Whole chromosome mutations may occur in which the number or structure of chromosomes in the cell changes.A diploid cell should have two sets of chromosomes. Each of the pair of homologous chromosomes inherited is from each parent.If the cell has three or more sets of chromosomes, this is known as polyploidy. Polyploidy occurs mostly in plants.Meiosis is a type of cell division that occurs in the formation of gametes.Meiosis separates the homologous chromosomes so that each gamete has half the chromosome number so that the zygote has the correct number of chromosomes when fertilisation occurs and two gametes fuse.If during meiosis non-disjunction occurs, a pair of homologous chromosomes fail to separate and one gamete will have two copies of the chromosome and the other will have none.At fertilisation the zygote formed from these gametes will have either one or three copies of the chromosome.
Chromosome Mutations
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Specification: AQA Biology (7401), AS-level, 3.4.3 Genetic diversity can arise as a result of mutation or during. Topic: Genetic Diversity.
Key terms in this lesson
- homologous chromosomes
- A pair of chromosomes, one from each parent, that carry the same genes at the same loci but may carry different alleles.
- diploid
- Having two complete sets of chromosomes, one from each parent, as in a normal body cell.
- mutation
- A random change in the amount, arrangement or base sequence of the DNA of an organism.
- meiosis
- A type of nuclear division that produces four genetically different haploid daughter cells (gametes) from a diploid parent cell.
More in Genetic Diversity
- Mutations
- Gene Mutations
- Substitution of Bases
- Deletion of Bases
- Polyploidy and Hybrids
- Meiosis
- The Process of Meiosis
- Genetic Recombination by Crossing Over
All 19 lessons in Genetic Diversity · All AQA AS-level Biology topics