Definition of Cells

• DNA


  Chemical which carries the genetic code
• Alleles 


  Different forms of a particular gene
• Locus 


  Position of a gene on a chromosme
• Chromosome


  Structure in nucleus consisting of DNA and stone proteins
• Chromatid


  One of the two identical strands of a replicated chromosome
• Centromere


  Point at which two chromatids are attached in a chromosome and where spindle fibres attach
• Homologous Pair


  Pair of chromosomes with same genes (but not necessarily alleles) - one from each pair
• Haploid 


  Having a single set of chromosomes
• Gametes


  Haploid sex cells - sperm, egg or pollen, ova
• Meiosis


  Cell division giving rise to gametes
• Zygote

  Fertilised egg
• Fertilisation 


  Fusion of male and female gametes
• Diploid

  having a paired set of chromosomes
• Mitosis


  Cell division that gives rise to further diploid somatic cells
• Genotype


  The genetic constitution of an organism
• Phenotype


  the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment