3.1 - Genes
Assessment statements
| DCS Topic Code | Statement | Guidance |
| 3.1.U1 | A gene is a heritable factor that consists of a length of DNA and influences a specific characteristic. | |
| 3.1.U2 | A gene occupies a specific position on a chromosome. | |
| 3.1.U3 | The various specific forms of a gene are alleles. | |
| 3.1.U4 | Alleles differ from each other by one or only a few bases. | |
| 3.1.U5 | New alleles are formed by mutation. | Deletions, insertions and frame shift mutations do not need to be included. |
| 3.1.U6 | The genome is the whole of the genetic information of an organism. | |
| 3.1.U7 | The entire base sequence of human genes was sequenced in the Human Genome Project. | |
| 3.1.A1 | The causes of sickle cell anemia, including a base substitution mutation, a change to the base sequence of mRNA transcribed from it and a change to the sequence of a polypeptide in hemoglobin. | Students should be able to recall one specific base substitution that causes glutamic acid to be substituted by valine as the sixth amino acid in the hemoglobin polypeptide. |
| 3.1.A2 | Comparison of the number of genes in humans with other species. | The number of genes in a species should not be referred to as genome size as this term is used for the total amount of DNA. At least one plant and one bacterium should be included in the comparison and at least one species with more genes and one with fewer genes than a human. |
| 3.1.S1 | Use of a database to determine differences in the base sequence of a gene in two species. | The Genbank® database can be used to search for DNA base sequences. The cytochrome C gene sequence is available for many different organisms and is of particular interest because of its use in reclassifying organisms into three domains. |
Video lessons
Class activities
Review materials
| 3.1 - Chromosomes |