Term | Definition |
Allele | Alternative form of the same gene. |
Asexual Reproduction | Reproduction in which genes are passed down from only one parent. |
Base | The four bases: Adenine(A), Cytosine(C), Guanine(G) and Thymine(T). They make up the 'rungs' of the DNA 'ladder'. Are always in the same pairings - A+T, C+G |
Carrier | A person whose cells have both a normal and faulty allele. Symptomless carriers show no sign of the genetic disorder they are carrying. |
Cell | The basic 'unit of life' consisting of a nucleus and cytoplasm, surrounded by a membrane. |
Characteristic | A feature of an organism. A result of a genes instructions to a cell. |
Chromosome | Thread-like structures in the nucleus made up of DNA. |
Clone | A group of genetically identical plants or animals produced asexually from the one parent. |
DNA | A chemical containing the code which tells a cell how to develop. DNA stands for deoxyribonucleic acid. |
Dominant | An allele which overrides other alleles of a gene so that their affects are hidden. |
Environment | The surrounding conditions in which an organism develops. |
Fertilisation | When the nuclei of two sex cells such as egg and sperm join together. |
Gamete | A sex cell. For example an egg or a sperm. Gametes only carry one copy of an allele. |
Gene | A section of DNA that contains the instructions of a particular characteristic (or protein) such as eye colour. |
Generation | A term used to describe the descendents of a pair of individuals. For example the first generation is their children and the second generation is their grandchildren. |
Genetics | The science concerning the inheritance of characteristics. |
Genotype | The combination of alleles held by an individual. |
Heterozygous | A genotype where both alleles are different. |
Homozygous | A genotype where both alleles are the same. |
Inheritance | A term used to describe the passing of genes from parents to offspring. |
Nucleus | Part of a cell which contains genetic information in the form of chromosomes. |
Phenotype | The physical characteristics produced by a particular genotype. |
Punnet Square | A diagram showing how alleles can combine during fertilisation. |
Recessive | An allele whose effects are hidden by the presence of a dominant allele. A recessive allele must be inherited from both parents in order to show it's effects in the offspring. |
Selective Breeding | Breeding plants or animals from individuals that have the characteristics you most want. |
Sexual Reproduction | Reproduction in which half the genes are inherited from each of the two parents. |
Variation | This describes the differences shown in a group of organisms. |
Zygote | An ovum (egg cell) that has been fertilised by a sperm cell. |