating energy by electron transfer to oxygen; it has own DNA carrying genetic information. This is why mitochondria can be reproduced only by division of mitochondria.

mitosis

division of cell nucleus; the content of the nucleus is organised in chromosomes and each of them is divided in two equal copies. They are separated to opposite poles and formed in two daughter nuclei. This is the mechanism of distribution of equal sets of genetic information.

monoclonal antibody

the antibody produced by a clone of one cell that is obtained by the fusion of a lymphocyte and a tumour cell. The tumour cell induced infinite division. As the clone has identical genetic information, the antibodies the cells form have identical structure an consequently equal specificity for the antigen the lymphocyte was induced by.

monogenic

a trait regulated by one gene only

mRNA

RNA resulting from the transcription of DNA; if the DNA contains introns, the part corresponding to them is excised and the rest (corresponding to exons) leaves the nucleus. It is used by ribosomes as a template for the synthesis of proteins.

mutagenesis

artificial induction of mutations

mutation

is a change of genes that may result in a change of traits

mutualism

interaction of two organisms providing profit to both

mycotoxine

a chemical substance produced by moulds (lower fungi) exhibiting adverse physiological effects (e.g., leading to tumour induction)

N

nuclease

an enzyme hydrolysing the sugar –phosphate bonds in polynucleotide chain

nucleoside

a nucleic acid base (A, G, C, T, U) substituted by ribose

nucleotide

a phosphate ester of nucleoside

nucleus

an organelle of eukaryotic cells containing genetic material (DNA in a complex with proteins)

O

oligosaccharide

a polymer of few sugar units

oncogene

a gene capable under certain conditions of inducing tumour growth

operator

see operon

operon

a group of adjacent genes transcribed as a single chain of mRNA and regulated by a single regulatory gene called operator

organelle

a component of a cell separated from the cell content by a membrane and having specific function

Ostrinia nubilalis

moth belonging to Lepidoptera called “(European) corn borer”; very serious pest of maize

P

pairing rule

also called Watson-Crick pairing, means the binding of adenine to thymine or uracil (A-T or A-U) by two hydrogen bridges and guanine to cytosine (G-C) by three hydrogen bridges

PCR

polymerase chain reaction; a method of in vitro preparing multiple copies of a polynucleotide chain by the use of enzyme

pectin

plant polysaccharide with branched chains and carrying negative charges

peptide

a chain of amino acids connected by peptide bonds

peptide bond

the bond connecting the carboxyl group of one with the amino group of other amino acid

pesticides

a chemicals suppressing pests (e.g., herbicides, insecticides, fungicides, etc.)

PHA

poly(hydroxy) alkanoate – a polymer synthesised under certain condition from acyl-CoA by bacteria or plants; a biodegradable plast.

phagocytosis

endocytosis of solid particles

pharming

abbreviation for “pharmaceutical products farming”; main target are pharmaceutical important peptides.

PHB

poly(hydroxy)butyrate – PHA composed from hydroxybutyric acid as a monomer

phenotype

a sum of apparent traits of an organism

phosphinotricine

total herbicide – see gluphosinate

phospholipids

glycerol esters containing two long-chain acids and one phosphoric acid

photosynthesis

the conversion of the energy of light to chemical energy stored in chemical compounds – primary sugars – through the reduction of carbon dioxide; oxygen is the by-product in plants; this process take place in plant chloroplasts.*

phylogenesis

history of biological evolution

phytochrome

compound absorbing light in the visible region and converting this absorption to regulatory signal in plants

phytohormones

chemical substances in plants with an activity similar to animal hormones – they represent an information signal regulating various processes

phytoremediation

removal of pollutants using plants

pinocytosis

endocytosis of liquid droplets

plasmides

small circular molecule of DNA in bacteria independently replicating in the cell; carries several genes. Plasmids are used as vectors in genetic engineering.*

plastids

plant cell organells: chloroplasts contain chlorophyll, amyloplasts form starch, chromoplasts contain dyes, etc. Carrying own DNA they multiply only by division of existing plastids.

polygenic

a trait regulated by several genes

polypeptide

a polymer of amino acids

polyploid

organism (cell) with many copies of each chromosome

polysaccharide

a polymer of many sugar units

predator

an animal using other living animals as prey

primary production

energy accumulated by plants in organic substances

primary structure of proteins

sequence of amino acids in the polypeptide chain

programmed cell death

see apoptosis

prokaryotic cell

cell lacking a nucleus as a distinct organelle separated by a membrane

promoter

segment of DNA serving as the attachment site for the RNA polymerase; the transcription starts at this segment.

protoplast

content of plant cell surrounded by cell membrane that results from the removal (dissolution) of the cell wall

R

receptor

a structure usually located at the cell surface specifically binding certain substance(s) (e.g., hormone)

recessive

see dominant

recombinant DNA

DNA with added segment(s) of other DNA molecule(s), e.g., DNA with an insert

recombination

an exchange if genetic material

regeneration

the process bringing a system to the original state. Cells removed from a plant may be grown in a culture and then regenerate in the whole plant.

repair

usually means the correction of damage in the DNA molecule that results from e.g., irradiation, or chemical substances.

replication

means copying molecules of nucleic acids or sometimes used for vegetative multiplication of unicellular organisms (e.g., bacteria)

repressor

a molecule blocking certain process, e.g., transcription

restriction endonucleases

endonucleases that cleaves the DNA double-strand molecule at specific sequence of nucleotides; the cleaving points in both strands may be shifted by several nucleotide units. Therefore the ends readily adhere due to base pairing. They are called sticky ends.

retrovirus

a virus with RNA as a carrier of genetic information and copying it to DNA molecule in the host cell by an enzyme reverse transcriptase

reverse transcriptase

an enzyme polymerising DNA molecule using RNA as a template

ribose

pentose, i.e. sugar having five carbon in the molecule

ribosomes

particles composed from specific (ribosomal) RNA and proteins; they execute the synthesis of proteins using mRNA as a template for the amino acid sequence.

RNA

see ribonucleic acid

RNA polymerase

an enzyme catalysing the synthesis of RNA

Roundup

a commercial name of a total herbicidewith glyphosate as an active component

S

secondary structure of proteins

three-dimensional organisation of a polypeptide chain; see ?-helix or ?-sheet

selection

the choice of certain individuals; natural selection is accomplished by environmental conditions, artificial selection is a result of breeding

selection advantage

see selection pressure

selection gene

a gene in an insert that facilitate the survival of transformed cells (i.e., with expressed the inserted genes) in conditions suppressing the non-transformed cells

selection pressure

environment conditions supporting the reproduction of certain members of the population, so that the frequency of their genes increases; such individuals posses selection advantage

sequence

linear array of monomers (e.g., amino acids, nucleotides) in a polymer (peptide, nucleic acid)

sequencing

laboratory method of determining the sequence

signal gene

a gene in a insert coding for an unique trait that indicate that the cell or organism contains the insert in its genome and the inserted genes are expressed; in many cases the gene coding of a fluorescing protein is used as a signal gene.

somatic cell

all cells except gametes

stem cells

are animal cells that are not differentiated and are able to differentiate in various types of cells; they are classified according to the origin: embryonic, somatic, bone marrow, umbilical cord blood, etc.

T

T

usually stays for thymine

t-plasmid

a plasmid of soil microorganism Agrobacterium tumefaciens. It can be transferred in plant cells and since it carries genes coding for plant hormones, it causes the division of host cells. As a result the plant forms a structure resembling tumour; This plasmid is used as a vector in genetic engineering of plants.

telomerase

a reverse transcriptase that synthesises telomeres using their own RNA as a template

telomeres

simple repeated sequences at the end of chromosomes

terminator

regulatory segment of the gene giving the signal to stop the transcription

thylakoid

internal membrane structure of a chloroplast

thymine

2,4-dioxy-5-methylpirimidine, a DNA base pairing with adenine

thymine dimmers

covalently bond two thymine molecules in the DNA; most common damage due to ultraviolet light irradiation

tissue culture

a differentiated part of an organism grown in vitro

TMV

virus of mosaic disease of tobacco

transcapsidation

wrapping the viral nucleic acid in a protein envelope of other virus

transcription

synthesis of mRNA on DNA template; this process passes the genetic information from DNA to mRNA

transduction

a transfer of DNA between bacteria executed by a bacteriophage

transgene

gene introduced to the genome of an organism by genetic engineering; the origin of this gene is usually another organism, i.e., the gene is transferred from it.

transgenic

cell or organism with a transgene in its genome

translation

synthesis of polypeptide using the information from mRNA; this process transforms the information encoded in the sequence of bases (triplets, codons) into the sequence of amino acids in the polypeptide chain. See also tRNA.

TRICHOCAP

commercial name for the product of BASF designed for suppression of a maize pest Ostrinia nubilalis . It contains capsules with several hundreds of cocoons of Trichogramma brasicae

Trichogramma brasicae

little wasp laying eggs in eggs of other insects, including Ostrinia nubilalis. The host eggs are used as food for the larvae of Trichogtamma.

triplet

three adjacent bases representing codon for particular amino acid

tRNA

transfer RNA is a molecule of RNA with an anticodon and carrying activated particular (i.e. corresponding to the codon) amino acid attached to its end. The anticodon recombines with the codon on the mRNA molecule associated with ribosome and the activated amino acid is added to the polypeptide chain. In this way the process of translation is performed on ribosomes.

turgor

a hydrostatic pressure inside the plant cell usually due to the water solution in the vacuole. Turgor keeps the shape of the cell and in this way of the plant soft parts.

U

U

usually means uracil

uracil

2,4-dioxypirimidine; in RNA stays instead of thymine

V

vacuole

a cellular organelle filled with liquid, sometimes also with particles (crystals, dyes)

vector

generally a subject that deliver certain agens; e.g., mosquito is a vector of malaria plasmodium. In molecular genetics vector means a nucleic acid or virus that introduces the construct into the cell

viroids

particles resembling virus but more simple, containing single chain of circular RNA and lacking protein envelope. Pathogenic for plants.

virus

particle composed from nucleic acid (DNA or RNA) enclosed in a envelope built from protein(s). It penetrates the host cell and multiplies in it misusing the synthetic apparatus of the host. After completing the synthesis of own nucleic acid and envelope protein(s) virus particles are assembled and by various ways leave the host cell. The host cell is either destroyed or survives. Due to this type of reproduction virus is not regarded as an organism.

W

Watson

Crick pairing, see pairing rule

Z

zygote

a fertilised egg