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NCEA Level 1 genetic
NCEA Level 1 genetics external
Term | Definition |
---|---|
Haploid | Half a set of chromosomes from only one parent (23 for humans) |
Diploid | A full set of chromosomes, half from the mother and half from the father (46 total, 23 from each parent) |
DNA Replication | The copying of genetic information that occurs before a cell divides to ensure that there are enough chromosomes in each daughter cell |
semi-conservative | A strand of each double helix is a parent and the other is a daughter |
Meiosis | Cell division that produces sex cells (gametes) |
Mitosis | A type of cell division that creates daughter cells genetically identical to each other and the parent |
Trait | A characteristic that determines someone's appearance or personality |
Gene | A segment of DNA that codes for a particular trait |
Allele | A particular version of a gene |
complementary base pairing | The rule that determines which bases can connect; A-T, C-G |
Homologous pairs | Pairs of chromosomes, one from each parent, that contain the same genes in the same loci. The alleles can be different |
Natural Selection | The increased survival of a organism with a particular trait due to changes in the environment and selection pressures |
Heterozygous | A genotype with two different alleles e.g Nn |
Homozygous | A genotype with two of the same alleles e.g NN |
Recessive | An allele that can only be expressed in the phenotype if there is no dominant allele to mask it |
Dominant | An allele that is expressed in the phenotype and masks any recessive allele. |
Genotype | The two alleles (one from each parent) that determine the phenotype of an organism |
Phenotype | The way alleles are expressed/The trait expressed |
Selection Pressures | Pressures such as lack of food that cause natural selection |
Variation | The difference in traits within a population |
Mutation | A permanent change in the sequence of DNA due to addition, deletion or substitution. They can be harmful, beneficial or neutral. |
Nucleuotide | the sequence that makes up DNA; a sugar, phosphate and a base |