Biology: Inheritance, Variation and Evolution: Key terms

• Asexual reproduction


  produces new individuals that are identical to their parents; does not involve the fusion of gametes
• Gamete


  a specialised sex cell formed by meiosis
• Runners


  long shoots from plants, such as strawberries, that are used for asexual reproduction
• Meiosis


  cell division that forms daughter cells with half the number of chromosomes of the parent cell
• DNA


  nucleic acid molecules that contain genetic information and make up chromosomes
• Chromosomes


  long molecules found in the nucleus of all cells; made from DNA
• Gene


  part of a chromosome, made of DNA, which codes for a protein
• Genome


  all the genetic material found in an organism or a species
• Polymer


  a large molecule that is made up of many repeating units
• Nucleotide


  a molecule made of a phosphate group, a sugar and an organic base
• Collagen


  a protein found in connective tissue under the skin and in tendons
• Mutation


  a spontaneous change in the genetic material of a cell
• Allele

  an alternative form of a particular gene
• Genotype


  the combination of alleles an individual has for a particular gene, e.g. BB, Bb or bb
• Phenotype


  the physical expression of the genotype, i.e. the characteristic shown
• Dominant


  an allele that only needs to be present once in order to be expressed; represented by a capital letter
• Recessive


  an allele that will only be expressed if there are two present; represented by a lower case letter
• Homzygous


  when an individual carries two copies of the same allele for a gene, e.g. BB or bb
• Heterozygous


  when an individual carries two different alleles for a gene, e.g. Bb
• Monohybrid inheritance


  the pattern of inheritance shown when a characteristic is controlled by a single gene
• Punnett square


  a type of diagram used to work out the outcome of genetic crosses
• Polydactyly


  a genetic disorder caused by a dominant allele, where affected people have extra fingers or toes
• Cystic fibrosis


  a genetic condition that causes a build-up of mucus in the lungs
• Sex chromosomes


  the pair of chromosomes that determine the sex of organism
• Variation


  differences between individuals of the same species
• Evolution


  a gradual change in a group of organisms over a long period of time
• Natural selection


  the survival of individual organisms that are best adapted to their environment
• Fossils


  the remains of animals / plants preserved in rock
• Selective breeding


  the breeding process used by scientists and farmers to produce organisms that show the characteristics that are considered useful
• Genetic engineering


  the process of moving a gene from one organism to another
• Genetically modified (GM)


  organisms that have had specific areas of their genetic material changed using genetic engineering techniques
• Clone


  an offspring that is genetically identical to the parent organism
• Cuttings


  a method of asexually reproducing plants, used by gardeners, by planting small lengths of plant shoots
• Tissue culture


  a method of producing large numbers of plants asexually by growing small parts of plants in a nutrient jelly
• Surrogate


  a female that gestates and gives birth to an organism that has not been produced from one of her own egg cells
• Binomial system

  the method of naming organisms by using their genus and species
• Genus


  a group of closely related species
• Species


  a group of organisms that can reproduce with each other to produce fertile offspring
• Three-domain system


  a new classification system that divides organisms into three domains rather than five kingdoms
• Extinct


  describes a species that has died out