BRAINCAKEGenetic Diversity
Revision notes for Genetic Diversity in AQA Biology (7401). Read the start of any lesson here, then sign in free for the whole lesson, the R.E.C.I.P.E. recall steps and the quiz.
- MutationsAny change in the quantity or base sequence of the DNA of an individual is called a mutation.
- Chromosome MutationsWhole chromosome mutations may occur in which the number or structure of chromosomes in the cell changes.
- Gene MutationsA change in the sequence of DNA is called a gene mutation.
- Substitution of BasesA mutation may arise where one nucleotide base is substituted for another.
- Deletion of BasesBase deletions almost always lead to loss of function of the protein as they involve a shift of the reading frame to the left They are therefore…
- Polyploidy and HybridsModern varieties of wheat are the result of hybridisation of different varieties of wheat over 10,000 years.
- MeiosisMeiosis is a type of nuclear division that halves the number of chromosomes during the formation of gametes and recombines genetic material from…
- The Process of MeiosisMeiosis involves two nuclear divisions: Meiosis I and Meiosis II.
- Genetic Recombination by Crossing OverEach pair of homologous chromosomes have the same genes in the same loci but do not neccessarily have the same alleles.
- Independent Segregation of ChromosomesDuring meiosis 1 the 23 homologous chromosomes line up on the equator side by side arranged in a random order.
- Independent Segregation of ChromatidsChromosome segregation is the process in eukaryotes by which two sister chromatids formed as a consequence of DNA replication, or paired homologous…
- Number of Chromosome CombinationsAsexual reproduction results in clones.
- Genetic DiversityGenetic diversity is the total number of alleles found in a population.
- Natural SelectionReproductively successful individuals are able to pass on their alleles to their offspring and the population will continue to have these alleles in…
- Peppered MothsThe peppered moth Biston betularia is a species of night-flying moth.
- Types of SelectionNatural selection is the process by which organisms that are better adapted to their environment survive, reproduce and pass on their alleles to the…
- Directional SelectionThe phenotype of an individual is an observable characteristic of that individual.
- Antibiotic ResistanceSome antibiotics such as penicillin are no longer effective against some bacteria.
- Stabilising SelectionStabilising selection is a type of natural selection that results in phenotypes around the mean being selected for and those phenotypes at the…