DP Syllabus details - 2016 version
Relevant elements
Core
3.1 Genes
3.5 Genetic modification and biotechnology
AHL
10.2 Inheritance
Key words
Core
3.1 Genes
- A gene is a heritable factor that consists of a length of DNA and influences a specific characteristic.
- A gene occupies a specific position on a chromosome.
- The various specific forms of a gene are alleles.
- New alleles are formed by mutation.
- The genome is the whole of the genetic information of an organism.
- Eukaryote chromosomes are linear DNA molecules associated with histone proteins.
- In a eukaryote species there are different chromosomes that carry different genes.
- Homologous chromosomes carry the same sequence of genes but not necessarily the same alleles of those genes.
- Diploid nuclei have pairs of homologous chromosomes.
- Haploid nuclei have one chromosome of each pair.
- Sex is determined by sex chromosomes and autosomes are chromosomes that do not determine sex.
- Gametes are haploid so contain only one allele of each gene.
- The two alleles of each gene separate into different haploid daughter nuclei during meiosis.
- Fusion of gametes results in diploid zygotes with two alleles of each gene that may be the same allele or different alleles.
- Dominant alleles mask the effects of recessive alleles but co-dominant alleles have joint effects.
- Many genetic diseases in humans are due to recessive alleles of autosomal genes, although some genetic diseases are due to dominant or co-dominant alleles.
- Some genetic diseases are sex-linked. The pattern of inheritance is different with sex-linked genes due to their location on sex chromosomes.
3.5 Genetic modification and biotechnology
- DNA profiling involves comparison of DNA.
- Clones are groups of genetically identical organisms, derived from a single original parent cell.
- Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells.
AHL
10.2 Inheritance
- Gene loci are said to be linked if on the same chromosome.
- Variation can be discrete or continuous.
- The phenotypes of polygenic characteristics tend to show continuous variation.
Key words
- Allele
- Autosome
- Co-dominance
- Dominant
- Gene
- Genotype
- Heterozygous
- Homozygous
- Intermediary/intermediate
- Incomplete dominance
- Locus
- Monohybrid cross
- Phenotype
- Punnett square
- Recessive
- Sex chromosome
- Seks linked