GENETICS AND INHERITANCE notes

Genetics is the study of heredity: how characteristics are passed on from parents to their offspring. Gregor Mendel is known as the "father" of genetics, because his experiments with pea plants…

Genetics uses a set of precise terms. This section covers chromatin and chromosomes, genes and alleles, dominant and recessive alleles, genotype and phenotype, homozygous and heterozygous, and the…

A monohybrid cross follows the inheritance of one characteristic. This section covers how to set out a genetic cross, Mendel's Principle of Segregation, the three types of dominance, and how to work…

A person's sex is determined by their sex chromosomes (gonosomes). This section covers the difference between autosomes and sex chromosomes, how to tell male and female karyotypes apart, and a…

Sex-linked inheritance is the inheritance of characteristics whose genes are on the sex chromosomes, usually the X chromosome. This section covers why males are affected more often, how to write…

The inheritance of the ABO blood groups is an example of multiple alleles. Three alleles, $I^A$, $I^B$ and $i$, combine to give four blood groups. Blood groups show both complete dominance and…

A dihybrid cross follows two different characteristics at the same time, such as the height of a plant and the colour of its flowers. It is explained by Mendel's Principle of Independent Assortment…

A pedigree diagram (genetic lineage) traces how a characteristic is inherited in a family over many generations. This section covers the symbols used, how to work out the genotypes of the people in…

A mutation is a sudden change in the genetic material of an organism. Mutations create new alleles, so they add to genetic variation. This section covers the effects of mutations, the difference…

Biotechnology uses living things to meet human needs. Genetic engineering is one part of biotechnology. This section covers three examples: stem cell research, genetically modified organisms (GMOs)…

Paternity testing finds out whether a man is the biological father of a child. Two methods are used: blood grouping and DNA profiles. Blood groups can show that a man is not the father, but cannot…

This section covers how mutations in mitochondrial DNA are used to trace female ancestry, and how the different parts of genetics link together. Mitochondrial DNA (mtDNA) is the small, circular DNA…