Unit of heredity found on a chromosome, and is an instruction to the cell to make a particular substance, a protein, which helps regulate a trait (characteristic) of an organism. gene The process of changing the information in a gene into a protein and the effect that protein has on the organism. gene expression Spontaneous change in a single gene, i.e. a change in the DNA structure. This changes the nucleotide sequence; which changes the amino acid sequence; which in turn changes the protein produced, e.g. sickle cell anaemia, phenylketonurea (PKU). gene mutation Using transgenic farm animals for the production of pharmaceuticals, e.g. sheep to produce factor VIII. gene pharming All the genetic information possessed by members of a population. gene pool The insertion of genetically altered or normal genes into cells using recombinant DNA technology, to replace the defective genes that cause genetic disorders. gene therapy Condition resulting from a change in a gene or the number of chromosomes. genetic disorder Modern techniques or processes used to artificially alter the genetic information in the chromosome of an organism. The process involves the following: isolation of gene cutting (restriction) transformation (ligation), introduction of base sequence changes expression. genetic engineering
The process of transcribing RNA into DNA (the reverse of transcription); used by retroviruses and in biotechnology. reverse transcription A monosaccharide found in ATP and in nucleotides of RNA. ribose A type of RNA found at the ribosomes, functions during protein synthesis. ribosomal RNA (rRNA) A nucleic acid found in cell nucleus (10%) and cytoplasm (90%). Involved in protein synthesis. There are three types. RNA Enzyme involved in protein synthesis – manufactures messenger RNA from DNA. RNA polymerase To separate a pair of allelic genes during the process of meiosis and resulting in each gamete having only one of the pair of genes. segregate A process which favours one adaptation of organisms over another adaptation found in the population. This occurs through reproduction. Those with the favoured adaptation produce more offspring and become a great- er percentage of the population in the next generation. selection The selection of individual plants or animals that have desirable traits and crossing/mating them in the hope that the progeny/offspring produced will have the combined desired characteristics. selective breeding
One of a pair of chromosomes contains the genes that helps determine the sex of an individual, e.g. in humans XX = female, XY = male. The X chromosome is longer than the Y chromosome. sex chromosome carried on the sex chromosomes, i.e. X and Y chromosomes. They are transmitted together so the phenotype is related to the sex of the individual. Examples of such genes are those controlling haemophilia and red/green colour-blindness in humans. sex-linked / sex-linkage Group of animals or plants that can interbreed and produce viable, fertile offspring. Members of these groups share the same characteristics and differ only in minor details. Each member of a group is unique. species Simple (unspecialised) cell from which specialised cells will develop. stem cell One of the nitrogenous bases found in DNA – a pyrimi- dine. Known by the abbreviation T. thymine Character or distinguishing feature of an organism, e.g. eye colour, height, sex, etc. trait / characteristic The making of RNA from a single strand of DNA. transcription An organism whose genetic content has been changed by adding a gene by genetic engineering. transgenic organism