Inheritance, Variation and Evolution

• Adult cell cloning


  A type of cloning that forms an embryo from an adult body cell
• Allele


  A version of a gene
• Amino acids


  Small molecules from which proteins are assembled
• Archaea


  Primitive bacteria existing in extreme environments
• Asexual reproduction


  A form of reproduction involving a single parent. Creates genetically identical offspring
• Binomial system


  The universal system of naming organisms using their genus and species
• Charles Darwin


  The scientist who developed the theory of evolution by natural selection
• Chromosome


  A long, coiled molecule of DNA that carries genetic information in the form of genes
• Classification


  The organisation of organisms into groups based on their characteristics and structure
• Coding DNA


  A sequence of DNA that codes for the production of a protein
• Complementary


  Describes how the chemical bases in DNA pair up with each other. A pairs with T and C pairs with G
• Cuttings


  The simplest method of cloning plants. A branch is cut from a parent plant and replanted in compost after removing the lower leaves
• Cystic fibrosis


  A cellular membrane disorder resulting from the presence of a recessive allele
• DNA


  A double-stranded polymer wound to form a double helix. Carries the genetic code
• Dominant


  Describes an allele that is always expressed. Represented by a capital letter
• Embryo screening


  A procedure used to determine the presence of faulty genes in an embryo produced by IVF. A few embryonic cells are removed and screened for defective alleles
• Embryo transplants


  The simplest method of animal cloning. Cells are removed from a developing embryo, split apart and grown in culture, before being transplanted into host mothers
• Evolution


  The gradual change in the inherited traits within a population over time. Occurs due to natural selection
• Evolutionary tree


  A diagram which illustrates the evolutionary relationships between organisms
• Extinction


  The death of all members of a species
• Family tree


  A chart used to show the inheritance of a condition in a family
• Fertilisation


  The fusion of the nucleus of male and female gametes. Restores the full chromosome number
• Fossil


  The remains of dead organisms found in rocks which are millions of years old
• Gametes


  Sex cells (sperm and egg cells) with half the usual number of chromosomes
• Meiosis


  The formation of four non-identical cells from one cell
• Gene


  A section of DNA that codes for a specific sequence of amino acids which undergo polymerisation to form a protein
• Mitosis


  The formation of two identical cells from one cell
• Genetic engineering


  The modification of the genome of an organism by the insertion of a desired gene from another organism, enabling the formation of organisms with beneficial characteristics
• Sexual reproduction


  1. Joining of male and female gametes, each containing genetic information from the mother or father

  2. Sperm and egg cells in animals

  3. Pollen and egg cells in flowering plants
• Genome


  The complete genetic material of an organism
• Gametes are formed by meiosis, as they are non identical
• Normal cell


  Has 46 chromosomes, two sets of 23 chromosomes (one from each parent)
• Gamete


  Has 23 chromosomes, fuses in fertilisation
• Genotype


  An organism's genetic composition. Describes all alleles
• The genetic information from each parent is mixed, producing variation in the offspring
• Asexual reproduction


  1. One parent with no gametes joining

  2. Happens using the process of mitosis, where two identical cells are formed from one cell

  3. No mixing of genetic information

  4. Leads to clones, which are genetically identical to each other and the parent
• GM crops


  Crops that have had their genomes modified by the insertion of a desired gene from another organism
• Organisms that reproduce asexually

  • Bacteria
  • Some plants
  • Some animals
• Heterozygous


  When someone has two different alleles of a gene e.g. Ff
• Meiosis


  1. Cell makes copies of its chromosomes

  2. Cell divides into two cells, each with half the amount of chromosomes

  3. Cell divides again producing four cells, each with a quarter the amount of chromosomes

  4. These cells are called gametes and they are all genetically different from each other